Question

Refractories used in furnaces are required to have

• A. High electrical conductivity
• B. Low melting point
• C. Resistance to high temperature and chemical attack
• D. High thermal expansion

Hint:

Logic Tip: A furnace is just a giant, super-hot cooking pot for chemicals. The pot itself needs to survive the fire without melting down, and it must not dissolve into the chemical soup it is cooking!

Answer 1

The Correct Option is C

Concept:
Refractories are specialized non-metallic materials (like firebrick or alumina) used to line the inside of high-temperature industrial equipment like furnaces, kilns, and reactors.

Step 1: The inside of an industrial furnace is incredibly hostile. It features extreme heat (often thousands of degrees) and highly corrosive chemical byproducts (liquid slags and hot gases).

Step 2: A refractory lining must contain the heat. If it had a low melting point (B), the furnace walls would literally melt into a puddle during operation.

Step 3: If the bricks expanded greatly when heated (D), the entire furnace lining would buckle, crack, and destroy itself. They need low thermal expansion.

Step 4: To survive, the material must absolutely possess a high melting point (resistance to high temperature) and it must not dissolve into the liquid metals/slags it is holding (resistance to chemical attack).