The impact of sintering promoter oxides on magnesia-doped zirconia crystals synthesized by sol spray pyrolysis process

Homogeneous crystalline 11 mol.% magnesia doped partially stabilized zirconia (Mg-PSZ) and ZrO/sub 2/ ceramics with and without addition of sintering promoter oxides such as CuO, MnO/sub 2/ and CuO-MnO/sub 2/ were synthesized by hydrothermal treatment of zirconium and magnesium salts using sol spray process. The spray dried ZrO/sub 2/ and Mg-PSZ powders were calcined at 900 deg. C and sintered up to 1200 deg. C for 4 h. The relative density (- 93% of theoretical) was achieved at 1100 deg. C. The impact of sintering promoter oxides like 0.5 mol % CuO, 0.5 mol%MnO/sub 2/ and 0.5 mol% CuO-MnO/sub 2/ on phase, microstructure development, texture properties (porosity, surface area, particle size distribution) and on the densification behavior of dense Mg-PSZ ceramic were examined. Sinterability of Mg-PSZ ceramic powder was found to depend upon the stoichiometric concentration of mixed salt solutions, flow rate of carrier gas and sintering promoter oxides. It was observed that both the Cu and Mn oxides are very effective as sintering aids. The small addition of sintering aid oxides, 0.5 mol% CuO and 0.5 mol% MnO/sub 2/ reduced sintering temperature (by 150-200 deg. C) and promoted densification rate of Mg-PSZ with respect to the mixed CuO-MnO/sub 2/ addition. Addition of CuO enhanced the relative density and MnO/sub 2/ decreased the relative densities. However, the addition of mixed CuO-MnO/sub 2/ has an insignificant effect on the sintered density. The cubic structure Mg/sub 0.2/Zr/sub 0.8/O/sub 1.8/ was detected by X-ray diffraction. The scanning electron microscope analysis revealed that sintering aid oxides CuO and MnO/sub 2/ distorted surface morphology of Mg-PSZ nano crystals rounded into dumb-belled shape with diameter of > 500nm. (author)