Effect of LaMgAl11O19 addition and temperature on the mechanical properties of Al2O3-based ceramics

Abstract

In this study, the effect of the LaMgAl11O19 content on the mechanical properties of pressureless sintered Al2O3–LaMgAl11O19 composites, including room-temperature fracture toughness and flexural strength from room temperature to 1400°C, was systematically investigated. Results indicated that Al2O3–LaMgAl11O19 ceramics exhibit enhanced mechanical properties as compared with those of monolithic Al2O3 ceramics both at room and elevated temperatures, with the maximum fracture toughness and flexural strength values of 4.88MPam1/2 and 472.8MPa at room temperature, respectively. The flexural strength of Al2O3–LaMgAl11O19 ceramics gradually decreased with increasing test temperature below 1000°C and sharply decreased thereafter. The improved mechanical properties of Al2O3–LaMgAl11O19 composites at ambient temperature were primarily attributed to the combination of crack deflection and bridging of LaMgAl11O19 platelets, while under elevated temperatures, the presence of LaMgAl11O19 platelets also played a crucial role in effectively hindering the grain boundaries sliding, thereby endowing superior bending strength to the composites.