Effect of ZnF2–TiO2–SiO2 additions on the two-step sintering behavior and mechanical properties of sol–gel derived corundum abrasive

The synergistic effect of ZnF 2 –TiO 2 –SiO 2 and seeds on the sintering behavior and microstructure of corundum abrasive was investigated. Significant improvement on microstructural homogeneity, densification and mechanical property was achieved by the co-doping and two step sintering (TS) for the abrasive samples. All the doped samples showed relative densities higher than 98% and single particle compressive strengths larger than 30   N. Besides, the two-step sintering samples attained smaller particle sizes, slightly higher densities, and narrower particle size distributions . Sample sintered by TS method with MgTiO 3 seed and the addition of ZnF 2 /TiO 2 /SiO 2 in the molar ratio of 5:7:5 obtained single particle compressive strength of 56.3   N, theoretical density of 99.4% and an average grain size of 0.46   μm. The phase transformation temperatures of doped samples were much lower than that of un-doped ones and they dropped significantly as the content of ZnF 2 raised. The relationship between microstructure and mechanical properties was also discussed.