Introduction to Special Ceramics

date:2019-01-04 15:06 author:Cahngyu

In general, special ceramics, also known as "fine ceramics," are excellent ceramics that use highly selective raw materials, accurately control chemical composition, and facilitate structural design and manufacturing techniques. Special ceramics are generally made of oxides, carbides, nitrides, silicides, borides, etc., and are widely prepared by vacuum sintering, protected atmosphere sintering, hot pressing sintering, and thermal and other static sintering processes. In terms of performance, special ceramics have special properties and functions such as high strength, high hardness, corrosion resistance, electrical conductivity, and insulation, and are widely used in high temperature, machinery, electronics, aerospace, and medical engineering. Some economically developed countries, especially Japan, the United States and Western European countries, have invested a great deal of human, material and financial resources in the development of special ceramics in order to speed up the new technological revolution and lay the material foundation for the development of new industries. The size of the international market for special ceramics at the beginning of this century is expected to reach US$ 50 billion.

Since most special ceramics are materials with strong Ionic bonds or Covalent bonds, they have high melting points, good corrosion/oxidation resistance, hardness, and high temperature strength compared to metals and polymers. For example, Al2O3, ZrO2, TiC, ZrC, SiC, Si3N4, etc. have become excellent high-temperature structural materials. However, like traditional ceramics, the biggest disadvantages of special ceramics are poor plastic deformation ability, low toughness, and difficult to process. The mechanical properties of ceramics are much more sensitive than metals and alloys, and brittle fractures are easy to occur. The toughening problem of special ceramics is still one of the important research fields of ceramic materials.
There is a large class of metal ceramics produced by adding metals to ceramics, such as oxide base ceramics, carbide base ceramics, boride base ceramics, etc.. It is also an important variety of modern ceramics. In order to improve the brittleness of ceramics, metal fibers and inorganic fibers have been added to the ceramic matrix. The fiber reinforced ceramic composite material formed in this way is the youngest but most promising branch of the ceramic family.
Many special ceramics have excellent dielectric properties, wear resistance, thermal insulation, piezoelectric properties and new light transmission. For example, Si3N4 ceramics have excellent mechanical properties and can be used as structural materials; It also has high hardness, low thermal expansion coefficient, high thermal conductivity, etc.. It can also be used as a tool material and electromagnetic material. TiC's melting point(3250 °C) is higher than WC(2630 °C), its density is only one-third of that of WC, its antioxidant performance is much better than that of WC, and during the sintering process, it can be moistened by liquid and can be used as a high-temperature bearing, cutting tool, and measuring tool. Examples such as the WZ series of the Austrian Metallwerk Plansee company, the K series of the Kennedy company in the United States, and the TN series of the Kyocera company are successful examples of the development and application of special ceramics.
Special ceramic materials are known as "new materials for the 21st century." Therefore, we must actively explore the comprehensive potential of Taotezhong porcelain materials and continuously expand its new application areas to adapt to the requirements of the development of new technologies on the material side.

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