Carborundum used for making crucibles for melting non-ferrous metals is chemically________________? A. Silicon carbide B. Silicon nitride C. Crystalline magnesia D. Zirconium sulphate
Permeability of bricks is a measure of the___________________? A. Refractoriness B. Melting pointC. Rate at which a fluid will pass through the pores D. Expansion during heating
Which form of silica has the highest specific gravity ? A. Quartz B. Cristobalite C. Tridymite D. All have the same specific gravity
Thermal conductivity of refractory bricks____________________? A. Increases with decrease in porosity B. Decreases with decreases in porosity C. Is independent of its porosity and is maximum for insulating bricks D. Increases with the amount of air entrapped in pores
Magnesite refractories are generally not used in the__________________? A. Electric furnace wallsB. Steel melting furnace C. Open hearth furnace D. Burning zone of cement kilns
Which is not an acidic refractory ? A. Silica B. Fireclay C. High alumina refractoryD. Carbon black
Which is a neutral refractory ? A. Graphite B. Magnesite chrome C. Silica D. Magnesia
Which is an acidic refractory ? A. Magnesite B. DolomiteC. Fireclay D. Chrome magnesite
In panel test for spalling resistance, the average face temperature of panel assembly is maintained at _____________ °C for 24 hours? A. 700 B. 1000C. 1600 D. 2000
Fireclay bricks is not used for lining the_______________? A. Cupola B. Gas producerC. Bottom of hot metal mixer D. Roof of open hearth furnace