A. Depends on the nature of slag & refractory
B. Decreases at higher temperature
C. Decreases, if defective joints & cracks exist in the refractory
D. All A., B. and C.
Related Mcqs:
- Magnesite bricks have poor resistance to attack by _____________ slag?
A. Lime
B. Basic
C. Acid
D. None of these - Rate of slag attack on refractories increases with rise in temperature due to the___________________?
A. Decreased viscosity of slag
B. Increased thermal conductivity of brick
C. Oxidising condition in the furnace
D. None of these - Sillimanite (Al2O3.SiO2) refractory, which is a neutral refractory, is not used in________________?
A. Pottery furnace
B. Glass melting furnace
C. Crucibles
D. Gas retorts - Spalling resistance of a refractory cannot be increased by ____________________?
A. Increasing its porosity
B. Using a coarser grog during its manufacture
C. Decreasing its thermal co-efficient of expansion
D. Making it denser - Dolomite bricks have good resistance to attack by_____________________?
A. Molten steel
B. Iron oxide
C. Lime slag
D. None of these - Spalling of a refractory means its____________________?
A. Softening
B. Fracture due to uneven expansion at high temperature
C. Resistance to compressive loads
D. Resistance to chemical action of gases and molten fluxes - Fusion point of an acidic refractory material is________________?
A. Increased by the addition of basic oxides
B. Reduced by the addition of basic oxides
C. Not affected by the addition of basic oxides
D. Always more than 2500°C - Which is not a basic refractory ?
A. Chrome magnesite
B. Magnesite
C. Dolomite
D. Silicon carbide - 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 - Which of the following is not a high alumina refractory material ?
A. Kyanite
B. Sillimanite
C. Diaspore
D. Periclase
