Basic Casting Questions on “Crucibles – Advantages and Production”.
1. Among the following, production through which material is not possible in a crucible?
a) Glass
b) Metal
c) Pigment
d) Oils
Answer: d
Clarification: Crucibles are known for operating under high temperature conditions. These crucibles can be employed for the production of glass, metal and pigment, but not oils.
2. Which of the following metals or alloys cannot be used for making crucibles?
a) Nickel
b) Zirconium
c) Mercury
d) Platinum
Answer: c
Clarification: For the making of crucibles, nickel and zirconium have been employed in the recent times. Platinum had been used for this purpose in the earlier times, owing to its inertness, but mercury cannot be used for making it.
3. The crucible process is used for production of which material?
a) Pig iron
b) Cast iron
c) Tool steel
d) Gray iron
Answer: c
Clarification: The crucible process is used for the production of tool steel. Hammered iron which had rich carbon content in it was first used for producing tool steel.
4. Which of the following is not a property of a crucible?
a) Retention of thermal conductivity
b) Resistance to chemical attack
c) Retention of electrical conductivity
d) Resistance to erosion
Answer: c
Clarification: It is very necessary for the crucible to have retention of thermal conductivity, to possess resistance to chemical attacks and to erosion. But, there is no need for retention of electrical conductivity.
5. What is the maximum pressure which the isostatic presses can take for making crucibles?
a) 890 atm
b) 1270 atm
c) 1000 atm
d) 1100 atm
Answer: c
Clarification: Isostatic presses are one of the most advanced methods of making a crucible. For forming, these presses can work up to a pressure of 1000 atmospheres.
6. Which of the following does not hold valid for an isostatic press?
a) Consistent mixture
b) High pressure operation
c) High density of product
d) Wet mix used
Answer: d
Clarification: An isostatic press is considered to be one of the most advanced methods of making a crucible. The entire operation is at high pressure conditions. The mixture used is consistent, because of which the product formed has high density. But the mixture that is taken, is completely dry.
7. Which of the following cannot be counted among the advantages of a crucible?
a) Uniform heating
b) Low flexibility
c) Low installation cost
d) No contamination of charge
Answer: b
Clarification: Melting various materials through crucibles is an old process. This process has the advantage of uniform heating and no contamination of charge by the product obtained from combustion. The operation is inexpensive, and the flexibility is high.
8. Production of crucibles is inexpensive.
a) True
b) False
Answer: a
Clarification: Production of crucibles is a very inexpensive process. It does not include much capital and the installation costs are also not very high.
9. Which of the following is not a raw material for making a crucible?
a) Clay
b) Wax
c) Graphite
d) Silicon carbide
Answer: b
Clarification: For making a crucible, various types of clays are used, carbon in the form of graphite is used, since, graphite has a higher melting point and also silicon carbide is used, but not wax.
10. Crucibles do not possess refractoriness.
a) True
b) False
Answer: b
Clarification: Crucibles work at conditions of very high temperature, hence it is extremely important for the crucible to possess the ability to withstand high temperature, that is, refractoriness.
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