Properties of special ceramic materials are determined by two factors. First, the structure of the material, the main bonding properties, the crystal structure. They determine the properties of ceramic materials, such as high temperature resistance, semiconductor and insulation. Secondly, microstructure, including distribution, grain size, shape, pore size distribution, impurities, defects, etc. Ordinary ceramics with clay, feldspar, quartz as raw materials, made by preparation, sintering. This kind of ceramic is hard, no oxidation rust, corrosion resistance, non-conductive, high temperature resistance, good processing molding, low cost, but low strength. Generally the highest use temperature does not exceed 1200 degrees Celsius, this kind of ceramic production, many kinds, widely used in electrical, chemical and other industries.
Silicon carbide powder for silicon carbide ceramics is made by reactive sintering or hot-press sintering process with powder metallurgy. Silicon carbide ceramics have the greatest characteristics of high temperature strength, good thermal stability, good wear resistance and creep resistance. Suitable for pouring metal throat, thermocouple sleeve, gas turbine blade, bearing and other parts. At the same time because of its high heat conduction ability, also suitable for high temperature conditions heat exchange equipment materials, also can be used to make a variety of pump seal ring.
Silicon nitride ceramics have abundant raw materials and good processability, which can be used to produce various precise parts with low cost, especially complex parts with higher yield than other ceramic materials. Silicon nitride ceramic temperature resistance degeneration is good, high hardness, its hardness is second only to diamond and boron nitride material, made of silicon nitride ceramics engine, due to the working temperature up to 1370 degrees Celsius, engine efficiency can be increased by 30%. At the same time because of the increase in temperature can make the fuel burn adequately, discharge waste gas pollution components dropped substantially, not only reduce energy consumption, and reduce the pollution of the environment.
Some other special ceramic material, the kind is very various still, they have characteristic each, can make a variety of function element. Lithium oxide ceramics are high-temperature materials, talc ceramics are high-frequency insulation materials, thorium oxide ceramics are dielectric materials, barium titanate ceramics are photoelectric materials, borides, nitrides, silicides and other metal ceramics are ultra-high-temperature materials. Ferrite ceramics are made of permanent magnet, memory magnet and magnetic head, rare earth cobalt porcelain is used as storage material, semiconductor porcelain is used as sub-sensitive elements, solar cells and other materials.
