Improved sinterability and thermal shock resistance of MgO-ZrO2 composites due to in-situ formed MgAl2O4

To solve the problems of high cost and high firing temperature of ZrO2 inserted rings of slide plates, the in-situ MgAl2O4 (MA) toughened MgO-ZrO2 new ring materials were prepared using lightly calcined MgO, m-ZrO2 and nanoscale Al2O3. The effects of MgO/ZrO2 ratio and the amount of nanoscale Al2O3 on properties of samples were investigated. The results showed that the sinterability and mechanical properties of MgO-ZrO2 composites improved significantly due to the MA formed in situ by reaction between MgO and Al2O3, which promoted reactive sintering and densification of the samples. The improved thermal shock resistance (TSR) in MA-toughened MgO-ZrO2 composites was attributed to microcracks developed due to thermal expansion mismatch, MA and ZrO2 also acted as bridging particles, improving the ability to prevent crack propagation of the composites. The optimum MgO/ZrO2 ratio and addition amount of nanoscale Al2O3 were 7/3 and 3 wt%, respectively.