INTRODUCTION

          Non-ferrous metals and alloys do not contain any significant quantity of iron. The most common non-ferrous metals used in engineering applications are Copper, Aluminium, Tin, Lead, Cobalt and Zinc. Nickel, Magnesium and Antimony are also used for alloying the fore said non-ferrous metals.

There are 7 types of non-ferrous metals, namely

1. Copper
2. Aluminium
3. Tin
4. Lead
5. Zinc
6. Cobalt
7. Nickel.

Copper

Copper:

          Copper is one of the comparatively few metals that are found in metallic state. It occurs in some minerals such as Copper glance (Cu2S), Malachite (CuCO3.CuO2.H2) and Azurite (2CuCO3.CuO2.H2). Copper ores are found in Burma, Sikkim and Singhbhoom (Bihar).
Not much of copper is available in India. We import atleast 50-60% of our requirement every year.

Physical and mechanical properties:

1. Extremely ductile and malleable either hot or cold.  
2. Copper is a corrosion resistant metal of an attractive reddish Brown color.
3. It is an extremely good conductor of heat and electricity.
4. Melting point = 1084°C.
5. Boiling point = 2592°C.
6. Specific gravity = 8.9.
7. Electrical resistivity = 1.68 Ohms /m.
8. Its tensile strength varies from 300 to 47o MN/m2.
9. It forms important alloys like Bronze and Gun metals.
10. It can also be drawn in wires, beaten into sheets and plates. 

Uses:

• It is extensively used in electrical industry for making armature coils, field coils, current carrying wires, house hold utensils etc.,
• But its great usefulness lies in the fact that it alloys with Zinc, Tin and Nickel to yield Brass, Bronze and Cupro-nickels respectively which are widely used in engineering industry.
• Copper, as such, is used for many decorative items.
• It is used for roofing, spouts,rivets, boilers, condenser and other purposes where corrosion resistance with fair strength and flexibility is essential.

Aluminum

Aluminum:

          Aluminum metal is difficult to extract from its main ore called Bauxite. However, bauxite is available in India very plentifully and we have a thriving aluminium industry. Commercially aluminium is obtained from clay in which it exist in great quantities. Bauxite is hydrated aluminium oxide generally believed to consist of mixture of monohydrate Al2O3.H2O and trihydrate Al2O3.3H2O. It is found in districts of Bihar, Madras, and Madhyapradesh.

Physical and mechanical properties:

          Pure aluminium has silvery color and luster, while the commercial grades show a characteristic bluish tinge. Aluminium is light in weight. Aluminium is also very corrosion resistant (because an adherent oxide layer protects it from further oxidation). It is again a very good conductor of heat and electricity (although not as good as Cu). It is ductile and malleable and is much cheaper than copper. Hence, it has all but replaced copper wires for transmission of electricity. It is also used for house-fold utensils including pressure cookers. However, since it can be converted into thin foils, it is now extensively used for beverage cans and in packaging industry. Its specific gravity is 2.7. Its melting point = 658°C, Boiling point = 2057°C. Its tensile strength varies from 95 to 157 MN/m2 .

Uses:

          Its density is about a third of steel, hence it is also used for aircraft and helicopter frames and in transport vehicles (car body panels). In finely divided flakes form, aluminium is employed as a pigment in paint. Aluminium paint is used as a priming coat for wood, as a protective coat for metals. Aluminium foil is used as silver paper for packing chocolates, food items etc.,

          Sometime ago, in India, 1, 2, 5, 10 and 20 paisa coins were made of an aluminium-magnesium alloy. Aluminium forms a series of alloys with magnesium, which are harder and stronger than pure aluminium.

Tin

Tin:

          The chief source of Tin is Tinstone (or cassiterite) SnO2. Large deposits of Tinstone occurs in Tairy (Burma) and small qualtities in Hazribagh (Bihar).

Physical and mechanical properties:

          It has an attractive silvery white color. It has very good resistance to acid corrosion.It is extremely ductile and malleable.  Before the advent of plastic tin coated steel sheets of thin gauge were used for manufacture containers for storage of ghee, mustard and other oils (moisture proof). It does not oxidise. Melting point = 232°C, Boiling point = 765°C. Its specific gravity is 7.3. Today tin is mostly used for alloying purposes. Tin and Lead melted together give a series of soft-solders. Tin has a low melting point.

Lead

Lead:

          Lead is ore is sulphide, PbS, called Galena or galenite. Its distribution is wide. There are practically no important deposits of lead in which galena is not present to some extent. Silver sulphide is scarely ever absent from galena, the amount is small, however, generally being less than 0.3 per cent.

Physical and mechanical properties:

          Lead is a heavy metal with dull grey appearance. It has good corrosion resistance and has got good malleability. Sheet metal folds easily can be soldered. Resistant to atmospheric conditions. Its melting point = 419°C. In Europe, it was extensively used for roof protection. It was also used in plumbing. It can withstand sulphuric acid and previously this acid used to be stored in lead lined vessels. It has self lubricating properties. It was therefore used in lead-pencils. Sometimes, a small quantity of lead is added to steel and tin bronze to impart free cutting properties. It is used as accumulator plates for car batteries.

Zinc

Zinc:

      The common ores of zink are zincite (ZnO), calamine (ZnCo3) and zinc blende (ZnS). These are available in Burma.

Physical and mechanical properties:

          Zinc processes a bluish grey metallic appearence. It has high corrosion resistance. In fact, steel sheets are often covered by a thin coating of zinc. Such zinc cozted sheet are known as Galvanised iron sheets (G.T. Sheets). The zinc coating provides protection to steel sheets from corrosion for many years. Melting point = 419°C. 

      Zinc is currently the fourth most widely consumed metal in world after Iron, aluminium and copper. Zinc has a low melting point and high fluidity making it suitable for items to be produced by die-casting process. Zinc is incidentally much cheaper than either copper or tin; making brass, an alloy of copper and zinc much cheaper than copper or tin-bronze. Zinc is also used in torch light batteries. zinc is also important for health, it is a necessary element for the proper growth and development of humans, animals and plants. Zinc is also useful for roofing purpose. 

Important properties of some non-ferrous metals

Important properties of some non-ferrous metals

In the following table, color, tensile strength, melting point, specific gravity and important properties of some non-ferrous metals are given:

ALLOYS OF NON-FERROUS METALS

          An alloy may be defined as coherent metallic mass produced by the intimate association of two or more metals. In some cases also the introduction of non-metals such as carbon, silicon, phosphorous, boron, sulphur and even nitrogen or oxygen may produced marked effects.

Important non-ferrous alloys are:

1. Copper alloys.

2. Cupro nickels.

3. Aluminium alloys.

4. Nickel alloys.

5. Titanium alloys.

6. Magnesium alloys.

Bronzes

Bronzes:

          Bronze is an alloy of copper and tin although commercial bronzes may contain other elements besides tin. In fact, alloys of copper with aluminium, silicon and beryllium, which may contain no tin are also known as bronzes. The simplest bronze contains 88% Cu with 12% Tin.

          Tin bronzes are of a beautiful golden color. As in brasses, both tensile strength and ductility of bronzes increase gradually with increases in the amount of tin content. However, more that 20% tin is not used in bronze as it results in the formation of a brittle inter metallic compound, Cu3Sn, and also its tensile strength very rapidly decreases. Addition of tin to copper up to 10% increase the strength, hardness and durability to a much greater extent than the addition of zinc to copper.

          As cast the alloy containing 9% of the tin has a tensile strength of about 215 MN/m2.

       By alloying 2 parts copper with 1 of tin, a very hard, brittle while alloy is produced called 'Spectrum metal'. When highly polished it serves excellently for mirror and reflectors.

The following varieties of tin bronzes are commonly used:

(i) Phosphor-Bronze:

          Addition of 0.5% phosphorous to tin bronze results in production of phosphorous bronze. It is certain, however, that whatever good qualities the bronze might have, they are greatly increased by the addition of phosphorous. Phosphorous increases fluidity of moltan metal and fine castings and rolling can be made. It seems to resist corrosion better than ordinary bronze, especially by sea water, so that it is much used for propeller blades. On account of its toughness, elasticity and strength it may serve as a substitute for steel as in the manufacture of corrosion-resistant mine cables, ship sheathing, valve parts, springs etc.,

(ii) Leaded-Bronze:

          Addition of lead to tin bronze, results in production of leaded bronze. Lead is actually a source of weakness, but adds to machinability and has self lubricating properties. Usually, lead percentage does not exceed 2%.

(iii) Gun-metal:

         It contains 2% zinc, 10% tin and 88% copper. It is a very famous composition. This bronze is used for bearing bushes, glands, pumps, valves etc.,

(iv) Bell-metal:

          It is a tin bronze but having a very high percentage of tin (20–25%). It gives a good tinkling sound on being struck with a hammer. Such alloys are very hard and brittle, but are sonorous and are employed, therefore, in making bells.

Bronzes having no tin:

The following bronzes contain no tin and are commercially well known:

(i) Aluminium-bronze:

          Composition: 14% Aluminium, 3% of iron, o.5% tin(Sn), rest copper. Color: Golden yellow. It possesses good strength and good corrosion resistance. It is somewhat difficult to cast because of oxidation. It's melting point is about 1040. The commercial aluminium bronzes are practically non-magnetic, but certain complex bronzes containing appreciable proportions of iron are magnetic. Often used for costume Jewellery. It is also used in massive work, bearing metal in locomotives.

          A disadvantage of aluminium bronze is that it usually develops surface films of high electrical resistance when used for current carrying purposes; these films tend to give rise to high electrical resistance and render jointing a matter of difficulty.

(ii) Silicon-bronze:

          Composition: 1–4% Silicon, and up to 1% of manganese rest mainly copper with little amounts of tin, zinc and iron. Possesses extremely good corrosion resistance. Can be cold worked and strain-hardened. Used for boiler fitting and marine fitting as screws, belts, tubing's, pumps etc.,

(iii) Manganese- bronze:

          Composition: 40% zinc and 55–60% copper with 3–5% manganese. It is essentially a brass to which manganese has been added. It is used for ship's propellers.

(iv) Beryllium-bronze:

          It contains about 2% Be. Beryllium is very costly. It has very good mechanical properties (high yeild point and high fatigue limit) and can be cold worked and age-hardened. It has excellent cold and hot resistance. It is mainly used for bellows, bourdon gauge tubes, heavy duty electrical switches and cams etc.,

          Being sparking, it is utilized for making chisels and hammers under conditions where spark might cause an explosion.

CUPRO-NICKELS

CUPRO-NICKELS:

  Cupro-nickels are alloys of copper and nickel. Copper and nickel, when melted together in any proportion are perfectly miscible and dissolve each other. When the alloy solidifies, the solubility continues forming a solid solution.

          Cupro-nickels are silvery white in color and have extremely good corrosion-resistance. They are extensively used for marine fittings. They also possess good strength, hardness and ductility (mechanical properties). Coins of rupee five are made of 75% copper and 25% nickel. However, another alloy containing 45% Ni and 55% copper is called "Constantine". Mangenine resistant wire with a very low temperature co-efficient of resistance, consist of 80% copper, 5% nickel and 15% of manganese.

          Nickel silver and German silver are ternary alloys of copper containing from 5 to 45% of zinc and from 5 to 30% of nickel. They have fair strength, good plasticity and low thermal conductivity. They are used extensively as the base metal on which silver is plated for table ware and for high grade plumbing and hardware. They are used for electrical wares and numerous fittings.

ALUMINIUM ALLOYS

            Aluminium as such is a soft metal of relatively low strength. Most of the alloys of aluminium are made by alloying it with various percentage of magnesium; these are harder and stronger. It prevents the formation of a coarse crystalline structure during heat treatment. These alloys known as L-M series alloys can be extruded and are used extensively for structural work.

• Copper s the main hardening element added while the addition of a small percentage of magnesium to an aluminium copper alloy still further improves the hardness and strength after heat treatment. Strength may also be improved by addition of small quantities of manganese and nickel to a copper-aluminium alloy.
• Silicon, is next in importance to copper as a main alloying element, since in combination with magnesium it forms a hard compound known as magnesium silicate which is largely responsible for the hardness obtained on the treatment.
• Manganese acts as a strengthening agent and prevents the formation of a coarse crystalline structure during heat treatment.

Some of the important aluminium alloys are discussed below: 

(i) DURALUMIN:

          A famous alloy of Aluminium containing 4% copper, 0,5% magnesium, 0.5% manganese, a trace of iron and rest aluminium is called DURALUMIN.

          It can be forged, cast and stamped. It has high strength and a low specific gravity (2.8). However, its corrosion resistance is much lower as compared to pure aluminium. Sometimes, duralumin is covered or clad by thin aluminium layer on all side, such material is called "ALCLAD". If 5-15% silicon is alloyed with aluminium, we get alloys which are temperature resistant. The alloy is soft enough for a workable period after it has been quenched. Its melting point = 650°C .

1. It is widely used for sheets, tubes, forgings, rivets, nuts, bolts and similar parts.
2. It is used in making cables.
3. Casting made of Al-Si alloys are used for manufacture of pistons of two wheeler on a large scale.
4. Alclad is extensively used in air planes and other machines where weight is a deciding factor.
5. It is also used in surgical and orthopaedic work and non-magnetic and other instrument parts.

(ii) HINDALIUM:

          Hindalium is an alloy of aluminium, magnesium, manganese, chromium and silicon etc., and is the trade name of the aluminium alloy produced by Hindustan Aluminium corporation Ltd. Mirzapur (U.P).

       It is manufactured as a rolled product mainly for anodized utensil manufature (cost of hindalium is 1/3 of stainless steel). during this special care is taken to maintain the necessary mechanical and surface characteristics.

Hindalium utensils possess the following advantages: 

1. Strong and hard.
2. Non reactive with food acids.
3. They cannot be easily scratched.
4. Good surface finish.
5. They can be easily cleaned.

(iii) MAGNELIUM:

It is alloy of aluminium, magnesium, copper and tin etc.,

It has the following properties:

1. It is a light weight alloy.
2. Brittle and poor castability.
3. Percentage of elongation is 7% for cold worked state and 30% for annealed state.
4. Good mechinability.
5. It can be welded.

          It is mostly used in the aircraft and automobile industries like gear box housings, vehicle door handles, Tyre rim of racing cars, skeletel body of aeroplanes. Coffee-grinder parts, fixtures and racks, phone body etc.,

ALLOYS OF NICKEL

The important nickel alloys are : German silver, Monel metal, Nichrome, inconel.

(i) German silver:

          It is a cupro nickel to which zinc has been added. A typical composition is 60% copper, 30% nickel and 10% zinc. Addition of zinc brings down the cost. Its color is silvery with as light pale tinge. It is very ductile and malleable and corrosion resistant. It is used for making electrical contacts, costume jewellery and high quality taps etc., Before the advent of stainless steel, it was also used for household utensils and coinage.

(ii) Monel metal:

          Its composition is 68% nickel, 30% copper, with small percentage of the elements 1% iron, silver remainder manganese etc., 

          Monel metal is superior to brass or bronze in resisting corrosion and in retaining its strength at high temperatures. Its mechanical properties are improved by cold working. Addition of elements like aluminium and beryllium makes the alloy amenable to heat treatment. It is only slightly attacked by acetic, citric and tartaric acids.

          Because of its excellent corrosion resistance properties, it is widely used for parts of water-pumps, propellers, domestic water storage tanks. it is also used for making turbine blades and chemical food handling plants.

(iii) Nichrome:

It is an alloy of nickel and chromium, its composition is 60% of nickel, 15% of chromium and 20% iron.

1. It is practically non-corrosive.
2. It can with stand high temperatures without oxidation, its melting point is 14000°C . 
3. Alloyed with cast iron, it increases resistance of the latter to corrosion and heat, as well as to wear. 
4. Electrical Resistivity at room temperature: 1.0 x 10-6 to 1.5 x 10-6 ohm-m,
5. Thermal Conductivity: 11.3 W/moC, 
6. Magnetic Attraction: None,
7. Specific Gravity: 8.4,
8. Density: 8400 kg/m3.

          It is used in the explosives, fireworks, and ceramic making industry, as a heating element. The alloy is very useful in the process of ceramic making, as it can withstand the high temperatures that are generated when a clay object is fired in a kiln. It is also used in motorcycle silencers and in certain microbiological lab apparatus. The chromium present in the wire oxidizes on being heated, and forms a protective layer of chromium oxide. which is used as heat resistant electrical wire in furnaces, and electrical heating devices like geysers, electric iron etc., the alloy is expensive because of its high nickel content.

(iv) Inconel and incoloy:

Alloys principally containing, nickel, chromium and iron. its composition is 75% nickel, 15% chromium, and 9 % iron.

1. It has high corrosion resistance at ordinary and high temperatures.
2. Its melting point is 1395C 
3. Specific gravity = 8.55
4. Brinell hardness is about 160
5. It can be welded by the oxyacetylene and metallic arc methods without difficulty.

          Used in electrical industry. It is used for making springs which have to stand high temperature and are exposed to high temperatures. It is also used in exhaust manifold (manifold is the main pipe which carries the explosive mixture from the carburattor to the cylinders of an internal combustion engine) of aircraft engines.