Experimental study on impact resistance and mechanical characteristics of low-temperature sintered Al2O3-ZrO2 composites with anti-sandwich structure

摘要

Al2O3-ZrO2 composites with anti-sandwich structure prepared by two-step pressing method were sintered at a low temperature of 1540 °C in air. As a reference, Al2O3-ZrO2 monolithic composites without this structure were also fabricated using the same process. In the study, relative density, fracture strength, fracture toughness, residual stress and especially impact energy of different composites were tested. Furthermore, interface and fracture morphologies were observed. The results indicated that current process was available in preparing Al2O3-ZrO2 composites based on the requirement of low-temperature sintering. Al2O3-ZrO2 composites with the anti-sandwich structure exhibited both better impact resistance and other mechanical properties than those without the special structure. The better properties resulted mainly from the anti-sandwich structure, which led to a change of fracture mechanism: from priority of intergranular fracture to that of transgranular fracture. SI sample with the compositions of 95 wt% Al2O3 4- ZrO2 in the surface layer and 85 wt.% Al2O3 + ZrO2 in the center layer exhibited the best properties in the whole series, where its fracture strength, fracture toughness and impact energy were 577 MPa, 10.56 MPa·m~(1/2) and over 1.4 J, respectively.