Abstract
3YSZ + (x) Al2O3 composites (x = 20, 40, 60, 80 wt%) were fabricated and the influences of particle sizes of Al2O3 on their microstructures and mechanical properties were investigated with XRD, SEM, vickers hardness and fracture toughness. Al2O3-3YSZ composites containing Al2O3 powder of a 0.3 μm and an 1.0 μm, which are here in after named as Al2O3(0.3 μm)-3YSZ and Al2O3 (1.0 μm)-3YSZ, respectively, were made by mixing raw materials, uni-axial pressing and sintering at 1,400℃, 1,500℃, and 1,600℃. Al2O3 (0.3 μm)-3YSZ composites show the higher density and the better mechanical properties than Al2O3 (1.0 μm)-3YSZ composites. The Vickers hardness of the Al2O3 (0.3 μm)-3YSZ composites show a peak value of 1,997 Hv at the content of 60 wt% Al2O3, which is a slightly higher value in comparison with 1,938 Hv of the Al2O3(1.0 μm)-3YSZ composite. However, the fracture toughness of Al2O3-3YSZ composites monotonically increases with decreasing the content of Al2O3 without any peak values. Al2O3 (0.3 μm)-3YSZ and Al2O3 (1.0 μm)-3YSZ composites sintered at 1,600℃ have a maximum value of a 6.9 MPa·m1/2 and a 6.2 MPa·m1/2, respectively at the composition of containing 20 wt% Al2O3. It should be noticed that the mechanical properties and the sintering density of the Al2O3-3YSZ composites can be enhanced by using more fine Al2O3 powder due to their denser microstructure and smaller grain size.
