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Home⇒ Engineering⇒
Refractory technology
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ The main raw material for manufacture of silicon carbide refractories is carborundum [other wrong options] [Discuss in forum] corrundum bauxite periclase |
Q22 ⇒ Pick out the wrong statement. Carbon refractories can not be used in the furnaces operating under reducing conditions. [other wrong options] [Discuss in forum] Sand & coke is the main raw material for the manufacture of silicon carbide. Mullite can be obtained by the heating of alusite, kyanite or silimanite. Silica occurs in nature in all cellular, amorphous or crystalline form. |
Q23 ⇒ Fireclay bricks are used in the all (a), (b) and (c) [other wrong options] [Discuss in forum] furnaces allowed to cool frequently flues chimney linings |
Q24 ⇒ Quartz is all (a), (b) and (c). [other wrong options] [Discuss in forum] stable form of silica upto 870°C. converted to tridymite on firing between 870 to 1470°C. transformed to crystoballite on heating above 1470°C. |
Q25 ⇒ Test piece for determination of RUL of a refractory is heated in a/an electric furnace [other wrong options] [Discuss in forum] oxidising atmosphere reducing atmosphere neutral atmosphere |
Q26 ⇒ 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 cost [other wrong options] [Discuss in forum] electrical conductivity thermal conductivity fusion point |
Q27 ⇒ Which one expands on heating ? Silica bricks [other wrong options] [Discuss in forum] Fireclay bricks Both (a) & (b) Neither (a) nor (b) |
Q28 ⇒ Firing temperature is minimum (1250-1400 °C) for __________ bricks. fireclay [other wrong options] [Discuss in forum] direct bonded basic silica magnesite |
Q29 ⇒ Maximum alumina content in high alumina refractory can be as high as __________ percent. 90 [other wrong options] [Discuss in forum] 30 50 70 |
Q30 ⇒ Chromite refractories are neutral refractory. [other wrong options] [Discuss in forum] acidic refractory. basic refractory. fired at a temperature of 600°C only. |
Q31 ⇒ Which is not an alumino-silicate refractory? Tar dolomite bricks. [other wrong options] [Discuss in forum] Fireclay bricks. Mullite bricks. High alumina bricks. |
Q32 ⇒ With increasing alumina content, the fusion point of high alumina refractories increases. [other wrong options] [Discuss in forum] decreases. remains constant. may increase or decrease ; depends on its alumina content. |
Q33 ⇒ Which of the following is not a neutral refractory ? Magnesite [other wrong options] [Discuss in forum] Silicon carbide Chromite Graphite |
Q34 ⇒ Cold crushing strength of ordinary fireclay brick is about 950 kg/cm2 . On exposure to a temperature of about 1500°C, its crushing strength may come down to as low as __________ kg/cm2 . 65 [other wrong options] [Discuss in forum] 450 250 150 |
Q35 ⇒ Carbon refractory blocks are used in the hearth of blast furnace. [other wrong options] [Discuss in forum] are wetted by molten iron. are acidic in nature. all (a), (b) and (c). |
Q36 ⇒ Thermal conductivity of refractory bricks increases with decrease in porosity. [other wrong options] [Discuss in forum] decreases with decreases in porosity. is independent of its porosity and is maximum for insulating bricks. increases with the amount of air entrapped in pores. |
Q37 ⇒ Faster rate of drying of moulded refractories results in high __________ of refractories. both (b) and (c) [other wrong options] [Discuss in forum] green strength voids shrinkage |
Q38 ⇒ Carborundum used for making crucibles for melting non-ferrous metals is chemically silicon carbide [other wrong options] [Discuss in forum] silicon nitride crystalline magnesia zirconium sulphate |
Q39 ⇒ Pick out the wrong statement. Ceramic materials do not undergo vitrification on heating. [other wrong options] [Discuss in forum] A ceramic material which becomes fluid upon heating and can be moulded in liquid/viscous state is termed s glass. Ceramic materials are brittle in nature. Non-oxide ceramic materials generally act as a semi-conductor. |
Q40 ⇒ Magnesite chrome refractories have better spalling resistance than chrome magnesite refractories. [other wrong options] [Discuss in forum] have very low thermal co-efficient of expansion. are not at all resistant to the corrosive action of iron oxide. have very low (50 kg/cm2 ) cold crushing strength (C.C.S.), and can not be used in metalcase form. |
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