# Fluidization Engineering Questions and Answers – Coating on Plastic Materials on Metal Surfaces

This set of Fluidization Engineering Interview Questions and Answers for freshers focuses on “Coating on Plastic Materials on Metal Surfaces”.

1. What is the time required for complete coating to take place in the fluidized bed?
a) 2-3 sec
b) 5-10 sec
c) 1 sec
d) 20 sec

Explanation: It is optimum time, if more than that coating will be irregular and less than that incomplete coating will take place.

2. Which variety of plastic powders can be used for metal ware coating?
a) Polyvinyl
b) Polypropylene
c) Polyvinyl Chloride
d) All of the mentioned

Explanation: Any plastic material can be used.

3. For coating using plastic in fluidized bed, thermoplastic powders are always used, true or false?
a) True
b) False

Explanation: If there is any irregular coating, thermoplastics can be remoulded.

4. What will happen if the metal ware is kept for long time for coating of polymer in the fluidized bed?
a) Better coating
b) Irregular thickness
c) Time is independent of time
d) None of the mentioned

Explanation: More time it stays more irregular the coating.

5. What is the best method for application of plastic coating on the metal coating?
a) Fluidized bed
b) Spray
c) Electrostatic painting
d) Brush

Explanation: Best work possible with cheaper cost and less time required.

6. What should be the temperature of the metal ware for best coating to occur?
a) Little more than the melting point of the polymer
b) Same as melting point temperature of the polymer
c) Very high temperature
d) None of the mentioned

Explanation: Little more energy for melting the plastic and still remaining hot.

7. According to Gaynor, how is the thickness of the film varies with time?
a) Exponentially
b) Linearly
c) Independent
d) Sinusoidally

Explanation: Based on research done by Gaynor, he concluded relation is exponential.

8. Since the rate of deposition is proportional to the rate of heat transfer, thickness varies exponentially with film, true of false?
a) True
b) False

Explanation: Based on results provided by Gaynor.

9. In below fig, if the coolants are not present in the fluidized bed, how will it effect the film formation?

a) Molten plastic will drip down from the metal ware
b) No effect on the film formation
c) Increases the cooling the period
d) None of the mentioned

Explanation: Coolant is required to cool the plastic for film formation.

10. If the flow rate of coolants is increased in the fluidized bed, how will it effect the film formation?
a) Time duration of film formation will decreased
b) No effect
c) Time duration for film formation increases
d) None of the mentioned

Explanation: Duration for cooling will increase and hence for short duration for film formation.

Sanfoundry Global Education & Learning Series – Fluidization Engineering.

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