Main Uses of Isostatic Graphite
Isostatic graphite is a new type of graphite materials which developed in the 1940s and has a series of excellent properties. Isostatic graphite has good heat resistance, in an inert atmosphere, its mechanical strength increased with the increase of temperature and reached the highest value at around 2500 °C, compared with ordinary graphite, Isostatic graphite has fine structure, and uniform good performance; low coefficient of thermal expansion, excellent thermal shock resistance; isotropy, chemical resistance, good thermal and electrical conductivity; excellent mechanical processing properties. Because of this series of excellent performance that isostatic graphite has been widely used in chemical, semiconductor, electrical, metallurgy, mechanical, nuclear and aerospace fields. Moreover, the application field is still expanding with the development of science and technology.
Main uses of isostatic graphite
1.Graphite for Solar Cells and Semiconductor Wafers
In the solar and semiconductor industries, isostatic graphite is used in large quantities to produce single-crystal direct-heating furnace hot-field graphite parts, polycrystalline silicon casting furnace heaters, compound semiconductor manufacturing heaters, and crucibles. In recent years, the development of solar photovoltaic power generation has been rapid. The monocrystalline silicon and polysilicon production in the photovoltaic industry has a great demand for graphite. At present, monocrystalline and polycrystalline silicon products have grown toward large-scale and high-end development, and the isostatic graphite also has higher requirements, greater specifications, higher strength, and higher purity.
2. Nuclear graphite
Isostatic graphite has moderate mechanical properties, excellent mechanical properties at high temperature, high thermal conductivity, and low coefficient of linear expansion. In high-temperature gas-cooled reactors, it is mainly used as a reflector, a moderator, and an active zone structural material, and constitutes a nuclear fuel assembly together with nuclear fuel. At a temperature of 400-1200° C., high-energy γ-rays and fast neutron radiation are liable to cause radiation damage for a period of several years, thereby changing the structure and properties of graphite. Therefore, the degree of graphitization of the material is required to be high. It should has good isotropic property, uniform composition and low elastic modulus.
3. EDM graphite
Graphite has no melting point, is a good conductor of electricity, has good thermal shock resistance and is an excellent electrode material for EDM machining. Ordinary graphite materials, which are low-density anisotropic graphite with coarse grain structure, can not meet the demand of EDM. However, the isostatic graphite electrode structure is uniform, dense, and has high processing accuracy, which can meet the requirements in this respect.
