Refractoriness/fusion points of ‘Superduty’ refractories is _____________ °C?

Capacity of a refractory brick to withstand-sudden changes in temperature is denoted by the property called_________________?

A. Spalling resistance

B. Refractoriness

C. Refractoriness under load (RUL)

D. None of these

With increase in the porosity, thermal spalling resistance of fireclay brick_______________?

A. Increases

B. Decreases

C. Remain same

D. May increase or decrease

Quartz is__________________?

A. Stable form of silica upto 870°C

B. Converted to Tridymite on firing between 870 to 1470°C

C. Transformed to Cristobalite on heating above 1470°C

D. All A., B. and C.

Pure oxide refractories are generally monocrystalline in nature and are self bonded ______________ bricks are generally used as moderator in nuclear reactors?

A. Beryllia

B. Carborundum

C. Corundum

D. Thoria

Ceramic recuperators used for waste heat recovery from high temperature flue gas going out of the furnace is made of ________________?

A. Fireclay

B. Silicon carbide

C. Corundum

D. Siliceous fireclay