Presence of MgO in alumino-silicate refractories _______________ its refractoriness?

Related Mcqs:

1. Which is not an alumino-silicate refractory ?

   A. Fireclay bricks B. Mullite bricks C. Tar dolomite bricks D. High alumina bricks...

2. Refractoriness/fusion points of ‘Superduty’ refractories is _______________ °C?

   A. 1520-1630 B. 1630-1670 C. > 1730 D. > 2000...

3. Because of its very high refractoriness of the order of __________ °C, silicon carbide refractories are used in zinc smelting furnace, muffle furnace and for supporting the wares in tunnel kilns ?

   A. 1800 B. 2200 C. 2400 D. 2700...

4. Faster rate of drying of moulded refractories results in high _____________ of refractories?

   A. Green strength B. Voids C. Shrinkage D. Both B. and C....

5. With increase in the alumina content in firebricks, its fusion point (refractoriness) ?

   A. Decreases linearly B. Remains unchanged C. Increases D. Decreases...

6. Which of the following impurities reduces the refractoriness of magnesite bricks ?

   A. Al2O3 B. CaO C. SiO2 D. All A., B. & C....

7. High refractoriness of refractory bricks means, that it has a________________?

   A. High spalling resistance B. Low spalling resistance C. High resistance to fusion D. Low porosity...

8. Refractoriness under load (RUL) is the most important property for the refractory bricks_________________?

   A. At the hearth bottom of the furnace on which stock is placed B. Used for furnace insulation C. Used in the roof of the furnace D. None of these...

9. . Refractoriness under load (RUL) of fireclay bricks (under a load of 2 kg/cm2) is ______________ °C?

   A. 500 B. 1000 C. >1350 D. >2000...

10. Refractoriness under loads (RUL) is quite close to the fusion temperature (PCE) for _____________ bricks?

    A. Fireclay B. Silica C. Dolomite D. Very low alumina...