Question

In salvaging of castings, the metallic powder coating can improve the heat transfer by_____

(a) 5-10%

(b) 10-30%

(c) 30-50%

(d) 100%

The question was posed to me in an international level competition.

Question is taken from Salvaging Techniques topic in section Salvage of Defective Castings of Casting-Forming-Welding I

Answer 1

Correct option is (c) 30-50%

For explanation I would say: In order to boost heat transfer by salvaging of castings, the average coating thickness of metallic particles must be at least about 0.2 mm and less than about 0.4 mm. This metallic coating provides 30-50% improvement in heat transfer which forms the casting defects free and highly efficient.