Which is required in an insulating refractory ?

Related Mcqs:

1. 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...

2. Porosity is induced in insulating refractories by adding________________?

   A. Powdered naphthalene B. Ammonium chloride/sulphate C. Calcium phosphate D. All A., B. and C....

3. Insulating refractories should have_______________?

   A. High porosity B. Low thermal conductivity C. Both A. and B. D. Neither A. not B....

4. 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....

5. Which is not a natural insulating material ?

   A. Diatomaceous earth/kieselgur B. Asbestos C. Vermiculite D. None of these...

6. Refractory castables are used for__________________?

   A. Producing monolithic linings B. Patch work C. Minimising the number of joints in the structure D. All A., B. and C....

7. An ideal refractory should have high__________________?

   A. Spalling rate B. Fusion point C. Shrinkage ability D. None of these...

8. _____________ is not a single oxide-refractory?

   A. Zirconia B. Silicon carbide C. Magnesia D. None of these...

9. 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...

10. Thoria is an expensive refractory material and is radioactive in nature. Thorium oxide is used in the manufacture of______________?

    A. Segar cones B. Muffles for muffle furnaces C. Insulating bricks D. Crucibles used for melting of high purity metals...