duration between re-linings. Very often cracks can be seen in this sacrificial inner lining shortly after being put into operation. They revealed more expansion joints should have been put in the first place, but these now become expansion joints themselves and are of no concern as long as structural integrity is not affected. Silicon carbide, with high abrasive strength, is a popular material for hearths of incinerators and cremators. Common red clay brick may be used for chimneys and wood-fired ovens. See also Harbison-Walker Refractories Company Equivalent VIII Niles Firebrick References Further reading Bricks Refractory materials Silicates