Refractory is any nonmetallic material or object that can withstand high temperatures without becoming soft. Refractories are used to line furnaces for melting metals and glass, in crucibles for inducing chemical reactions and for melting materials, as insulation in the walls of furnaces and kilns, and in other places where resistance to temperature and corrosion is required. A common refractory called firebrick contains aluminum silicates and minor amounts of titanium and iron oxides. Other refractory substances include alumina, magnesia, silica, zirconia, silicon carbide, and graphite.
