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Kilns for firing ceramics are lined with firebrick, which are also ceramic. Note that heating elements are often placed in grooves in the walls. However, different ceramics have different firing temperatures, so it may be the case that the walls can only be fired at even higher temperatures. I would think that this is the case, as ceramics at firing temperature are often weak and not far from the point where they start to soften and deform under gravity.

Is the maximum safe operating temperature of most kilns below the temperature that could fire the kind of bricks in their walls? If so, are these bricks fired in a graphite furnace or other special ultra-high temperature process?

fred_dot_u
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Kevin Kostlan
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  • Firing produces changes in the brick, giving it properties that allow it to tolerate very high temperatures. The changes associated with firing don't require the maximum temperature the finished brick will tolerate. – fixer1234 Aug 12 '20 at 19:26

2 Answers2

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Firebrick are thermally stable for the temperature range they are specified. However , some materials may cause chemical changes in certain types of fire brick and develop lower melting phases. I am thinking of glazes dripping onto brick. The normal Nichrome elements will not do this. Also silicon carbide elements will not deteriorate the brick.

blacksmith37
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Your firebricks will already have been fired, I'm not sure anyone makes kilns with green firebricks, they would move around when firing.

On the other hand if you have used fire clay , fire cement, or refractory cement to put your kiln together, then you need to ramp temperature slowly , fire clay cures with heat using the appropriate temperature and ramp temperature slowly, other products set with water addition, but need slow heat the first time around. Refer to manufacturers data sheet e.g. https://www.wtknowles.co.uk/wp-content/uploads/Fireclay-Fire-Cement-Data-Sheet.pdf

BobT
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    Hi Bob, can you maybe quote the information you're referring to in the document? It's aimed at a specific product and only a single A4, and it will improve your answer (especially since links can change). – Joachim Aug 13 '20 at 08:13