科研之友
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摘要
In this work, the influence of La2O3 on microstructure and mechanical properties of 5 wt% alumina dispersed in 2.3 mol% yttria-stabilized zirconia was investigated, with the aim of optimizing flexural strength and fracture toughness by changing the amount of La2O3. The alumina-dispersed zirconia with different La2O3 contents (0.4, 0.8, 1.2 wt%) were prepared by sintering at 1500 degrees C for 2 h in air. Structural examinations were performed using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). Mechanical properties of the composites were determined as hardness by conducting Vickers indentation tests, flexural strength by 3-point bending method, and fracture toughness by SEVNB method. Addition of La2O3 had influences on the phase composition by forming long rod-shaped LaAl11O18, which consumed alumina and then increased the fracture toughness by increasing the volume of phase transformation of t-ZrO2. But excess La3+ in zirconia grains would form solid solution and decreased fracture toughness by suppressing phase transformation in t-ZrO2. The composite with 0.8 wt% La2O3 addition was found to be an optimum combination between flexural strength and fracture toughness. The obtained flexural strength and fracture toughness were 947 +/- 55 MPa and 6.5 +/- 0.1 MPa m(1/2), respectively.
