Refractory Technology

201. Which of the following is not an acidic refractory?

1. Silica bricks
2. Fireclay bricks
3. Bauxite bricks
4. Magnesia bricks

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202. Which one contains maximum percentage of Al2O₃?

1. Firebrick
2. Sillimanite
3. Magnesite
4. Aluminous firebrick

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203. Which one contains minimum percentage of SiO₂?

1. Firebrick
2. Sillimanite
3. Semi-silica
4. Aluminous firebrick

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204. Which one expands on heating?

1. Silica bricks
2. Fireclay bricks
3. Both (A) & (B)
4. Neither (A) nor (B)

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205. Which property is important for bricks used in the combustion chamber & dome of blast furnace stoves?

1. High refractoriness
2. High resistance to spalling
3. High strength and density
4. All (A), (B) and (C)

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206. Which refractory must have controlled atmosphere (temperature and humidity) for its safe storage?

1. Tar bonded dolomite bricks
2. Fireclay bricks
3. Mullite bricks
4. Magnesite bricks

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207. With decrease in porosity, the _________ of the refractories decreases.

1. Strength
2. Thermal conductivity
3. Spalling resistance
4. None of these

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208. With increase in the alumina content in firebricks, its fusion point (refractoriness)

1. Decreases linearly
2. Remains unchanged
3. Increases
4. Decreases

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209. With increase in the alumina content, the refractoriness of high alumina refractories

1. Increases
2. Decreases
3. Remain same
4. May increase or decrease

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210. With increase in the density of silica refractories, its

1. Resistance to slag attack increases
2. Spalling resistance reduces
3. Both (A) and (B)
4. Neither (A) nor (B)

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