چكيده به لاتين
Abstract:
The present study aimed to investigate the synthesis, microstructural and mechanical properties of alumina/zirconia-cobalt composite. The compositions containing 5, 10, 20 Vol.% of the sum of ZrO2 and Co were studied. The composite powders were prepared through mixing of alumina powder with partially stabilized zirconia and cobalt sulfate powders followed by calcination treatment at 1100℃ for 3h and reduction of cobalt by aluminum powder additive, in carbon bed at 950℃ for 3h. The XRD analysis showed the presence of Al2O3, t-ZrO2, Co and a little m-ZrO2. In order to investigate the properties of Al2O3/ZrO2-Co, the reduced powders were sintered by pressureless and spark plasma sintering. The composite powders were pressed by cold isostatic pressing (CIP) at 400 MPa. The prepared discs were sintered in carbon bed at 1550℃, 1600℃, 1650℃ for 5h. In spark plasma sintering the specimens were sintered at 1500℃, 1600℃ with a holding time of 5min and 30MPa pressure. The final results showed that in pressureless sintering, with sintering temperature increment, relative density of the specimens increased and by using of spark plasma sintering can achieve higher relative densities. Furthermore with the addition of cobalt and zirconia particles, the hardness of the composites decrease in comparison with monolithic alumina. In the composite specimens with higher relative densities, an increase of strength was observed. The relative density, bending strength and hardness of the 90vol.%Al2O3/5vol.%ZrO2 -5vol.%Co composite densified by spark plasma sintering were 89.2%TD, 340±28 MPa and 12.20 GPa respectively.
Keywords:
alumina-zirconia-cobalt composite, pressureless sintering, spark plasma sintering
