Traditional ceramics are fired from clay as the main raw material, and its composition contains silicate. In modern times, compound ceramics without silicates have been developed, such as ceramics made of oxides, carbides, amides, borides, silicide, sulfides or other inorganic non-metallic materials, in addition to ceramics mixed with Metallic, cermet and ceramics reinforced with metal fibers or inorganic non-metallic fibers.
The forming methods of traditional ceramics generally include compaction, casting and spinning, while high-performance ceramics have various forming methods such as hot die casting, hot pressing, isostatic pressing and vapor deposition. These ceramics are microscopic due to their chemical composition. The structure and performance are different from ordinary ceramics, so they are called special ceramics or high-tech ceramics, and they are called fine ceramics in Japan. Due to its different chemical composition and organizational structure, it has different special properties and functions (such as high strength, high hardness, high toughness, corrosion resistance, conductivity, insulation, magnetism, light transmission, semiconductor and piezoelectric, ferroelectric, photoelectric , electro-optic, acousto-optic, Magnetolysis, etc.). Due to their special properties, this kind of ceramics can be used as engineering structural materials and functional materials in machinery, electronics, chemical industry, smelting, energy, medicine, laser, nuclear reaction, aerospace and other aspects.
High-performance ceramics are widely used due to their many excellent properties. Special ceramics with excellent heat resistance are expected to be used as ultra-high temperature materials for high-temperature structural materials and high-temperature electrode materials related to atomic energy. Special ceramics with excellent thermal insulation can be used as new high-temperature thermal insulation materials for high-temperature heating furnaces, heat treatment furnaces, high-temperature reaction vessels, nuclear reactors, etc. Special ceramics with excellent thermal conductivity are very promising to be used as heat sinks with large-scale integrated circuits and VLSI electronic devices inside. Hard special ceramics with excellent wear resistance are widely used, and the current work is mainly concentrated on bearings and cutting tools. High-strength ceramics can be used for burners, blades, turbines, sleeves, etc. of gas turbines; they can be used for machine bodies, bearings, combustion nozzles, etc. on processing machinery. At present, a lot of work has been carried out in this area, and many countries, such as the United States, Japan, and Germany, have invested a lot of manpower and material resources in an attempt to gain a leading position. Such ceramics include silicon nitride, silicon carbide, sialon, aluminum nitride, alumina, etc. Ceramics with lubricity, such as hexagonal boron nitride, are very attractive, and the research is being stepped up all over the world. In terms of bioceramics, alumina and Phosphorus carbon are currently being studied as artificial teeth, artificial bones, and artificial joints. The application of this aspect has also attracted great attention.