Effect of sintering profile on densification, microstructure and mechanical properties of Al2O3-3YSZ-Ni composite

In the present study, the effect of heating schedules on densification, microstructure and mechanical properties of the Al2O3-3YSZ-Ni composite was investigated. The composites were fabricated by one-step sintering (OSS) at temperatures T for 3 h (T/3 h), and two-step sintering (TSS) starting by preheating to a temperatures T-1 for 0.5 h, followed by a drop in temperature to T-2 equal to 1600 degrees C for 3 h (T-1/0.5 h, 1600 degrees C/3 h). The contribution of smaller grain size and the improvement of relative density produced by TSS lead to enhanced hardness and fracture strength of the composite without destroying its fracture toughness. The hardness of composites increased with increasing sintering temperature, where its highest value 14.51 GPa was attained at T-1 = 1720 degrees C for TSS. As well, strength was enhanced and reached 417 MPa. However, the toughness for TSS was decreased slightly with increasing T-1 and attained its highest value of 6.21 MPa m(1/2) at T-1 = 1650 degrees C.