This set of Engineering Materials and Metallurgy Interview Questions and Answers focuses on “Copper and its Alloys – 2”.
1. Tin content in bronzes is kept below 12% due to their tendency to become _______
a) Less conductive
d) Less corrosion resistant
Explanation: Even though the strength of bronze increases with increasing tin content, they are kept below 12% as they tend to become brittle. Bronzes have better corrosion resistance than brasses.
2. Bell bronze is an alloy containing _______
a) 78% Cu, 22% Sn
b) 95.5% Cu, 3% Sn, 1.5% Zn
c) 95% Cu, 3% Si, 1% Mn, 1% Fe
d) 75% Cu, 5% Sn, 18% Pb, 2% Ni
Explanation: Bell bronze is a hard and brittle alloy with a resonance ability. It consists of 78% copper and 22% tin. It is typically used for making bells.
3. Which bronze alloy is commonly used as bearing alloy?
a) Phosphor bronze
b) Silicon bronze
c) Aluminum bronze
d) Leaded bronze
Explanation: Leaded bronze has increased strength, due to which it can carry high leads, and has the ability to work at higher speeds. It is used as a bearing alloy. It consists of 75% copper, 5% tin, 18% lead, and 2% nickel.
4. ______ is added to aluminum bronze to increase strength and hardness.
Explanation: Aluminum bronzes are used for making gears, propellers, cams, and other parts which require good strength and hardness. Therefore, iron is added to aluminum to achieve this result. The composition of iron is 3.5%, with the remaining being 89% copper, 7% aluminum, and 0.35% tin.
5. Why is silicon bronze classified as a bronze alloy despite having no tin?
a) Due to strength
b) Due to its color
c) Due to ductility
d) Good machinability
Explanation: Silicon bronze contains 95% copper, 3% silicon, 1% manganese, and 1% iron. Although it does not contain tin, it is still classified as a bronze alloy due to its color. Silicon is added to increase strength and improve corrosion resistance.
6. Copper coins are made using ______
a) Bell bronze
b) Aluminum bronze
c) Coinage bronze
d) Silicon bronze
Explanation: Coinage bronzes have good strength and corrosion resistance. This makes them ideal for making copper coins. It consists of 95.5% copper, 3% tin, and 1.5% zinc.
7. Alloys containing copper, tin, and zinc are known as ______
Explanation: Gunmetal is an alloy of copper containing tin and zinc. They are used to make pumps, valves, marine castings etc.
8. Addition of zinc to gun metals results in ______
a) Improved fluidity
b) Increased machinability
c) Increased castability
d) Improved toughness
Explanation: Gunmetal, when added with zinc, improves fluidity during casting and also acts as a deoxidizer. Since zinc is cheaper than tin, it also results in a decrease in overall cost. Increased machinability and castability are due to the addition of lead.
9. Which of the following is an application of admiralty gunmetal?
b) Marine castings
c) Hydraulic valves
Explanation: Admiralty gun metals have high corrosion resistance and casting properties. They are used for making pumps, valves, statuary and other castings. They contain 88% Cu, 10% Sn, 2% Zn, and 2% Ni. Leaded gunmetal is used for making bearings, marine castings, hydraulic valves etc.
10. Highest corrosion resistance in seawater is found is ______ copper alloys.
a) Nickel silver
Explanation: Cupronickels are alloys of nickel and copper. They are ductile, malleable, and can be hot-worked or cold-worked. They have better corrosion resistance than most copper alloys in seawater.
11. Monel metal is a type of ______ alloy.
a) Nickel silver
d) Sterling silver
Explanation: Monel metal is a type of cupronickel containing 29% Cu, 68% Ni, 1.25% Fe, and 1.25% Mn. It has excellent corrosion resistance and good mechanical properties. They are used for making propellers, condenser tubes, pump fittings etc.
12. Which of the following is a heat treated alloy?
a) Monel metal
c) German silver
d) K monel
Explanation: K monel is a type of cupronickel alloy. It is a heat treated alloy and has good mechanical properties. It is used for making motorboat propeller shafts.
13. Which copper alloy is used for making cutlery?
a) German silver
Explanation: German silver is an alloy of copper, containing copper, nickel, and zinc. It is also known as nickel silver. They are used for manufacturing cutlery and decorative items.
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