Synthesis and two-step sintering behavior of solution derived corundum abrasives with plate-like grains

Corundum abrasives with plate-like grains were fabricated by a two-step sintering technique using the solution-based process with the addition of the ternary compound additive Na3AlF6-CaO-SiO2. The two-step sintering method showed obvious advantages over conventional sintering methods in promoting sample densification, suppressing grain growth, and homogenizing the microstructure of the corundum abrasives. The sample doped with 2.5 wt% Na3AlF6 and 4 wt% CaO + SiO2 in the molar ratio of 1:1 possessed a relative density of 99.3%, average grain size of 0.54 µm, and single-particle compressive strength of 49 N. The introduction of seeds reduced the temperature of θ- to α-Al2O3 phase transformation. The relationship between the microstructure and the mechanical properties of the abrasives was also discussed.