Fracture toughness (K_(IC)), hardness, sintering and grain growth behaviour of 8YSCZ/Al_2O_3 composites produced by colloidal processing

摘要

The influence of Al_2O_3 content on fracture toughness, hardness, sintering and grain growth behaviour of 8YSCZ/Al_2O_3 composites were determined using high purity commercial powders of 8 mol percent yttria-stabilized cubic zirconia (8YSCZ) doped with 0, 1, 5, 10 wt.percent Al_2O_3. 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 Al_2O_3 content up to 1 wt.percent and further increase in Al_2O_3 content led to a decrease in sintered density. The grain growth in the 0-10 wt.percent Al_2O_3 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 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 for the addition of Al_2O_3 from 0 to 10 wt.percent. The introduction of Al_2O_3 significantly enhanced the hardness and fracture toughness of 8YSCZ/Al_2O_3 composites. The hardness and fracture toughness increased with increasing Al_2O_3 content. The maximum hardness and fracture toughness values reached 1459 kg/mm2 and 2.41 MPa/m~(1/2), respectively with the addition of 10 wt. percent Al_2O_3 while these values were 1314kg/mm2 and 1.5MPa/m~(1/2) for undoped 8YSCZ.