NON- FERROUS METALS AND ALLOYS

NON- FERROUS METALS AND ALLOYS

Introduction

Non-ferrous metals and alloys are used for special purpose in engineering field.  Non ferrous metals and alloys are not iron based (Ferrous means iron)

The common nonferrous materials are the following metallic elements and their alloys:-

Aluminum, Copper, Nickel, Zinc, Tin, Lead, Magnesium, Cobalt etc.

Purpose or Need for non-metal and alloys

1. They are used where resistance to corrosion is essential
2. They also possess special electrical and magnetic properties
3. They also possess low density can have some attractive colour
4. They have good fusibility, ease of casting and formability
5. They are soft, which facilitates for cold working.

1.1     Aluminum and its Alloys

     Aluminum is a silvery white metal and is possesses the following characteristics or properties

1. It is a light metal (having a density of 2.7)
2. It is a very good conductor of electricity
3. It has a higher resistance of corrosion.
4. It is a good conductor of heat   
5. It is very ductile
6. It is a non-magnetic
7. Melting point of pure aluminum is  600°C.
8. It is good reflector of light and other radiant energy.

      Although pure aluminum is not particularly strong, it forms high strength alloys in conjunction with other metals, such as (copper, chromium, nickel, silicon, zinc etc)

1. They are malleable and ductile
2. They exhibit toughness and become stronger at temperatures below the ordinary atmospheric range.
3. Some of the aluminums alloys are more than four times as strong as same the weight of mild steel.
4. Aluminum and its alloys can bea) Cast (b) welded (c) Rolled (d) forged (e) extruded.

Uses of Aluminum and its Alloys

1. Aluminum and its alloys are frequently used for
2. Transportation industry: - Structures are made.
3. In food industry: - Food preparation equipments (pans etc) refrigeration, storage containers.
4. In architectural fields: - Window frames, roofing, fasteners, grills etc
5. As heavy-duty structure: - convey or supports bridges etc.
6. In process industries parts made up of aluminum an its alloys are used to handle organic chemicals petrochemicals and drugs
7. Cryogenic applications
8. Overhead conductors and heat exchange parts.
9. Used in metallurgical industry, as it is a powerful deoxidiser.
10. Generally used as container for plastics, rubber, rayon’s, synthetic resins, etc.

Types of Aluminum Alloys

     Aluminum alloys can be classified as

1)      Wrought Alloys

2)      Cast Alloys

3)      Heat treatable Alloys

4)      Non heat treatable alloys

Aluminum alloys - casting Applications

a)      Piston and cylinder heads

b)      Air and water-cooled, cylinder blocks, valve bodies etc.

c)      Sand casting and gravity die casting suitable for architectural ornamental and marine applications

d)      Sprit levels, molding flask etc.

e)      Vacuum cleaners, cast utensils steam pipes

Important aluminium alloys

1.            Aluminium –Silicon and Al-Si-Cu alloys

                  Composition- LM6-12%Si and LM2- 10%Si, 2% Cu

                  Uses: -

            Used for automobile castings, Water cooled manifolds, motor housings, pump parts.

2.            Aluminium-Magnesium Alloys (Magnelium)

                  Composition:- LM5-5% Mg, 0.5%Mn and LM10-10% Mg.

                  Uses:-

            Used for aircraft and automobile components, dairy equipments, architectural work.

3.            Aluminium Copper alloys

Composition:-LM 11-4.5% Cu- Similar to Duralumin.

Uses:-

For Aircraft castings.

4.         Y-alloy

            Composition:- LM14-4%Cu, 2% Ni, 1.5% Mg

            Uses:-

            For pistons and Cylinder Heads of Diesel and Heavy duty petrol engines.

1.2    Copper

     Copper is red in colour and has a crystalline structure and it possesses the following properties

1)      Excellent resistance to corrosion

2)      High thermal and electrical conductivity

3)      Non magnetic properties

4)      It is ductile and malleable

5)      Very good mach inability

6)      Resistance to fatigue, abrasion and corrosion

7)      It can be soldered, brazed or welded

8)      It can be easily polished, plated and possesses a pleasing appearance

9)      Ease of forming alloys with other elements like zinc, tin, aluminum, lead, silicon, nickel etc.

10)    Melting point of copper is  1080^°C.

             

Uses of copper

     Copper is used for the following

(1)     Electrical parts, Condensers, heat exchangers, household utensils, bus bars etc.

(2)     Automobile radiators, pressure vessels.

(3)     For bolts, studs, welding tips,

    Types of Copper Alloys

 .

1)       Copper zinc alloy (Brass)

      Brass is an alloy of copper and zinc it has high resistance to corrosion and is easily machinable.  It also acts as good bearing material.  Zinc in the brass increase ductility along with strength. Brass possesses greater strength than copper.  However it has a lower thermal and electrical conductivity. The properties of brass varies with the percentage of zinc varies from 5 - 45%.

Types of Brasses

Brasses are classified based on

1)            Structure- alpha brasses, alpha –beta brasses

2)            Colour- red brass and yellow brass.

Alpha brass contain zinc less than 30% and alpha-beta brass contain zinc between 30-44%.

Alpha Brass-They are soft, ductile, malleable and have good corrosion resistance. These are suitable for cold working.

Types of Alpha-Brass

1)            Cap Copper-contains zinc between 2-5%. It is very ductile. Used for caps of detonators.

2)            Gilding Metal- contains zinc 5-15%. Used for bullet envelopes, containers, condenser tubes, coins, emblems, jewellery.

3)            Cartridge brass (70-30 Brass) contains zinc 30%. Used for cartridge cases, radiator fins, lamp fixtures, rivets, springs.

4)            Admiralty Brass-contains zinc 30% and Tin 1%. Used for condensor tubes and heat exchangers.

Alpha-Beta Brass

They contain zinc between 30-40%, they are hard, strong, compared to alpha brasses, and they are hot worked.

Types of Alpha-Beta Brasses

1. Muntz Metal (60-40 Brass)- contain zinc 40%. Used for utensils, shafts, nuts, bolts, pump parts, condensor tubes.
2. Naval Brass (Also called Tobin Brass)- Contain zinc 39% and Tin 1%, used for marine hardware, propeller shafts, piston rods, nuts and bolts, welding rods.
3. Leaded Brass-contain zinc 39% and lead 1-3%. Used for parts requiring high machinability.
4. High Tensile Brass-contain zinc 39%, Fe 2%, Mn 1%, used for marine engine pumps, ships, propellers, gears, and valve bodies.
5. Brazing Brass- contains Zinc 50% and is very brittle. Used for brazing purpose.

2)         Copper Tin alloy (Bronze)

     Bronze is basically an alloy of copper and tin.  It possesses superior mechanical property and corrosion resistance than brass.  It is comparatively hard and it resists surface wear.  It can be shaped in to various forms. The tin content varies from 10 -15%.

Types Of Bronze and uses:

1 Aluminium Bronze-contain aluminium 4 to 11%, Fe, Ni, Mn, Si are added in small amount.

Properties:

a.            Good Strength, ductility and toughness.

b.            Good bearing properties.

c.            Good Corrosion resistance.

d.            Good fatigue resistance

e.            Good lustre

Uses:

For jewelry, heat exchangers, chemical plants, pimp castings, valve fittings, cylinder heads, gears, dies, bearings, spark plug bodies and electrical parts,

2.Tin Bronzes-contain tin 8-25%, zinc 1-2%

Properties:

a)            Good ductility and malleability

b)            Good corrosion resistance.

Uses:

For making coins, pumps, gears, bearings, bells, statues, pipe fittings, ornamental fixtures, gun barrels.

3. Beryllium Bronzes-contain beryllium 2%

Properties:

a)            Good corrosion and fatigue resistance.

b)            Good bearing properties.

c)            High resilience.

Uses:

Used for springs, diaphragms, bellows, gears, bearings, and electrical contacts.

4. Silicon Bronze-contain silicon 1-5%

Properties:

a)            High resistance to corrosion.

b)            High tensile strength

c)            High toughness.

Uses:

For high strength bolts, rivets, springs, propeller shafts, bells.

1.4    Nickel and its Alloys

     Nickel is a hard lusterless white metal and it posses the following properties.

1)   It possesses good corrosion and oxidation resistance.

2)   It has high tensile strength and can be easily formed hot and cold.

3)   It can be fabricated using processes similar for mild steel

4)   It can take up high polish.

5)   It is Ferro-magnetic of ordinary and low temperature but becomes paramagnetic at elevated temperature.

6)   Melting point of nickel is1453^oC

NOTE: - Ferro magnetic: - Strong attraction by the magnetic field

               Para magnetic: - Week attraction by the magnetic field.

Uses and application of nickel

1)         Nickel is used for in electroplating

2)         In electronic and low current electrical application

3)         For corrosion protection of iron and steel part and zinc based die-casting used in the automotive field.

4)         Incandescent lamp and radio industries

5)         In permanent magnet

6)         In the chemical industry for the construction of evaporators tanks, heating coils and tubular condensers.

1.4.1  Types of Nickel alloys

A)       Nickel-copper alloys

The major nickel base alloy with copper in Monel

Properties of Monel

1)         It has a brighter appearance than nickel

2)         It is stronger than mild steel

3)         It has excellent resistance to atmospheric and sea water-corrosion

4)         Generally it is more resistant than nickel to acid, less resistance to alkalis and equally resistant to salt.

Uses and application of Monel

     Monel is used in architectural and marine application where appearance and corrosion resistance is important and in specialized equipment used by the food pharmaceutical, paper, oil and chemical industries.

B)  Nickel- Copper- Zinc alloys (nickel silver )

      Nickel copper zinc alloys the known as nickel silver, do not contain silver and in actually they are brasses with sufficient nickel added to give a silvery white color improved corrosion resistance and high strength.

     These alloys are used as low cost substitutes with silver in tableware and jewellary usually with silver or gold electroplate on the surface.  Nickel silvers are also construction material for many musical, drafting and scientific instruments and also used for marine and architectural parts.