CHAPTER # 04NON FERROUS MATERIALS

Al, Cu, Zn, Mg, Tin and their alloys.

NON-FERROUS MATERIALS:

• Introduction. Non-ferrous material are those materials which does not contain the iron,

• or The non-ferrous metals and alloy include all the metals, which don’t contain iron as well as carbon, Cu, Al, Zn and Mg.

• Brass, Bronze (alloys) are the examples of non-ferrous metals & alloys.

• The non-ferrous metals and their alloys are used for special purposes in engineering field.

• The non-ferrous metals are generally used for parts requiring considerable fabrication & properties.

• No single property will be the basis for every choice, but one or more of the following criteria is often involved.

• Ease of fabrication, corrosion resistance, electrical & thermal conductivity, weight strength etc.

• In this regard we have described a few non-ferrous metals and their alloys with their properties and uses.

• ALUMINUM AND THEIR ALLOYS: • Aluminum is a silvery white metal with a brilliant luster,• it is light in wt: and low melting pt: (approx: 660OC). • It is malleable and ductile, it is good conductor of heat & electricity. • Al doesn’t occur in free form in nature but it widely distributed in

combined form as silicates, fluoride, and sulphate and an oxide on the surface of earth.

• It comes third in abundance after oxygen & silicon in nature since the demands have led to the development of Al technology and increase in production of metal until now it is second only to iron in the world.

• ORES:• Its important ores are given below.• (i). Silicate:• (a). Kaolin (Al2 O3.2SiO2.2H2O)• (b). Potash felspar (K2O.Al2O3.6SiO2)• (c). Potashmica (K2O.Al2O3.6SiO2.2H2O).

• (ii). Fluoride:• (a). Cryolite (Na Al F6)• (iii). Sulphate:• (a). Alunite [K2SO4.Al (SO4)3.4Al(OH)3]• (iv). Oxides:• (a). Bauxite (Al2O3.2H2O)• (b). Gibbisile (Al2O3.3H2O)• (c). Diaspore (Al2O3.H2O)• (d). Corundum (Al2O3)• Occurrence: • Consequently, most Al ores are found in USA,• Canada, Australia, India, France • Pakistan (Muzzferabad, Marcella, Tharparkar and Dist:

Dadu etc.)

• Processing of Aluminum: • Al is processed from its ore bauxite which is the chief ore of commercial

interest which contains about 55-60% Al2O3, 3-13% SiO2, 2-4% TiO2 and 10-18% hydrate water.

• Note: (The less silica in a bauxite the higher its quality as an Aluminum ore).

• The extraction /processing of Aluminum comprise two processes.• (i). Extraction of primary aluminum by the electrolysis of Alumina.• (ii). Purification of Aluminum.• (i). Extraction of primary aluminum by the electrolysis of

Alumina.• Hall Heroults Process.• Aluminum posses great affinity for oxygen and thus the reduction

of Al2O3 by carbon is not possible under ordinary conditions.• Because at high temperatures reduction takes places, but Al reacts with C

to for Al4C3. The reduction can be carried out by electrolytic, but this too encounters the following difficulties.

• (i). Pure Al2O3 has very high Melting Point (2000OC).• (ii). Al2O3 is a bad conductor of electricity.• (iii). If electrolysis of fused Alumina is carried out at 2000oC, Al formed

vaporizes • as its boiling pt: is about 1800OC.

• To obtained metallic aluminum, the Hall-Heroults (scientist) over come these difficulties by mixing Alumina with Cryolite (Na3 Al F6) and fluorspar (CaF2).

• Cryolite is used as a flux which lowers the melting pt: of the Alumina.

• Where by the mixture is becomes good conductor and is fused at about 900OC.

• Alumina undergoes electrolytes is in electrolyzing baths, also called aluminum reduction cells.

• This cell is consisting of an iron box lined with (inside) carbon, which serves as cathode (-ve charge).

• Carbon electrodes serving as the anode and connected to positive pole of power source, which are suspended above the cell from the control lamps.

• The bottom of the cell is included to wards a tapping hole from which we pour the aluminum.

Working of the cell.

Before beginning electrolysis the carbon electrodes are lowered into contact with lining at the bottom a current is switched on and it pass b/w the cell bottom and the electrodes.

When the carbon lining of the cell becomes red hot, Cryolite is added.

As the Cryolite melts, the anode are raised up to the middle of the middle of the cell, at this stage the Alumina is charged in to the bath where it dissolve.

As soon as alumina is dissolves, electrolysis starts forming Al and oxygen.

The aluminum formed collects at the bottom of the cell (cathode) form where it is with drawn from time to time through tapping hole.

The oxygen librated attacks the carbon electrodes (anodes) forming CO and CO2 which become partly oxidizing in some cases the electrodes replaced due to electrolysis the alumina content of the Cryolite solution decrease when it become less than 1 or 2%, a lamp connected is show the sparking this indicates the anode affect. .

This can be eliminated by immediately charging a new portion of alumina and normal operation of the cell will be restored and process continues.

• (ii).Purification of Aluminum. (Hoops Process):

• Aluminum obtained by hall Heroults process is about 90% Pure.

• Further purification can be carried or effected by Hoops electrolytic process as follows.

• The electrolytic cell consists similarly as an iron tank lined at the bottom with carbon which serves as anode.

• A number of graphite rods, suspended form above serves as cathode.

• The cell is filled with three liquid layers of different densities.

• (i). The top most layers consist of molten pure aluminum which is in touch with

• cathode.• (ii). The middle layer is of

electrolyte consists of mixture of molten fluoride & Al.

• (iii). The bottom layer consist of molten impure aluminum.

• On passing electric current the aluminum ion form the middle layer are discharge at the cathode and collect in the top most layer,

• Similarly same amount of Aluminum iron from the bottom layer goes in to the middle layer and then top most layer the pure aluminum collect at the top is tapped out from time to time.

• Crude or impure Al, is added to the bottom layer through Hooper from time to time.

• The process is thus continuous.• The production of one ton

aluminum requires about 1.98 tons of Alumina, 0.1 ton of Cryolite, 0.6 ton of carbon electrodes (anodes) and from 16,600 to18000 kWh electric energy is required.

• As a rule the liquid aluminum is tapped once every 3 or 4 days.

• A bath can run-continuously for 2 to 3 years.

• Characteristics of Aluminum:• Pure aluminum is silvery white metal which takes place very high polish.• In pure state the metal would be weak and soft. • It is high resistance to corrosion.• It is has good electrical conductivity.• It has high reflecting power.• It has very light in weight.• It is has good thermal conductivity.• Pure Al has no effect of water. • It is non toxicity.• Application: • It is extensively used in air craft and automobile components due to it

light in weight.• It is used for cooking utensils due to non toxicity.• It is used for reflectors, mirror and telescope due to high reflecting.• It is not used on lath machines because it sticks with the tools due to

softening.• It is used for (Al foils) wrapping cigarettes, sweets and confectionary.• Al is used for overhead cables due to good electric conductively.

• Aluminum Alloys: Aluminum finds its widest uses when alloyed with small amounts of other metals.

• The addition of small quantities of other alloying elements convert this soft, weak metal in to a hard and strong metal, while still retaining its light wt: more widely used industry are aluminum alloys which a can be divided into two main groups.

• (a). Wrought Aluminum Alloys.• (b). Casting Alloys.• (a). Wrought Aluminum Alloys: Wrought aluminum alloys have a

high mechanical strength which in some cases approaches that of steel. • The ductility of these alloys as well as their hot and cold workability has

found them extensive application in all branches of industry.• An important and interesting wrought alloy is known as duralumin.• This type of alloy contain 4.4% Cu, 0.6%Mn, 1.5%Mg and remaining % of

Al.• it is widely used for making the great variety of articles by mean of rolling,

drawing, forging and press working like sheets, bars, tubes etc.

• (b). Casting Alloys: Casting alloys are employed in foundry industry.

• For the casting of general engineering use,• Aluminum is alloyed with small amount of Cu & Zn in the portion of

12.5 to 14.5% Zn and 2.5 to 3.0% Cu. • In important series of casting alloys having high strength have

recently been developed for use in aero plane construction.• One example of such alloy is contain. 5% Zn, 3% Mg, 2.2% Cu, 1%

Ni and Aluminum the remainder.• In this type of alloy has good casting properties, has good ductility

and corrosion to resistance.• Aluminum Bronze Alloy: It is an alloy of Aluminum which contain

90% Cu and 10% Al. • it is golden in colour, it has good corrosion resistance and has high

strength.• It is used for making the coins, frames, die casting, jewellery and

decoration pieces etc.• Magnelium: This type of alloy contains 5.6% Mg and 94.4% Al. • It is tough, strong and can be worked on lathe because it does not

struck (stick) to tools.

COPPER And its alloys• Cu is an important metal for engineering purposes.• Cu is a reddish brown in color and is softer than iron.• It is meal able and ductile.• Cu is a metallic element, it has great technological and historical

importance.• It is one of the most which widely used in the different industries.• It has Melting point of about 1083OC.• The Cu is found in both states, i.e. in free as well as well as in

sulphides and oxide ores.• Mostly Cu extracted form sulphides ore.• Ores (Common):• (i) Sulphides:• (a) Chalcocite (Cu2 S) • (b) Chalcopyrite (Cu Fe S2) Cu-pyrite • (c) Bronite

• (ii). Oxides:• (a). Malachite Cu CO3 Cu (OH)2• (b). Cuprite Cu2 O• (c). Brochanite Cu SO4.3Cu OH2. Occurrence: The above ores are available at north &

South America, Congo, Canada, Zambia, Zaire, North Rhodesia etc.

• The most important or chief ore of Cu is Cu pyrite (Cu FeS2). Which about contain 60% Cu.

• Processing of Cu from its chief ore (Cu pyrite): Actually the Cu ore is containing some impurities like S, Fe and others etc.

• In this regard all impurities first eliminated from its ores this involves crushing and pulverizing, concentration, roasting, smelting, reduction and finally it may be refined pure form by electrolyzing process.

• Crushing and pulverizing. In this the big stones, minerals of ore are first crushed to small pieces in gyratory crushers and then pulverized to fine or small in size by ball mill.

• Concentration: Concentration of ore is achieves by froth floatation process this is especially suitable for sulphides ores.

• This process is based on the fact that the sulphides ore particles are only moistened by oil while those of oxide and gangue particles are moistened only by water.

• In this process the powdered ore is mixed with water and a little pine oil (foaming agent) and the whole mixture is then stirred vigorously by blowing compressed air.

• The oil forms a foam (or forth) with air.

• The ore particles tend to get coated with froth rises to the surface.

• On the other hand, the gangue particles are left in water.

• The froth ,skimmed off form the top to get the concentrated ore.

• Roasting: • in this process the concentrated ore

is heating strongly in excess of air to a temperature at which the ore does not melt. Roasting is usually done to sulphides ores.

• The purpose of roasting are to convert sulphides in to oxide and sulphide.

• To remove water of hydration.• To remove arsenic impurities and

excess sulphur.• To make the porous mass so that it

can be easily reduced in next operation.

• This is carried out in in a reverberatory furnace the following reactions takes place .

• A Part of the sulphur is converted to sulphur dioxide and other impurities such as arsenic which are burnt off.

• 2CuFeS2 + O2 ----------Cu2S + 2FeS + SO2 (oxidized). Major reaction.

• Thus the resulted roasted ore contains Cu2S, FeO and little Cu2O and FeS.

• The resulting mass become porous.

• Smelting: • In the smelting process, the roasted

ore is mixed with (sand silica SiO2) and a little coke (which acts as a flux) heated strongly in a small water jacketed blast furnace until it melts.

• During smelting FeS is oxidized to FeO, which reacts with sand to form iron silicate slag according to the following reactions.

• 2FeS+ 3O2 ----------FeO + 2So2 oxidized.

• Cu2O + FeS ------- Cu2S + FeO.• FeO + Sio2 ---------FeSio3 fusible slag. • This (slag) removed from the top of the

molten mass and discarded. • The molten mass which remarks is

called “Matte” and consists of mixture of copper sulphides and a little of FeS in the hearth of the furnace.

• The matte and slag are tapped out separately.

• Reduction/ (Bessemerization): • Reduction of matte is carried out

in a converter in which we pour the molten matte directly.

• which is fact a mixture of Cu Sulphides & iron sulphides where air is blown through this mixture (molten material) and also mixed the SiO as flux to remove the iron as the ferrous silicate (Fe SiO3) (slag) which floats on the surface of molten copper.

• At this copper is called blister of Cu (because it has small holes on the surface made by escaping sulphur dioxide (SO2).

• There fore it is further purified because the blister Cu contain still some impurities.

• As such types of Cu are not suitable for particular work so, it is thus refined.

• Refining /purification of Cu: • The blister Cu is refined by electrolysis. • The electrolysis is carried out in a tank (steel) in which the

blocks of blister Cu are used as anode and thin sheets of pure Cu as cathode.

• The cathode sheets are coated with graphite electrolyte; the current of 1.3 volts is used for electrolysis.

• On passing the current. • The impure copper dissolve (iron tracts), at the anode and

is deposited in the form of pure Cu at the cathode. The impurities settle down under anode.

• The Cu by this method is obtained is appox: 99.90% pure.

• Characteristics/properties:• It is good conductor of electricity.• Non magnetic.• Excellent resistance to corrosion.• High thermal conductivity.• It is malleable and ductile.• It can with stand severe bending and forging with out failure.• Cu boils at about 2600OC.• Application/ Uses:• Cu is used to make electrical wiring.• Cu is used to make cooking wares.• It is used for water pipes.• It is used for marine application.• It is used for steam pipes.• It is used boilers.• Cu is for motor winding etc.

• Copper alloys: • Cu alloys normally posses excellent corrosion

resistance, electrical and thermal conductivities and formability.

• some Cu alloys combine high strength and corrosion resistance, a combination desirable for marine applications.

• Some Cu alloys, because of their wearing properties, high hardness or corrosion resistance are used as surfacing metals.

• Some Cu alloys are selected for decorative application because of appearance.

• There are so many elements which are used to from alloys with Cu.

• For example: Al, Zn, Tin (Sn), Be (beryllium), Ni, Si, Pb (lead) etc.

• Basically there are three main types of alloys of Cu, which are:

• 1. Brass:• Basically brass is an alloy of Cu and Zn, this alloys

contain 43% Zn as a main constituent and remaining% is Cu.

• The properties of a brass vary with the % of Zn in it. • In some cases the %age of Zn may varies up to 45%.

These types of alloys are highly resistance to corrosion against the water.

• They posses greater strength, ductility and mach inability than pure copper, how ever it has a lower thermal & electrical conductivity. Due to the Zn in brass increase ductility along with strength.

• Applications: In general this type of alloy is used (widely) for marine application, condenser plates, piston rods, valve and for shafts also etc.

• Various types of Brasses are Discussed below in (General):• Red brass: Red brass contains less 20% Zn,• it is used for plumbing of pipes and connections, rivets, hardware

etc.• Cartiridge brass: This type of alloy contains 28% to 35% Zn.• It is more ductile and is used for deep drawing, wires and tubes etc.• Admiral’s brass: This alloy contains 29% Zn, 60% Cu and

10% Sn (tin). It is highly corrosion resistant, because of the small amount of tin added.

• It is widely used for propeller due to abrasion resistance also for marine applications.

• Muntz metal or yellow metal: It contains 60% Cu & 40% Zn and is essentially a hot working material.

• It has greater tensile strength and lesser ductility. • It is suitable for rolled plates. Rolled rod (hot) or extruded in a great

variety of shapes and sizes.

• Bronze: • Bronze is a broad term defining an alloy of copper and

elements other than nickel or Zn.• Basically bronze, is an alloy of Cu and tin. • It contains 80-95% Cu and 5-20% tin.• It is fairly hard and cane be machined easily. Bronze

possess superior mechanical wear, but it is more expansive due to high price of tin.

• Bronze can be shaped or rolled in to wire rod and sheets.

• This alloy can also be easily casted. • There are also other metals which are added to

increase hardness, strength; the main bronze alloys are discussed below:

• (i).Phosphorous bronze:• It contain 90% Cu, 7% Sn, 2% Pb, and 1% of P.• it is an ordinary alloy of bronze with a small amount of “P”, the main

function of phosphorous is to act as a cleanser to the metal so that good & sound castings can be produced.

• Due to other alloying elements, it is quite tough, elastic and good corrosion to resistance to sea water.

• It is used for making springs, turbine blades, bushes, bearings, • It may be obtained in the form of cast bar and hollow tubes.• (ii).Aluminum bronze:• It is also a ordinary alloy of bronze which contains 90-93% Cu, 7-10% Al.• it is quite strong, it has good casting properties, • it also posses good corrosion to resistance even at high temperature.• Also it has golden yellow color. • This type of alloy is used for valves, pumps, coins, bushes, photo frames,

and for artificial armaments, etc.

• (iii). Nickel bronze: • It contains 15% Ni, 12% Zn, 3% Sn and 0.1%Mg remaining % of Cu.• It is quite hard and has very good tensile strength with negligible

elongation.• It posses superior corrosion resisting properties there for it is used

in contact with sea water or other waters containing corrosive salts.• It is also used for hydraulic components (like bearing faces).• 3. Gun Metal:• Gun metal is an alloy of Cu, tin and Zn.• It contains 85-88% Cu, 5-10%Sn and 2-5% Zn.• Due to presence of Zn, it (Zn) cleans the metal and increase the

fluidity and also some times a small amount of lead (Pb) (0.3-1.5) may be added to improve cast ability and mach inability.

• This type of alloy is highly resistance to corrosion, but originally it was made for castings guns because of it is tough and strong & to resist the force of explosion.

• It is also used for foundry works, hydraulic fittings, and heavy load bearings & for steam pipe fittings etc.

• Types of Gun Metal Alloys:• 1.Admiralty Gun metal:• It contains 10% Sn, 2% Zn, 1.5% Pb (max) 1.5 % Ni (max) and

balance Cu.• It has tensile strength of 260-340 N/mm2. • It is widely used for pumps, valve and miscellaneous castings etc. • 2.Nickel Gun metal:• This type of alloys contains 7% Sn, 2.25 % Zn, 03% Pb, 5.5%Ni

and balance Cu. • It has good strength, good fluidity and good wear resistance.• This type of alloy is used for bushes, valves.• 3.Leaded Gun metal: • It contains 5% Sn, 5% Zn, 5%Pb, and 2% Ni (max) remaining is Cu. • This is among the most widely used grades, particularly, where

pressure tightness is required.• Finally in general gun metals are used for bearings, steam pipe

fitting, hydraulic valves, gears and guns and bullets etc.

ZINC & ITS ALLOYS:

• (introduction): • Zinc is one of the four most important metal form the stand points

of quantity used our highly industrialization, being exceeded only by steel, Al, and Cu in that order.

• Zn is bluish white metal; it is brittle at ordinary temp: but malleable and ductile b/w 100 to 150OC at 200OC it becomes brittle again and can be easily powdered.

• Zn metals 419 to 420 OC.• Zn has considerable resistance to atmospheric corrosion

because the oxidation formed initially on its surface protects it from further attack, for this reason, Zn is used as a protective coating for iron and steel sheets.

• Zn has out standing chemical property is its electro positive characteristics which it the basis for the used of zinc in galvanizing.

• Ores:The Common Ores of Zn are:• Zn blended/Zn sulphides (Zen’s).• Calamine/Smith sonite (Zn CO3).• Oxidized Zincates (ZnO).• Marmatile (Zn Fe)3.

• Occurrence: Zinc ores are found in USA, Canada, Australia, Mexico, Germany and Poland etc.

• The chief ore of Zn is blended (Zinc sulphide) from which the Zn may be mostly processed.

• The Zn is extracted by concentration, roasting, reduction

• The Zn ore is crushed, concentrated by floatation and roasted, all by which the same procedure as those for Cu ores.

• Actually complete elimination of sulphur is desirable.

• Except reduction all the steps are same as in cu.

• Reduction. • The zinc oxide is then reduced by

strong heating at about 1400 to 1500oc with carbon in closed retort when metallic zinc is formed as vapors which are condensed and collected in receivers out side the reduction furnace.

• ZnO + C ------------------- Zn + Co.

• Reduction of zinc oxide is usually carried in a vertical retort.

• In this process a mixture of roasted ore and powdered bituminous coal of high coking qualities 2:1 in the form of small briquettes is fed in to a vertical retort.

• The retort is heated externally by the combustion of producer gas.

• The vapors of zinc and carbon mono oxide produced by reduction are passed through a condenser where the zinc cadences which is drawn off periodically.

• The residual ashes etc formed in side the retort.

• Zn alloys: • Zn make alloys with the following elements. Al, Cu, Pb,

Cd, Mg and Sn etc, mostly the major used of Zn as a structural materials in the form of Zn dies castings because of Zn die casting alloys are low in cost, and have good strength, they can be close dimensional limits, require minimum machining, and posses good resistance to surface corrosion.

• Zn base die casting alloys find applications as wide variety of hardware items, including automobile hardware, eg: car burettor body, radiator grill, door, handle etc.

• generally Zn (pure form) finds application as shell, for dry batteries, building materials (as for flashing, roofing, gutters etc).

• for drawing, extrusions rolling and so on.

NICKEL & ITS ALLOYS: • Nickel is a silvery white metal capable of taking high polish. • It in malleable, ductile and hard its Melting point is 1450-1455OC.• Nickel is extremely resistant to corrosion and has excellent strength

at low temperature.• For this reason nickel and its alloys are widely used in chemical

industry where corrosion resistance is off importance. • Nickel is not tarnished by air as it has the ability to form a minutely

thin protective oxide film on it is surface.• It is non-toxic.• Occurrence: The nickel ore are found mostly in Canada, Norway

and Australia.• Important ores: The most important ore of nickel are:• (i). Pentlandite (Fe.Ni) S• (ii). Garnierite (Ni, Mg) SiO3.H2O• (iii). Small tile (Fe, Co, Ni)• (iv). Kupfer -nickel Ni As• (v). Nickel glance Ni. As.S etc.

• Nickel is obtained commercially from the chief ore penladite is found in Sudbury district of Ontario (Canada).

• About 90% of world’s supply of metal (Ni) comes from this source.

• As we know Pentlandite is a sulphides ore in nature which contain Ni sulphides , Fe and Co.

• The Nickel is extracted from this ore, by the following steps.

• (The aim is to make Nickel in pure form by eliminates the impurities).

• Except removal of copper (Monds process) all the steps are same as in cu.

Monds process.• It is based on the following steps.• Only nickel (and not Cu, Fe etc) forms a volatile carbonyl Ni(Co)4 when Co is

passed over it at 50oc.• The nickel carbonyl decomposes at 180oc to yield pure nickel.• Process. The bessemerized matte is first heated in air a special type of

furnace when sulphides of Ni and Cu are converted in to oxides.• These oxides then extracted with hot 15% dilute H2So4 which dissolve oxides of

copper and ferrous to form soluble sulphates while Nio is left behind un dissolved and separated.

• CuO + H2So4 -----------------CuSo4 +H2O.• FeO + H2So4------------------FeSo4 + H2O.• The residue consisting mostly of NiO is heated care fully in a tower (furnace) at

350oc in which a current of water gas (Co+H2) is passed.• At this temperature only Nio is reduced to metallic state.• After this the tiny particle of nickel so released so then combine with carbon

monoxide present in the water gas to a volatile compound called nickel carboxyl.• After this the tiny particle of nickel so released so then combine with carbon

monoxide present in the water gas to a volatile compound called nickel carboxyl.• 2Nio + Co+H2(water gas)-----------------2Ni + Co2 (oxidized) + H2.

• The reduced mass is then placed on shelves in tower which is kept at 50 to 60oc and a current of Co is passed through it .

• Nickel alone forms a volatile carbonyl while Cu and Fe are left behind un affected.

• The vapors of nickel carbonyl is led through a tower which is filled with pellets of nickel an maintained at 180oc.

• Here nickel carbonyl under goes decomposition and the nickel (99.8%) pure formed get deposited on the pellets.

• Ni(Co)4 -------------(180oc) Ni + Co (oxidized).• Carbon mono oxide thus set free is pumped to volatizer

for re use.• Note: Water gas, the mixture of hydrogen and carbon

monoxide produced by passing steam through hot coke.

• Uses: It is widely used for nickel plating and electroplating due to its silvery white luster and great resistance due to atmospheric corrosion.

• Since Nickel can be hot and cold worked successfully. • it is used in the manufacture of chemical and food processing plant, • used in petroleum industries.• Nickel Alloys: The greatest quality of Ni is used in the manufacture

alloys, but here we shall deals with those alloys in which Ni is the primary constituent, either in quality or in terms of importance.

• MonalMetal: (67% Ni, 30% Cu & 30% Fe) / Ni – Cu Alloys: It has a bright appearance than Nickel.

• it is stronger and tougher than mild steel.• It has excellent resistance to atmospheric and sea water corrosion

and generally is more resistance than Ni. • Uses: Monel is used in architectural and marine application where

appearance and corrosion resistance is important. • It is used for acidic proof machinery, food – processing equipments,

and turbine blades.

• Ni Chrome Alloys: The major Ni base alloy with Cr and Fe which contains 60% Ni, 25% Cr and 15% Fe.

• This type of alloy possess a very high melting point and shows a marked resistance to heat, electricity and chemical agent attack.

• Uses: These types of alloys are used for making resistance coils, hearting elements, toasters and other electrical appliance.

• German silver / Ni – Cu – Zn Alloys: This alloy contains 50% Ni, 25% Cu, and 25% Zn.

• It is hard ductile this is usually bright silvery colour, but may also assume various other passing colour by adjusting the proportions of Cu, Ni, & Zn.

• It has good mechanical & corrosion resistance properties.• Uses: These type of alloys are used for an armaments, cutlery (like

spoons), musical instruments, scientific instrument and also used for thermo couples resistance coil, the rest uses to increase %age of Ni from 20% - 24% Ni.

MAGNESIUM & ITS ALLOYS:

• Magnesium: • (Introduction): • Mg is a silvery white metal, although does not occur in free in

nature,• It is the eighth most abundant element in the earth crust.• Mg is very light in weight as compare to aluminum and Cu. • Commercially pure Mg has so little tensile strength that it is of

practically no value as material of structural / construction.• Mg can be fabricated by any of the industrial method such as

welding, foundry and hot working etc.• Mg has low meting point i.e. 650oC it is relatively expensive to

produce.• Mg is not employed in pure state (because it is not strong).• Mg is corrodes badly (because it is not good corrosion to

resistance).• Mg being costly, where light weight is required (because of it is

difficult and expensive to extract).

• Sources of Mg / ores:• The ores from which Mg is produced commercially

are:• 1. Natural brines, Mg Cl2• 2. Sea water Mg Cl2 + Mg SO4• 3.Magnesite Mg CO3.• 4.Dolomite Mg Ca (CO3)2.• 5.Brucite Mg (OH)2.• Actually, the above Mg ores are found in Russia,

Canada, U.S.A, Austria, India & Dolomite occur in Europe.

• Extraction. Different methods are employed for large scale preparation of Mg are.

By the electrolysis of fused

MgCl2. • Mg is processed from MgCl2

by electrolysis but some difficulties are there which are:

• (i). Fusion Temperature of MgCl is quite high

• (ii). MgCl2 is not good conductor of electricity

• (iii). Mg has great affinity with Oxygen, it burns with an intensely hot flame.

• These difficulties have been over come in the modern electrolytic method, either carnality a mixture of anhydrous MgCl2 and NaCl Or Kcl in right portion be added for lower diffusion point of MgCl2 and also to raise the electrical conductivity.

• This processing is carried in U-Shaped covered iron vessel, this vessel is made cathode, while graphite rod surrounded by a porcelain hood and dipping in molten mass (Graphite rod) is made an anode. (Note: The vessel is heat strongly for the get a clear liquid).

• Air inside the vessel is replaced by inner gas (otherwise Mg will combined with O2).

• On passing the electric current MgCl2.

• After this the reaction may start and Cl2 escapes through an opening in the hood, While the Mg being lighter than fused electrolyte, floats on the molten mass and is run of from time to time in the ladles.

• Alloys of Mg:• Basically Mg being costly, finds applications where light weight is

very important requirements,• Mg corrodes badly under many conditions and therefore need to be

alloyed to avoid such property and also other properties which are essential for engineering purposes.

• Mg is alloyed with elements such as: Al, Zn, Mn and Zr etc.• In this regard the some Mg alloys are discussed with their

composition and with characteristics.• (i) .Dow Metal: • This type of alloy is containing 90% Mg and 10% Al and a small

addition of Mn. • It has good hardness, good strength and had good fluidity.• (ii). Cast Alloy Of Mg: • This type of alloy contains 0.8% Al, 0.5% Zn, 0.3% Mn.• It has good ductility; good shock resistance and improve the

corrosion to resistance etc.

• Properties:• (i). High strength to weight ratio.• (ii). Good Fatigue• (iii). Good dimensional stability in service• (iv). Good damping capacity• (v). High thermal conductivity• (vi). Relatively high thermal conductivity• Applications: • (i). For making parts such as airframes, engines, gear boxes,

for • aero planes. helicopters, missiles and satellites etc.• (ii). They also used for jet engine parts like piston.• (iii). Moving parts of textile machines.• (iv). It is also used for printing (dies) equipment etc.• (v). For typewriters, calculators, camera bodies.• (vi). For storage tanks, electric drills, chain saws, power hammer • etc.• (vii). For foundry equipments and lending wheels of aircrafts etc.

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