A refractory material is one that retains its strength at high temperatures. ASTM C71 defines refractories as "non-metallic materials having those chemical and physical properties that make them applicable for structures, or as components of systems, that are exposed to environments above 1,000 °F (811 K; 538 °C)".
Refractory materials are used in linings for furnaces, kilns, incinerators and reactors. They are also used to make crucibles.
Read more about Refractory: Refractory Materials, Classification of Refractory Materials, Refractory Anchorage, Refractory Heat-up