This set of Engineering Materials & Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Bearing Materials”.
1. White bearing metals contain ______ of antimony.
a) 10%
b) 25%
c) 50%
d) 75%
View Answer
Explanation: All white bearing metals contain about 10% of antimony (Sb) making up its composition. It combines with tin to form an intermetallic compound SbSn. They are hard and have low friction.
2. Tin-based or lead-based alloys are types of ______
a) White metals
b) Copper base alloys
c) Aluminum base alloys
d) Ceramics
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Explanation: White bearing metals are either tin-based or lead-based alloys. They contain about 10% of antimony. They are used for medium and high-duty, or low pressure bearing metals.
3. Babbit metals are also known as _______
a) Tin-base alloys
b) Lead-base alloys
c) Copper-base alloys
d) Aluminum-base alloys
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Explanation: Tin-base bearing alloys are a type of white bearing metals. They are also known as Babbit metals. They have been named after Isaac Babbitt.
4. How much tin is contained in a Babbit metal?
a) 10%
b) 82%
c) 4%
d) 13%
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Explanation: Babbit metals are primarily composed of tin, which is 82% of the total composition. It also contains antimony (10%), copper (4%), and lead (4%). These metals are of better quality than Lead-base alloys.
5. How much antimony does a lead-base alloy contain?
a) 13%
b) 12%
c) 74%
d) 0.75%
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Explanation: Lead-base alloy is a bearing metal primarily composed of a lead with a 74% share. It consists of 13% antimony, 12% tin, 0.75% copper, and 0.25% arsenic. These alloys are cheaper than tin-base alloys.
6. ________ types of bearing alloys contain powdered copper and tin.
a) Plain tin bronze
b) Phosphorus bronze
c) Leaded bronze
d) Sintered bronze
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Explanation: Sintered bronze is a type of Copper-base bearing alloy. It contains 90% copper powder and 10% tin powder. They are usually self-lubricated.
7. Which type of bearing bronze is the weakest?
a) Plain tin bronze
b) Phosphorus bronze
c) Leaded bronze
d) Sintered bronze
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Explanation: Leaded bronze is a Copper-base bearing alloy containing 75% Cu, 5% Sn, 18% Pb, and 2% Ni. They are less stronger than other bearing bronzes. However, they can sustain higher loads than white metals, at higher speeds.
8. Plain tin bronze contains _____ of copper.
a) 85%
b) 88%
c) 75%
d) 90%
View Answer
Explanation: Plain tin bronze is a type of Copper-base bearing alloy which contains 85% Cu and 15% Sn. Phosphorus bronze contains 88% Cu, whereas leaded bronze contains 75% Cu. 90% of powered Cu is used in sintered bronzes.
9. Which of the following is an application of leaded bronze?
a) Washing machine
b) Extractor fan
c) Vacuum cleaner
d) Aero engine
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Explanation: Leaded bronze can sustain high loads at high speeds. This is the reason why they are used to manufacture main bearings of aero engines, and for automobile crankshaft bearings. The outstanding choices indicate applications of sintered bearings.
10. Tin-base alloys are replaced by aluminum-base alloys due to _______
a) High cost
b) Low strength
c) Corrosion
d) Low availability
View Answer
Explanation: Tin-base bearing alloys are generally more expensive to manufacture. This is the reason why they are being replaced with aluminum-base alloys, as they possess similar strength and characteristics.
11. Bearing materials used for low load applications are ______
a) Ceramic bearing materials
b) Plastic bearing materials
c) White bearing materials
d) Copper-base bearing materials
View Answer
Explanation: Plastic bearing materials have low coefficients of friction. They are used for low load applications, especially where oil lubrication is undesirable. The common types of plastic bearing materials are Nylon and Teflon.
12. Superalloys have resistance to creep temperatures as high as ______
a) 100
b) 250
c) 500
d) 1000
View Answer
Explanation: Superalloy is a term used to describe nickel-base and cobalt-base alloys. They have high strength, resistance to corrosion, and resistance to creep even at 1000.
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