Fracture toughness (KIC), hardness, sintering and grain growth behaviour of 8YSCZ/Al2O3 composites produced by colloidal processing

The influence of Al2O3 content on fracture toughness, hardness, sintering and grain growth behaviour of 8YSCZ/Al2O3 composites were determined using high purity commercial powders of 8 mol% yttria-stabilized cubic zirconia (8YSCZ) doped with 0, 1, 5, 10 wt.% Al2O3. Colloidal processing was used for the mixing of powders in order to achieve a uniform distribution and homogeneous microstructure. The experimental results showed that sintered density increased with Al2O3 content up to 1 wt.% and further increase in Al2O3 content led to a decrease in sintered density. The grain growth in the 0-10 wt.% Al2O3 doped 8YSCZs was studied. The 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 for the addition of Al2O3 from 0 to 10 wt.%. The introduction of Al2O3 significantly enhanced the hardness and fracture toughness of 8YSCZ/Al2O3 composites. The hardness and fracture toughness increased with increasing Al2O3 content. The maximum hardness and fracture toughness values reached 1459 kg/mm2 and 2.41 MPa/m1/2, respectively with the addition of 10 wt.% Al2O3 while these values were 1314 kg/mm2 and 1.5 MPa/m1/2 for undoped 8YSCZ.