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
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 - 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 - Refractoriness/fusion points of ‘Superduty’ refractories is _____________ °C?
A. 1520-1630
B. 1630-1670
C. > 1730
D. > 2000 - Which is an acidic refractory ?
A. Magnesite
B. Dolomite
C. Fireclay
D. Chrome magnesite - 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 - 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. - 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. - 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 - 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
