Thermal spalling mainly occurs during _____________ of furnaces?

A. Cooling down
B. Warming up
C. Both A. & B.
D. Neither A. nor B.

High alumina refractories are used in the ___________________?

A. Dome of blast furnace stoves
B. Electric arc furnace roof
C. Glass melting furnaces
D. All A., B. and C.

_____________ is not a single oxide-refractory?

A. Zirconia
B. Silicon carbide
C. Magnesia
D. None of these

Chrome magnesite brick is not used for lining the___________________?

A. Hearth of soaking pits
B. Bottom hearth of reheating furnace
C. Coke oven regenerator
D. Burning zone of limestone rotary kilns

Most Cermets, which normally have high thermal conductivity and high thermal shock resistance, comprises of ceramic & metallic components of ______________ percent respectively?

A. 80 and 20
B. 20 and 80
C. 50 and 50
D. 60 and 40

____________ of carbon blocks in the hearth of blast furnace helps in avoiding skull formation, when it becomes cold?

A. High thermal conductivity
B. Low porosity
C. Non-wetting characteristics
D. High density

Rotary kilns meant for calcination of limestone are lined with chrome magnesite in ______________ zone?

A. Preheating
B. Cooling
C. Burning
D. All the above

Semi-silica bricks compared to silica bricks have_______________?

A. Less fusion point
B. Better spalling resistance
C. Both A. and B.
D. Neither A. not B.

Which of the following impurities reduces the refractoriness of magnesite bricks ?

A. Al2O3
B. CaO
C. SiO2
D. All A., B. & C.

SiO2 percentage in firebrick is about____________________?

A. 35-40
B. 55-60
C. 80-85
D. > 94