The main composition of alumina ceramics is Al2O3, which is generally greater than 45%. Alumina ceramics have various excellent properties. High temperature resistance, generally can be used for a long time at 1600 ℃, corrosion resistance, high strength, its strength is 2 to 3 times that of ordinary ceramics, and the higher can reach 5 to 6 times. The disadvantage is that it is brittle and cannot accept sudden changes in ambient temperature. Extremely versatile, can be used as crucible, engine spark plug, high temperature refractory material, thermowell, seal ring, etc., can also be used as tools and molds.