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
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 - Thermal diffusivity of a refractory brick is high, when its ______________ is high?
A. Density
B. Specific heat
C. Thermal conductivity
D. None of these - Refractories used in/for ______________ should have low thermal conductivity?
A. Coke ovens
B. Insulation
C. Regenerators
D. Muffle furnaces - Pick out the wrong unit conversion of thermal conductivity ?
A. 1 BTU/ft2.hr.°F/ft = 1.488 kcal/m2. hr.°C/m
B. 1 BTU/ft2.hr.°F/inch = 1.488 kcal/m2. hr.°C/m
C. 1 kcal/m.hr.°C = 0.672 BTU/ft.hr.°F = 1.163 W/m. °K
D. 1 W/cm.°C = 85.985 kcal/m.hr.°C = 57.779 BTU/ft.hr.°F - According to the kinetic theory, the thermal conductivity of a monatomic gas is proportional to___________________?
A. T
B. T0.5
C. T1.5
D. T2 - Which is an acidic refractory ?
A. Magnesite
B. Dolomite
C. Fireclay
D. Chrome magnesite - 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 - Addition of zircon to silica refractory brick improves its_________________?
A. Crushing strength
B. Resistance to slag attack
C. Both A. and B.
D. Neither A. nor B. - Test piece for determination of RUL of a refractory is heated in a/an__________________?
A. Oxidising atmosphere
B. Reducing atmosphere
C. Electric furnace
D. Neutral atmosphere - Fusion point of a basic refractory material is________________?
A. Reduced by the addition of acid oxides
B. Increased by the addition of acid oxides
C. Not affected by the addition of acid oxides
D. Always less than 1000°C
