Question

The ________ is used to activate the clay binders to perform its functions.

(a) Water

(b) Helium gas

(c) Nitrogen gas

(d) Alkali metals

The question was asked in a job interview.

I'm obligated to ask this question of Moulding Sand Binders and Additives in section Pattern Materials & Moulding Sand Tests of Foundry and Forging

Answer 1

Right choice is (a) Water

The best I can explain: In a foundry, clay is used in the form of bentonite which requires water to activate itself. Bentonite can absorb more water which increases its bonding power. The clay also activates the other basic constituents like mixtures of lime and alkalis to reduce refractoriness.