ashu project of metals

8/10/2019 Ashu Project of Metals

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AluminiumAluminium is achemical element in theboron group with symbol Alandatomic number 13. It is a silverywhite, soft, ductilemetal.Aluminium isthe third most abundant element (afteroxygen andsilicon), andthemost abundant metal in theEarth'scrust.It makes up about 8% by weight of the Earth's solid surface.Aluminium metal is so chemically reactive thatnative specimens are rare and limited to extremereducingenvironments. Instead, it is found combined in over 270 differentminerals.[5]The chiefore of aluminiumisbauxite.Aluminium is remarkable for the metal's lowdensity and for its ability to resistcorrosion due to the phe-nomenon ofpassivation.Structural components made from aluminium and itsalloys are vital totheaerospace industry and are important in other areas oftransportation and structural materials. Themost useful compounds of aluminium, at least on a weight basis, are theoxides andsulfates.

CharacteristicsPhysicalAluminium is a relatively soft, durable, lightweight,ductile andmalleablemetalwith appearance rangingfrom silvery to dull gray, depending on the surface roughness. It is nonmagnetic and does not easily ig-nite. A fresh film of aluminium serves as a good reflector (approximately 92%) ofvisible light and an ex-

cellent reflector (as much as 98%) of medium and farinfrared radiation. Theyield strength of pure alumin-ium is 711MPa,whilealuminium alloys have yield strengths ranging from 200 MPa to 600MPa.[7]Aluminium has about one-third thedensity andstiffness ofsteel.It is eas-ilymachined,cast,drawn andextruded.

ChemicalCorrosion resistance can be excellent due to a thin surface layer ofaluminium oxide that forms when themetal is exposed to air, effectively preventing furtheroxidation The strongest aluminium alloys are lesscorrosion resistant due togalvanic reactions with alloyedcopper.[7]This corrosion resistance is also oftengreatly reduced by aqueous salts, particularly in the presence of dissimilar metals.

IsotopesAluminium has many knownisotopes,whose mass numbers range from 21 to 42; however, only 27Al

(stable isotope)and26

Al (radioactive isotope,t12= 7.2105

y)occur naturally.27

Al has a natural abun-dance above 99.9%. 26Al is produced fromargon in theatmosphere byspallation caused bycosmic-rayprotons.Aluminium isotopes have found practical application in datingmarine sediments, manganesenodules, glacial ice,quartz inrock exposures, andmeteorites

Natural occurrence

In theEarth's crust,aluminium is the most abundant (8.3% by weight) metallic element and the third mostabundant of all elements (after oxygen and silicon).[16]Because of its strong affinity to oxygen, it is almost
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never found in the elemental state; instead it is found in oxides or silicates.Feldspars,the most commongroup of minerals in the Earth's crust, are aluminosilicates. Native aluminium metal can only be found asa minor phase in low oxygenfugacity environments, such as the interiors of certain volcanoes.[17]Nativealuminium has been reported incold seeps in the northeasterncontinental slopeof theSouth ChinaSea and Chen et al.(2011)

[18]have proposed a theory of its origin as resulting byreduction from tetrahy-droxoaluminate Al(OH)4

to metallic aluminium bybacteria.Recycling

Aluminium is theoretically 100% recyclable without any loss of its natural qualities. According totheInternational Resource Panel'sMetal Stocks in Society report,the globalper capita stock of alumin-ium in use in society (i.e. in cars, buildings, electronics etc.) is 80 kg. Much of this is in more-developedcountries (350500 kg per capita) rather than less-developed countries (35 kg per capita). Knowing theper capita stocks and their approximate lifespans is important for planning recycling.

BronzeBronzeis analloy consisting primarily ofcopper.The addition of other metals (usuallytin,sometimesarsenic), produces an alloy much harder thanplain copper. The historical period where the archeological record contains many bronze artifacts is

known as theBronze Age.Because historical pieces were often made ofbrasses (copper andzinc)and bronzes with differentcompositions, modern museum and scholarly descriptions of older objects increasingly use the moreinclusive term "copper alloy"instead.

HistoryThe discovery of bronze enabled people to create metal objects which were harder and more dura-ble than previously possible. Bronze tools, weapons, armor, andbuilding materials such as decora-tive tiles were harder and more durable than their stone and copper ("Chalcolithic") predecessors.Initially, bronze was made out of copper andarsenic,formingarsenic bronze,or from naturally or arti-ficially mixed ores of copper and arsenic. It was only later that tin was used, becoming the majornon-copper ingredient of bronze in the late 3rd millennium BC.[6]Tin bronze was superior to arsenicbronze in that the alloying process could be more easily controlled, and the resulting alloy wasstronger and easier to cast.

PropertiesTypically bronze only oxidizes superficially; once a copper oxide (eventually becoming copper car-bonate) layer is formed, the underlying metal isprotected from further corrosion.However, if copperchlorides are formed, a corrosion-mode called "bronze disease"will eventually completely destroyit.[18]Copper-basedalloys have lowermelting points than steel or iron, and are more readily produced
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from their constituent metals. They are generally about 10 percent heavier than steel, although al-loys usingaluminium orsilicon may be slightly less dense. Bronzes are softer and weaker thansteelbronzesprings,for example, are less stiff (and so store less energy) for the same bulk.Bronze resistscorrosion (especially seawater corrosion) andmetal fatigue more than steel and is abetter conductor of heat and electricity than most steels. The cost of copper-base alloys is generallyhigher than that of steels but lower than that ofnickel-base alloys.

UsesBronze was especially suitable for use in boat and ship fittings prior to the wide employmentofstainless steel owing to its combination of toughness and resistance to salt water corrosion.Bronze is still commonly used in ship propellers and submerged bearings.It is also widely used for castbronze sculpture.Many common bronze alloys have the unusual andvery desirable property of expanding slightly just before they set, thus filling in the finest details ofamold.Bronze parts aretough and typically used forbearings,clips,electrical connect-ors andsprings.Bronze also has very low metal-on-metalfriction,which made it invaluable for the building ofcan-non where iron cannonballs would otherwise stick in the barrel.[19]It is still widely used today forsprings, bearings, bushings, automobile transmission pilot bearings, and similar fittings, and is par-ticularly common in the bearings of smallelectric motors.Phosphor bronze is particularly suited to

precision-grade bearings and springs. It is also used in guitar and piano strings.

CopperCopper is achemical element with symbol Cu (fromLatin:cuprum) andatomic number 29. It isaductile metal with very highthermal andelectrical conductivity.Pure copper is soft and malleable;a freshly exposed surface has a reddish-orange color. It is used as a conductor of heat and electrici-ty, a building material, and a constituent of various metalalloys.The metal andits alloys have been used for thousands of years. In the Roman era, copper was prin-cipally mined onCyprus,hence the origin of the name of the metal as yprium(metal of Cyprus),later shortened to uprum. Its compounds are commonly encountered as copper(II) salts, which of-ten impart blue or green colors to minerals such asazurite andturquoise and have been widely used

historically as pigments. Architectural structures built with copper corrode to givegreenverdigris (orpatina).Decorative art prominently features copper, both by itself and as part ofpigments.

Applications
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The major applications of copper are in electrical wires (60%), roofing and plumbing (20%) and in-dustrial machinery (15%). Copper is mostly used as a pure metal, but when a higher hardness is re-quired it is combined with other elements to make analloy (5% of total use) suchasbrass andbronze.[15]A small part of copper supply is used in production of compounds for nutri-tional supplements and fungicides in agriculture.[32][66]Machining of copper is possible, although it isusually necessary to use an alloy for intricate parts to get good machinability characteristics.

RecyclingLike aluminium, copper is 100% recyclable without any loss of quality, regardless of whether it is in araw state or contained in a manufactured product. In volume, copper is the third most recycled metalafter iron and aluminium. It is estimated that 80% of the copper ever mined is still in use to-day.[27]According to theInternational Resource Panel'sMetal Stocks in Society report,the global percapita stock of copper in use in society is 3555 kg. Much of this is in more-developed countries(140300 kg per capita) rather than less-developed countries (3040 kg per capita).The process of recycling copper is roughly the same as is used to extract copper but requires fewersteps. High purity scrap copper is melted in a furnace and thenreduced and cast in-tobillets andingots;lower purity scrap is refined by electroplating in a bath of sulfuric acid.

GoldGold is achemical element with symbol Au andatomic number 79. It is a bright yellow dense, soft,malleable andductilemetal.The properties remain when exposed to air or water. Chemically, gold isatransition metal and agroup 11 element.It is one of the least reactive chemical elements, and issolid understandard conditions.The metal therefore occurs often in free elemental (native) form,asnuggets or grains, in rocks, inveins and inalluvial deposits.Less commonly, it occurs in mineralsas gold compounds, such as withtellurium ascalaverite,sylvanite,orkrennerite.

As the metallicnative element mineral,gold structurally belongs to theisometriccopper group. It alsoforms asolid solution series with the native elementsilver (Ag) to which it is often naturally alloyed(electrum). Other common natural gold alloys are with copper andpalladium (Pd).Gold resists attacks by individual acids, but it can be dissolved byaqua regia(nitro-hydrochloric ac-id), so named because it dissolves gold. Gold also dissolves in alkaline solutions ofcyanide,which

have been used in mining. It dissolves inmercury,formingamalgam alloys; it is insoluble innitricacid,which dissolvessilver andbase metals,a property that has long been used to confirm thepresence of gold in items, giving rise to the termacid test.This metal has been a valuable and highly sought-afterprecious metal forcoinage,jewelry,and otherarts since long before the beginning ofrecorded history.In the past, theGold standard has been im-plemented as amonetary policy,but it was widely supplanted byfiat currency starting in the 1930s.The lastgold certificate andgold coin currencies were issued in the U.S. in 1932. In Europe, mostcountries left the gold standard with the start ofWorld War I in 1914 and, with huge war debts, didnot return to gold as a medium of exchange. The value of gold is rooted in its medium rarity, easyhandling, easy smelting, non-corrosiveness, distinct color and non-reactiveness to other elements;qualities most other metals lack.

A total of 174,100tonnes of gold have been mined in human history, according toGFMS as of2012.[2]This is roughly equivalent to 5.6 billiontroy ounces or, in terms of volume, about 9261 m3, or

a cube 21.0 m on a side. The world consumption of new gold produced is about 50% in jewelry, 40%in investments, and 10% in industry.[3]Besides its widespread monetary and symbolic functions, gold has many practical usesindentistry,electronics,and other fields. Its highmalleability,ductility,resistance to corrosion andmost other chemical reactions, and conductivity of electricity have led to many uses, includ-ingelectric wiring,colored-glass production, andgold leafing.Most of the Earth's gold probably lies at its core, the metal's high density having made it sink there inthe planet's youth. Virtually all discovered gold is considered to have been deposited laterbymeteorites that contained the element
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ki/Krenneritehttp://en.wikipedia.org/wiki/Sylvanitehttp://en.wikipedia.org/wiki/Calaveritehttp://en.wikipedia.org/wiki/Telluriumhttp://en.wikipedia.org/wiki/Alluvial_deposithttp://en.wikipedia.org/wiki/Vein_(geology)http://en.wikipedia.org/wiki/Gold_nuggethttp://en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressurehttp://en.wikipedia.org/wiki/Group_11_elementhttp://en.wikipedia.org/wiki/Transition_metalhttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Ductilehttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Ingothttp://en.wikipedia.org/wiki/Billet_(semi-finished_product)http://en.wikipedia.org/wiki/Redoxhttp://en.wikipedia.org/wiki/Metal_Stocks_in_Society_reporthttp://en.wikipedia.org/wiki/International_Resource_Panelhttp://en.wikipedia.org/wiki/Copper#cite_note-27http://en.wikipedia.org/wiki/Machininghttp://en.wikipedia.org/wiki/Copper#cite_note-Boux-32http://en.wikipedia.org/wiki/Copper#cite_note-Boux-32http://en.wikipedia.org/wiki/Copper#cite_note-emsley-15http://en.wikipedia.org/wiki/Bronzehttp://en.wikipedia.org/wiki/Brasshttp://en.wikipedia.org/wiki/Alloy


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ProductionAt the end of 2009, it was estimated that all the gold ever mined totaled 165,000 tonnes.[2]This canbe represented by a cube with an edge length of about 20.28 meters. At $1,600 pertroy ounce,165,000 metric tonnes of gold would have a value of $8.5 trillion.

IronIronis achemical element with symbolFe(fromLatin:ferrum) andatomic number 26. It is ametal in

thefirst transition series.[3]It is by mass the most common element on Earth, forming much of

Earth'souter andinner core.It is the fourth most commonelement in the Earth's crust.Its abundance

inrocky planets likeEarth is due to its abundant production byfusion in high-massstars,where the

production ofnickel-56 (which decays to the most common isotope of iron) is the lastnuclear fusion

reaction that isexothermic.Consequently,radioactivenickel is the last element to be produced before

the violent collapse of asupernova scattersprecursorradionuclide of iron into space.

Like othergroup 8 elements,iron exists in a wide range ofoxidation states,2 to +6, although +2 and

+3 are the most common. Elemental iron occurs inmeteoroids and other lowoxygen environments, butis reactive to oxygen andwater.Fresh iron surfaces appear lustrous silvery-gray, butoxidize in normal

air to givehydratediron oxides,commonly known asrust.Unlike many other metals which

formpassivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, expos-

ing fresh surfaces for corrosion.

Iron metal has been used sinceancient times,thoughcopperalloys,which have lower melting temper-

atures, were used even earlier in human history. Pure iron is soft (softer thanaluminium), but is unob-

tainable bysmelting.The material is significantly hardened and strengthened by impurities, in particu-

larcarbon,from the smelting process. A certain proportion of carbon (between 0.002% and 2.1%) pro-

ducessteel,which may be up to 1000 times harder than pure iron. Crude iron metal is produced inblast

furnaces,where ore is reduced bycoke topig iron,which has a high carbon content. Further refine-

ment with oxygen reduces the carbon content to the correct proportion to makesteel.Steels and lowcarbon ironalloysalong with other metals (alloy steels)are by far the most common metals in industri-

al use, due to their great range of desirable properties and the abundance of iron.

Iron chemical compounds have many uses. Iron oxide mixed with aluminium powder can be ignited to

create athermite reaction,used in welding and purifying ores. Iron forms binary compounds with

thehalogens and thechalcogens.Among its organometallic compounds isferrocene,the

firstsandwich compound discovered.
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wikipedia.org/wiki/Nickel-56http://en.wikipedia.org/wiki/Starshttp://en.wikipedia.org/wiki/Nuclear_fusionhttp://en.wikipedia.org/wiki/Earthhttp://en.wikipedia.org/wiki/Rocky_planetshttp://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crusthttp://en.wikipedia.org/wiki/Inner_corehttp://en.wikipedia.org/wiki/Outer_corehttp://en.wikipedia.org/wiki/Iron#cite_note-3http://en.wikipedia.org/wiki/First_transition_serieshttp://en.wikipedia.org/wiki/Metalhttp://en.wikipedia.org/wiki/Atomic_numberhttp://en.wikipedia.org/wiki/Latin_languagehttp://en.wikipedia.org/wiki/Chemical_elementhttp://en.wikipedia.org/wiki/Troy_ouncehttp://en.wikipedia.org/wiki/Gold#cite_note-World_Gold_Council_FAQ-2


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Iron plays an important role in biology,forming complexes with molecular oxygen

inhemoglobin andmyoglobin;these two compounds are commonoxygen transport proteins in verte-

brates. Iron is also the metal used at the active site of many importantredoxenzymes dealing

withcellular respirationandoxidation and reduction in plants and animal

ApplicationsIron is the most widely used of all the metals, accounting for 95% of worldwide metal production. Its low

cost and high strength make it indispensable in engineering applications such as the construction of ma-

chinery andmachine tools,automobiles,thehullsof largeships,and structural components

forbuildings.Since pure iron is quite soft, it is most commonly combined with alloying elements to

make steel.

Commercially available iron is classified based on purity and the abundance of additives.Pig iron has

3.54.5% carbonand contains varying amounts of contaminants such assulfur,silicon andphosphorus.

Pig iron is not a saleable product, but rather an intermediate step in the production of cast iron and

steel. The reduction of contaminants in pig iron that negatively affect material properties, such as sulfur

and phosphorus, yields cast iron containing 24% carbon, 16% silicon, and small amounts

ofmanganese.It has amelting point in the range of 14201470 K, which is lower than either of its two

main components, and makes it the first product to be melted when carbon and iron are heated togeth-

er. Its mechanical properties vary greatly and depend on the form the carbon takes in the alloy.

SilverSilveris achemical element with symbolAg(Greek:rguros,Latin:argentum, both from

theIndo-Europeanroot *arg-for "grey" or "shining") andatomic number 47. A soft, white, lus-

troustransition metal,it possesses the highestelectrical conductivity of any element, the high-

estthermal conductivityof any metal and is the most reflective metal on the planet. The metal occurs

naturally in its pure, free form (native silver), as analloy withgold and other metals, and in minerals

such asargentite andchlorargyrite.Most silver is produced as a byproduct ofcopper,gold,lead,andzincrefining.

While silver has long been valued as aprecious metal it is also used in currencycoins,solar pan-

els,water filtration,jewelry and ornaments, high-value tableware and utensils (hence the

termsilverware)and as an investment in the forms of coins andbullion.Silver is used industrially in

electrical contacts andconductors,in specialized mirrors, window coatings and incatalysis of chemical

reactions. Its compounds are used inphotographic film andX-rays.Dilutesilver nitrate solutions and
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other silver compounds are used asdisinfectants and microbiocides (oligodynamic effect), added

tobandages and wound-dressings,catheters and other medical instruments.

CharacteristicsSilver is produced during certain types of supernova explosions bynucleosynthesis from lighter ele-

ments through ther-process,a form of nuclear fusion that produces many elements heavier thaniron,

of which silver is one.[2]

Silver is a veryductile,malleable (slightly harder thangold),univalentcoinage metal,with a brilliant

white metallic luster that can take a high degree ofpolish.It is the mostreflective metal on Earth.[3]It

has the highestelectrical conductivity of allmetals,even higher than copper, but its greater cost has

prevented it from being widely used in place of copper for electrical purposes. An exception to this is in

radio-frequency engineering, particularly atVHF and higher frequencies, where silver plating to im-

prove electrical conductivity of parts, including wires, is widely employed. DuringWorld War II in the

US, 13,540 tons were used in theelectromagnets used for enrichinguranium,mainly because of the

wartime shortage of copper

ApplicationsMany well-known uses of silver involve itsprecious metal properties, including currency, decorative

items, and mirrors. The contrast between its bright white color and other media makes it very useful to

the visual arts. By contrast, fine silver particles form the dense black in photographs and

insilverpoint drawings. It has also long been used to confer high monetary value as objects (such as sil-

vercoins and investment bars) or make objects symbolic of high social or political rank. Silver salts have

been used since the Middle Ages to produce a yellow or orange colors tostained glass,and more com-

plex decorative color reactions can be produced by incorporating silver metal in blown, kilnformed or

torch worked glass.
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