TYPES OF ALLOYS

An alloy is a homogeneous mixture of two or more metals and non-metals.Alloys containing mercury as three constituent element are called amalgams Alloy containing mercury (a liquid at ordinary temperature for example sodium

amalagam is an alloy of sodium and mercury. Chemically , alloys may be a mixture or solid solution of constituent in one another.

TYPES OF ALLOYS

•Ferrous Alloys –

•Alloy having iron as main constituent are called ferrous alloys. For example , steel is an alloy of iron and carbon.

•Non Ferrlous- •Alloy which don not have iron as one of the main constituent are called non ferrous alloys.

For example , brass is an alloy of copper and zinc.

Pure metal possess useful physical properties like high malleability , ductility, luster and good electrical conductivity. But they are very soft and highly chemically b reactive. These

properties make them poor shock wear and chemical resistant. The properties of a given metal can be improved by alloying it with some other metal and non-metal.

The main purpose of making alloy are as follows;

1. To improve the hardness of metals: Pure metals are generally soft. The hardness of a metal is enhanced by alloying it with other metal and non metal. An alloy is harder than is

component element. For example, gold and silver become harder on alloying them with them copper.

2. To lower the melting point of metals: When a metal or non metal is added to metal , the melting pint of metal is zero. In general, the melting point of an alloy is ,lower than

those of its constituent elements. This fact is utilized in making useful alloy called solder. A solder possess lower melting point than the metal to be soldered and should contain the

some metal of its constituents.

3. To increase the tensile strength : Alloy formation, in general , enhance the tensile strength of the base metal . consequently alloy with desired tensile can be prepared to suit

the given purpose. Addition of 1% carbon increase the tensile strength of pure iron by about ten times.

1. STAINLESS STEEL:

Stainless steel is an alloy steel which resists corrosion by atmosphere and by chemical.

Stainless steel contains essentially chromium together with other element such as nicked, molybdenum . Chromium is especially effective if its content is 16% or more. The protection against corrosion is due to various formation of dense , tough film of chromium oxide at the

surface of metal.

Types of stainless steel:

a) Martensitic stainless steel: This steel contains chromium from 0% to 14%. These are magnetic in nature and can be hardened by heat-treatment. They show remarkable resistance

to weathering and attack by fruit and vegetable acids,ammonia and other corrosive agents.

USES

A. It is used for pumps and valve parts.

B. It is used for making surgical instruments.

C. It is used for making turbine brackets.

D.

b. Ferritic Stainless Steel : This steel contains chromium in two ranges either 14-18% Cr or 20-30% Cr. These are not ameable to heat treatment and their structure can only be refined by re- crystallization after cold working. The micro-structure consist of ferric grains and carbide particles. This steel possess considerable ductility, ability to be work cold or hot and excellent corrosion resistance. These are relatively expensive. Chromium content is kept at about 25-

30%for resisting oxidation at high temperature.

1. It is used for lining in petroleum industry.

2. It is used for interior decorative work. 3. It is used for making screen and fittings and is used for heating elements for furnaces.

c. Austenitic stainless steel : This is the most important group of stainless steel (CR 15-20 , Ni 7-10% and C = 0.5%) They are not amenable to heat treatment except to annealing by quenching from 1270 k. Their alloy

content kis high except to stabilize the austenitic even at room temperature. A widely used category of this stainless steel is known as 18/8 stainless steel contains 18% chromium and 8%

nickel.

USES: 1. It is used in making utensils.

2. It is used for making trailers and railway cars..

2. NICKEL STEEL: Nickel steel improves tensile strength, ductility, toughness, elasticity, heat and corrosion resistance of steel.

1) Invar steel: It is an alloy steel containing : C = 0.3 – 0.5%

NI = 30-36% Fe = 63.5%

Uses

1. It has practically zero co-efficient of expansion. It is used for making measuring taps, clocks pendulums, surveyour instruments , wheels of watches and balances etc.

3. Alnico steel: It or Aluminium Nickel-Coblat is an alloy of aluminium, nickel,cobalt and steel containing:

Al= 12%

Ni=20%

Co=6%

Fe=40% with traces of C

USES: It is highly magnetic and used for making powerful permanent magnets.

4. Copper Alloys : Copper and its alloys rank next to steel as engineering materials. The most important copper alloy of commercial importance is given in table no. 4.

Copper alloy table.

ALLOYS COMPOSITION CHARACTERSTICS USERS

Brasses

Cu=60-90% Zn=40-10%

They posses greater strength , durability and mechanicability than original copper. They have good corrosion resistance against water.

The main brasses are:

(i)Commercial brass of French gold. (ii)Dutch metal or low brass

Cu=90% Zn=10% Cu=80% Zn=20%

Golden in colour. Stronger and harder than pure copper. Golden in colour, sutaible for all drawing and forming operations.

Used for making hardware screws , forgings ,rivets and jewellery. Used for making cheap jewellery, musical instruments, name plates and flexible hoses.

(i) German sliver

Contains metal (s) other Cu=25-50% Zn=10-35% Ni=5-35%

It has extremely ductile, malleable and looks like silver and have good Strenth.

Used for making utensils, bolts,screws and decorative articles.

(ii)Admiralty brass or Tobin bronze

Cu=70% Zn=29% Sn=1%

It posses high corrosion and abrasion resistance.

For propeller and marine works.

Composition: Nichrome is usually is an alloy of nickel and chromium. Nichorme word itself shows its composition Ni

‘chrome’ stands for chromium. It contain NI=60%,Cr=12%,Mn=2% and Fe=26%.

Properties:

It is chemical and heat resistant.

It has high electrical resistance.

It possess high melting point and is not easily oxisied in air on heating

USES

• It is used for making resistant coil, heating elements in stoves, electri cirons and other electric appliances.

COMPOSITION : It is an alloy of aluminium containing Al=95% , Mg=0.5% and Mn=0.5%.

PROPERTIES

• It is light, tough , highly ductile and good conductor of heat and electricity.

• It can easily be worked and possess high machinability.

• It approaches steel in strength and yet it is density is one third of steel.

• It hardness spontaneously when exposed to room temperature.

USES

1. It is used in making cables.

2. It is used for sheets, tubes, rivets , nuts and bolts etc.

3. It is used for aeroplanes and other machines where weight is a deciding factor.

4.

(7)MAGNALIUM:

Composition: It is only an alloy of aluminium and magnesium containing Al=70-9-% and Mg = 30-10%

Properties:

•It is quite strong, tough and lighter than Al

•It possesses mechanical properties similar to brass.

USES

It is used for making cheap balanced , aeroplanes parts and scientific instruments.

It is also used for coffee grinder parts.

CONTROLLING ON CORROSION

The loss of metals due to corrosion is

causing great concern to the nations

of the world. Efforts are being made

to prevent this loss by saving metals

From corrosion. Some important

measures for protection of metals

are given below:

1.Alloying of metals:

Noble metals like platinum and gold are

corrosion-resistant, whereas most of the

other metals suffer corrosion if used alone.

The corrosion resistance of some of they can

be improved by alloying them with suitable

metals or non-metals. The alloy formed

should be uniform and homogenous. Alloy of

steel with chromium prevents corrosion of

the metal to a large extent.

2.Providing Metallic Coatings:

The life of certain metals can be prolonged

by applying coatings of some corrosion

resistant metals on their surfaces. Such

coatings act as a barrier and Prevent the

penetration of the environment to the

material it protects. The metallic coatings

often used are Zinc, Tin, Nickel, Copper,

Chromium, Aluminum and Lead. Metallic

coatings are usually applied in one of the

following ways:

a. Hot dipping method:

In this method, the metal to be coated is dipped in a

bath containing superior molten metal. It is kept in the

bath for a sufficient time and then removed with the

adhering film. However, care is taken that the

melting point of base metal should be much higher

than the coating metal. Generally, this method is used

for applying coatings of low melting metals and

alloys such as Zinc, Tin and Lead. The process of

providing Tin coating on iron is called tinning. The

iron on which zinc has been coated is known as

galvanised iron.

b. By Electroplating:

In this method, the metal to be protected is thoroughly

cleaned and made cathode in an electrolytic bath.

The coating metal in pure form is taken as anode. An

electrolyte containing a suitable salt of the metal to

be coated is added in the bath. On passing a current

a coating of the superior metal is obtained on the

base metal. The nature of the deposit depends on the

current density, concentration of electrolytic solution

and temperature of the bath. This is an important

method for importing coatings of metals such as

Copper, Zinc, Nickel, Gold, Silver Chromium.

c. Metal Cladding:

It is the process by which a homogenous and

dense layer of coating metal is bonded firmly

around the surface of metal to be coated. The

thin sheets of coating metals are sandwiched on

the surface of sheets of base metals. These are

then passed through rollers under the action of

heat and pressure. The metals unite and stick

fast with each other. Metals like nickel alloys

and copper alloys can be used as cladding

materials. This method is not suitable for rough

and non-uniform surfaces.

d. Metal Spraying:

This is a fine and easy method. In this method, the

metal to be coated in the molten state is filled in a

spray gun and then sprayed on the cleaned base

metal. This method is very useful, because:

i. Coating can be applied at any desired cost.

ii.Large surface can be coated in a short duration of

time.

iii.Coating of desired thickness can be obtained.

iv.Coating can be applied even on non-metallic bases

made of glass, wood, plastic.

However, this method is limiting to low-melting metals

like Zinc, Lead, Tin.

e. Cementation:

In this method, the metal to be coated is packed in the

powdered coating metal along with a filler and

packed in boxes. The boxes are then heated to a

temperature just below the melting point of more

fusible metal. An alloy of the metals is formed by the

diffusion of coating metal into the surface of metal to

be coated. The cementation of zinc with iron and

steel is called sherardizing. Diffusion of Al in iron

and steel is called colorizing and with that of Cr

and Si is called chromizing and siliconizing

respectively.

3. Cathodic Protections:

The principle involved in this method is

to force metal to be protected to

behave like cathode, thereby,

preventing corrosion. It can be carried

in two ways:

a)Sacrificial anodic protection method,

and;

b)Impressed current cathodic protection.

a)Sacrificial anodic protection method:

In this method, the metal which is used for coating

is more ‘anodic’ than the metal which is to be protected i.e., the base metal. Anodic coatings

protect the underlying base metal sacrificially.

Metals commonly employed as sacrificial

anodes are Mg, Zn, Al and their alloys.

Important applications of sacrificial anodic

method are protection of buried pipelines,

underground cables, water tanks and ship hulls.

b) Impressed current cathodic protection:

In this method, current is applied from opposite

direction to nullify the corrosion current and convert

the corroding metal from anode to cathode. Usually,

the impressed current is derived from an external

source like a battery or rectifier on A.C. line. An

insoluble anode like graphite or stainless steel is

buried (or immersed in the corroding medium) and

connected to the structure to be protected through the

source of D.C. current. This method is generally used

to protect open water boxes, coolers, water-tanks

and ships for long period of time.

EXTRACTION OF COPPER

THERE ARE VARIOUS TYPE OF EXTRACTION OF COPPER:-

1).CONCENTRATION

2).ROASTING

3).SMELTING

4).BESSEMERISATION

5).ELECTROLYTIC REFINING

CONCENTRATION

• THE ORES ARE GENERALLY

ASSOCIATED WITH EARTHY

AND SILICEOUS IMPURITIES

CALLED GANGUE OR

MATRIX. THE REMOVAL OF

THESE IMPURITIES IS KNOWN

AS CONCENTRATION.

ROASTING & SMELTING

• ROASTING IS THE

PROCESS OF HEATING

THE ORE STRONGLY

IN THE PRESENCE OF

EXCESS OF AIR AT A

TEMPERATURE BELOW

ITS MELTING POINT.

THESE PROCESS IS

COMMONLY USED

FOR THE

CONCENTRATION OF

SULPHIDE ORE IS

KNOWN AS

ROASTING.

The rosted ore is

mixed with sand

(flux) and little coke

and heated

strongly in a blast

furnace is known as

smelting

2FeS + 3O2

2FeO + 2SO2

FeO + SiO2

FeSiO3

BESSEMERISATION

• THE MOLTEN MATTE IS TAKEN IN A PEAR SHAPED BESSEMER CONVERTER.

WHICH IS LINED INSIDE WITH CALCIUM OXIDE OR MAGNESIUM OXIDE

AND BLAST OF AIR DURING SMELTING IS OXIDISED TO FERROUS OXIDE.

• 2CU2S + 3O2 2CU2O + 2SO2

• 2CU2O + CU2 6CU + SO2

REFINING OF COPPER

• THE IMPURE COPPER PLATE IS MADE THE ANODE THIN SHEET OF PURE METAL IS

MADE AS COPPER FROM THE ELECTROLYTE GET DEPOSITED AT THE CATHODE,

WHILE THE EQUIVALENT AMOUNT OF COPPER FROM ANODE DISSOLVE INTO THE

ELECTROLYTE.

EXTRACTION OF IRON

Extraction of iron

• Process involved in the

extraction of iron.

1.Crushing and

pulvarisaton.

2.Concentration.

3.Calcination and

roasting.

4.Smelting.

5.The blast furnance.

Crushing and pulvarisation.

Big particles of iron ore are cushed

Manually by the help of jaw crusher

To get in small form and further

Crushed up to get in powdered form

Concentration • The crushed or pulvarised particles are then

Concentrated in a beaker by the process of gravity separation

In gravity seperation process

The ore which are agitated with

Sand and clay is washed by

which the impurities get

washed.

The washed ore is then

subjected

To electomagnetic eparation in

which magnetic ore particle are

seperated from non magnetic

impurities.

Calcination and roasting.

The concentrated ore is then heated in

shallow kilns in the presence of oxygen

strongly. Fowllowing changes Takes place during calcination.

1. Most of the moisture is removed

2.Impurities like sulphur and aresenic are removed in the form of their volatile

Matter

3.Carbonates decomposed into oxides.

FeCo3----FeO+CO2

4. Sulphides ore converted to oxides.

Smelting.

The calcined ore is mixed with suitable

quantity of coke (reducing agent) and lime

(flux) and then smelted in blast furnance.

The blast furnance.

Working of the blast furnance

The blast furnace is made

up of steel li ed with fire

bricks it is about 30 m high

and 8 m in diametre. It has

three zones.

1. Zone of combustion

2. Zone of reduction

3.Zone of slag formation.

It is used to get the pure

iron.

Thank you

TYPES OF FUELS

What is fuel?

Fuels are defined as the combustible substance which on burning produce energy in the form of heat.

TYPES OF GASEOUS FUELS:- 1. NATURAL GAS

2. L.P.G GAS

3. C.N.G GAS

4. WATER GAS

5. COAL GAS

6. OIL GAS

7. BIO GAS.

8. PRODUCER GAS

The naturally occurring gases fuel is know as natural gas. It mainly consist of methane and some saturated hydrocarbon. It is generally associated with parolium gas.

COMPOSITION: Methane 85%,Ethane 8%

Propane 4%,Butane 1.5% remaining hydrocarbons

USES: It is mainly use for domestic purpose.

Properties:- It is having calorific value 12000to 14000 kgcal/m3

NATURAL GAS:

• It is having hydrocarbon containing 3 to 4

carbon atoms the maximum ratio of

butane ,which is followed by small amount

of propane & propene .

• USES:- It is having mainly use in gas

calendar in domestic .

• Properties:- Calorific value 27800kgcal/m3

L.P.G

C.N.G

It is known as (compressed natural gas)

which is produce by compressing at a very

high temperature the main consistent is

methane and small amount of ethane and

propane are also present.

USES:- It is mainly use in automobile industry.

WATER GAS

It is formed by the mixture of carbon monoxide and hydrogen.

Composition :- carbon monoxide - 41%

Hydrogen. - 51%

Carbon dioxide - 4%

Nitrogen. -4%

Properties:- 1) Due to the presence nitrogen it formed blue flame over burning due to which it is also known as blue water gas.

2) presence of carbon mono oxide makes a poisonous .

3) It's calorific value is 3200kgcal/m3.

4) The temperature for burning is 1200•c .

USES:- It us mainly use in commerical area.

It is produce by heating coal at a of 300•c.in a presence of air.

Properties:- It is having calorific value value 5000kgcal/m3.

Uses:- It is mainly use in metallurgical process.

Composition:- Hydrogen 45% to 48%

Methane 30 % to 35 %

Carbon mono oxide 1%

Acitiality 2%

Eathileane 2%

Nitrogen 4to 8%

Carbondioxide 1%remaining hydrocarbon.

COAL GAS

It is produce by kerosene oil into lower form of

hydrocarbon

COMPOSITION:- Methane-25%to 30%

Hydrogen - 50to 55%

Carbon monoxide -10 to12%

Carbon dioxide- 3%

PROPERTIES:-Calorific value 4500- 5400kgcal/m3

USES:- It is manually use in commercial area.

OIL GAS

• It is produce bio logical bacterial degradation of bio matter.

• COMPOSITION:- Methane 55%

Carbon dioxide 25%

Hydrogen 8%

Nitrogen 2%

USES:- It is mainly used in village for domestic purposes.

PROPERTIES:- Calorifi value 2000kgcal/m3.

BIO GAS

Producer gas

It is formed by the combination of carbon monoxide and nitrogen.

Composition:- Carbon monoxide 35%

Nitrogen 65%

Small traces of carbon dioxide and hydrocarbon are also present.

Properties:- 1) Due to the presence of carbon monoxide . It is positive in nature. 2) It is calorific value is 1300 kgcal/m3

USING:- It is mainly use in opoen hearth process and muffed furnaces