Materials and Construction

71. Atmospheric corrosion of metals result from their

1. Slow oxidation
2. Fast oxidation
3. Fast hydration
4. Slow dehydration

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72. Austenitic manganese steel used for making jaws of crushing machines contains about _________ percent manganese.

1. 1.5-2
2. 3.5-4.5
3. 44081
4. 41974

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73. Babbitt metal (used for making bearings) comprises of

1. Mainly tin (85%) and lead
2. Saw dust and iron dust mixture
3. Zinc and aluminium
4. Copper and aluminium

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74. Babbitt metal is not a

1. Tin base alloy
2. White metal
3. Lead base alloy
4. Pure metal

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75. Babbitt metal used for bearings is a _________base alloy.

1. Tin
2. Lead
3. Aluminium
4. Copper

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76. Babbitt metal used for making bearings should have

1. High co-efficient of friction between journal and bearing
2. Ability to retain lubricant on its surface
3. Low co-efficient of friction between journal and bearing
4. Both (B) & (C)

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77. Babbitt metals used for making bearings are

1. Tin or lead based alloys
2. Short of antifrictional properties
3. Having homogenous microstructure
4. Yellow metals

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78. Ball bearings are generally made of

1. Plain carbon steel
2. Chrome carbon steel
3. Stainless steel
4. Malleable cast iron

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79. Ball bearings are normally made of _________ steel.

1. High speed
2. High carbon
3. Chrome
4. Silicon

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80. Balls in a ball mill are usually made of

1. Steel
2. Cast iron
3. Stainless steel
4. Bronze

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