Ceramic materials refer to a class of inorganic non-metallic materials made by forming and sintering at high temperatures with natural or synthetic compounds. It has the advantages of high melting point, high hardness, high wear resistance and oxidation resistance. It can be used as a structural material or a tool material. Since ceramics also have some special properties, they can also be used as functional materials.

Mechanical properties

Ceramic materials are the materials with the highest stiffness and hardness in engineering materials, and their hardness is mostly above 1500 HV. Ceramics have higher compressive strength, but lower tensile strength and poor plasticity and toughness.

Thermal characteristics

Ceramic materials generally have a high melting point (mostly above 2000 ° C) and have excellent chemical stability at high temperatures; ceramics have lower thermal conductivity than metallic materials, and ceramics are good thermal insulation materials. At the same time, the coefficient of linear expansion of ceramics is lower than that of metals. When the temperature changes, the ceramics have good dimensional stability.

Electrical characteristics

Most ceramics have good electrical insulation, so they are widely used to make insulation devices of various voltages (1kV~110kV). Ferroelectric ceramics (barium titanate BaTiO3) have a high dielectric constant and can be used to make capacitors. Ferroelectric ceramics can change shape and convert electrical energy into mechanical energy (with piezoelectric properties) under the action of an external electric field. Can be used as a sound amplifier, record player, ultrasonic instrument, sonar, medical sonograph, etc. A small number of ceramics also have the characteristics of a semiconductor and can be used as a rectifier.

Chemical properties

Ceramic materials are not easily oxidized at high temperatures and have good corrosion resistance to acids, alkalis and salts.

Optical properties

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 lamps. Magnetic ceramics (ferrites such as: MgFe2O4, CuFe2O4, Fe3O4) have a wide range of applications in audio tapes, records, transformer cores, and large computer memory components.