This set of Powder Metallurgy Multiple Choice Questions & Answers (MCQs) focuses on “Atomization Unit Advantages – 1”.
1. Which of the following is not an advantage of atomization process?
b) Processing capability
c) Reduced versatility
Explanation: The major advantages of atomization process include: processing capability, freedom to alloy, cleanliness, versatility, and productivity.
2. Atomization process is used for production of metal powders of very high melting point.
Explanation: Atomization is suitable for producing powders of pure metals and alloys (of miscible and immiscible system) whose melting point is not very high. Very high temperature materials such as W, Mo, and Hf are not usually produced by atomization.
3. Which of the following are major components of atomization set-up?
a) Melting, atomization chamber
b) Melting, atomization chamber, dry collection
c) Melting and superheating facility
d) Melting, atomization chamber, collection tank
Explanation: The major components of a typical atomization set-up include: (1) Melting and superheating facility, (2) Atomization chamber, and (3) Powder collection tank which is further of two types- dry collection and wet collection.
4. Complex alloys are melted by ________
a) Vacuum induction melting
b) Vacuum melting
c) Air melting
d) Inert gas melting
Explanation: Any of the standard furnaces can be used for producing the liquid metal. This is accomplished by air melting, inert gas or vacuum induction melting. Complex alloys which are highly susceptible to contamination are usually melted in vacuum induction furnaces.
5. The atomization chamber consists of _______
c) Atomizing atmosphere
d) Atomizing nozzle system
Explanation: The atomization chamber consists of an atomizing nozzle system. The nozzle, is usually located at the base of the tundish, controls the shape and size of the metal stream.
6. Which gas is used for purging the atomization chamber?
Explanation: The atomization chamber is purged with nitrogen gas to minimize the oxidation of the powder produced by high-velocity atomizing medium issuing out of the nozzle, which breaks the molten stream into very fine droplets, which cool and solidify as they settle at the bottom of the chamber.
7. _______: where particles solidify before the reach the bottom of the tank.
a) Top collection
b) Wet collection
c) Dry collection
d) Bottom collection
Explanation: Dry collection refers to a type of collection where the particles solidify before they reach the bottom of the tank. Thus, the collection tank should have sufficient height to ensure complete solidification of the particles before they fall to the bottom.
8. In ________ the collection of powder is done in a water tank.
a) Hydrated collection
b) Wet collection
c) Water collection
d) Dry collection
Explanation: In wet collection, the powder is collected in a water tank provided at the bottom of the atomization unit. The tank may be cooled externally when large quantities of powders are produced. The powders are then dried to remove the moisture.
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