Microstructure and mechanical properties of Al_2O_3/Ti(C, N) ceramic tool materials by one-step and two-step microwave sintering

摘要

Al_2O_3/Ti(C,N) ceramic tool materials were fabricated by one-step and two-step microwave sintering respectively. Microstructure and mechanical properties of sintered compacts were studied. Two-step microwave sintering can effectively restrain grain growth (1.32 μm for two-step sintering, 2.15 μm for one-step sintering), but the density of sintered was only 88.5% (98.2% for one-step sintering). The optimal mechanical properties were obtained by one-step microwave sintering (sintering temperature 1550 ℃ with the holding time of 10 min). The relative density, fracture toughness and Vickers hardness were 98.2 ± 0.35, 6.75 ± 0.73 MPa m~(1/2) and 18.7 ± 0.85 GPa, respectively. Ti(C,N) whiskers were formed by the two-step microwave sintering, which might be ascribed to the effects of single densification mechanism. As grain boundary diffusion played a leading role in densification while grain boundary migration was absent at 1300 ℃.