40 TOP REFRACTORY TECHNOLOGY Online Test – Multiple Choice Questions and Answers 1. Which is not an alumino-silicate refractory? Tar dolomite bricks Fireclay bricks High alumina bricks Mullite bricks 2. Except __________ , all other refractories are bad conductors of electricity (i.e, have low electrical conductivity) graphite chromite carborundum fireclay 3. Spalling resistance of a refractory can not be increased by using a coarser grog during its manufacture increasing its porosity decreasing its thermal co-efficient of expansion making it denser 4. Silica bricks are attacked by basic slags at high temperature. Which of the following is not used solely as a binding material? aluminium phosphate plaster of paris water lime 5. Which of the following is not a neutral refractory ? Silicon carbide Chromite Graphite Magnesite 6. Fireclay refractories have poor thermal spalling resistance tendency to expand unduly high during firing low co-efficient of thermal expansion very high cost 7. With increasing alumina content, the fusion point of high alumina refractories may increase or decrease ; depends on its alumina content remains constant increases decreases 8. Electrical resistor bars are made of zirconia silicon carbide alumina graphite 9. Refractoriness under load (RUL) is the most important property for the refractory bricks used in the roof of the furnace at the hearth bottom of the furnace on which stock is placed used for furnace insulation none of these 10. Which is a basic refractory ? Chrome magnesite Silica Fireclay None of these Loading … Question 1 of 10
