Properties of Al2O3 ceramics
Al2O3 ceramics have a wide range of usages. Different purity of Al2O3 means different properties, which result in the different uses.
1. Strong mechanic strength. The bending strength of sintered Al2O3 ceramic products can reach 250 MPa, and that of hot-pressed products can reach 500 MPa. The purer the Al2O3% is, the higher the strength is. The strength can be maintained even at the high temperature of 900℃. Due to its strong mechanic strength, Al2O3 ceramics can be used for mechanical components. The Mohs hardness of Al2O3 ceramics can reach 9. With its excellent anti-weary performance, it is widely used in the manufacture of knives, grinding wheels, ceramic nails, bearings, etc. Among them, Al2O3 ceramic knives and industrial valves are mostly used.
2. It features high resistivity and good electrical insulation performance. The resistivity at room temperature is 1015 Ω · cm, with the insulation strength of 15kV/mm. So it can be made into base plate, tube base, spark plug and circuit shell.
3. High hardness. With the Mohs hardness at 9 and excellent weary resistance, it is widely used in manufacturing, grinding wheels, abrasives, drawing dies, extrusion dies, bearings, etc. When Al2O3 ceramic is used to process automobile engine and aircraft parts, high precision can be obtained with high cutting speed.
4. High melting point, corrosion resistance. The melting point is 2050 ℃, which can well resist the erosion of Be, Sr, Ni, Al, V, Ta, Mn, Fe, Co and other molten metals. It also has high resistance to the corrosion of NaOH, glass and slag. It does not interact with Si, P, Sb and Bi in inert atmosphere. Therefore, it can be used for refractory material, furnace tube, glass wire drawing crucible, hollow ball, fiber, thermocouple protection sleeve, etc.
5. Good chemical stability. Many sulfides, phosphide, arsenide, chloride, nitride, bromide, iodide, oxide, sulfuric acid, hydrochloric acid, nitric acid, do not react with Al2O3. Therefore, Al2O3 can be made into pure metal and single crystal crucibles, human joints, artificial bones, etc. Good chemical stability.
6. Optical properties. It can be made into transparent materials (transparent Al2O3 ceramics), which can be used to make sodium vapor tubes, microwave fairings, infrared windows, laser oscillation elements, etc.
7. Ionic conductivity. It can be used as solar cell material and battery material.