What are the properties of ceramics?

Mechanical properties
Ceramic materials are the materials with the best stiffness and highest hardness among engineering materials, and their hardness is mostly above 1500HV. Ceramics have high compressive strength, but low tensile strength, poor plasticity and toughness.
Thermal characteristics
Ceramic materials generally have a high melting point (mostly above 2000 ℃) and excellent chemical stability at high temperatures; The thermal conductivity of ceramics is lower than that of metal materials, and ceramics are still good 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 temperature changes.
Electrical characteristics
Most ceramics have good electrical insulation, so they are widely used in the production of insulation devices with various voltages (1kV~110kV). Ferroelectric ceramics (Barium titanate BaTiO3) have a high dielectric constant and can be used to make capacitors. Under the action of an external electric field, ferroelectric ceramics can also change shape and convert electrical energy into mechanical energy (with the characteristics of piezoelectric materials), which can be used as loudspeakers, phonographs, ultrasonic meters, sonar, medical spectrographs, etc. A few ceramics also possess the characteristics of semiconductors and can be used as rectifiers.
chemical properties
Ceramic materials are not easily oxidized at high temperatures and have good corrosion resistance to acids, alkalis, and salts.
optical characteristics
Ceramic materials also have unique optical properties, which can be used as solid laser materials, Optical fiber materials, optical storage devices, etc. Transparent ceramics can be used for high-pressure sodium lamp tubes, etc. Magnetic ceramics (ferrites such as MgFe2O4, CuFe2O4, Fe3O4) have a broad prospect in the application of recording tapes, phonographs, transformer cores, Mainframe computer memory components.