2. Ceramic material refers to a kind of inorganic nonmetallic material formed by natural or synthetic compounds through molding and high-temperature sintering. It has the advantages of high melting point, high hardness, high wear resistance and oxidation resistance.
1. Ceramic materials have the best rigidity and the highest hardness among engineering materials, and the hardness is mostly above 1500HV. The compressive strength of ceramics is high, but the tensile strength is low, and the plasticity and toughness are poor.
2. Ceramic materials generally have high melting point (mostly above 2000℃) and excellent high-temperature chemical stability; The thermal conductivity of ceramics is lower than that of metal materials, and ceramics are still good thermal insulation materials. At the same time, the linear expansion coefficient of ceramics is lower than that of metals, and ceramics have good dimensional stability when the temperature changes.
3. Ceramics have good electrical insulation, so they are widely used to make insulating devices with various voltages (1kV~ 1 10kV). Ferroelectric ceramics (BaTiO3) have high dielectric constant and can be used to make capacitors. Under the action of external electric field, ferroelectric ceramics can also change shape and convert electric energy into mechanical energy.
4. Ceramic materials also have unique optical properties, which can be used as solid laser materials, optical fiber materials, optical storage and so on. Transparent ceramics can be used for high-pressure sodium lamp tubes and so on.