the vital metal - copper development association...

Copper Development Association

Copper – The Vital Metal

CDA Publication 121, 1998

Copper – The Vital MetalCDA Publication 121

April 1998(This book replaces CDA Book 1 ‘Introduction to Copper’, 1988)

Members as at 1st January 1998ASARCO IncBoliden MKM LtdThomas Bolton LtdThe British Non-Ferrous Metals FederationChile Copper LtdGecaminesIMI plcInco Europe LtdNoranda Sales Corporation of Canada LtdRio Tinto London LtdSouthern Peru Copper Corporation

AcknowledgementsThis publication is financed by the members of Copper Development Association, European CopperInstitute, British Non-Ferrous Metals Federation and Aalco. CDA is glad to acknowledge with thanks theprovision of illustrations where noted.

Copper Development AssociationCopper Development Association is a non-trading organisation sponsored by the copper producers andfabricators to encourage the use of copper and copper alloys and to promote their correct and efficientapplication. Its services, which include the provision of technical advice and information, are available tothose interested in the utilisation of copper in all its aspects. The Association also provides a link betweenresearch and user industries and maintains close contact with other copper development associationsthroughout the world.

Website: www.cda.org.uk

Email: [email protected]

Copyright: All information in this document is the copyright of Copper Development Association

Disclaimer: Whilst this document has been prepared with care, Copper Development Association can giveno warranty regarding the contents and shall not be liable for any direct, indirect or consequential lossarising out of its use

http://www.cda.org.uk/

mailto:[email protected]

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ContentsContents........................................................................................................................................................3

Overview ......................................................................................................................................................5

Section 1 - Attributes and Applications .....................................................................................................7The Vital Modern Metal ................................................................................................................................7

Where would we be without copper? ........................................................................................................7Copper and copper alloys are essential for:...............................................................................................7Basic Properties of Coppers ....................................................................................................................10Applications of Copper and Copper Alloys ............................................................................................11Features and Benefits of Copper and Copper Alloys ..............................................................................16Typical Applications of Copper and Copper Alloys ...............................................................................16Application Examples .............................................................................................................................23

Section 2 – Availability..............................................................................................................................27Forms available............................................................................................................................................27

Wrought Forms .......................................................................................................................................28Castings ...................................................................................................................................................28

Buying copper and copper alloys.................................................................................................................31Manufacturers .........................................................................................................................................31Foundries.................................................................................................................................................32Stockists ..................................................................................................................................................32

Primary Copper Reserves ............................................................................................................................32Recycling Copper and Copper Alloys .........................................................................................................33Sustainability of Copper Supplies................................................................................................................35Section 3 - Copper in Health and Environment ......................................................................................36Copper and Health.......................................................................................................................................36Copper in the Environment..........................................................................................................................37Copper in Farming.......................................................................................................................................37Section 4 - Copper and its Alloys..............................................................................................................38Coppers........................................................................................................................................................38Copper alloys...............................................................................................................................................38

Copper and High Conductivity Copper Alloys........................................................................................39Bronzes and Phosphor Bronzes...............................................................................................................41Aluminium Bronzes (Copper-Aluminium Alloys) ..................................................................................42Brasses ....................................................................................................................................................42Gunmetals ...............................................................................................................................................45Nickel Silvers ..........................................................................................................................................45Copper-Nickel alloys...............................................................................................................................46Copper-Nickel-Silicon ............................................................................................................................47Copper- Beryllium Alloys .......................................................................................................................48Copper in other Metals............................................................................................................................48Copper Compounds.................................................................................................................................49

Section 5 - Making Components...............................................................................................................50Fabrication, Joining and Finishing...............................................................................................................50

Fabrication ..............................................................................................................................................50Hot Working ...........................................................................................................................................50Cold Working..........................................................................................................................................50Machining ...............................................................................................................................................51Joining.....................................................................................................................................................52Finishing..................................................................................................................................................52

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Section 6 - Mining and Extraction ........................................................................................................... 53Mining of ores and copper extraction.......................................................................................................... 53

Copper and Mineral Ores........................................................................................................................ 53Extraction................................................................................................................................................ 56

Section 7 - Standards, Compositions and Properties.............................................................................. 58A Variety of Standards ................................................................................................................................ 58The New BS EN Standards ......................................................................................................................... 58

Withdrawal of old standards ................................................................................................................... 58Numbers and Titles of Standards ............................................................................................................ 60Product Forms......................................................................................................................................... 60Material Designations ............................................................................................................................. 60Material Condition (Temper)Designations ............................................................................................. 61Castings................................................................................................................................................... 62Examples................................................................................................................................................. 62Typical Properties ................................................................................................................................... 62

Section 8 - Historical ................................................................................................................................. 63Copper through the ages.............................................................................................................................. 63

The Copper Age...................................................................................................................................... 63The Bronze age ....................................................................................................................................... 63Middle Ages and beyond ........................................................................................................................ 64

Brass............................................................................................................................................................ 65The Outlook for Copper .............................................................................................................................. 67Section 9 - Glossary, Reference and Further Information.................................................................... 70Glossary....................................................................................................................................................... 70References and Further information ............................................................................................................ 75

Internet .................................................................................................................................................... 75References............................................................................................................................................... 75

TablesTable 1 – Some copper and copper alloy attributes and applications.......................................................... 11Table 2 – Properties not considered ............................................................................................................ 14Table 3 – Descriptions of terms for wrought products ................................................................................ 28Table 4 – Minerals of Copper ..................................................................................................................... 54Table 5 - BS EN Standards for Copper and Copper Alloys ....................................................................... 59Table 6 - Cuprobraze vs brazed aluminium for radiators ............................................................................ 67Table 7 - Comparison of lifetime costs of typical roofing materials ........................................................... 69Table 8 – Abbreviations for chemical elements used as alloying additions or found as impurities............. 74

FiguresFigure 1 – Reasons for using copper ........................................................................................................... 16Figure 2 – Production routes for the manufacture of copper and brass castings, semi-finished and finished

products .............................................................................................................................................. 27Figure 3 – Recycling of copper ................................................................................................................... 34Figure 4 - Some of the effects of alloying additions on the properties of copper ........................................ 39Figure 5 – Comparison of machinabilities of common engineering metals................................................. 52Figure 6 – Production of copper in each continent...................................................................................... 55Figure 7 – Flowsheet for primary copper production .................................................................................. 57

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OverviewCopper and Copper AlloysIntroduction, Applications, Compositions and Properties

Section 1 - Attributes and Applications

Statue of LibertyThis well known statue has long lasting coppercladding which withstands the harsh marineenvironment of New York.(International Copper Association (ICA)

Section 2 - Availability

Stocks of free-machining brass rod.(Currie and Warner)

Section 3 - Copper in Health and EnvironmentHealthy pigthriving on a well balanced diet including sufficientcopper.(Vin Callcut)

Section 4 - Copper and its Alloys

CoinsSpecial copper alloys are used for the manufactureof most coins. The British £1 coin is basically an80/20 brass, the ‘silver’ coins are made fromcopper-nickel alloys and coinage bronze, with lowtin content, is used for low denomination coins.(Vin Callcut)

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Section 5 - Fabrication, Joining and Finishing

Copper-nickel water box for shipboard seawatercooling system.(James Robertson Ltd)

Section 6 - Mining and Extraction

Bingham Canyon copper mine(Vin Callcut)

Section 7 - Standards, Compositions and Properties

Section 8 - HistoricalPulley wheels from the ‘Mary Rose’

Section 9 Glossary, Index, References and Further Information

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Section 1 - Attributes and Applications

The Vital Modern Metal

Where would we be without copper?Copper and copper alloys meet the challenges of modern life in many ways. Often seen inplumbing systems and good quality roofing, they are also frequently unseen providing essentialservices inside equipment in houses, offices, commercial and industrial buildings. They areamongst the most necessary materials needed to provide the means to keep home, commerceand industry running.

Copper and copper alloys are essential for:• Power cables for home, commerce and industry

Submarine power cable (Pirelli plc)

This is one of the cables which links Britain and France across the English Channel, providingeach country with up to 2000MW of power from the other’s national supply.

• Message cables for telephones, fax machines, computer networks and cable television.

Modern Telephone (Vin Callcut)

Printed circuit boards, connectors, cables and coils all depend on high conductivity copper.

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• Winding wires for motors, transformers and other electromagnetic coils.

Transformers (GEC Transformers)

Transformers rely on copper to ensure low energy loss and many years without maintenance.

• Electrical contacts, terminals, connectors, plugs and sockets.

A variety of electrical connectors of good reliability and long service life made from rolledcopper alloy strip.

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• Plumbing tube for water supplies, central heating and fire safety sprinklers.

Globe Theatre sprinkler pipework

When space is limited, the ease with which copper tube can be joined is a distinct advantage.Good resistance to corrosion and immunity from degradation leads to a long, reliable,maintenance-free installation life ensuring fire safety in this thatched building.

• Pumps, tubes and fittings for marine, offshore and chemical engineering.

Marine self-priming pump (Gilbert Gilkes and Gordon Ltd)

This cross section reveals a variety of copper alloy castings within this component.

• Durable architectural items such as roofs, flashings, balustrades, handrails and functional,decorative items.

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Copper roof of the Usher Hall, Edinburgh (Vin Callcut)

• Essential trace element effects for the survival and growth of plant, animal and human life.

Maize (National Agricultural Research Station, McKechnie)

Maize samples grown with and without trace element, copper

Copper is probably the most versatile metal in common use.

Basic Properties of CoppersCopper possesses the highest conductivity of any of the commercial metals. Hold a piece ofcopper and it will feel cold, an indication of how quickly hand heat can be conducted away.Each time you press a switch to light a room, think of the high electrical conductivity of thecopper in the circuit that makes that simple operation possible. We take for granted theelectrical power and also the metal essential for its efficient arrival at our homes. Lightningconductors in copper are a familiar sight protecting tall buildings - 200 years ago a conductorwas attached to St Paul's Cathedral to lead lightning strikes safely to earth for that historiclandmark.

Each time you turn on a water tap, think of the copper tubing that delivers the water hygenicallywithin your home. Copper has excellent resistance to atmospheric and marine corrosion andgood corrosion resistance when used in many industrial process environments. Add otherelements to copper and we can get alloys that show good mechanical strength at low, ambientand elevated temperatures combined with high ductility and many other advantages.

The surface lustre and warm colour of copper and copper alloys makes them beautiful to look atand this means they find widespread use in architecture. The attractive green surface patinaenhances the appearance of copper roofing. Bronze sculpture may have exquisite toning orpatination. Jewellery and household ornaments and fittings gleam satisfyingly. If you look nofurther than your domestic surroundings, you will start to appreciate the huge role played bycopper in the production of useful, attractive items that enhance our lives.

The word copper is used in everyday speech in the expression "a copper bottomed guarantee" asan assurance of long-term reliability.

Could you imagine a world without copper?

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Applications of Copper and Copper AlloysThe following table shows some of the reasons why copper and copper alloys are vital to themajor types of application that benefit from combinations of the great many attributes available.

Table 1 – Some copper and copper alloy attributes and applications

Property Industry/Type of application (Picture Reference)

Aesthetics ArchitectureSculptureJewelleryClocksCutlery.

Reproduction carriage clockshowing many brass components.(Vin Callcut)

Bactericide Door furnitureAgricultural crop treatments.

Brass handrails - Royal Museumof Scotland (Vin Callcut)

Bearing/anti-galling propertiesBiofoulingresistance

General and heavy engineeringMetal workingAerospaceInternal combustion enginesBoat buildingOffshore oil and gas platforms.

Morecambe Bay gas platform.The steel legs of the platform areclad with 90/10 copper nickelalloy sheet to protect them fromcorrosion, abrasion and biofoulingcaused by the sea. (British Gas)

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Table 1 (continued)


Corrosionresistance

Plumbing tubes and fittingsRoofingGeneral and marine engineeringNaval vessel and boat buildingChemical engineeringIndustrial processes e.g. pickling, etching anddistilling,Domestic plumbingArchitectureDesalinationTextilesPaper making.

Brass searchligh tfor demandingmarine applications. Usually it islacquered black.(Francis Searchlights)

Ease offabrication

All of the above plus printing.

Electricalconductivity

Electrical engineeringCommunicationsResistance weldingElectronics.

Rotor for a heavy duty motor(Brush Electrical Machines Ltd)

Environmentalfriendliness

Vital for health of crops, animals and humans.

Healthy wheat alongside othersamples grown in copper-deficientsoils. (ICA)

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Table 1 (continued)


Fungicide AgriculturePreservation of food and wood.

Hardness Non-sparking toolsSprings.

Low temperatureproperties

CryogenicsLquid gas handling.

Mechanicalstrength/ductility

General engineering,Marine engineeringDefenceAerospace.

Non-magnetic InstrumentationGeological survey equipmentMine counter-measure vesselsOffshore drilling.

Non-sparking Mining toolsOxygen distribution.

Nickel-Aluminium Bronzechisels. These non-sparking toolsare used in hazardousenvironments such as in minesand the petrochemical industry.(Delta (Manganese Bronze) Ltd)

Resistance tohydrogenembrittlement

Offshore oil and gas (subsea),Boat/ship construction.

Strength Architectural fixingsEngineering components.

Springiness Electrical springs and contactsSafety pinsInstrument bellows.

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Table 1 (continued)


Thermalconductivity

Heat exchangersAutomotive radiatorsDies for plastics mouldingInternal combustion enginesMining.

New design of economic, high-efficiency light weight automotiveradiator(ICA)

Wear resistance General and heavy engineeringShipbuildingMoulds and dies.

Adjusting nut for a rolling millcast in high-tensile brass.(Westley Brothers plc)

Table 2 – Properties not considered

Coppers and copper alloys do not suffer from the following problems:Rusting Corrosion of steel is a continuous process giving a large volume of rust

that spalls off. This has a particularly bad effect underneath plating orwhen embedded in concrete.

Degradation by sunlight orultra-violet light

Many plastics suffer this phenomenon which results in loss ofproperties and appearance.

Attack by ozone Many plastics suffer this problem as well as the effect of ultra-violetlight.

Migration of plasticiser Many plastics suffer this problem.

Loss of properties at slightlyelevated temperatures

Many plastics lose strength rapidly above ambient temperatures.

Low temperatureembrittlement

Many plastics and other metals become brittle at low temperatures.

Rapid formation of a non-conducting oxide layer

Aluminium develops a film with an insulating layer that gives highelectrical resistance.

Requirement for expensivemoulding tools

Production processes for many plastics are expensive to set up.

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Features and Benefits of Copper and Copper AlloysThe unique combination of properties offered by copper and its alloys results in benefits whenthey are used in the many industries referred to. In many instances the ideal propertycombination required can be met only by a copper base material. There may be no betteralternative material choice - other material types such as iron base alloys (carbon, alloy andstainless steel), nickel base alloys, aluminium alloys and alloys based upon titanium do not, invery many cases, combine all the required properties or their cost may be too high.

Figure 1 shows the main results of a survey of the important properties required when copper isbeing selected for the manufacture of components.

Figure 1 – Reasons for using copper

Typical Applications of Copper and Copper Alloys

Domestic/HouseholdCopper and copper alloys fulfil a vast number of requirements in and around the home, beingboth economically functional and superbly decorative. Domestic applications include electricalcables and switches, electric motors for refrigerators, freezers, vacuum cleaners and other powertools, bathroom fittings, water tanks, pipes for drinking water and central heating, plumbingfittings, door furniture, ornaments, cutlery, clocks, cooking utensils, solar panels and solderingirons, to name but a few. Copper is the usual choice for domestic plumbing tube because it issafe, reliable, durable, easy to install and easy to join with either soldered copper or screw-tightened brass fittings.

Brass mixer taps - The economic costing of these taps belies a complex design withintricate internal passages for the hot and cold water (Armitage Shanks)

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Electrical Applications

Copper Cabling:

Copper has the highest electrical conductivity of all the common metals and is used incommercial and domestic buildings to provide the energy-efficient, safe, electrical distributionsystems upon which we all rely. The copper wire is strong enough for the purpose, yet fullyductile when bending to shape is needed. It does not react with modern insulation materials. Ithas a low contact resistance throughout its long life, giving safe terminations. It has a goodcreep strength, meaning that sound joints made in screwed terminals do not relax when theoperating temperature is reached.

Domestic:

The amount of high conductivity copper used in domestic buildings is on the increase to copewith the demands of modern living i.e. the increased number of electrical appliances in use, inparticular home personal computers. Older properties often have an insufficient number ofsocket outlets to cope with this high demand and even new homes have inadequate provision ifthe Fire Brigade’s recommendation of ‘One plug-One socket’ is to be followed and so avoid theneed for hazardous multi-socket adapters. If consumer demand and customer satisfaction are tobe taken into account, electrical specifications of new homes must be doubled to meet safely theneeds of the 21st century.

Commercial/industrial:

The continuous availability of a high quality, energy efficient power supply is essential to theeconomy of a business. Power failures can mean loss of data and customer confidence. Whendesigning electrical installations, either for new buildings or to upgrade existing buildings, it isvital that power quality, reliability, resilience, energy efficiency, earthing and future loadgrowth are taken into consideration.

Energy Efficiency: By selecting energy-efficient motors and larger sized copper conductors forindustrial applications or heating and ventilation systems in commercial buildings, considerablesavings in running costs can be made with relatively short payback periods. The reduction inpower consumed by energy-efficient installations including transformers, cables, busbars andmotors, leads to cost savings to users and reduced emissions to the environment from powerstations.

Power Quality: Modern electronic loads, such as motor controllers, and the switched modepower supplies used by personal computers, draw high levels of harmonic currents which do notcancel in the neutral of a three phase system. The common practice of using half-sized neutralsis unsound wherever harmonics are likely to be present, which nowadays means almost everycommercial and industrial installation, and a good case can be made for the use of double sizedneutrals. One easy solution is to use five-core copper power cable – three cores for the phasesand two for the neutral. Integrating the fifth core with the cable ensures good current sharingbetween the neutral cores.

Earthing: Where earthing must have a low impedance, there is a strong case for adding an extracopper conductor rather than relying on unreliable joints in steel armouring and conduit. Powersupplies for computers and the electronic controls for most modern equipment rely on an earthleakage current to stabilise the voltage. Any breakage of earthing circuits will now result indangerous voltages and must therefore be avoided at all costs.

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Electrical EngineeringHigh conductivity copper is used for electrical windings of all types of equipment to ensurereliability, compactness and energy efficiency. There are also many demanding applications thatrequire specialised high-strength high conductivity copper alloys. Other typical applicationsinclude contacts, switches, railway electrification, communications, motor end rings andcomputing.

Overhead wiring for railways (Vin Callcut)

Only copper has the high conductivity and wear resistance needed for 25kV high speed railwaytraction

Separate books are available on the topics of ‘Electrical Energy Efficiency’[1], ‘Busbars’[2],‘Earthing’[3] and ‘Electrical Design – A Good Practice Guide’[4].

General EngineeringCopper and copper alloys are tailored to meet almost any foreseeable need in engineeringindustries ranging from hi-tech miniaturised modern requirements to the needs of heavy industryfor strong, versatile materials with excellent corrosion resistance. Typical engineeringapplications include valves, pumps, heat exchangers, vessels, vehicle components such asradiators and valve guides, hydraulic tubing, bolting, mining wagon brakes and plasticsmoulding dies to name just a few.

Copper lined steel pressure vessel for heavy duty service (IMI Rycroft)

BearingsCopper alloys can be used to make many types of bearings since these need a specialcombination of properties.[5] Usually the alloy has a distributed hard phase that makes a goodlubricant set in a matrix of softer material that supports it and conducts heat from the bearingsurface. Hard alloys such as phosphor bronze and aluminium bronze are used against hardenedsteel shafts. Softer materials such as leaded bronzes are used when the shafts are conventionallow alloy steel.

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Precision brass bearing used in aircraft generators (MPB Corporation)

Marine EnvironmentsThe excellent corrosion resistance in marine environments possessed by specially formulatedcopper alloys is combined with resistance to biofouling which confers a very useful advantagefor desalination piping, pumps, valves, naval vessel components, boat propellers, shafts andrudders, yacht fittings, boat hulls, fish farming cages, Offshore oil and gas equipment made incopper alloys includes pumps, splash zone and subsea bolting, drill collars, piping systems,valves, deluge system sprinklers and anti-fouling collars.

Aluminium bronze propeller (Stone Manganese Marine)

Aluminium bronze is the standard material to meet requirements for high strength and corrosionresistance.

Building and ConstructionRoofing: Copper has been used as a roofing material from as early as 27 BC. When thePantheon in Rome was built it was roofed with copper. The suitability of the metal as a roofingmaterial has been proved over the succeeding centuries. The essential attributes of good long-life roofing material include an attractive appearance, high corrosion resistance, minimummaintenance requirement and good economy[6]. Copper combines all of these qualities betterthan any other weathering material and is therefore an excellent choice for a roof covering.

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Copper roof on the Commonwealth Institute, London, now patinated to an attractive green colour.

Putney Bridge Restaurant

New Standard Life Building, Edinburgh

Architecture: As well as being ideal for roofing, copper is also used for wall cladding and isexcellent as a flashing material. Besides the corrosion resistance and attractive appearancecopper also acts as an algaecide and fungicide, keeping growths such as moss and lichens at aminimum. Copper and its alloys are used for many decorative features such as window frames,weather vanes, urns, finials, balustrades and shop fronts.

Copper alloys, like brass, are also ideal for interior uses[7]. They make durable, good-lookinghandrails, stanchions, decorative panels and are suitable for heavy duty use in lift door tracks,hinges, locks and other door furniture. As door furniture, brass has the advantage of being abactericide, reducing the transmission of infections. It is therefore popular for use in hospitalsand other public buildings. Note, though, that this benefit is mostly lost if the components arelacquered. Nevertheless, they still look good and do not need such frequent polishing.

For statues, bronze has been the accepted standard material for centuries. Cast with expertprecision, then assembled, finished, patinated and waxed with great craftsmanship, they fittinglycommemorate many fine achievements.

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Bell founder and his bell - This intricate bronze casting represents the bellfounder’s art.(R Bracegirdle, courtesy John Taylor Bellfounders Ltd and the Bellfoundry Museum, Loughborough)

Structural Components: For many years phosphor bronze securing bolts and anchor plates werestandard for masonry fixings for heavy wall cladding. The application illustrates the strengthand long term reliability of copper alloys. Correct choice of alloy and diameter means minimumsensitivity to fatigue, crevice corrosion and stress corrosion. More advanced applicationsinclude bearings for bridges and similar structures that must allow for expansion. Aluminiumbronzes have been used successfully for many years to take the entire weight of the reinforcedconcrete roof structure at the Physics and Mathematics Building at the University of Aberdeen.The cast aluminium bronze feet are seated in sockets made of similar material deep set inconcrete and continue to pass inspection with no problems reported.

Aluminium bronze ball and socket joints support the immense weight of the concrete arches of Aberdeen University Science Building (Vin Callcut)

Copper Tube and Fittings: The properties of copper tube and fittings make them the idealchoice for pipework systems within buildings. Copper is the preferred material chosen forplumbing, heating and natural gas and fire sprinkler system pipework. Copper tube can bequickly and neatly jointed by soldering to form leak proof joints. When space is limited, theease with which copper tube can be joined is a distinct advantage, as is the relationship betweenthe outside diameter and the bore of the tube. The strength of copper allows the wall thicknessto be kept small, so that, for the same bore size, the outside diameter of a copper tube will besmaller than a tube of other, weaker, materials. The lightness of copper tube, compared to other

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metals, and its rigidity, makes it easier to install in confined spaces with few hangers andsupports for straight pipe runs. Good resistance to corrosion and immunity from degradationleads to a long, reliable, maintenance-free installation life.

Globe Theatre roof drenchers, part of the precautions against fire

Automotive: Copper represents 6 to 9% by weight of the content of a typical car, being essentialfor the full wiring harness, for the windings of the alternator, the starter motor and other motors,for actuators. Copper alloys are needed for conductive spring clips, terminals and connectors.Copper alloys can be used for bearings, gears and valve guides. Small machined componentscan be made cheaper in brass than in steel and do not need such critical protection againstcorrosion.

Brake pipes in a Volvo car made of copper-nickel for long servicein the corrosive environments caused by salt on roads (Vin Callcut)

Defence: Defence requirements are for components made to meet the most demanding serviceneeds. These involve fitness for purpose when made and many years of totally reliable life. Thishas meant the continuous evolution of materials made to the most rigorous demands onmanufacturing techniques and quality control. Many new alloys have been developed andmanufacturing procedures perfected for materials to meet these needs that also have madesignificant advances possible in non-defence applications.

Original defence applications were mainly for bronzes for spears, swords and cannon.

Later came the use of copper sheet cladding on ships, to prevent the attack of the Toredo worm,that had the added advantage of preventing the drag caused by marine biofouling. Brass orbronze was also used for pulley blocks such as those recovered from the wreck of 'The MaryRose'.

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Model of ship showing the copper cladding that was used to protect the timbers from attack by enemiessuch as the Toredo worm and the hampering growth of marine biofouling (Tony Rayne)

Modern requirements are for high-performance, high pressure valves, pump bodies and shafts,hydraulic tubing, bolting, heat exchangers, flexible pipe systems, flanges, hose couplings, sonarequipment, bow plane control gear, steering mechanism and turret gears in tanks, aircraftundercarriage components and periscopes.

Most of the vital equipment developed has similar applications in industry. Materials originallydeveloped for naval condenser tubes are now produced in large tonnages for other marinesystems, desalination plant and the chemical industry. The new use of corrosion-resistant 90/10copper-nickel for automotive brakelines is another good example of technology transfer.

The technology of alloying, casting and fabricating the high-strength, corrosion resistantaluminium bronzes was developed mainly for defence requirements. It now applies especially tothe pumps, valves, fittings and pipelines used for marine seawater systems in all types of shipsand offshore platforms.

Application ExamplesAs examples, the following brief case studies give an indication of the wide variety ofapplications where there is a need for a property combination and cost-effectiveness foundideally in copper base materials:

Architecture

New office building for the Houses of Parliament with aluminium bronze columns and roofing structurefor durability, longevity and good appearance

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For the new office building for the Houses of Parliament in Westminster, aluminium bronze waschosen for structural roof beams. High strength combined with atmospheric corrosion resistanceand outstanding aesthetic appeal mean that maintenance free structures can be produced whichlook attractive. The hollow columns are also used to funnel rainwater unobtrusively to thedownpipes, while the chimneys are a vital part of the drafting for the air conditioning system.

Offshore oil and gas

Marinel fasteners with high strength for underwater petrochemical installations (Langley Alloys)

High strength copper-nickel chosen to give the required strength and seawater corrosionresistance combined with good galling/seizure resistance, hydrogen embrittlement resistanceand galvanic compatibility with adjacent stainless steel. This means that, even with high stressesinvolved, a "fit and forget" material selection solution has been found for this safety criticalapplication and that trouble free continuous oil/gas production can proceed for many years.

Automotive

Electric motor under car bonnet Copper wiring is essential to all motors, actuatorsand harnesses in the modern car. (Vin Callcut)

High conductivity copper for wiring harnesses, windings for alternators, motors and actuators,alloys for terminals, fitments and conducting clips, copper-nickel tubing for long-life brakelines, brasses cheaper than steel for hydraulic fittings, alloys for bearings, gears and valveguides.

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Aerospace

High strength copper alloy control rod bearing for an Airbus (Delta (Manganese Bronze) Ltd)

Copper-nickel-silicon material provides high strength, corrosion resistance, good bearingproperties, high fatigue resistance and good thermal conductivity and gives the benefit in serviceof an efficient, reliable and therefore safe bearing construction material.

Copper conductors form the vital links for power and communications. High performancecopper alloys with a good strength-to-weight ratio, bearing strength and corrosion resistance areused for undercarriage components, aeroengine bearings, various bushing, head-up display unitcomponents and helicopter motor spindles.

Saab fighter plane nose wheel strut with nickel-aluminium bronze bushings (Delta (Manganese Bronze) Ltd)

Electrical engineering

Copper windings of a modern, efficient electric motor.

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High conductivity copper is used at constant operating temperatures up to 150°C under loadwith low contact resistance. The centrifugal forces developed at the high speeds at whichelectrical machines rotate mean that very high stresses have to be allowed for. This is providedby a material which not only gives the benefit of an efficient motor winding but is also readilydrawn down in size to the wire or section needed. For short term uses such as spot and seamwelding electrodes, operating temperatures can be much higher.

Boatbuilding and offshore

#

Aluminium bronze ship propeller and copper-nickel clad rudder (ICA)

The need for marine corrosion and biofouling resistance leads to the choice of copper-nickel.This confers the benefit of negligible material loss by corrosion attack and, in the case of avessel hull, means that costly dry-docking for removal of biofouling is not needed. Higherspeeds can consistently be achieved due to less resistance to movement through the water. Itmay also be possible to design with smaller engines, reduced size of fuel bunkers and increasedcargo space. On offshore structures the use of copper-nickel clad steel means that it is possibleto design with smaller corrosion factors and reduce allowances for the stresses caused whenstrong currents drag on extensive biofouling.

Semiconductors

Scanning Electron Micrograph of newtechnology microchip showing the metalinterconnects in a chip with six copper layersand one local interconnection layer of tungsten.At the bottom of the photo you can see amagnification of the silicon transistor 1/1000ththe size of a human hair. (Tom Way and IBMCorporation)

Isometric of the CMOS 7S technology processshowing the new copper interconnections abovethe tungsten local interconnect. Magnification x

50,000 (Fred Perkins and IBM Corporation)

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Copper is used in a new generation of higher performance, high function microprocessors thatare smaller, lighter and require less power. The use of copper in the new microchips gives aperformance gain of 30% and permits miniaturisation of current channel lengths to 0.12microns, allowing up to 200 million transistors to be packed in to a single chip.

In these examples a number of different copper base materials are utilised in a variety ofcompositions and forms, it is important to recognise the benefit provided by the ease ofmachining, forming and joining of copper alloys in terms of lower cost products/components,produced on time.

In addition to the global variety of applications for copper and its alloys, copper as an alloyingcontent markedly improves other materials. This includes improvements to the strength ofaluminium alloys, the corrosion resistance of the weldable structural steels and the corrosionresistance and strength of duplex (two phase) stainless steels and high nickel super-austeniticsteels.

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Section 2 – Availability

Forms availableCopper alloys are readily available in a very wide range of cast and wrought (hot- or cold-worked) forms. It is an advantage that many forms are easily obtainable – this means that ahuge range of small to large shaped components can be produced with a minimum of fabricationtime and cost [8].

Fabrication involves processes such as hot forging, cold working, bending and machining. Thesequence in which these operations may be carried out is shown in Figure 2.

Figure 2 – Production routes for the manufacture of copper and brass castings, semi-finished and finishedproducts

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'Near net shape forming' is a term applied to production processes that quickly and easily makeshapes which can be readily finished by a minimum of further processing to give the finalcomponent shape. The choice between a cast or wrought starting shape will depend on morethan just the final component required.

For example:

• Is the component hollow or does it have some internal shape?

• What precise property combination is needed?

• Ηow is it to be made?

• Can the chosen alloy composition be produced by a particular fabrication method? (Theproperties of the cast and wrought versions of the same alloy type, where available, will notbe identical.)

Wrought FormsMany wrought forms can be obtained – this allows the most economic to be selected relative tothe final component shape. The following list gives an idea of some of the supply forms, whichmay be considered during the component design process.

Table 3 – Descriptions of terms for wrought products

Bar A wrought product of rectangular section along its whole length, supplied instraight lengths.

Foil A rolled product with thickness of 0.10mm or less, supplied flat or in coil.Forgings A shape produced by hammering between open or closed dies, normally when hot.Plate A flat rolled flat product greater than 10mm in thickness.Rod A solid wrought form of uniform cross section (circle, square or regular polygon)

along its whole length, supplied in straight lengths.Profile A solid wrought form of irregular cross section produced as extrusions from

specially shaped dies.Round tube A hollow form, circular in cross section, supplied in straight lengths or coils.Sheet A flat rolled product with uniform thickness from 0.2 up to and including 10mm.Strip Produced by rolling with uniform thickness from 0.1 to 5.0 mm supplied in a coil.

The thickness does not exceed one tenth of the width.Wire A solid product supplied in coil form or on spools or reels.

Castings(There is a comprehensive CDA book on this topic ‘Copper and Copper Alloy Castings –Properties and Applications’.)

Casting processes using refractory moulds

Sand casting

Most castings are produced by this technique. Moulds are made from sand bonded with clays orsilicates or various organic mixes. Cores to define the internal shape of hollow castings are also

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of sand – they are accurately located in the hollow cavity made inside the sand mould – thecavity having been made by a pattern, usually constructed from wood.

Brass breather valve sand casting cast as one piece with simple fettling required andminimal scrap, production costs are kept low (Enfield Foundry Company Ltd)

Shell moulding

Gear for locomotive braking system cast in aluminium bronze ensuring long life in aggressive operating conditions (British Rail)

Investment (precision) casting – investment casting by the ‘lost wax’ process has been used forcenturies to produce statues. The process uses a pattern of wax, which is coated with severallayers of refractory slurry to build up a shell. Finally, the wax is melted out and a cavityremains into which is poured the molten metal.

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Clarinet keys precision cast to a near-net shape that needs little finishingbeyond fettling, polishing and decorative plating (Boosey and Hawkes Ltd)

Casting by permanent mould processesPermanent moulds (usually of metal) are often used as an economic way of producing a highvolume of castings. After the molten metal has been poured in to them and allowed to solidify,the moulds are opened so that the component can be removed and then closed again and madeready for the next casting.

Gravity diecasting

In this process the metal moulds or dies (normally in steel) are made in two halves which opento allow removal of the casting.

Sectioned gravity diecast brass tap showing structure of hollow core (Armitage Shanks Ltd)

Pressure diecasting

Molten metal is injected into steel dies under high pressure. Multi-cavity dies are employed togive high production rates and reduce costs.

Pressure diecast brass components with close tolerances and thin walls for a variety of applications (J W Singer Ltd)

Centrifugal casting

This process involves the pouring of molten metal into a steel mould or die rotating at fairlyhigh speed.

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Spuncast aluminium bronze pipes used to suspend seawater pumpsbelow lowest water level on offshore oil platforms (Spunalloys)

Continuous casting

Used for the production of rods, sections and hollows, this technique utilises a graphite die ofrequired shape into which metal pours from a furnace. The metal solidifies as it passes throughthe water-cooled die.

A selection of the complex sections which can be continuously cast tovery accurate dimensional tolerances (Delta Enfield Metals Ltd)

Buying copper and copper alloysCopper and copper alloy products can be bought from foundries, manufacturers or stockists asappropriate. The CDA Information Service can discuss requirements and give the names ofcontacts known to be able to supply.

Costs of fabricated materials may be quoted per unit length but are more likely to be sold byweight. As with castings, the price reflects the cost of the metal plus production and handlingcosts. The price of the metal does vary according to supply and demand but can be agreed at thetime an order is placed.

ManufacturersMedium and large sized orders for semi-finished raw material are best obtained directly fromfabricators, especially if the requirement is ongoing. This applies particularly where hotstampings are needed or if extrusions need to be made through specially shaped dies. Needs forcompositions, properties and surface finishes to suit particular applications, can be discussedand special requirements can be agreed for economic quantities.

Over recent years, manufacturers have made large investments to improve production facilitiesto meet requirements for reproducible close tolerances on dimensions, composition andproperties at minimum production costs. Economic order sizes for special orders are now

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significant. Delivery lead times may be typically about eight weeks but are subject to variationwith mill loading and any die production requirements. Some fabricators have an associatedstockholding facility.

FoundriesWhen required cast to shape, items will be procured from a foundry. The components will bemade from patterns prepared from drawings but with allowances made for feeding the liquidmetal in to the casting and for reduction in size due to solidification shrinkage. The priceagreed will depend on the cost of the alloy plus the costs appropriate to the casting method,pattern costs and the amount of finish machining and testing that may be required. Familiaritywith casting techniques is useful when designing components to be produced to good qualitystandards at minimum cost. Discussions with foundry personnel will be found invaluable at thisstage.

StockistsSmall and medium size quantities of fabricated copper and copper alloys are best bought from astockist. Material to most common specifications and sizes is frequently available from stockfor delivery within 24 to 48 hours and can be programmed for regular supply of small quantities.This ‘JIT’ (Just in Time) approach to material management has brought considerable benefits tomanufacturing industry. It means that working capital and storage space are not tied up in rawmaterial stocks. The supply source chosen must be knowledgeable, reliable, flexible and holdlarge stocks of a wide product range, generally of a greater range than can be supplied by anyone manufacturer.

From their stock lists it is possible to select the materials most appropriate or to discussrequirements with trained staff. Many stockists can cut to special lengths or sizes and arrangefor surface finishing and protective coatings.

London Metal ExchangeBesides being essential for the production of components, copper is also a traded commodity.Daily dealings on the London Metal Exchange fix the price for that day. Deals can also bemade to buy copper at a fixed price some time in the future and prices for three months aheadare commonly quoted to enable production costs to be stabilised. According to marketconditions, prices for future delivery may be higher or lower than the spot price on the day.

Many 25 tonne lots are traded each day as buyers meet their needs and sellers supply them.Most copper producers supply their copper direct to the manufacturers, priced at a contractedrate based on current LME values. Many good newspapers quote recent LME prices in their‘commodities’ news section.

Primary Copper ReservesThe estimation of available resources of copper cannot be an exact science. There are:

• Deposits found, evaluated and being worked.

• Deposits known to be available but not yet worked.

• Deposits known to be available but not yet economic

• Deposits yet to be found.

• Deposits on the seabed still being built up by precipitation from the sea.

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The usability of a deposit depends of course on the average copper content to be economic, andalso on the availability of transport and fuel. Proven reserves workable with present techniquesare about 310 million tons [10}, more than sufficient for 50 years. Present estimates are thatthere are over 2,120 million tons of copper likely to be available in other deposits, sufficient forover 250 years at current extraction rates [11].

More reserves remain to be found as more land is geologically explored. As extractiontechniques on land improve, the minimum economic copper content is reduced, making evenmore available from known resources. The extraction of copper from seabed deposits ofmodules is feasible, but techniques for raising the ore to the surface economically are still beingdeveloped. Recycling has always been economic. With increased emphasis on recovering,separating and re-using all materials, it is making an increasing contribution to supplies.

Recycling Copper and Copper AlloysThe entire economy of the copper and copper alloy industry is dependent on the economicrecycling of any surplus products. Process scrap arising from manufacturing processes is savedand sold for recycling to keep down the cost of the product. On average, 40% of all productionis from recycled metal. For some products the proportion is over 90%.

Copper and copper alloy scrap can be recycled relatively cheaply, with low power consumption,and with minimal losses. The recycling of copper and its alloys plays an important part in theeconomics of production and has been undertaken since the copper industry began. The cost ofthe raw material can be significantly reduced if an alloy can be made with recycled material. Ifthe scrap is pure copper and has not been contaminated by other metals, a high quality productcan be made from it. Similarly, if scrap is kept segregated and consists only of one alloycomposition it is easier to remelt to a good quality product conforming to standard.

When costing the production of a component, allowance can be made for recovery of moneythrough the reclamation and sale of clean process scrap. There are many forms and sources ofscrap, which may be utilised. Components that are beyond their useful life are a valuable source.In addition, scrap from manufacturing processes such as trimming, fettling (of castings) andmachining is most useful.

Good quality high conductivity copper scrap, for example, generated during power cabledrawing, can be recycled by simple remelting. Where contamination has occurred, it is normallyremelted and cast to anode shape so that it can be electrolytically refined. In cases where scrapis contaminated with certain elements such as tin and lead - as a result of being tinned orsoldered - it is more economic to take advantage of this contamination to produce a copper alloy(gunmetal or bronze) which needs these additions as alloying elements.

Where copper and copper alloy scrap is very contaminated and unsuitable for melting, it can berecycled by other means to recover the copper either as the metal or to give some of the manycopper compounds essential for use in industry and agriculture.

The recycling of brass by melting is a basic essential of the industry. All of the feedstock for themanufacture of billets for extrusion of rod comes from scrap, including

• process scrap such as offcuts from within the mill,

• process scrap such as turnings from machine shops

• scrap from brass components being recycled after a useful life.

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Figure 3 – Recycling of copper

This summarises, by decreasing copper content, and hence conductivity, the types of scrap that can ariseand the products most efficiently made from them. The material being recycled is shown on top of the

diagonal; the products that can be made from it underneath. Products with higher alloy content than thescrap are economically made. Products of high purity can only be made economically from primary

copper or high grade scrap.

For thousands of years, copper and copper alloys have been recycled. This has been a normaleconomic practice, even if the loss of some works of art is regretted by some. One of thewonders of the Old World, the Colossus of Rhodes, an enormous statue at the entrance toRhodes Harbour, was said to have been made of copper. No trace of it remains since it wasrecycled to make useful artefacts.

In the Middle Ages it was common that after a war the bronze cannon were melted down tomake more useful items. In times of war even church bells were used to produce cannon.

Scrap copper baled for recycling (Ampthill Metal Company Ltd)

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Sustainability of Copper SuppliesCopper can be regarded as one of the few metals that is fully sustainable. As described above, itis fully economic to recycle copper and its alloys. As an essential trace element for plant, animaland human life it also cycles through the entire food chain. In addition, copper that is leachedout of agricultural or other land flows with the water down the rivers and in to the sea. Here iteventually precipitates out in areas where the water chemistry is suitable. High concentrationsof mineral-rich nodules are found in these areas. Deposits of this type are thought to haveformed the high copper content found in some of the ore bodies now being worked after earthmovements have forced them well above sea level. While it is not yet economic to extractcopper from undersea nodules, that time will not be long coming.

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Section 3 - Copper in Health and Environment

Copper and HealthCopper as a trace element is essential to the health of plants, animals and humans[12] . Toolittle copper can cause deficiency diseases. We absorb copper into our bodies throughnutritional intake i.e. meat, fish, cereals and vegetables.[13]

Copper is an effective biocide which results in it controlling organisms such as legionella inwater circulating systems and in it restricting marine biofouling when used, for example, ascopper-nickel alloy cladding on boat and ship's hulls and offshore structures. Coppercompounds are used for their beneficial fungicidal effects on plants; for example, cupriccarbonate is employed in copper-based fungicide.

Fungicides containing copper are essential for the production of healthy grapes (Vin Callcut)

The use of brass or copper instead of other materials for doorknobs and fingerplates in hospitalshelps to reduce the spread of nosocomal infections such as the common cold. Copper braceletsare worn by many people and are said to improve the health of the wearer; for example,absorption through the skin can help to relieve arthritic discomfort.

We cannot live without Copper

Copper is one of a relatively small group of metallic elements that are essential to human health.These elements, along with amino and fatty acids as well as vitamins, are required for normalmetabolic processes. Copper is a constituent of many enzymes involved in numerous bodyfunctions and is a constituent of hair and of elastic tissue contained in skin, bone and other bodyorgans[14]. There are a number of important copper-containing proteins and enzymes, some ofwhich are essential for the proper utilisation of iron. Dietary deficiency is rare, but does occur incertain acquired or hereditary disorders that impair intestinal absorption. Several abnormalitieshave been observed in copper-deficient animals, including anaemia, skeletal defects anddegeneration of the nervous system.

The enzymes act as catalysts to help many body functions. Amongst others, this is especiallyimportant for the health of heart and arteries. However, as the body cannot synthesize copper,regular amounts of copper must be included in a normal diet.

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Everyone needs to know about the benefit to health of awell balanced diet including copper as a trace element (Vin Callcut)

How much copper?

The adult body contains between 1.4 and 2.1mg of copper per kilogram of body weight. Tomaintain this concentration, it is recommended that the daily intake of copper should be0.4mg/day for children aged 1-3 years and 1.2 mg/day for adults.

Copper-rich foods include most nuts, seeds, chickpeas, liver and oysters. Natural foods such ascereals, meat and fish generally contain sufficient copper to provide up to 50% of the requireddaily intake. The copper content of supply water is usually measurable but insufficient in itsown right to provide the balance of the normal daily intake.

It is rare that problems are found with too much copper in a system. Most copper salts in excessare powerful emetics and overdoses are usually rejected. Only very occasionally, as with thevery rare Wilson’s Disease, does a body retain excessive copper.

Copper in the EnvironmentBeing a trace element essential for the health of plants, animals and humans, the distribution andconcentration of copper in the environment is important. Typically there is 1 µg/l of copper infresh water supplies. The optimal concentration in living organisms is around 1,000 µg/l and themetabolism normally adjusts the concentration to be within optimum range.

In the ground, copper is normally present in compounds that are not easily soluble in water.Only a limited percentage, normally less than 1%, is available in soluble form forbioavailability. This can be taken up by the roots of plants as required and is then recycled asleaves and wood decay, concentrating in the top 100mm or so of the soil. Additionally oralternatively, copper is replenished when organic manure is spread. Intensive farming withoutthis recycling can lead to copper deficiency that has to be made up when fertiliser is applied.

Copper in FarmingBesides being essential for the health of plants, animals and humans, copper and coppercompounds can be used in fungicides, biocides, bacteriastats, molluscicides, insecticides andpreservatives[15]. Copper is a vital ingredient of Bordeaux mixture, Burgundy mixture,Cheshunt compound and Paris Green. Nearly three hundred plant diseases amenable to controlby copper fungicides are listed in ‘Uses of Copper Compounds’[16].

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Section 4 - Copper and its Alloys

CoppersThere is a wide range of shapes/forms available in copper base materials. There is also a verylarge variety in generic types of copper alloy and chemical compositions available.

This provides many possible property combinations, often unique to copper base alloys, makingthe alloys suitable for applications in virtually every area of human activity.

Coppers and copper alloys are produced to conform to a wide variety of national andinternational specifications prepared to suit differing conditions and requirements. Allmanufacturers and good stockists are approved to supply material, if required, under the qualityassurance requirements of BS EN ISO 9000 series.

The starting point for the production of coppers and copper alloys in the range of shapesavailable is the casting of molten copper into one of five standard 'refinery shapes'. Modernproduction processes are usually continuous and the cast product is either cut to length by flyingsaws or passed directly towards mills for fabrication. The shapes - ingots, ingot bars, billets,cakes and cathodes - are appropriate to further processing (often through intermediate forms) tospecific final shapes/forms. In the case of copper alloys the shapes for further processing arecast from melted copper ingot with the addition of appropriate master alloys to provide theelements needed for the alloy type.

The majority of copper used for electrical purposes is High Conductivity Copper made frommaterial that has originally been electrolytically refined to high purity before being melted andcast without the addition of alloying elements or impurities. A little oxygen is all that is presentto ensure that conductivity remains high, now around 101.5% compared with the standard set bythe IEC in 1913.

For applications where good welding and brazing properties are more important thanconductivity, phosphorus-deoxidised copper is used. This is the standard type of copper used fortubing and for water cylinders and pressure vessels. Further details of these materials follow.

Other types of copper are described in the CDA book No 122 'High Conductivity Coppers forElectrical Engineering'.

Copper alloysCopper forms alloys more freely than most metals, and with a wide range of alloying elements.Zinc, tin, nickel and aluminium are the most common alloying additions and produce thefollowing alloy types -

COPPER with

• tin makes Bronze

• tin and phosphorus makes Phosphor bronze

• aluminium makes Aluminium bronze

• zinc makes Brass

• tin and zinc makes Gunmetal

• nickel makes Copper-nickel

• nickel and zinc make Nickel silver

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Figure 4 - Some of the effects of alloying additions on the properties of copper

Alloys based upon copper are classified as non-ferrous (ferrous materials are iron-base, forexample, steel). Useful alloying additions of other elements to these alloys in small amounts caninclude aluminium, arsenic, beryllium, cadmium, chromium, cobalt, iron, lead, manganese,nickel, niobium, oxygen, phosphorus, silicon, silver, sulphur, tellurium, tin, zinc and zirconium.All are found in standard coppers and copper alloys and are added as required in small amountsto give specific properties suitable for many demanding applications.

Some alloying elements have been in use with copper since early times. Initially there may havebeen no full understanding of what type of copper alloy had been produced and why itpossessed its particular characteristics. However, the development of metallurgical andcorrosion science knowledge has provided many answers and also led to the use of otheralloying elements with copper. Further development of copper alloys is still taking place andwill continue into the 21st century to meet modern application challenges.

Copper and High Conductivity Copper AlloysA third to one half of all copper produced is used in some form for applications in electricalengineering and the supply of domestic electricity. The reason is simple - among the readilyavailable engineering materials copper is unique. Not only is it extremely ductile and capable ofbeing formed into a wide range of products with ease, but it has almost uniquely high values ofthermal and electrical conductivity, exceeded only by silver. The high electrical conductivity isespecially important for the efficient transmission and utilisation of electrical energy, andcopper is therefore the principal material for busbars[17], electric cable and windings[18].

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High conductivity copper busbars for carrying heavy electric currents (Vin Callcut)

These are the popular types of copper, each suitable for a variety of end uses.

• High conductivity (HC) electrolytically refined copper (sometimes known as tough pitchcopper or 'electro'), with a nominal conductivity of 100% IACS (International AnnealedCopper Standard), is used for most electrical applications such as busbars, cables andwindings. High conductivity copper is very readily worked hot and cold. It has excellentductility which means that it can be easily drawn to fine wire sizes and it is available in allfabricated forms.

• Deoxidised copper (usually deoxidised with phosphorus - or boron in the case of castings)is a material that can readily be brazed or welded without fear of embrittlement. It may beknown colloquially as 'Deox' and is used for the manufacture of tubing for fresh water andfor hot water cylinders.

• Oxygen free high conductivity copper (OFHCTM is a registered trade mark) is producedby casting in a controlled atmosphere and is used where freedom from the possibility ofembrittlement is required.

• A special grade of oxygen-free high conductivity copper (certified grade) with lowresidual volatile impurities is used for high vacuum electronic applications such astransmitter valves, wave guide tubes, linear accelerators and glass to metal seals.

• Free-machining copper - An addition of 0.5% sulphur or tellurium raises the machinabilityrating of copper from a rating of 20% (based on 100% for free-cutting brass) to 90%.Applications for these free-machining grades include electrical components, gas-weldingnozzles and torch tips and soldering iron tips.

A wide variety of high conductivity copper alloys is available for special purposes of whichthree are the most common.

Copper-silver (0.01 to 0.14% Ag) has better creep resistance than copper itself and is thereforeused in the manufacture of commutators, alternators and motors, where the capacity to resisttemperature and stress is essential.

Copper-cadmium alloys, with about 1% cadmium, are used for their wear-resistant propertiesfor some heavy duty catenary wires, which are familiar as the overhead electrical conductorwire seen on electric railway systems.

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Commutator for a heavy duty DC propulsion motor (Laurence Scott and Electromotors Ltd)

For electrical applications such as resistance welding electrodes where service is at hightemperature under heavy stress, a copper-chromium (up to 1% Cr) alloy is often employed.This is heat treatable to give good room temperature mechanical properties which aremaintained well as the operating temperature rises (400° continuous rating is possible) and itretains conductivity of around 80% IACS. The addition of up to 0.2% zirconium confers evenbetter elevated temperature fatigue resistance.

Deoxidised copper is used for the other major area of application of the coppers in building, theprincipal uses being for central heating systems, pipe for gas and water supply, householdelectrical wiring and sheet for roofing. The ability of copper to form a protective andaesthetically pleasing surface, or patina, by weathering has encouraged its use for roofing largebuildings over many centuries.

Bronzes and Phosphor BronzesBinary alloys of copper and tin are called bronzes and can contain up to 12% tin. An increase inhardness and strength is gained at minimal cost by the addition of phosphorus to a level ofaround 0.25% to make phosphor bronzes. Tin contents range from 4% up to 8% in wroughtmaterials or higher if the alloy is used as cast. Alloys containing the higher tin level areparticularly suitable for severe operating conditions. Possessing high corrosion resistance,excellent tensile and fatigue strength, superior wear resistance and bearing/frictional properties,this type of alloy finds application for heavy duty bearings, bushes and gears, high performanceengine components, high strength switch parts, thrust washers, slides, pistons and many others.Leaded phosphor bronzes can be produced that machine almost as easily as free-cutting brass.

Close tolerance bearings for heavy duty use machined from continuously cast copper alloys such as phosphor bronze and leaded bronze (J Roberts Components Ltd)

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Special compositions with around 20% tin are suitable for bell founding. These alloys are brittleand of little use for more general engineering purposes.

Aluminium Bronzes (Copper-Aluminium Alloys)These are a range of copper alloys containing up to 14% aluminium and frequently otherelements such as nickel, iron, manganese and silicon. Varying the proportions of these results ina range of strong, tough alloys with excellent resistance to corrosion and wear that are ideal fora wide variety of demanding engineering applications[19].

Their strength, and in many respects their corrosion resistance, is better than most stainlesssteels, especially in aggressive marine environments[20]. They are available both as high-integrity castings in weights up to many tons and in the usual wrought forms such as plate,forgings, extrusions and as welding wire. They are readily weldable for fabrication of largecomponents. [21]

The aluminium bronzes possess the excellent natural corrosion resistance of all copper alloysenhanced by the protective film of aluminium oxide formed very rapidly under normal operatingconditions. If damaged, this film is self-healing, which means that the alloys can be used inservice conditions when abrasion can be expected.

This type of alloy is specified for the manufacture of pumps, turbines, propellers, valves, tees,branches and other water fittings, pressure vessels, pickling hooks, heavy duty journal and flatbearings, gearbox components and masonry fixings.

Nickel aluminium bronzes containing around 10% aluminium, with additions of iron andmanganese to increase strength and toughness still further[22], are widely specified forapplications on surface and submarine naval vessels and are often produced to NES (NavalEngineering Standard) designations.

Silicon bronzes and aluminium silicon bronzes contain silicon to a level of 1% up to around 4%and offer low magnetic permeability for navigation equipment and mine hunting vesselequipment. High aluminium alloys are cast to make very hard die materials for pressing steelsand for glass bottle moulds.

BrassesBrasses are copper alloys in which the main alloying element is zinc. The generic term 'brass'covers a wide range of materials suitable for many different types of application[23]. Goodcorrosion resistance, machinability, formability and conductivity are properties characteristic ofall the brasses together with toughness retained above and below ambient temperatures, goodspark-resistance and low magnetic permeability[24]. The old British Standards included 37different compositions of wrought brasses and 9 of the most popular casting brasses, so correctchoice of brass is important. The range of compositions preferred across Europe and included inthe new BS EN series of standards gives even more choice.

Copper-zinc alloys with up to about 30% zinc have a single-phase metallurgical structure, thealpha phase, a solid solution of zinc in copper. Cap copper (up to 5% Zn) is used forammunition percussion caps. The gilding metals (10 to 20% Zn) are used for architecturalmetalwork, papermaking, jewellery strip and applications requiring suitability for brazing andenamelling.

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Brass door furniture - Economy, longevity and durability are only some of the attributes needed for doorfurniture. Brass also has strength, wear resistance, bactericidal properties and an attractive appearance

(Vin Callcut)

The cartridge brasses (30% Zn) have the maximum ductility of the copper-zinc range and areused for deep drawing. Common brass, containing 36% zinc, is the most usual compositionused for brass sheet.

Light Bulbs- Good quality light bulbs have brass caps which will last the life of the bulb withoutcorroding or sticking in the holder. They are made by repetition stamping from brass sheet and the

webbing scrap is recycled.(Lamp Caps Ltd)

Brasses with more than about 37% zinc have a binary metallurgical structure (two-phase) andare known as alpha-beta alloys. The beta phase is readily deformable when hot, and these alloyslend themselves more readily to hot forming techniques than almost any other alloy used inengineering. Such compositions, all derived from Muntz metal, with about 40% zinc, allow theproduction of complex machinable high strength shapes at low material cost.

Other elements are added to the brasses to produce materials for different applications. Free-machining brass (containing 39% Zn and 3% Pb) has for decades been the standard alloyagainst which the machinability of other metals has been judged. The lead is present as fineparticles that help chip forming of the swarf so that it can clear away from the tool tip.

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Turned brass components - These components are all made rapidly and economically on automatic lathesfrom extruded high-speed machining brass rods and hexagonal sections (Delta Extruded Metals Co Ltd)

Figure 5 shows comparisons of machinability reported by an experienced manufacturer[25].Machining speed is not the only factor that affects the cost of machined components. Amongstothers is the cost of keeping the tool tip clear of long strands of swarf produced from non free-machining materials.

The addition of manganese, iron and aluminium produces high tensile brasses (sometimesknown as manganese bronzes) which, with enhanced strength and resistance to wear, impact andabrasion, are used for architectural and heavy duty engineering applications.

High tensile brass bolt and nut for marine service (Vin Callcut)

High tensile brass (with higher alloy content - particularly aluminium - than normal hightensile brass). This offers very significant increases in strength and hardness and similar to thoseproperties associated with aluminium bronzes and is employed for aircraft landing gearcomponents.

When about 1% tin is added to copper-zinc, Naval brass or Admiralty brass is produceddepending upon the ratio of copper and zinc.

Under certain conditions in seawater and aggressive domestic water supplies, brass can besubject to a corrosive attack called dezincification. The addition of around 0.1% arsenicproduces an alloy free from this problem and, meeting the requirements of the water supplyindustry, is used for pipe fittings, stop-cocks, water meters and other components of plumbingand heating installations.

Another special brass with a Trade Name of ‘Tungum’, contains aluminium, nickel and siliconadditions to give a combination of high strength and ductility with excellent resistance tocorrosion and shock. In tube form it is used in the hydraulic systems of offshore platforms and

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associated vessels as well as winch controls, lifeboat davit and deck crane systems and marinedrive systems. It also finds application in high pressure gas storage systems, aircraft productionand test rig hydraulic systems.

Tungum tube installation within the control cabin of an offshore pedestal crane (Stothert and Pitt Ltd)

GunmetalsThese are copper-tin-zinc alloys that have improved corrosion resistance due to the tin and goodfluidity for casting conferred by the zinc. Today most gunmetals have an addition of lead toimprove machinability.

Gunmetal water fittings give a have a long service life above and below ground (F W Birkett)

Nickel SilversThese copper-nickel-zinc alloys, closely related to the brasses, contain no silver but take theirname from their silvery appearance - which becomes whiter with increasing nickel content - andability to take a high polish. Nickel content can range from 10 to 25% though for most purposes18% is the maximum - an alloy with this content is commonly used for spectacle frames.

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Spectacle frames - Nickel-silver, gold plated, has the good strength, ductility and corrosion resistance necessary for the fabrication of precision frames for spectacles (Vin Callcut)

The mechanical properties are somewhat higher than those of the brasses. The alloys are usedextensively for decorative ware and for cutlery, especially for goods destined for silver plate,which is stamped EPNS (electroplated nickel silver). Strip and wire are used to make springsand contacts for electrical equipment. In architectural applications they are sometimes known as‘silver bronzes’ and can be used for decorative metalwork, door handles and handrails.

Copper-Nickel alloysLike the aluminium bronzes, the copper-nickel alloys (or cupronickels) have come into theirown during this century. Following the 1914-1918 war the British Navy required condensertubes with improved resistance to failure when handling seawater in harbours, estuaries andother polluted waters. This led to the development of copper-nickel-iron alloys in the 1930s.

The three most used alloys of copper and nickel contain around 1, 10 and 30% nickel with otherelements[26]. The addition of nickel to copper improves strength and corrosion resistance butgood ductility is retained[27]. Excellent resistance to corrosion attack by marine environmentsis combined with the resistance of copper to biofouling.

Copper-nickels can be readily welded to build up complexfabrications very economically (James Robertson Ltd)

90/10 copper-nickel, containing 1% each of iron and manganese, is used for seawater pipingaboard ships[28] and offshore oil and gas production platforms[29]. The alloy is also employedin sheet form to sheath the hulls of ships[30] and clad the legs of offshore platforms. 70/30copper-nickel was developed initially to provide an even better material for condenser tubing.

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Other applications for these copper-nickels include plant construction for desalination bydistillation, vehicle hydraulic systems and the production of coinage.

In the past few decades high strength copper-nickels (with strength up to 5 times that of thealloys already described and similar to that of carbon steel) have been developed. These alloys,strengthened by the presence of minute nickel-aluminium precipitates in the microstructure, areselected for bolting (with resistance to hydrogen embrittlement) and other highly loadedcomponents on naval vessels and offshore oil and gas structures. High strength cast copper-nickel, containing chromium, is used for pumps and valves in naval vessels.

Copper-Nickel-SiliconDuring the second half of this century wide use has been made of an alloy based upon copperand containing 2.0 to 3.5% nickel and 0.4 to 0.8% silicon. This precipitation-hardening alloypossesses high strength and good ductility combined with high electrical conductivity andthermal conductivity 40% that of copper. Resistance to corrosion in marine and industrialenvironments is excellent and the alloy has good anti-frictional and bearing properties. With amagnetic permeability <1.001, the alloy is essentially non-magnetic.

The versatility of this type of alloy is demonstrated by widespread use in diverse industrysectors. These applications include valve guides, piston tops and little end bushes in highperformance internal combustion engines, aero-engine bearing cages, aircraft undercarriagecomponents, gears and bushes, resistance welding electrodes, electrical contacts, naval vesselhose connectors, piston crowns, plastics moulding dies, clutch plates in marine engines and non-magnetic naval vessel winches.

Piston top for high speed two-stroke Deltic diesel engine - A high strength copper alloywith excellent conductivity is required to give long service life in the

high performance, high speed Deltic diesel engine (Vin Callcut)

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Copper- Beryllium Alloys

Copper-beryllium oil and gas components - These are hard wearing components with good anti-galling properties, high strength and corrosion resistance and are

used in aggressive offshore environments (Brush Wellman)

The addition of beryllium to copper gives an alloy capable of being heat-treated and coldworked to provide exceptionally good mechanical properties at room and at elevatedtemperatures. For many years these alloys have been used extensively for demandingapplications such as springs, contacts, heavy-duty engineering and electrical components andmoulds for plastics and glass production.

Because of their high strength and hardness they are used for the manufacture of non-sparkingtools for use in hazardous environments. There are two basic types of alloy - one contains nearly2% beryllium with some nickel and/or cobalt, the other contains about 0.5% beryllium and 2%cobalt.

There are health hazards involved when beryllium fume is present during melting or weldingoperations.

Copper in other MetalsApart from use in the copper-base alloys, there are other base metals to which copper can beadded, though of these only iron, nickel and aluminium have any engineering importance.Structural steels can be made resistant to weathering and heavy progressive rusting under manyconditions by the addition of copper. These grades are known as weathering steels and containabout 0.5% copper.

The addition of copper (around 2 to 4 %) to duplex stainless steels and high nickel superaustenitic steels enhances corrosion resistance in acid environments and can also confer greaterresistance to certain forms of attack by seawater.

The most important alloy of nickel with copper is known as Monel metal and contains about 30-35% copper. It originated from the copper-nickel mattes derived from the mixed ores found atSudbury, Ontario. These mattes were smelted to give the alloy directly. It was found that it washighly resistant to many forms of corrosion, especially in chemical processing and marineapplications.

Alloys of aluminium with about 4% of copper are age hardening and by careful choice ofcomposition and thermomechanical processing, very high levels of mechanical strength can beobtained, though at the expense of corrosion resistance. The original aluminium-copper alloywas known as ‘Duralumin’.

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Copper CompoundsCopper sulphate is commercially the most important copper compound, once called ‘bluevitriol’ from its close association with sulphuric acid. It is generally the starting stock for themanufacture of most other copper compounds. World consumption is around 200,000 tons peryear, of which approximately 75% is used in agricultural applications. Other uses include:

• electrolyte for copper refining

• anti-fouling paints

• catalysts for many industrial processes in the petrochemical and rubber industry andfor textile manufacture.

• additives to cement for controlling setting rate and lichen growth

• addition as fungicide to plaster

• mordants for dyeing

• colourings for paints, glass and fireworks

• preservatives for paints, adhesives, timber, textiles and bookbindings

Cupric oxide, cuprous oxide, copper acetate, cupric chloride, copper oxychloride, cupric nitrateand copper napthenate are used selectively for these purposes for their ease of use or otherspecial properties.

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Section 5 - Making Components

Fabrication, Joining and Finishing(‘Design for Production’ is the title of a comprehensive CDA book on this topic[31] )

FabricationThis is a term, which describes the means by which the required form/shape is produced. Thecasting techniques referred to in the section on 'Forms Available' are fabrication methods. Tothese we need to add methods involving hot and/or cold working since the various wroughtforms available are produced by these methods. A number of fabrication processes will often berequired to produce the shape needed, for example, a cast billet or cake (which may be a piececut from a continuous cast length) is used as the starting material for hot working to shape. Thefinal shape may be made by more than one hot working process and could also require a coldworking method to be adopted - machining will frequently be employed to achieve thedimensions required. Electro-deposition is employed for the production of printed circuitboards.

All these processes have been examined in detail over the past years to continue development oftechniques to improve quality, raise production rates and reduce the cost of processing at thesame time as improving working conditions and the effect on the environment.

Hot WorkingThe main processes are rolling, extrusion (forcing hot metal through a die), forging (hammeringbetween open dies to produce simple shapes such as blocks, discs, shafts and rings - hollowforgings can be produced with the use of loose tooling/formers) and stamping (a near-net shapeprocess involving forging between shaped, closed dies). Other processes are - metal powdercompaction, ‘Hipping’ at very high isostatic pressures and metal injection moulding.

A small hot rolling mill for brass cakes, reducing the thickness from 150mm to 6mm (Vin Callcut)

Cold WorkingProcesses used with sheet and strip are bending, stamping from sheet or strip, spinning of thedished ends for vessels, rolling, deep drawing and thread rolling. Wire is usually finished to sizeby cold drawing.

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Multi-spindle wire drawing machine (Delta Enfield Wires)

MachiningMachining of all coppers and copper alloys can be successfully carried out using conventionaltechniques[32]. Materials with special additions, such as leaded brasses and sulphur, telluriumor leaded coppers, are generally easier to machine. They can be used to manufacture fullyfinished components with a cost much less than that of others made from materials of lowerinitial cost. The ease of machining has a significant effect on the rate at which components canbe produced. This makes them cheaper than similar components made from other materials.Relative machinability rates of various metals are given below.

Free-machining brass gives fine chips of swarf which minimisetool wear and the need for lubrication (Vin Callcut)

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Figure 5 – Comparison of machinabilities of common engineering metals

JoiningJoining of copper base materials can be easily achieved by a wide variety of techniques[33].That chosen will depend upon factors such as speed, cost, required joint strength, conductivityand corrosion resistance. Techniques available for selection include arc welding, induction andresistance welding, friction welding, cold pressure welding, brazing, silver soldering, softsoldering, mechanical joining and the use of adhesives. Further details are included in CDAPublication No 98 ‘Joining of Copper and Copper Alloys’.

Fabrication of tubular copper-nickel components to form a bend for seawater pipelines for use on a North Sea Oil platform (George Clark and Sons (Hull) Ltd)

FinishingFinishing methods, which are employed, include pickling clean in an acid solution (sometimesfollowed by bright dipping in an acid mixture), polishing, plating (less often required forcorrosion protection with copper alloys) and lacquering. Techniques for plating copper are wellestablished. Lacquers used should be suitable for copper-based materials in order to inhibittarnishing. Care should be taken to select lacquers suitable for use on copper, brass and othercopper alloys. These should include tarnish inhibition of the type described in the CDA book'Clear Surface Finishes'[34].

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Section 6 - Mining and Extraction

Mining of ores and copper extractionCopper minerals and ores are found in both igneous and sedimentary rocks. Mining of copperores is carried out using one of two methods.

• Underground mining is achieved by sinking shafts to the appropriate levels and then drivinghorizontal tunnels to reach the ore.

• Open pit mining is employed when the ores are near the surface and can be quarried afterremoval of the overlaying surface layer.

Bingham Canyon copper mine (Vin Callcut)

Typical copper mineral (Codelco)

Copper and Mineral OresCopper is found in the earth’s crust and the oceans although the amount in the latter is thoughtto be negligible, amounting to no more than about 8 months mine production at present dayrates. The upper 10 kilometres of the crust is thought to contain an average of about 33 ppm ofcopper. For commercial exploitation, copper deposits generally need to be in excess of 0.5%copper, and preferably over 2%. The known reserves of higher-grade ore in the world amount tonearly 1 billion tons of copper. At the present rate of smelter production, which is about 9million tons a year, known reserves of copper could be depleted in about 100 years. However,successful exploration for new mineral deposits, technological advances and the increasedrecycling of scrap is forestalling the eventual depletion by a considerable period. As previouslymentioned, these advances in technology now known mean that supplies are estimated to beassured for a minimum of 250 years. Future developments and sourcing may extend this timeindefinitely.

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Over 160 copper minerals are known, of diverse appearance and colour. Most of these are veryrare, and fewer than a dozen are at all common. Of these the most brilliantly coloured are thebright green banded malachite; bornite, which is iridescent, giving rise to its alternate name ofpeacock ore, and chalcopyrite, a mixed sulphide of copper and iron, which is a bright yellowcrystalline mineral resembling pyrite, or ‘fool’s gold’. Table 4 shows some of the most commoncopper minerals. Some of these have long had a value in their own right, such as malachite,prized for its unusual and pleasing appearance - never the same and always striking - and usedfor millennia in jewellery and ornaments.

Malachite - This copper mineral has an unusual and striking appearanceand has been used for millennia in jewellery and ornaments.

Table 4 – Minerals of Copper

Mineral Composition Wt% Copper

Colour Lustre

Nativecopper

Cu 100.00 Copper red Metallic

Cuprite Cu2O 88.8 Red Adamantine to earthy

Chalcocite Cu2S 79.9 Dark grey Metallic

Covellite CuS 66.4 Indigo blue

Bornite Cu5FeS4 63.3 Golden brown to copperred Metallic

Malachite CuCO3Cu(OH)4 57.5 Bright green Silky to earthy

Azurite 2CuCO3Cu(OH)2 55.3 Blue Vitreous to adamantine

Antlerite Cu3SO4(OH)4 53.7 Green

Chrysocolla CuSiO32H2O 36.2 Bluish green, sky blue,turquoise

Vitreous to earthy

Chalcopyrite CuFeS2 34.6 Golden yellow Metallic to opaque

The largest single mass of native copper was found in Minnesota in 1857 and weighed 420 tons,but most are usually very much smaller and native copper is in fact of no commercialimportance. There are two varieties of commercially significant copper ore - the ‘sulphide’ oresand the ‘oxidised’ ores. The principal sulphide minerals are chalcocite, covellite, bornite, andchalcopyrite. The ores often consist of one or more of these minerals in a matrix of some varietyof copper-free rocks.

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The rock, or ‘gangue’ has to be separated from the sulphide minerals in order to smelt themetallic copper from the ore. By far the greatest proportion of copper is extracted from thesulphides. These ores originate from sulphur-bearing magmas, which have separated into metalsulphides and siliceous melts. The copper has concentrated almost entirely into the sulphidefraction, and if this becomes separated from the siliceous melt it can become deposited in veinsby hydrothermal or other geological activity. Where these mineralised rocks become outcroppedor shattered, the sulphide minerals undergo chemical change due to air, groundwater and heat,giving rise to the other main variety of copper minerals - the oxidised ores.

Commercially exploited deposits of copper ores are found in many parts of the world, frequentlyassociated with mountain building processes. Deposits occur at many locations in the westerncordillera of the Americas, mainly in the United States and Chile, and in areas of the North Americanplains like Michigan, Ontario, Quebec and Manitoba, at sites associated with the Pre-Cambrianshield. In Africa, the largest deposits are found in Zambia and Zaire, but copper is also mined inseveral other locations in Central and Southern Africa.

World map showing the location of copper producers (Deutches Kupfer Institut)

Deposits also occur throughout Europe, which is still collectively a significant producer as maybe seen from Figure 6. In Asia, the most extensive deposits are found in the CIS, with smallerdeposits at widely scattered locations such as Indonesia, The Phillipines, India, and Turkey.Further medium sized deposits occur in Australia.

Figure 6 – Production of copper in each continent

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The erosion of copper bearing rocks leads to the solution of copper in surface waters and itseventual re-deposition in seabeds or dry continental basins - with re-precipitation as sulphides,burial in sediments and folding. This is thought to have happened in what is now the AfricanCopper Belt of Zambia and The Republic of Congo, where up to 20 metres thickness of oreoccurs, with copper contents from 2% to over 4%.

Frequently, copper deposits are associated with other common metals such as nickel and zinc. Itis also common to find commercial quantities of precious metals such as silver and gold in theore.

ExtractionModern methods of extraction allow economic leaching and electrowinning of copper from lowgrade ores and extraction techniques are continuously being refined and developed to achievethe most efficient removal of copper from a wide variety of ores from sources around the globe.The techniques for extraction of copper from oxidised ores are quite different from thoseemployed for the sulphide ores. The oxidised ores, consisting of the silicates, carbonates andsulphates, are treated by several methods, all involving some form of leaching of the crushed orewith sulphuric acid to produce impure solutions of copper sulphate.

If these leach solutions are very weak they are agitated with copper chelating agents dissolved ina paraffin base. The copper loaded solvent is then stripped of its copper by contacting with astrong sulphuric acid, producing a concentrated copper sulphate solution which is used as anelectrolyte for electrowinning by the deposition of metallic copper on copper cathodes. Thisbypasses the fire-refining stage of conventional extraction.

Copper cathodes being lifted out of the electrolyte at the refinery (Deutches Kupfer Institut)

Sulphide ores are first mechanically crushed and ground so that nearly all copper mineralparticles are freed from the rock or 'gangue'. Flotation by the injection of air and violentagitation is carried out with the pulverised ore held in suspension in water, to which surface-active agents have been added. The sulphide minerals are continuously drawn off from thesurface and dewatered to produce copper sulphide concentrate, which is further treated in one oftwo ways.

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Controlled roasting is a process in which the sulphides are burnt in air to give a product ofcopper sulphates and oxides suitable for acid leaching as described earlier. The other method,matte smelting, is the most important for the extraction of copper from sulphides. There areseveral methods of smelting mattes (copper-iron sulphide and oxide slag) by the melting ofconcentrate at about 1200°C. The molten matte is then turned into 'blister-copper' by oxidationin a furnace. Finally, anodes (in what is known as tough pitch copper) for electrolytic refiningare produced in a furnace in which sulphur is burned off with air blown through tuyeres, afterwhich excess oxygen is removed.

Continuous smelting and converting processes or flash smelting are now used to reduce costsand improve efficiency. Oxygen enrichment of the combustion air in the smelting process givessimilar benefits.

Microbiology can be utilised to recover copper from the spoil heaps of old mines, whichfrequently contain a small amount of insoluble copper sulphide. The bacterium ThiobacillusOxidans converts this to soluble copper sulphate, which is leached out and electrolysed torecover the copper.

The flowsheet shows simply the traditional mechanical and thermal refining processes forextraction of copper together with the more recent chemical solvent extraction technique.

Figure 7 – Flowsheet for primary copper production

The majority of high purity copper cathodes made in a refinery are bundled for transport to acopper rod mill where they are melted in a continuous shaft furnace and cast and hot rolled tomake high conductivity copper rod of around 9mm diameter. This is passed to the wire mills fordrawing to finished size.

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Section 7 - Standards, Compositions and Properties(More comprehensive coverage of this topic is in CDA Publication No120 'Copper and CopperAlloys - Compositions, Applications and Properties'[35])

A Variety of StandardsCoppers and copper alloys are specified in a very wide variety of ways by many differentorganisations. The British Standards that have been used since the old standards in Imperialunits were metricated in 1969 are now being withdrawn and replaced by new ones afteragreement across Europe. The corresponding European documents issued by other membercountries will also be replaced by the common specifications.

Other specifications used in the UK include many company specifications and those for defenceprocurement such as the NES (& DGS) specifications for Naval materials and the DTDdocuments. American specifications, mainly the ASTM standards that use the UNS (ex CDAInc.) material numbering system and the SAE specifications remain unaffected. Americanmilitary specifications (MIL series) are being based on the ASTM specifications where possiblebut include more stringent requirements for inspection, testing and packaging.

The New BS EN StandardsThe new BS EN series of standards for copper and copper alloys offer a selection of materials tosuit a very wide variety of end uses. They represent a consensus agreement on those mostfrequently ordered by consumers.

Commencing in the late 1980s, drafting of European Standards for Copper and Copper Alloysbecame a major activity for national standards organisations and their industrial partners.Within CEN, the work is being done in Technical Committee TC/133 ‘Copper and CopperAlloys’ with good representation from members of the corresponding BSI Committee NFE/34.

Because a large number of national preferences have needed to be taken into account against thebackground of a pan-European agreement to develop tight product standards, the new BS ENstandards (the British implementation of European standards) are more complex than thehistoric BS standards. Furthermore, the BS EN standards tend to cover narrower fields than BSstandards; hence there are more materials in the BS EN series than in the previous BS standards.

Withdrawal of old standardsAs the new standards are published they will be in conflict with the old British Standards. Thesewill therefore be withdrawn, as will those of other European countries, leaving Europe with oneharmonised series of standards published in each country but applicable across all.

The majority of the ratified versions of the new standards, published or due during the period1996-1998, caused, or will cause, withdrawal of conflicting national standards such as BS1400,the BS287x and the BS143x series.

Materials popularly used from the previous BS standards will of course continue to be availablebut the new designations should be used. Compositions, properties, tolerances and otherrequirements will conform to the standard quoted.

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Table 5 - BS EN Standards for Copper and Copper AlloysFor an up-to-date version of this table showing BS EN numbers please see Table 1 – CDA Publication 120

BS EN number (*) Title Nearest Old BSEquivalent

Unwrought products1978 Copper cathodes 6017

1977 Copper drawing stock (wire rod) 6926

1976 Cast unwrought copper products 6017

1982 Ingots and castings 1400

1981 Master alloys -

Rolled flat products1652 Plate, sheet, strip and circles for general purposes 2870, 2875

1653 Plate, sheet and circles for boilers, pressure vesselsand hot water storage units

2870, 2875

1654 Strip for springs and connectors 2870

1172 Sheet and strip for building purposes 2870

1758 Strip for lead frames -

(133/16) Hot dip tinned strip -

(133/18) Electrolytically tinned strip -

Tubes12449 Seamless, round tubes for general purposes 2871 Pt.2

12451 Seamless, round tubes for heat exchangers 2871 Pt.3

1057 Seamless, round copper tubes for water and gas insanitary and heating applications

2871 Pt.1

12452 Rolled, finned, seamless tubes for heat exchangers -

12735 Seamless, round copper tubes for air conditioningand refrigeration

-

Part 1 : Tubes for piping systems

Part 2 : Tubes for equipment

(133/26) Seamless, round copper tubes for medical gases -

12450 Seamless, round copper capillary tubes -

133/29 Pre-insulated copper tubes -

Tubes with solid covering

Rod/bar, wire, profiles12163 Rod for general purposes 2874

12164 Rod for free machining purposes 2874

12165 Wrought and unwrought forging stock 2872

12166 Wire for general purposes 2873

12167 Profiles and rectangular bar for general purposes 2874

12168 Hollow rod for free machining purposes -

(133/52) Rod and wire for welding and braze welding 1453, 1845, 2901

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Table 6 (continued)

BS EN number (*) Title Nearest Old BSEquivalent

Electrical purposes(133/60) Copper plate, sheet and strip for electrical purposes 4608

(133/61) Seamless copper tubes for electrical purposes 1977

(133/62) Copper rod, bar and wire for general electricalpurposes

1433, 1432

(133/63) Drawn round copper wire for the manufacture ofelectrical conductors

4109, 6811

(133/65) Products of high conductivity copper for electronictubes, semiconductor devices and vacuumapplications

3839

(133/66) Copper profiles for electrical purposes

Forgings and fittings12420 Forgings 2872

1254 – Pt.1 to 5 Plumbing fittings 864

(*) When the BS EN number is not yet available the number is expressed as : -(Technical CommitteeNumber / Work Item Number i.e. 133/xx)

Numbers and Titles of StandardsTable 5 shows BS EN standards’ titles, categorised by product type and the BS standards thatare replaced. During the standardisation process, at the stage of draft for public comment, an ENnumber is allocated. At this stage drafts are identified with the prefix ‘pr’. After successfulformal vote, when the draft is approved for publication throughout Europe, the BS ENimplementation uses the same number.

This publication lists the BS EN numbers, even if still the provisional ‘prEN’ at publication.When the number is still not known, the Technical Committee 133 Work Item Number is given,i.e. 133/xx.

Product FormsAs part of the standardisation process, uniform definitions have now been adopted for allproduct forms. This will result in some products having new terminology. As an example, theterm ‘wire’ now includes all material made in coil form.

Material DesignationsMaterial Designations (individual copper and copper alloy identifications) are in two forms,symbol and number. As with many other existing European national standards, symbols arebased on the ISO compositional system (e.g. CuZn37 is 63/37 brass). ISO and EN symbols maybe identical but the detailed compositional limits are not always identical and cannot beassumed to refer to unique materials.

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A new numbering system has therefore been developed to offer a more user- and computer-friendly alternative. The system is a 6-character, alpha-numeric series, beginning C for copperbased material; the second letter indicates the product form as follows:-

B Materials in ingot form for re-melting to produce cast productsC Materials in the form of cast productsF Filler materials for brazing and weldingM Master alloysR Refined unwrought copperS Materials in the form of scrapW Materials in the form of wrought productsX Non-standardised materials

A three-digit number series in the 3rd, 4th and 5th places is used to designate each material andcan range from 001 to 999; with numbers being allocated in preferred groups, each series beingshown below. The sixth character, a letter, indicates the copper or alloy grouping as follows:-

Number series Letters Materials000-099 A or B Copper

100-199 C or D Copper alloys, low alloyed (less than 5% alloying elements)

200-299 E or F Miscellaneous copper alloys (5% or more alloying elements)

300-349 G Copper – aluminium alloys

350-399 H Copper – nickel alloys

400-449 J Copper – nickel - zinc alloys

450-499 K Copper - tin alloys

500-599 L or M Copper – zinc alloys, binary

600-699 N or P Copper – zinc - lead alloys

700-799 R or S Copper – zinc alloys, complex

Material Condition (Temper)DesignationsMaterial condition (alternative term – Temper) designations are defined in BS EN 1173. In mostproduct standards, materials are available in a choice of material conditions. Depending on theproduct standard there may be one or more mandatory properties associated with the particularmaterial condition. For designation purposes the principle mandatory property for each materialcondition is identified by a letter, as follows:-

A ElongationB Spring Bending LimitD As drawn, without specified mechanical propertiesG Grain sizeH Hardness (Brinell or Vickers)M As manufactured, without specified mechanical propertiesR Tensile strengthY 0.2% proof strength

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Products can only be ordered to one material condition and not a combination. However,besides the designating property, other properties may be mandatory; check the standarddocument for full details.

Normally three digits, but in a few instances four digits, follow the material conditiondesignating letter, where appropriate, to indicate the value of the mandatory property with thepossibility of a final character, ‘S’, for the stress relieved condition. Normally the value refersto a minimum for the property. Sometimes, as with grain size, it refers to a nominal mid-rangevalue.

Tables 6 to 13 in Publication No 120 show not only the existence of copper or copper alloys inparticular standards but also the material conditions available as mandatory properties withinthose standards.

CastingsFor castings, properties are dependent on the casting process used. This is designated accordingto the system:

GS sand castingGM permanent mould castingGZ centrifugal castingGC continuous castingGP pressure diecasting

ExamplesCW614N – R420 refers to wrought CuZn39Pb3 copper-zinc-lead alloy to be supplied to aminimum tensile strength of 420 N/mm2

CC750S - GS refers to sand cast CuZn33Pb2 copper-zinc duplex alloy

Each product standard gives examples of the full ordering information required includingquantity, product form, standard number, designation, condition, tolerances and packaging.

Typical PropertiesIn Tables 6 to 13 of CDA Publication No 120, typical properties are usually shown as ranges.For materials available in both ‘soft’ condition, for example as forging stock, and ‘very hard’,for example as spring wire, then the ranges are very wide. Tables 14 to 18 show typicalproperties for ranges of brasses similar to those previously included in British Standards inorder to give a closer idea of the range of properties available in each product form.

It is vital that designers and purchasers consult with suppliers to clarify what property valuesand combinations are available to be best fit for purpose in the desired product form.

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Section 8 - Historical

Copper through the ages

The Copper AgePre-dynastic Egyptians knew copper very well and in hieroglyphs copper was represented by theankh symbol also used to denote eternal life, an early appreciation of the lifetime cost-effectiveness of copper and its alloys. The Egyptians obtained most of their copper from the RedSea Hills.

The older civilisation based on the Euphrates also knew copper and well developed smeltingtechniques. The earliest known artefacts made from smelted metal were copper, and excavationsat Catal Huyuk near Konya in Southern Anatolia, showing slags derived from the smelting ofcopper, have been dated to as early as 7,000 BC. Other civilisations in the Near and MiddleEast, Hindustan and China also developed the use of the vital metal.

Homer referred to the metal as ‘Chalkos’; the Copper Age is therefore referred to as theChalcolithic Age. Roman writings refer to copper as ‘aes Cyprium’ since so much of the metalthen came from Cyprus.

The Bronze ageThere is evidence that early workers knew that the addition of quantities of tin to copper wouldresult in a much harder substance. This alloy, bronze, was probably the first alloy made andfound particular favour for cutting implements. Numerous finds have proved the use of bothcopper and bronze for many purposes before 3,000 BC.

Some of the earliest bronzes known come from excavations at Sumer, and are of considerableantiquity. At first, the co-smelting of ores of copper and tin would have been either accidental orthe outcome of early experimentation to find out what kinds of rock were capable of beingsmelted. The smelting of lead was known by 3,500 BC, and lead, tin and arsenic all appear asadventitious alloying elements in smelted copper from early dates.

An appreciation of quality in bronze depending on the tin content emerged only slowly.Consistency of composition of bronzes dates back to about 2,500 BC at Sumer, with bronzescommonly containing 11 - 14% tin - reasonable evidence both of technological forethought andthe appreciation of metallurgical and founding properties. Indications of bronze production asfar back as 2,800 BC come from places as far apart as India, Mesopotamia and Egypt, and makea single origin for bronze smelting significantly further back in time a strong possibility.

Trade by land and sea, and the succession of cultures and empires, had dispersed knowledge ofthe copper-based metals slowly but surely throughout the Old World. By 1,500 BC it had spreadacross Europe and North Africa to the British Isles, and in other directions as far as India andChina. Copper, bronze, copper-arsenic, leaded copper, leaded bronze and arsenical tin bronzeswere all known by this date in most parts of the Old World.

‘Oetzti’, the 5,000-year-old mummified man found recently high in the Alps on the Italian-Austrian border was found with many implements including an excellent arsenical copper axe.It seems that he was probably a coppersmith himself, since his hair had high concentrations ofcopper and arsenic, which could probably have come from no other source.

Alloys containing zinc were also emerging at this time, from Cyprus and Palestine, though thealloying is believed to have been natural in origin, due to the local ore containing somesmeltable zinc minerals. Alloys similar to modern gunmetals were being cast before 1,000 BC,

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though the proportions of copper, tin, zinc and lead were not well established. Following theemergence of true brasses in Egypt in the first century BC, possibly from Palestine, theindustrious and methodical Romans rapidly consolidated the knowledge and usage of copper,bronzes, brasses and gunmetals.

Bell founding originated in China before 1,000 BC and in time Chinese bell design attained ahigh degree of technical sophistication. The technology spread eventually through Asia andEurope to Britain, where early evidence of bell making has been dated to around 1,000 AD,through excavation of a bell casting pit at Winchester. Several important books were writtenduring the Middle Ages concerning the extraction, smelting, casting and forging of copper.These established that the casting and working of copper and its alloys had its origins in crafttraditions and practices that had developed over several thousand years. How much of this wasoriginally handed down in writing is not known, since it is only from medieval times that thewritten tradition in technology is unbroken. It is through the Christian monastic and Islamiccultural traditions that detailed accounts of these early technologies have survived. The writingsof the monk Theophilus in the 11th Century and of Georgius Agricola and Johannes Mathesiusin the 16th Century, all describe in detail the metal producing technologies of their day. Oftenthese had changed little for centuries.

The output from the Bronze Age mines was considerable - an assessment based on old minemaps and studies of prehistoric workings at Mitterberg in the Austrian Alps indicated that about20,000 tons of black copper had been produced there over the period of the Bronze Age. Blackcopper was the usual product of ancient smelting and contained about 98% copper. It was tradedas flat cakes weighing a few kilograms for later refining to purer copper by ‘poling’.

Significant engineering uses had been found for copper as early as 2,750 BC, when it was beingused at Abusir in Egypt for piping water. Copper and bronze were employed for the making ofmirrors by most of the Mediterranean civilisations of the Bronze Age period. The obliteration ofCarthage by the Romans has obscured developments in Northern Africa at that time. It is onlyquite recently that evidence of the considerable engineering skills of the Carthaginians hasemerged, including the earliest known use of gear wheels, cast in bronze. Bronze was used inmany of the artefacts of every day Roman life - cutlery, needles, jewellery, containers,ornaments, coinage, knives, razors, tools, musical instruments and weapons of war. This patternof use tended to be repeated wherever the smelting of bronze and copper was introduced, thoughnecessarily on different time scales. The New World and Africa lagged in these developmentsby 3,000 - 3,500 years because of the distance and isolation of these areas from the trade routesthat loosely bound the ancient world.

MiningThe oldest methods for removing rock from underground mines were the sledgehammer andwedge and the equally ancient technique of fire setting. In the latter case a fire set up against arock face would produce thermal stresses - the rock would either crumble naturally or could beshattered by water quenching. It was some time after the Islamic world introduced blastingpowders to Europe in the 13th century, from China, that explosives were first used specificallyfor mining. Today the old mining techniques have been replaced almost entirely by blastingwith modern safe explosives, and the use of heavy duty mechanical cutting equipment, wherethe rock is soft enough to merit such treatment.

Middle Ages and beyondThe invention of printing increased the demand for copper because of the ease with whichcopper sheets could be engraved for use as printing plates. In Germany, playing card designswere engraved on copper as far back as 1430. Copper plates have long been adopted as the best

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means of engraving maps. The first known maps printed from copper plates are two Italianeditions, dated 1472, by the geographer Ptolemy. H.M. Ordnance Survey, continuously since1801 and the Admiralty both use copper plates for printing maps and charts.

Copper has other important uses at sea, as copper sheathing of the hulls of wooden ships wasintroduced in the middle of the 18th century. This was intended to protect the wood againstshipworm when in warm seas. It was found that it also kept the hulls free of barnacles and othermarine growth, preventing the consequent severe drag that slowed the ships. This enabledNelson’s ships to spend many months on blockade duty and still be swift when battlescommenced. Now, copper-nickel cladding can be applied to wood, polymer or steel hulls toprevent the fouling of ships operating at higher speeds.

In the early 18th century Swansea was becoming a major copper centre and by 1860 wassmelting about 90% of the world’s output. At first, Swansea obtained most of its ore from manymines in Cornwall and also Anglesey. By 1900, Morwelham on the River Tamar was theworld’s largest copper port and Parys Mountain near Amlych in Anglesey was the world’slargest copper mine. Then, as the industry developed and other sources were found abroad,almost all ores were imported. The smelting of the ores subsequently moved nearer the sourcesof supply.

During the 19th century Birmingham became the main centre for fabricating non-ferrous metalsin Britain, a position that is still held. Many major developments in the copper industryemanated from the Birmingham area.

• In 1832 George Muntz patented a process for the manufacture of brass consisting of 60%copper and 40% zinc.

• A method for the application of electrolysis to the refining of crude copper was invented bya Birmingham silver-plater, James Elkington, in 1864 and led to the establishment of thefirst such plant in Swansea in 1869.

• Towards the end of the 19th century Alexander Dick introduced the fundamental newprocess of hot extrusion for making brass rod from billet.

By far the greatest extension in the use of copper resulted from Michael Faraday’s discovery ofelectromagnetic induction in 1831 and the subsequent development of the electrical engineeringindustry. Copper has the highest conductivity of heat and electricity per unit volume of anyknown substance except silver, which is only slightly superior in this respect. Because theconductivity of copper is dependent on its purity, extensive use is made of copper in itsunalloyed form. Today about half of the world’s production of copper is for electricalrequirements.

It is now produced in continuous vertical melting furnaces that supply a constant stream ofmolten copper for casting between a water cooled grooved copper alloy wheel and a steelbelt to give a section that is passed directly in to a tandem hot rolling mill. At the end of theline, cool, clean copper rod that may be between 6 and 25mm diameter is coiled to packsizes to suit wire mill needs. Redrawing to size and continuous annealing gives the cheap,good quality wire that is now used in large quantities.

BrassBrass has been made for almost as many centuries as copper but has only in the last millenniumbeen appreciated as an engineering alloy. Initially, bronze was easier to make using nativecopper and tin and was ideal for the manufacture of utensils. While tin was readily available for

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the manufacture of bronze, brass was little used except where its golden colour was required.The Greeks knew brass as ‘oreichalcos’([36]), a brilliant and white copper.

Several Roman writers refer to brass, calling it ‘Aurichalum’ ([37]). It was used for theproduction of sesterces and many Romans also liked it especially for the production of goldencoloured helmets ([38]). They used grades containing from 11 to 28 per cent of zinc to obtaindecorative colours for all types of ornamental jewellery. For the most ornate work the metal hadto be very ductile and the composition preferred was 18%, nearly that of the 80/20 gilding metalstill in demand.

Before the 18th century, zinc metal could not be made since it melts at 420°C and boils at about950°C, below the temperature needed to reduce zinc oxide with charcoal. In the absence ofnative zinc it was necessary to make brass by mixing ground smithsonite ore (calamine) withcopper and heating the mixture in a crucible. The heat was sufficient to reduce the ore tometallic state but not melt the copper. The vapour from the zinc permeated the copper to formbrass, which could then be melted to give a uniform alloy.

In Mediaeval times there was still no source of pure zinc. When Swansea, in South Wales, waseffectively the centre of the world’s copper industry, brass was made from calamine found inthe Mendip hills in Somerset. Brass was popular for church monuments, thin plates being let into stone floors and inscribed to commemorate the dead. These usually contained 23-29% ofzinc, frequently with small quantities of lead and tin as well. On occasions, some were recycledby being turned over and re-cut.

One of the principal industrial users of brass was the woollen trade, on which prosperitydepended prior to the industrial revolution. In Shakespearean times, one company had amonopoly on the making of brass wire in England. This caused significant quantities to besmuggled in from mainland Europe. Later the pin trade became very important, about 15-20%of zinc was usual with low lead and tin to permit trouble-free cold working to size. Because ofits ease of manufacture, machining and corrosion resistance, brass also became the standardalloy from which were made all accurate instruments such as clocks, watches and navigationalaids. The invention by Harrison of the chronometer in 1761 depended on the use of brass for themanufacture of an accurate timekeeper that won him a prize of £20,000. There are manyexamples of clocks from the 17th and 18th centuries still in good working order.

With the coming of the industrial revolution, the production of brass became even moreimportant. In 1738, William Champion was able to take out a patent for the production of zincby distillation from calamine and charcoal. This gave great impetus to brass production inBristol.

Wire was initially produced by hand drawing and plate by stamp mills. Although the first rollingmill in Swansea was installed at Dockwra in 1697, it was not until the mid-19th century thatpowerful rolling mills were generally introduced. The Dockwra works specialised in themanufacture of brass pins, the starting stock being a plate weighing about 30kg. This was cut into strips, stretched on a water-powered rolling mill and given periodic interstage anneals untilsuitable for wiredrawing.

With the invention of 60/40 brass by Muntz in 1832 it became possible to make cheap, hotworkable brass plates. These supplanted the use of copper for the sheathing of wooden ships toprevent biofouling and worm attack.

With improvements in water communications, the centre of the trade moved to Birmingham tobe nearer to fuel supplies and to facilitate central distribution round the country. With theinvention of the extrusion press in 1894, Alexander Dick revolutionised the production of goodquality cheap rods. Subsequent developments in production technology, mentioned in many ofthe references given, have kept pace with customers’ demands for better, consistent quality in

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larger quantities. The brass now is cast to extrusion billet form in three-strand horizontalcontinuous casting machines, cut to length, reheated and extruded in modern presses designed togive high quality and minimum wastage. Subsequent straightening, drawing, annealing, cuttingto length, pointing and inspection is carried out under approved quality management schemesthat ensure that material is supplied as ordered.

The Outlook for CopperThe number of possible new copper alloys is endless, and research is constantly in progress tofind materials with superior properties. Some alloying combinations have as yet provedimpossible to make because of the earth's gravity. For this reason experimental work on newalloys has been undertaken during Skylab missions to take advantage of the weightlessconditions in space.

Copper or copper oxide, when contained in polyurethane plastic foams, significantly reduces theevolution of deadly hydrogen cyanide gas when such plastics are burnt.

Some copper alloys have been developed which display a phenomenon known as ShapeMemory Effect. These alloys find application in, for example, radiator mechanisms due to theircapacity to change from one shape to another upon an alteration of temperature.

New production methods have enabled the development by the International CopperAssociation of an enhanced efficiency car radiator. This has been achieved with the use ofcopper finstock rolled to much thinner gauge in modern mills, tubing made from precision stripby either high-frequency or laser welding and the use of new soldering/brazing techniques.

Table 6 - Cuprobraze vs brazed aluminium for radiators

Radiator Core BrazedAluminium

CuproBraze IIISame air pressure and coolant

pressure drop, smaller andlighter

Header Width, mm 432 395

Tube Length, mm 550 505

Fin Thickness, mm 0.114 0.038

Tube Wall Thickness, mm 0.381 0.102

Coolant Pressure Drop, kPa 4.75 4.75

Air Pressure Drop, kPa 0.307 0.307

Dry Core Weight, kg 1.67 1.56

Wet Core Weight, kg 2.04 1.89

The use of copper as a roofing material will continue to grow. In many countries it is wellaccepted as a standard material needing only basic support structures for its low weight. Thecolour of the patina developed is much appreciated and the long maintenance-free lifetime muchvalued. Until recently the low lifetime cost had not been quantified, but now that authoritativefigures are available it is being appreciated as much as an economic roofing material as for itslooks.

Copper has long been closely linked with the generation, transmission and utilisation ofelectricity. Now copper is not only one of the constituents in the new range of brittlesuperconductors but continues to provide the matrix material in which the superconductors areembedded. However, until superconductor developments ensure that the materials maintain their

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low resistivity under working conditions, copper will remain economical and pre-eminent whenfields of high magnetic flux are needed.

In other electrical and electronic applications, requirements for copper will remain paramount.Increasing demands are being made by new technologies and the precautions needed to guardlife safety and sensitive equipment from voltage and radiation effects. Better design of powercircuits has become essential, with full consideration being given to allowing for energyefficiency, reliability assurance, prevention of new power quality problems and earthing fit forcontinuos current situations over a long installed lifetime.

For message cables copper continues to be extremely effective in this Information Age.Extensive local area computer networks and telephone lines using ADSL (Asymetric DigitalSubscriber Lines) technology to buildings now rely on high quality copper wires. Twisted pairsof conductors made to the Cat 5 specifications are now normal. The development andintroduction of Cat 6, followed by Cat 7, will ensure that requirements for wide frequency bandswill be satisfactorily and economically met.

The uses of copper and its alloys and compounds will continue to change, as they have overthousands of years, to meet modern challenges. As an essential service material that isenvironmentally friendly, fully recyclable and fully sustainable, there is no viable alternative tocopper - the 21st century metal.

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Table 7 - Comparison of lifetime costs of typical roofing materials

Life Cycle CostsCost of

covering£/m2

ScrapValue£/m2

StripCovering

£/m2

SupportingStructure

£/m2

Cost toReplace

£/m2

TypicalLife

Years

Risk, % ofrepair costper cycle

Repair costper year

£/m2

Total cost toyear50£/m2

Metal PitchedCopper,half hard, 0.6mm

55.15 10.99 3.00 54.00 47.16 87.5 6.5 0.04 111.31

Aluminium,PVF2 colour coated, 0.7mm

38.97 2.04 3.00 54.00 39.93 47 14 0.13 139.16

Lead code 5,standing seams, 2.24mm

80.58 10.10 3.00 61.00 73.49 85 12 0.12 147.48

Stainless steel,terne coat, 439 grade, 0.4mm

52.87 6.28 3.00 54.00 49.59 97.5 6 0.03 108.59

Zinc, bright, 0.7mm 47.19 2.96 3.00 54.00 47.23 52 11 0.11 106.50

Non-metal Pitched

Tiles clay 33.97 0.00 4.00 61.00 37.97 60 10 0.06 98.14

Tiles concrete 24.68 0.00 4.00 61.00 28.68 50 10 0.06 117.24

Slate 68.61 0.00 4.00 61.00 72.61 100 10 0.07 133.24

Non-metal Flat

Asphalt 14.44 0.00 6.00 69.00 20.44 20 20 0.20 134.54

Bitumen felt 19.24 0.00 3.00 69.00 22.24 20 20 0.22 143.84

Source: – ECRC 1997.

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Section 9 - Glossary, Reference and Further Information

GlossaryAdmiralty brass 70/30 brass with 1% tin added for extra corrosion resistance.

Ageing Hardening an alloy by heating to a temperature where a precipitate formsfrom a super-saturated solid solution.

Alpha brass Brass containing up to 36% of zinc is usually the single alpha phase withgood cold working properties.

Alpha-beta brass Brass containing over 36% of zinc or with other additions usually has twophases present, alpha and beta.

Aluminium brass High copper brass with aluminium added for improved corrosion resistance.This is often used for condenser tubes.

Aluminium bronze Copper-aluminium alloy with up to 13% of aluminium, usually also withother additions such as iron, manganese, nickel and/or silicon.

Annealing Heating a metal in order to soften it after hardening by cold work or heattreatment.

Anode copper Cast slabs of copper from the fire refining processes used as starters forelectrolytic refining.

Antlerite Copper sulphide ore.

Arsenical copper Copper with arsenic additions used primarily for the manufacture of boilerfireboxes.

Arsenical brass Brass with improved corrosion resistance containing arsenic, and frequentlyaluminium.

ASM American Society for Metals.

ASTM American Society for Testing and Materials, responsible for standards formetals.

Azurite Copper carbonate ore.

Backwardation LME term used when the price for cash copper commands a premium overthe price for copper in three months time. Caused by temporary shortages inspot supplies.

Beryllium copper Heat treatable copper-beryllium alloy of high strength and hardness.

Beta brass A brass with very high zinc content may be mostly of beta structure. This isbrittle and used only as a brazing filler alloy.

Blue vitriol Copper sulphate.

Bordeaux mixture Copper sulphate-lime mixture used as an adherent fungicide, especially forgrapevines.

Bornite Copper sulphide ore.

Brass Copper-zinc alloy, also used to describe a memorial plate in a church,coinage or bearing block. Originally the term also covered copper-tin alloysnow called bronzes. Also used to describe a tin-zinc spelter made for themanufacture of organ pipes.

Brass lump Miners term for massive iron pyrites (fools’ gold).

Brinell Hardness Standard hardness test using a specified load on a ball indenter (HB).

Bronze Copper-tin alloy, term also loosely used for some other copper alloys.

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Burgundy mixture Solution of copper sulphate and sodium carbonate developed in 1885 for theprevention of mildew and other diseases on grape vines.

Busbars Copper bar or section used for carrying heavy currents. Busbars aregenerally rigid when compared to cables.

Cadmium copper Copper with an addition of cadmium for good strength and wear resistancewithout significant loss of conductivity.

Cathode copper Pure copper, the product of electrolytic refining supplied for melting for themanufacture of products.

Cartridge brass 70/30 brass with good cold working properties.

CEN European Standards Organisation. ‘EN’ standards are being adopted by allEuropean countries.

Chalcocite, copperglance

Cuprous Sulphide ore.

Chalcopyrite Copper sulphide ore.

Chrysocolla Copper silicate ore.

Cold working Deforming a metal at a temperature below that of recrystallisation so that themetal hardens.

Continuous casting Production method for castings where the molten metal is continuouslypoured into an open mould while the solidified metal is slowly withdrawnand coiled or cut to length by flying saw. May be a vertical, sidecasting orupcasting process.

Common brass 63/37 brass, standard cheap brass for cold working. It is now usually a 64/36alloy to give improved corrosion resistance.

Contango LME term applied when the price quoted for copper due for delivery in threemonths’ time is higher than that for cash copper on that day. This is thenormal market situation, financing the interest charge.

Copper bottom To sheath the bottom of ships with copper to prevent attack by the Toredoworm and prevent the attachment of biofouling including molluscs that slowthe ship, first applied to British ships in 1761. Now used as a term ofassurance of quality.

Copper head A venomous snake, common in the United States of America

Copper-nickel Covers copper alloys with less than 50% of nickel.

Copper nose Slang term for inflamed nose, acne rosaaca, a bacterial infection treatable byantibiotics.

Copper plate A polished plate of copper on which a design is engraved for printing.

Copper wall Term used in sugar making to describe a double row of copper pans servedby a common fire.

Covellite Copper sulphide ore.

Cuprite Copper oxide ore.

Cupronickel Obsolete term for copper-nickel alloy.

Deep drawing Forming hollow components by using a punch and die to give significantplastic deformation.

Deoxidised copper Copper that has had deoxidiser added to reduce oxygen. Phosphorus iscommonly added but other elements such as boron or magnesium may beused.

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Dezincification Selective corrosion of the beta phase of duplex brass that leaves a copperresidue under a ‘meringue’ of zinc oxide.

DIN German National Standards Organisation

DGS Director General Ships standards (obsolete, replaced by NES series)

DHP Phosphorus deoxidised copper (previously known as ‘Dona’ copper).

DLP Deoxidised copper, low phosphorus.

DTD Directorate of Technical Development, military specifications.

Drawing The process of pulling a metal through a die to reduce the cross section,usually performed cold.

Ductility Ease with which material can be formed, for example by drawing, bending orrolling. The property is usually measured as elongation in a tensile test or bya bend or deep-drawability test.

Duplex brass See alpha-beta brass.

ECI European Copper Institute

ETP Electrolytic tough pitch copper, standard high conductivity copper.

Extrusion A hot working process in which a heated billet is forced to deform by beingpushed through a die to produce a long product of uniform cross-section.

Extrusion ratio The ratio of the cross-sectional area of a billet to that of the extrudedproduct.

Fire-refined copper Copper refined by melting and processing in an open hearth or rotaryfurnace.

Galvanic compatibility When exposed to seawater, metals show a voltage dependent on theelectrochemical series. Metals with near-similar voltages are compatible.Metals with differing voltages are likely to cause galvanic corrosion.

German silver Obsolete term for nickel silver.

Gilding metal Brass with high copper, usually 90/10 but sometimes 80/20.

Gunmetal Copper-tin-zinc alloy.

Heat treatable alloy An alloy capable of being strengthened by heat treatment, usually involvingsolution treatment followed by ageing (precipitation) treatment.

High conductivitycopper

Standard form of copper with a purity giving a conductivity of 100% IACSor more.

High tensile brass Brass with additions, typically iron, nickel, manganese and/or aluminium togive better strength and, usually, better corrosion resistance.

Hipping A proprietary process for treating metals at very high pressures to compactthem to produce good properties.

Hot working Plastic deformation of a metal at a temperature high enough to promoterecrystallisation, thus preventing cold working.

IACS International annealed copper standard, a value for conductivity agreed in1913 with copper being given the value of 100%, equivalent to 58MS/m or amass resistivity of 0.15176 .g/m2. High conductivity copper is nowfrequently of 101.5% conductivity.

ICA International Copper Association.

INCRA International Copper Research Association, now superseded by ICA.

ISO International Standards Organisation.

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Leaded brass Usually a duplex brass with an addition of lead to give excellentmachinability.

LME London Metal Exchange.

Malachite Copper carbonate ore.

Manganese bronze Obsolete term for high tensile brass.

MIL American Military specifications.

Monel A nickel-copper alloy, usually 70/30, originally produced directly from acopper-nickel ore in Sudbury, Ontario.

Muntz metal A 60/40 brass with good castability and hot working properties.

Naval brass 60/40 brass with 1% tin added for extra corrosion resistance.

Near net shape forming Forming a product near to final shape so that it needs little further finishing.

NES Naval Engineering Standards.

Nickel silver Copper-nickel-zinc alloy.

Oxygen-free copper Copper melted and cast under controlled atmosphere to give low residualoxygen content.

Oxygen-free electroniccopper

Oxygen free copper containing low residual volatile elements.

Patina A protective film that develops on copper on exposure to the atmosphere. Inmost non-polluted environments it is basic copper carbonate but in industrialand urban areas it is mainly basic copper sulphate.

Paris Green Copper-arsenic compound.

Phosphor bronze A copper-tin phosphorous alloy, hard and strong.

Poling Part of the old fire refining process that involves reducing the oxidisedcharge by submerging green wood in the liquid copper.

Red Brass American term for copper-tin-zinc alloy (gunmetal).

Rivet brass American term for common brass.

Rockwell Hardness Standard American hardness test with several ranges of loads and indenters,HRB, HRC.

SAE Society of Automotive Engineers (USA)

Tough pitch copper Obsolete term for copper containing oxygen at about 0.03-0.07% which gavea level ‘set’ to the top of a wirebar when statically cast horizontally .

Verdigris A strikingly green corrosion product that forms on copper in somecircumstances, a complex basic copper acetate. Unlike a patina, it is water-soluble.

Vickers Hardness Standard hardness test using a load on a diamond pyramid indenter (HV,VPN or VHN).

Wrought product Component made by hot or cold deformation of a cast product, removing theoriginal cast structure.

Yellow brass American term for 67/33 brass.

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Table 8 – Abbreviations for chemical elements used as alloying additions or found as impurities

Al Aluminium

Ag Silver

As Arsenic

Au Gold

B Boron

Be Beryllium

Bi Bismuth

Cd Cadmium

Co Cobalt

Cr Chromium

Fe Iron

Mn Manganese

Nb Niobium

Ni Nickel

P Phosphorus

Pb Lead

S Sulphur

Si Silicon

Sb Antimony

Sn Tin

Te Tellurium

Zn Zinc

Zr Zirconium

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References and Further information• Contact the CDA Information Service for a full list of publications, Email:

[email protected], Website: www.cda.org.uk, Online enquiry form:www.cda.org.uk/enquiry-form.htm.

• CDA has a selection of wallcharts with teachers’ notes.

• Rio Tinto London, 6, St James’s Square, London SW1Y 4LD have available materialdescribing exploration for metals and the mining and extraction of copper.

Other sources of information include

• The Science Museum, London.

• Local and University libraries.

InternetMany subjects are covered in good detail on the ‘Copper Page’, located athttp://www.copper.org. This includes details of copper centre activities throughout the world,articles on many topics, illustrations and full access to the thousands of references accessiblethrough the Copper Data Centre (CDC).

References1. V Callcut, D Chapman, M Heathcote and R Parr, ‘Electrical Energy Efficiency’ CDA

Publication No 116, 1997, 80pp.

2. ‘Copper for Busbars’, CDA Publication No 22 1984 64pp.

3. T Charlton, ‘Earthing Practice’, CDA Publication 119 1997, 69pp.

4. 'Electrical Design - a Good Practice Guide' CDA Publication No 123, December 1997,76pp.

5. ‘Copper Alloy Bearings’, CDA Publication No 45, 1992, 26pp.

6. ‘Copper in Roofing’, CDA Publication No 32, 1985, 68pp.

7. ‘Architectural Brass’, CDA Publication No 89, 1981, 8pp.

8. V A Callcut, ‘Design for Production’, CDA Publication No 97, 1994, 64pp.

9. ‘Copper and Copper Alloy Castings’, CDA Publication No 42, 1991, 40pp.

10. US Government Geological Survey Report, 1997.

11. Scientific Counsel for Government Policy, Holland

12. ‘Copper in Plant, Animal and Human Nutrition’, CDA Book 35, 81pp.

13. ‘Copper and Human Health’ CDA Publication No 34 10pp 1985.

14. ‘Which Metals are Essential for Human Health? R A Goyer, International Council onMetals and the Environment Newsletter Vol 5 No 2, 1997, p5.

15. ‘Copper in Farming’, CDA Book No 2, 1971, 11pp.

16. ‘Uses of Copper Compounds’ CDA Technical Note TN11, 1974, 11pp. (out of print)

17. see ref 2

18. ‘High Conductivity Coppers- Properties and Applications’ CDA Book No 122, 1997, 32pp.

mailto:[email protected]


http://www.cda.org.uk/enquiry-form.htm

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19. ‘Aluminium Bronze – Essential for Industry’ CDA Publication No 86, 1998, 8pp.

20. ‘Aluminium Bronze Corrosion Resistance Guide’, CDA Publication No 80, 1981, 28pp.

21. ‘Welding Aluminium Bronzes’ CDA Publication No 85, 1980, 7pp.

22. ‘Aluminium Bronze Alloys – Technical Data’, CDA Publication No 82, 1981, 93pp.

23. ‘Design in Brass’, CDA Publication No 133, 1998, 8pp.

24. V A Callcut, ‘The Brasses – Design Compendium’, CDA Publication No 117, 1996, 68pp.

25. Hawke Cable Glands, quoted in ‘Design in Brass’, CDA publication No 133,1998, 8pp.

26. ‘Copper-Nickel Alloys’, CDA Publication No 30, 1982, 22pp.

27. ‘Copper-Nickel Alloys – Technical Data’, CDA Publication No 31, 1982, 20pp.

28. ‘Materials for Seawater Systems’, CDA Publication No 38, 1986, 10pp.

29. ‘Copper-Nickel Cladding for Offshore Structures’, CDA Publication No 37, 1986, 10pp.

30. ‘Copper-Nickel Cladding on Ships and Boat Hulls’, CDA Publication No 36, 1985, 12pp.

31. See ref 7.

32. ‘Machining Brass, Copper and Copper Alloys’, CDA Publication No 44, 1992, 66pp.

33. L. Brown, ‘Joining of Copper and Copper Alloys’, CDA Publication No 98, 1994, 44pp.

34. ‘Clear Protective Coatings for Copper and Copper Alloys’, CDA Publication No 41, 1991,16p.

35. ‘Coppers and Copper Alloys - Composition and Properties’, CDA Publication No 120,1997, 22pp

36. B Webster Smith, ‘Sixty Centuries of Copper’, CDA Publication No 69, Hutchinson,London 1965. (out of print)

37. De Re Metallica, Geogius Agricola, 1556, translated by H C and L H Hoover, 1950, DoverPublications Inc. New York.

38. G W Preston, ‘Copper through the Ages’, CDA Publication No 3, 62pp 1934, quotingGowland, ‘Copper and its Alloys in Early Times’, J Inst. Met 7, (1912) pp 35-36.

Copper Development Association5 Grovelands Business CentreBoundary WayHemel HempsteadHP2 7TE

Website: www.cda.org.ukEmail: [email protected]


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