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

Abstract

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.% Al 2O 3 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 Al 2O 3 content up to 0.5 wt.% and a further increase in Al 2O 3 content led to a decrease in density. The enhanced density with increasing Al 2O 3 content up to 0.5 wt.% could be due to the rearrangement of Al 2O 3 particles during the early stages of sintering. The decreased density and grain growth in higher amount of Al 2O 3-doped specimens were due to the lower grain boundary diffusivity and mobility. X-ray diffraction results showed that Al 2O 3 had very limited solubility of 0.3 wt.% into 8YSCZ. The grain growth in the 0–10 wt.% Al 2O 3-doped 8YSCZ was studied. The experimental results showed that the grain growth in Al 2O 3-doped 8YSCZ occurred slowly and was more sluggish than that in undoped 8YSCZ. Also, the grain growth rate decreased with increasing Al 2O 3 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 Al 2O 3 raised the grain growth exponent value to 3 and activation energy for the grain growth process was increased from 289 to 410 kJ/mol.