Discussion on corundum wear-resistant ceramics

Corundum wear-resistant ceramics refer to engineering ceramics with an alumina content higher than 90%, usually 92% 95% alumina ceramics. According to standards, corundum wear-resistant ceramics have characteristics such as high hardness, high strength, low coefficient of expansion, insulation, wear resistance, and corrosion resistance, and are widely used in fields such as mechanical manufacturing, aerospace, precision instruments, and petrochemicals.

Corundum wear-resistant ceramic parts are usually formed by hot pressing sintering. Due to sintering often causing deformation and shrinkage, further precision machining is generally required to ensure the dimensional and shape accuracy of the parts. Aluminum oxide ceramic materials generally have a relatively large elastic modulus, high hardness, high brittleness, and strong crack sensitivity, so their processing difficulty mainly lies in the processing hardness and brittleness. Al2O3 mainly has three crystal forms: alpha, beta, and gamma. Among them, alpha Al2O3 is relatively stable, and beta and gamma crystals almost completely transform into alpha crystals at 1300 ℃. In the crystal form of α - Al2O3, the atomic bonds formed by aluminum ions and oxygen ions are mostly covalent bonds, ionic bonds, or their mixed bonds. So the bonding energy between atoms is high, with strong directionality, manifested as high brittleness of the material, small plastic deformation, and easy cracking.

Its hardness is comparable to that of hard alloy and several times higher than that of steel. Usually, the density of pure alumina ceramics can reach 3980 (Kg m4), the tensile strength can reach 260 (MPa), the elastic modulus is between 350-400 (GPA), the compressive strength can reach 2930 (MPa), and especially the hardness can reach 99HRA