Alumina ceramic

Alumina ceramics are ceramic-like materials composed of AI203 as the main raw material and corundum (a-AI203) as the main mineral. The AI203 content is generally 75.0% ~ 99.9%. High-purity alumina ceramics (AI203 content is higher than 99%) are 2~3 times, or even 5~6 times stronger than ordinary ceramics; the hardness is very high, up to 90HRC, second only to diamond, carbide, boron nitride and Silicon carbide; has good wear resistance, high creep resistance and high temperature resistance, and can work at a high temperature of 1600C for a long time; alumina is a relatively stable compound, and alumina ceramics have good resistance to Corrosion resistance and good insulation, especially good electrical insulation against high-frequency current. The disadvantages are that it is brittle, has poor thermal shock resistance, and cannot withstand sudden changes in ambient temperature. It is a very important ceramic material.

The strength of alumina ceramics varies greatly with different preparation processes and organizational structures. Even under the same preparation process conditions, the strength also changes due to the density of the material itself. This is a typical feature of ceramic materials. There is still a big gap between the toughness of alumina ceramics and metal materials. In practical applications, alumina ceramics are mainly used for their high corrosion resistance, wear resistance and mechanical properties in harsh environments. High wear-resistant alumina ceramics must not only have high density, flexural strength and compressive strength, but also have high fracture toughness and hardness. Generally speaking, the fracture toughness of alumina ceramics is relatively low. This is a common weakness of ceramic materials.

Alumina structural ceramics are mainly used to manufacture spark plugs, bearings, ball mill balls and linings for internal combustion engines, ceramic armor materials, metal wire drawing dies, cutting tools for cutting chilled cast iron and quenched steel, sealing rings for petroleum and chemical industries, and textile machines. Wire guides, piles of molten metal, high-temperature thermowells, rocket and missile fairings, etc. It has become one of the most widely used ceramic materials in the world

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