Question

Which of the following is not an impregnant?

(a) Linseed oil

(b) Sodium silicate

(c) Silicon carbide

(d) Synthetic resin

The question was asked in my homework.

The above asked question is from Salvaging Techniques topic in section Salvage of Defective Castings of Casting-Forming-Welding I

Answer 1

Correct answer is (c) Silicon carbide

To explain I would say: Caulking and impregnation are one of the techniques used for salvaging defective castings. Among the following, linseed oil, sodium silicate and synthetic resins are regularly used as impregnants, but not sodium carbide.