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Chemical Engineering Objective Questions { Refractory Technology }



134. Faster rate of drying of moulded refractories results in high __________ of refractories.
A. Green strength
B. Voids
C. Shrinkage
D. Both B and C
Discussion
135. SiO2 percentage in firebrick is about
A. 35 - 40
B. 55 - 60
C. 80 - 85
D. > 94
Discussion
136. Which brick undergoes maximum shrinkage on drying?
A. Tar bonded dolomite bricks
B. Fireclay bricks
C. Magnesite bricks
D. Chromite bricks
Discussion
137. Natural silica
A. Mainly contains quartz
B. Is not stable at high temperature
C. Transforms to other allotropic forms i.e tridymite and cristoballite involving very high volume changes
D. All of the above
Discussion
138. Resistance to slag attack of a refractory
A. Depends on the nature of slag & refractory
B. Decreases at higher temperature
C. Decreases, if defective joints & cracks exist in the refractory
D. All of the above
Discussion
139. Slide gates in teeming laddie used for steel pouring in ingot moulds is lined with __________ bricks.
A. Bakelite impregnated or fused periclase
B. Silica
C. Semi-silica
D. Fireclay
Discussion
140. Graphite or carbon refractories
A. Exihibit wetting characteristics
B. Should be used in neutral or reducing atmosphere
C. Exhibit high shrinkage on thermal treatment
D. Are not resistant to corrosion by slag
Discussion

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