THE DENSIFICATION AND MICROSTRUCTURAL DEVELOPMENT OF AL2O3 WITH MANGANESE OXIDE ADDITION

The effect of MnO2 as an additive on the densification behaviour and m icrostructural evolution of alpha-Al2O3 has been investigated over a w ide sintering regime. A colloidal technique was applied for the mixing of MnO2 in order to achieve a uniform distribution and homogeneous mi crostructures. Sintered density, average grain size and microstructura l features were elaborated along with the microhardness and mechanical strength measurements. Manganese oxide was found to promote grain gro wth and an intergranular second phase formation was detected for addit ions over 0.5 wt% MnO2. Excessive grain growth and draining of the sec ond phase were observed in the samples with 3 wt% MnO2 additions sinte red above 1500 degrees C.