The Applications of Isostatic Pressing Graphite

Isostatic graphite is a new type of graphite material, which was developed in the 1940s and has a series of excellent properties. Isostatic graphite has excellent heat resistance. In an inert atmosphere, its mechanical strength increases with the increase of temperature, reaching the highest value at about 2500 ° C. Compared with ordinary graphite, isostatic graphite has a fine structure and uniform performance. ; Low thermal expansion coefficient, excellent thermal shock resistance; Isotropic, chemical resistance, outstanding thermal conductivity and electrical conductivity; Excellent machining performance. Because of this series of excellent properties, isostatic graphite has been widely used in the fields of chemistry, semiconductor, electrical, metallurgy, machinery, nuclear energy and aerospace.

The primary use of isostatic graphite

1 Graphite for solar cells and semiconductor wafers

In the solar energy and semiconductor industries, isostatic graphite is widely used to produce graphite components for single crystal direct heating furnaces, polysilicon foundry furnace heaters, compound semiconductor manufacturing heaters and crucibles. In recent years, solar photovoltaic power generation has developed rapidly. The production of monocrystalline silicon and polycrystalline silicon in the photovoltaic industry has a great demand for graphite. At present, monocrystalline silicon and polycrystalline silicon products have been developed towards large-scale and high-end development, and isostatic graphite also has higher requirements, larger specifications, higher strength and higher purity.

2. Nuclear graphite

Isostatic graphite has moderate mechanical properties, excellent mechanical properties at high temperatures, high thermal conductivity and low coefficient of linear expansion. In high-temperature gas-cooled reactors, it is mainly used as a reflector, moderator and active area structural material, and together with nuclear fuel to form a nuclear fuel assembly. At temperatures of 400-1200°C, high-energy gamma rays and fast neutron radiation tend to cause radiation damage over a period of several years, thereby altering the structure and properties of graphite. Therefore, a high degree of graphitization of the material is required. It should have outstanding isotropy, uniform composition and low elastic modulus.

3. EDM graphite

Graphite has no melting point, is an excellent conductor, has excellent thermal shock resistance, and is an excellent electrode material for EDM. The general graphite material is a low-density anisotropic graphite with a coarse-grained structure, which cannot meet the requirements of EDM. However, the structure of isostatic graphite electrodes is uniform, fine and compact, and the processing precision is high, which can meet the requirements in this regard.

4. Successive casting mold graphite and molded graphite

It is mainly used as a superhard material for continuous casting molds and high temperature and high pressure mold materials. Because of its uniform particle structure, high mechanical strength and uniform thermal conductivity, isostatic graphite makes continuous casting and molding products smooth on the outside, high in internal quality and long in service life. It is the best material for the crystallizer. Moreover, for large sintered materials, the mold wall should be as thin as possible, and it is necessary to use fine-strength isotropic graphite with high strength.

5. Other uses

High lubricity and high conductivity are very important when using carbon brushes, mechanical seals, contact plates, etc. that require precision. Generally, graphite materials need to be impregnated with resin and metal to increase strength and airtightness, but their application is limited in terms of corrosion resistance and high temperature resistance. Isostatic graphite has a low coefficient of friction and excellent thermal conductivity. It is generally used as a sliding friction material for bearings, mechanical seal rings and piston rings. In addition, isostatic graphite is also used to make diamond tools, thermal field components (heaters, insulating tubes, etc.) of optical fiber drawing machines, thermal field components (heaters, load structures, etc.) device.