Question

Which of the following is not the function of coating of refractory materials on the mould?

(a) Prevent the soldering of metal to the mould

(b) Minimize thermal shock to the mould

(c) Control the rate of casting solidification

(d) Increase the heat transfer rate

The question was asked in an online interview.

The doubt is from Permanent Mould Casting in chapter Special Casting Techniques of Casting-Forming-Welding I

Answer 1

Right option is (d) Increase the heat transfer rate

For explanation: The moulds are coated with a refractory material to increase the mould life by preventing the soldering of metal to the mould, by controlling the direction and rate of the casting solidification and also by minimizing the thermal shock to the moulding material. Coatings can be a mixture of sodium silicate, clay, soap, stone, talc etc.