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Characteristics of graphite materials
Graphite material graphite material is the most widely used friction pair material. It has the following characteristics:
(1) Good corrosion resistance.
(2) It has good temperature resistance.
(3) Good thermal conductivity and low coefficient of linear expansion.
(4) Good pairing performance.
(5) Easy to process. The graphite materials used in mechanical seal can be roughly divided into the following categories. Calcined graphite. When the graphite is roasted, because of the volatilization of the material in the binder and the polymerization, decomposition and carbonization of the binder, the pores (with 10% - 30% pores) will appear. When the graphite is used as the sealing ring, the permeability leakage will occur, and the strength is low. Therefore, it needs to be impregnated to strengthen the gaps, that is to say, after the impregnation, the graphite will become an airtight product, and the strength will also be improved. However, the temperature resistance and corrosion resistance decreased to some extent. There are three types of impregnations used: organic resin, inorganic material and metal. Resin bonded graphite. It is to crush the graphite after sintering, use phenolic resin or epoxy resin as binder, mix and then press and sinter to produce products. The resin in the matrix becomes carbon particles after sintering, so it is permeable graphite. It is suitable for mass production because of its poor thermal conductivity and large linear expansion coefficient. Low cost, mainly used for low load sealing of automobile cooling water pump, household appliances, etc.
Graphite codes are:
① Carbon graphite, code M121, temperature resistance 350 ℃.
② Graphite impregnated epoxy resin, code: m106h, m120n, m220n, service temperature: 200 ℃.
③ Graphite impregnated furan resin, code number m106k, m120k, service temperature 200 ℃, it is a common material for mechanical seal of centrifugal pump, with a wide range of applications.
④ Graphite impregnated aluminum, code m232l, service temperature 400 ℃. In addition, there are antimony, silver and copper impregnated graphite.
⑤ Graphite is impregnated with phenolic resin, which is not alkali resistant, and the service temperature is 170 ℃.
⑥ Graphite impregnated glass, code number M120, m162.
⑦ Antimony impregnated graphite material, it is used in high temperature pump, the use temperature is about 300 ℃, but the price is relatively expensive.