A class of inorganic nonmetallic materials with a refractory degree of not less than 1580 degrees. Refractivity refers to the temperature at which a conical specimen of refractory resists high temperature without softening the melting down without loading. However, the definition of refractoriness alone can not fully describe the refractories. 1580 degrees is not absolute. It is now known that any material that is allowed to be used in high temperature environment is called refractory material. Refractories are widely used in metallurgy, chemical industry, petroleum, machinery manufacturing, silicate, power and other industrial fields, the largest amount of metallurgical industry, accounting for 50% to 60% of the total output.