A. Poor resistance to the penetration of molten slag, metal & flue gases
B. Poor heat conductivity & low strength
C. Better thermal spalling resistance
D. All A., B. and C.
Related Mcqs:
- An insulating refractory brick should have high porosity and low thermal conductivity. Which of the following is not used for inducing porosity in the insulating refractory bricks during its manufacture ?
A. Cork
B. Saw dust
C. Sand
D. Chemically prepared foam - Refractory bricks having lower porosity have _____________________?
A. High insulating properties
B. Low heat capacity
C. Low thermal conductivity
D. Greater strength - Refractory bricks with lower permeability is produced by using _________________?
A. Higher firing temperature
B. Higher moulding pressure
C. Finer grog size
D. All A., B. and C. - Water content in ground refractory material to be shaped into bricks by hand moulding is about _____________ percent?
A. 5
B. 20
C. 40
D. 55 - Maximum alumina content in high alumina refractory can be as high as ____________ percent?
A. 30
B. 50
C. 70
D. 90 - Thermal diffusivity of a refractory brick is high, when its ______________ is high?
A. Density
B. Specific heat
C. Thermal conductivity
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 - 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 - Which is a neutral refractory ?
A. Graphite
B. Magnesite chrome
C. Silica
D. Magnesia - Which is not an acidic refractory ?
A. Silica
B. Fireclay
C. High alumina refractory
D. Carbon black
