Seven characteristics of alumina ceramics: 1. High mechanical strength The bending strength of alumina porcelain sintered products can reach 250MPa, and that of hot-pressed products can reach 500MPa. The purer the alumina composition, the higher the strength. Strength can be maintained at elevated temperatures up to 900°C, as shown in the graph below. Utilizing the mechanical strength of alumina porcelain, it can be made into mechanical parts such as device porcelain. The Mohs hardness of alumina ceramics can reach 9, and it has excellent wear resistance, so it is widely used in the manufacture of knives, ball valves, grinding wheels, ceramic nails, bearings, etc., among which alumina ceramic knives and industrial valves are the most widely used . 2. High resistivity, good electrical insulation performance The resistivity at room temperature is 1015Ω·cm, and the dielectric strength is 15kV/mm. Utilizing its insulation and strength, it can be made into substrates, sockets, spark plugs, circuit casings, etc. 3. High hardness With a Mohs hardness of 9 and excellent wear resistance, it is widely used in the manufacture of tools, grinding wheels, abrasive tools, wire drawing dies, extrusion dies, bearings, etc. When machining automotive engine and aircraft parts with alumina ceramic tools, high precision can be achieved at high cutting speeds. 4. High melting point, corrosion resistance The melting point is 2050°C, and it has good resistance to corrosion by molten metals such as Be, Sr, Ni, Al, V, Ta, Mn, Fe, Co, etc. Also highly resistant to attack by NaOH, glass and slag. Does not interact with Si, P, Sb, Bi in an inert atmosphere. Therefore, it can be used as refractory materials, furnace tubes, glass drawing crucibles, hollow spheres, fibers, thermocouple protective covers, etc. 5. Excellent chemical stability Many complex sulfides, phosphides, arsenides, chlorides, nitrides, bromides, iodides, oxides and sulfuric, hydrochloric, nitric and hydrofluoric acids do not interact with alumina. Therefore, alumina can be made into pure metal and single crystal growth crucibles, human joints, artificial bones, etc. 6. Optical properties It can be made into light-transmitting materials (transparent alumina porcelain), sodium vapor lamps, microwave fairings, infrared windows, laser oscillation components, etc. 7. Ionic conductivity Used as solar cell materials and battery materials.