Colloidal processing, sintering and static grain growth behaviour of alumina-doped cubic zirconia

In order to determine the influence of alumina content on sintering and static grain growth behaviour of cubic zirconia, high purity commercial powders of 8 mol% yttria-stabilized cubic zirconia (8YSCZ) doped with 0, 1, 5, 10 wt.% Al2O3 were used. Colloidal processing was used for the mixing of powders in order to achieve a uniform distribution and homogeneous microstructure. The specimens were sintered at different temperatures between 1250 and 1400 °C for 1 h. The density increased with Al2O3 content up to 0.5 wt.% and a further increase in Al2O3 content led to a decrease in density. The enhanced density with increasing Al2O3 content up to 0.5 wt.% could be due to the rearrangement of Al2O3 particles during the early stages of sintering. The decreased density and grain growth in higher amount of Al2O3-doped specimens were due to the lower grain boundary diffusivity and mobility. X-ray diffraction results showed that Al2O3 had very limited solubility of 0.3 wt.% into 8YSCZ. The grain growth in the 0-10 wt.% Al2O3-doped 8YSCZ was studied. The experimental results showed that the grain growth in Al2O3-doped 8YSCZ occurred slowly and was more sluggish than that in undoped 8YSCZ. Also, the grain growth rate decreased with increasing Al2O3 content. The static grain growth exponent value and the activation energy for undoped 8YSCZ were found to be 2 and 289 kJ/mol, respectively. The addition of Al2O3 raised the grain growth exponent value to 3 and activation energy for the grain growth process was increased from 289 to 410 kJ/mol.