Neutral refractories are mainly composed of alumina, chromium oxide or carbon. The corundum with more than 95% alumina is a kind of high quality refractory material. Chromium brick with chromium oxide as the main component has good corrosion resistance to steel slag, but its thermal shock resistance is poor, and the temperature of high temperature load is low. Carbon refractories with carbon bricks, graphite and silicon carbide products, low coefficient of thermal expansion, high thermal conductivity, good thermal shock resistance, high strength, resistance to acid and salt corrosion, especially weak acid has good resistance, without wetting of the metal and slag, light. It is widely used as the lining material for high temperature furnace, and also used as the lining of high pressure kettle for oil and chemical industry.