Q.5 Write short note on brass and bronze respectively and write its uses. (AKTU - 2008-09)
Related Questions -
Q. What are brasses ? List various types of brasses giving their uses. (AKTU - 2010-11)
Ans. Brass: -
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. In comparison, bronze is principally an alloy of copper and tin. Despite this distinction some types of brasses are called bronzes and vice-versa. Brass is a substitutional alloy. Brass has a muted yellow color, somewhat similar to gold. It is relatively resistant to tarnishing, and is often used as decoration and for coins. In antiquity, polished brass was often used as a mirror.
It is used for decoration for its bright gold-like appearance; for applications where low friction is required such as locks, gears, bearings, doorknobs, ammunition, and valves; for plumbing and electrical applications; and extensively in musical instruments such as horns and bells for its acoustic properties. It is also used in zippers. Because it is softer than most other metals in general use, brass is often used in situations where it is important that sparks not be struck, as in fittings and tools around explosive gases.
All brasses are basically alloys of copper and zinc. There are two main varieties of brasses:
(i) Alpha brass (upto 37% Zn) – for cold working.
(ii) Alpha Beta brass (33% to 46% Zn) – for hot working.
Common types of brasses in engineering use are the following:
Cartridge brass: -
It has 70% Cu and 30% Zn. It is very strong and ductile. It is used for a wide range of drawn components like cartridge cases, head lamp reflectors, radiator shells and drawn tubes.
Muntz Metal: -
It contains 60% Cu and 40% Zn and can be cast, rolled, extruded and stamped. It is used for casting pump parts, valves, taps and other similar items.
Naval Brass: -
It contains 60% Cu, 39%Zn and 1% tin. This alloy is, widely used for cast and forged fitting for ships.
Admiralty Brass: -
It contains 70% Cu, 29% Zn and 1% tin. It is widely used in ship fittings, bolts, nuts, washers and other items subjected to seawater corrosion. It is also used in condenser plant.
Gilding Brass: -
It contains upto 15% Zn and the rest Cu. It is a vary good cold working alloy and is used for jewellery, decorative and ornamental work. It is commercially available as cold rolled strip, wire or sheet, its colour, according to the percentage of Zn, varies from red to bright yellow.
Delta Brass: -
Also known as Delta metal, it consists of 60% Cu, 37% Zn and 3% iron. It can suitably replace steel castings.
Free Cutting Brass: -
It contains 60% Cu, 37% Zn and 3% Pb. It is specially used in machining work, such as producing components from bar stock on turret and automatic lathes.
Beta Brass: -
It contains 50% Cu and 50% Zn. Higher percentage of zinc renders it hard and brittle, but it softens quickly when heated and melts at 870°C. Its main application is as a brazing solder (spelter).
Colouring Brass: -
Various brass components can be imparted different colours by chemical treatment. A few examples are giving of golden colour and black colour, the former being used in decorative and ornamental work and the latter in optical instruments parts.
Silicon Brass: -
It contains 80% Cu,16% Zn and 4% Si. It responds well to welding and is widely used for refrigerators and fire-extinguisher shells. It can also be easily sand or gravity die cast, hot stamped and extruded. It can be used as a cheaper substitute for phosphor bronze.
Clock Brass: -
It contains 65% Cu, 34% Zn and 1% Pb. The lead content improves its bearing qualities and machinability. It is mostly available in strip form and is widely used in making small gears and pinions for clock work.
High Tensile Brass: -
It is similar to naval brass but carries small additions of Al, Mn, iron, Ni and Pb. Its tensile strenth is 69 tones / mm2. It is mainly used for large marine components, such as pump bodies and ship propellers.
Precipitation Hardening Brass: -
It contains about 70% Cu, 30% Zn and small additions of Ni and Al. It can be hardened by usual heat treatment. It is widely used for gears, pinions, formed and pressed parts where ability to harden after working is an advantage.
Bronzes: -
Bronze is basically an alloy of copper and tin. In general, it possesses superior mechanical properties and corrosion resistance than brass. Those containing upto 8% tin are called working bronzes. They can be easily cold worked, rolled, formed and drawn. They are available in various forms, as strip, wire and sheet etc.
With the increase in tin content, its strength and corrosion resistance increase. It is then known as hot working bronze. Small addition of phosphorus further improves its strength, ductility and bearing properties. The amount of phosphorus added is 0.5%. This is then known as phosphor bronze.
Phosphor Bronze: -
Various composition of this alloy are available for different uses. That having about 0.5% P is widely used for different types of springs in electrical instruments. Its drawn tubes are used in fuel systems and instruments. Cast phosphor bronze is used for bearings and gears. Bearing bronze contains 10% tin and small addition of lead. Gear bronze contains 13% tin for greater strength.
Gun Metal: -
It is a phosphor bronze having 2 to 5% Zn. Small amount of lead is also added to improve castability and machinability. It is used for bearing bushes, glands, pumps and valves etc.
Bell Metal: -
It is a straight bronze having 20 to 25% tin. It can be readily cast and is generally used for casting of bells.
Speculum Metal: -
Another straight bronze containing 30% tin. It is a hard alloy and takes good polish. It is largely used for decorative work and vacuum plating.
Aluminium Bronze: -
It contains upto 14% Al and the rest Cu, with sometimes a little addition of iron. It possesses good strength, high corrosion resistance and good heat resistance.
One variety, containing upto 8% Al, is known as cold working Al-bronze. It is available in the form of tubes for condensers, heat exchangers and steam and chemical plants. It is also used for springs.
Another variety, called hot working Al-bronze, contains 8% to 14% Al. It can be readily forged, extruded, stamped, sand and gravity die-cast and otherwise hot worked. It is used for a large range of cast and forged parts, such as gears, pinions, value seats, guides in I.C. engines, cams and rollers, etc.
Silicon Bronze: -
It contains 1 to 4% Si, 0.25 to 1.25% Mn, 0.5 to 1% iron (if added) and the rest copper. Small addition of upto 0.5% Pb will improve machinability. It is widely used for boiler parts, tanks, marine hardware and similar other items.
Manganese Bronze: -
It contains 55 to 60% Cu, 38 to 42% Zn, upto 1.5% tin, upto 2% iron, upto 1.5% Al and upto 3.5% Mn. It has superior mechanical properties and high corrosion resistance. It is used as ship propellers and rubbers etc.
Q.6 What do you mean by bearing metals?
Ans. Bearing Metals: -
A bearing metal should possess the following important characteristics:
(a) It should have enough compressive strength to possess adequate load carrying capacity.
(b) It should have good plasticity to allow for small variations in alignment and fitting.
(c) It should have good wear resistance to maintain a specified fit.
(d) It should have low co-efficient of friction to avoid excessive heating.
Some important bearing metals are the following:
Babbit Metal: -
It is a white metal containing 85% tin, 10% Sb and 5% Cu. It is used for heavy duty bearings.
Lead Alloy: -
It contains 40% lead and 60% Cu. It may be cast in position or fused as a thin shell to a bronze or steel reinforcing shell outside.
Phosphor Bronze: -
With 10% tin is used for light load low speed bearings. It can be sand and centrifugally cast.
Cadmium Alloy: -
It contains 95% cadmium, 5% silver and a very small amount of iridium. It is used for medium loaded bearings subjected to high temperature.
Cintered Metal: -
Bearings suitable for light and medium loads are made by sintering metallic powders. A popular composition consist of 90% Cu, 10% tin and a small addition of graphite. Cintering is done at 700°C. Oil retaining bearings can be made through this process.
[I] Fill in the Blanks
1. Bronze is an alloy of .................. and ..................
2. Brass is an alloy of .................. and ..................
3. Non-ferrous metals and alloys do not have .................. as a constituent.
4. German silver contains .................. % silver.
5. Strongest aluminum alloy produced by age hardening is ..................
6. Tin base bearing alloys are also called ..................
7. Lead, Zinc show creep property at .................. temperature.
8. Bell metal contains .................. % tin.
9. Finishing is the operation best done by ..................
10. Muntz metal contains .................. copper and .................. zinc.
11. Non ferrous metals are ..................
12. Zink has ..................
13. German silver is known ..................
Related Questions -
Q. What are brasses ? List various types of brasses giving their uses. (AKTU - 2010-11)
Ans. Brass: -
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. In comparison, bronze is principally an alloy of copper and tin. Despite this distinction some types of brasses are called bronzes and vice-versa. Brass is a substitutional alloy. Brass has a muted yellow color, somewhat similar to gold. It is relatively resistant to tarnishing, and is often used as decoration and for coins. In antiquity, polished brass was often used as a mirror.
It is used for decoration for its bright gold-like appearance; for applications where low friction is required such as locks, gears, bearings, doorknobs, ammunition, and valves; for plumbing and electrical applications; and extensively in musical instruments such as horns and bells for its acoustic properties. It is also used in zippers. Because it is softer than most other metals in general use, brass is often used in situations where it is important that sparks not be struck, as in fittings and tools around explosive gases.
All brasses are basically alloys of copper and zinc. There are two main varieties of brasses:
(i) Alpha brass (upto 37% Zn) – for cold working.
(ii) Alpha Beta brass (33% to 46% Zn) – for hot working.
Common types of brasses in engineering use are the following:
Cartridge brass: -
It has 70% Cu and 30% Zn. It is very strong and ductile. It is used for a wide range of drawn components like cartridge cases, head lamp reflectors, radiator shells and drawn tubes.
Muntz Metal: -
It contains 60% Cu and 40% Zn and can be cast, rolled, extruded and stamped. It is used for casting pump parts, valves, taps and other similar items.
Naval Brass: -
It contains 60% Cu, 39%Zn and 1% tin. This alloy is, widely used for cast and forged fitting for ships.
Admiralty Brass: -
It contains 70% Cu, 29% Zn and 1% tin. It is widely used in ship fittings, bolts, nuts, washers and other items subjected to seawater corrosion. It is also used in condenser plant.
Gilding Brass: -
It contains upto 15% Zn and the rest Cu. It is a vary good cold working alloy and is used for jewellery, decorative and ornamental work. It is commercially available as cold rolled strip, wire or sheet, its colour, according to the percentage of Zn, varies from red to bright yellow.
Delta Brass: -
Also known as Delta metal, it consists of 60% Cu, 37% Zn and 3% iron. It can suitably replace steel castings.
Free Cutting Brass: -
It contains 60% Cu, 37% Zn and 3% Pb. It is specially used in machining work, such as producing components from bar stock on turret and automatic lathes.
Beta Brass: -
It contains 50% Cu and 50% Zn. Higher percentage of zinc renders it hard and brittle, but it softens quickly when heated and melts at 870°C. Its main application is as a brazing solder (spelter).
Colouring Brass: -
Various brass components can be imparted different colours by chemical treatment. A few examples are giving of golden colour and black colour, the former being used in decorative and ornamental work and the latter in optical instruments parts.
Silicon Brass: -
It contains 80% Cu,16% Zn and 4% Si. It responds well to welding and is widely used for refrigerators and fire-extinguisher shells. It can also be easily sand or gravity die cast, hot stamped and extruded. It can be used as a cheaper substitute for phosphor bronze.
Clock Brass: -
It contains 65% Cu, 34% Zn and 1% Pb. The lead content improves its bearing qualities and machinability. It is mostly available in strip form and is widely used in making small gears and pinions for clock work.
High Tensile Brass: -
It is similar to naval brass but carries small additions of Al, Mn, iron, Ni and Pb. Its tensile strenth is 69 tones / mm2. It is mainly used for large marine components, such as pump bodies and ship propellers.
Precipitation Hardening Brass: -
It contains about 70% Cu, 30% Zn and small additions of Ni and Al. It can be hardened by usual heat treatment. It is widely used for gears, pinions, formed and pressed parts where ability to harden after working is an advantage.
Bronzes: -
Bronze is basically an alloy of copper and tin. In general, it possesses superior mechanical properties and corrosion resistance than brass. Those containing upto 8% tin are called working bronzes. They can be easily cold worked, rolled, formed and drawn. They are available in various forms, as strip, wire and sheet etc.
With the increase in tin content, its strength and corrosion resistance increase. It is then known as hot working bronze. Small addition of phosphorus further improves its strength, ductility and bearing properties. The amount of phosphorus added is 0.5%. This is then known as phosphor bronze.
Phosphor Bronze: -
Various composition of this alloy are available for different uses. That having about 0.5% P is widely used for different types of springs in electrical instruments. Its drawn tubes are used in fuel systems and instruments. Cast phosphor bronze is used for bearings and gears. Bearing bronze contains 10% tin and small addition of lead. Gear bronze contains 13% tin for greater strength.
Gun Metal: -
It is a phosphor bronze having 2 to 5% Zn. Small amount of lead is also added to improve castability and machinability. It is used for bearing bushes, glands, pumps and valves etc.
Bell Metal: -
It is a straight bronze having 20 to 25% tin. It can be readily cast and is generally used for casting of bells.
Speculum Metal: -
Another straight bronze containing 30% tin. It is a hard alloy and takes good polish. It is largely used for decorative work and vacuum plating.
Aluminium Bronze: -
It contains upto 14% Al and the rest Cu, with sometimes a little addition of iron. It possesses good strength, high corrosion resistance and good heat resistance.
One variety, containing upto 8% Al, is known as cold working Al-bronze. It is available in the form of tubes for condensers, heat exchangers and steam and chemical plants. It is also used for springs.
Another variety, called hot working Al-bronze, contains 8% to 14% Al. It can be readily forged, extruded, stamped, sand and gravity die-cast and otherwise hot worked. It is used for a large range of cast and forged parts, such as gears, pinions, value seats, guides in I.C. engines, cams and rollers, etc.
Silicon Bronze: -
It contains 1 to 4% Si, 0.25 to 1.25% Mn, 0.5 to 1% iron (if added) and the rest copper. Small addition of upto 0.5% Pb will improve machinability. It is widely used for boiler parts, tanks, marine hardware and similar other items.
Manganese Bronze: -
It contains 55 to 60% Cu, 38 to 42% Zn, upto 1.5% tin, upto 2% iron, upto 1.5% Al and upto 3.5% Mn. It has superior mechanical properties and high corrosion resistance. It is used as ship propellers and rubbers etc.
Q.6 What do you mean by bearing metals?
Ans. Bearing Metals: -
A bearing metal should possess the following important characteristics:
(a) It should have enough compressive strength to possess adequate load carrying capacity.
(b) It should have good plasticity to allow for small variations in alignment and fitting.
(c) It should have good wear resistance to maintain a specified fit.
(d) It should have low co-efficient of friction to avoid excessive heating.
Some important bearing metals are the following:
Babbit Metal: -
It is a white metal containing 85% tin, 10% Sb and 5% Cu. It is used for heavy duty bearings.
Lead Alloy: -
It contains 40% lead and 60% Cu. It may be cast in position or fused as a thin shell to a bronze or steel reinforcing shell outside.
Phosphor Bronze: -
With 10% tin is used for light load low speed bearings. It can be sand and centrifugally cast.
Cadmium Alloy: -
It contains 95% cadmium, 5% silver and a very small amount of iridium. It is used for medium loaded bearings subjected to high temperature.
Cintered Metal: -
Bearings suitable for light and medium loads are made by sintering metallic powders. A popular composition consist of 90% Cu, 10% tin and a small addition of graphite. Cintering is done at 700°C. Oil retaining bearings can be made through this process.
[I] Fill in the Blanks
1. Bronze is an alloy of .................. and ..................
2. Brass is an alloy of .................. and ..................
3. Non-ferrous metals and alloys do not have .................. as a constituent.
4. German silver contains .................. % silver.
5. Strongest aluminum alloy produced by age hardening is ..................
6. Tin base bearing alloys are also called ..................
7. Lead, Zinc show creep property at .................. temperature.
8. Bell metal contains .................. % tin.
9. Finishing is the operation best done by ..................
10. Muntz metal contains .................. copper and .................. zinc.
11. Non ferrous metals are ..................
12. Zink has ..................
13. German silver is known ..................
14. Tungsten filament on electric bulbs are made by ............... (AKTU - 2010-11)
[II] True or False Statements
1. Bell metal is an alloy of copper.
2. Gun metal and muntz metal have same composition of copper and zinc.
3. Lead base alloys are also known as Babbitt metals.
4. Aluminum and its alloys posses good formability and low density.
5. Monel metals constitutes mainly nickel and copper.
Answer -
[II] True or False Statements
1. Bell metal is an alloy of copper.
2. Gun metal and muntz metal have same composition of copper and zinc.
3. Lead base alloys are also known as Babbitt metals.
4. Aluminum and its alloys posses good formability and low density.
5. Monel metals constitutes mainly nickel and copper.
Answer -
Fill in the blanks
1. Copper, tin 2. Copper, Zinc 3. Iron 4. Zero
5. duralumin 6. babbitt metals 7. room 8. 20 to 25
9. grinding 10. 60%, 40% 11. Carbon, steel, wood, Al
12. high corrosion resistance 13. ni silver 14. William David Coolidge.
True or False Statements
1. (T) 2. (F) 3. (F) 4. (T)
5. (T)
1. (T) 2. (F) 3. (F) 4. (T)
5. (T)