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Machinable Hardness and Application of 99% Alumina Ceramics
* Machinable Hardness of 99% Alumina Ceramics
99% alumina ceramics is the most common industrial ceramic materials, and widely applied in modern society for its excellent properties. In this article, the machinable hardness and application of #99 alumina ceramics are briefly introduced.
AL2O3 mainly has 3 kinds of crystalline phases, which are α,β and γ crystalline phase. Among them, αcrystal phase Al2O3 has the most stable state. When temperature reaches up to 1300℃, β and γ crystals almost convert to αphase crystal.
In Al2O3 crystalline phase, most atomic bonds (formed by aluminum ion and oxygen ion) are covalent bonds, ionic bonds or mixed bonds of both, which results in high interatomic binding energy and strong directivity, therefore Al2O3 material manifests high brittleness, low plastic deformation, and high hardness. Its hardness is comparable with cemented carbide, and several times higher than steel.
Generally, density of high purity AL2O3 ceramics can reach up to 3980kg/m3, and strength of extension is 260MPa, the elastic modulus is between 350 to 400GPa, and compressive strength is 2930(MPa). For hardness, high purity AL2O3 could reach to 99HRA.
Although hardness of 99% refined AL2O3 ceramics is relatively lower than that of high purity AL2O3 ceramics, it could still reach to 70HRA at room temperature according to test result.
* Application of 99% Alumina Ceramics
Alumina oxide is the most proven engineering ceramics, with excellent electrical insulation performance, high hardness and wear-resistance, it is widely applied in machinery manufacturing, aerospace, precision instruments, petrochemical and other fields.
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