Preparation of sol-gel derived microcrystalline corundum abrasives with hexagonal platelets

The effects of different additives on the mechanical properties, microstructures, and wear behavior of corundum abrasives were investigated. When the number of additive phases increases, the sintering temperature and wear rate decrease, while the densification and mechanical properties increase. The additive SiO₂ is responsible for the development of equiaxed grains, whereas both CaO and MgO promote the development of platelike grains. By controlling the molar ratio of additives, it is possible to obtain different microstructures. With SiO₂-MgO-CaO (molar ratio, 2:1:1) as the additives and nano α-Al₂O₃ powders as the seed, microcrystalline corundum abrasives with hexagonal platelets were obtained using sol-gel process by sintering at 1300℃ for 0.5 h. The average diameter and thickness of hexagonal platelets are 1.38 μm and 360 nm respectively, the single-particle compressive strength is 26.44 N, and the wear rate is (3.06±0.21)×10⁻⁷ mm³/(N·m).