Beryllia (which is used in making crucibles for melting uranium & thorium) is superior to alumina in all respects for high temperature (> 1900°C ) use, except ?

Related Mcqs:

1. Carborundum used for making crucibles for melting non-ferrous metals is chemically________________?

   A. Silicon carbide
   B. Silicon nitride
   C. Crystalline magnesia
   D. Zirconium sulphate

2. Maximum alumina content in high alumina refractory can be as high as _____________ percent?

   A. 30
   B. 50
   C. 70
   D. 90

3. Pure bauxite is the best raw material for the manufacture of high alumina refractories, in which maximum alumina content can be as high as _____________ percent?

   A. 55
   B. 70
   C. 80
   D. 90

4. With increase in the alumina content, the refractoriness of high alumina refractories_______________?

   A. Increases
   B. Decreases
   C. Remain same
   D. May increase or decrease

5. With increasing alumina content, the fusion point of high alumina refractories__________________?

   A. Increases
   B. Decreases
   C. Remain constant
   D. May increase or decrease; depends on its alumina content

6. High alumina refractories are used in the ___________________?

   A. Dome of blast furnace stoves
   B. Electric arc furnace roof
   C. Glass melting furnaces
   D. All A., B. and C.

7. Hot face insulating linings of high purity alumina fused mullite are used, where_________________?

   A. Very high temperatures are involved
   B. Highly reducing conditions are involved
   C. Presence of iron or silica is harmful
   D. All A., B. and C.

8. Which is not a high alumina refractory ?

   A. Mullite
   B. Corundum
   C. Bauxite
   D. Dolomite

9. Which of the following is not a high alumina refractory material ?

   A. Kyanite
   B. Sillimanite
   C. Diaspore
   D. Periclase

10. High alumina refractory compared to fireclay bricks have____________________?

    A. Less load bearing capacity
    B. Less resistance to slag attack
    C. Low refractoriness
    D. High resistance to thermal shock and creep