Alumina ceramics are a common special ceramic with alumina as the main component. They have the advantages of high hardness, high strength, high heat resistance, high insulation, high chemical stability, and corrosion resistance. The melting point of alumina ceramics is 2072�°C, the Rockwell hardness is 80-90, the compressive strength is 2000-2160MPa, the bending strength is 280-310 MPa, the thermal conductivity is 20-30 W/mK, and the thermal expansion coefficient is 7-8x10^-6/°C. Alumina ceramics are widely used in high-temperature ceramics, such as making high-temperature crucibles, refractory furnace tubes, special wear-resistant materials, circuit substrates, transparent armor, missile hoods, radar covers, etc.