Microstructure and grain growth mechanism of corundum abrasive with La2O3-TiO2-SiO(2 )composite additives

Equiaxed crystal corundum abrasives were fabricated via sol-gel method with La2O3-TiO2-SiO(2 )composite additives and ZrO2 co-doping by using pseudo-boehmite as raw material. The effects of composite additives content on abrasive properties, microstructure, and grain growth were investigated. The results of XRD and XPS showed that the aluminum silicate liquid phase containing Ti and La was formed in the composite additives system. Grain morphology and crystal plane were characterized by a combination of SEM and TEM. Results showed that there was an optimal orientation in the doped samples, mainly (01 1( -) 2) and (0006). So, the morphology of the doped grain surface was completely different from that of undoped grains, which is hexagonal. The reason was that the nucleation rate of the basal plane and the non-basal plane were close to each other, resulting in the formation of three-dimensional equiaxed crystals. Furthermore, the second phase (Ti2ZrO6) and equiaxed grains significantly improved the hardness. Thus, the hardness of abrasives increased first and then fall as the content of composite additives increased. The best performance of abrasive was obtained when the composite additives content was 2.5 wt%. Its relative density and Vickers hardness were 99.6% and 24.1 GPa, respectively.