... extreme mechanical, chemical, or thermal stresses, such as the inside of a wood-fired kiln or a furnace, ... change, and their strength should hold up well during rapid temperature changes.To make firebrick, fireclay is ... other materials. For bricks of extreme refractory character, the aluminum oxide content can be as high as ... -brick is 9 x 4.5 x 3 in. (230 mm x 115 mm x 75 mm)The silica firebricks that ...