Question

Silica bricks have high thermal shock resistance above

• A. \(600^\circ C\)
• B. \(400^\circ C\)
• C. \(1000^\circ C\)
• D. \(1200^\circ C\)

Hint:

Silica bricks perform better under thermal shock conditions above \(600^\circ C\).

Answer 1

The Correct Option is A

Concept: Silica bricks show poor thermal shock resistance at lower temperatures because of phase transformations of silica. At higher temperatures, they become more stable.

Step 1: Silica exists in different polymorphic forms such as quartz, tridymite, and cristobalite.

Step 2: These forms undergo volume changes at certain temperatures.

Step 3: At low and intermediate temperatures, these transformations may create thermal stress.

Step 4: Above about \(600^\circ C\), silica bricks show better thermal shock resistance because the phase changes become less harmful in service. Therefore, silica bricks have high thermal shock resistance above: \[ \boxed{600^\circ C} \]