Mechanical Properties and Microstructures of Al 2 O 3 /TiC/TiB 2 Ceramic Tool Material.

In order to develop a new ceramic tool material with self-repairing capability, Al₂O₃/TiC/TiB₂ ceramic tool material was prepared by vacuum hot-pressure sintering method. The toughening and strengthening mechanism of TiB₂ on Al₂O₃/TiC substrate was analyzed. The results show that the ceramic tool material has good comprehensive mechanical properties when the TiB₂ content is 10 vol.%. Its flexural strength was 701.32 MPa, hardness was 18.3 GPa, and fracture toughness was 6.2 MPa·m^1/2, which were improved by 11.6%, 2.2% and 16.1% respectively, compared with the Al₂O₃/TiC tool material. Fracture surfaces of the Al₂O₃/TiC/TiB₂ ceramic tool material were characterized by SEM, EDS and XRD. The results showed that the fracture mode was a mixture of transgranular fracture and intergranular fracture. The growth of Al₂O₃ and TiC grains can be effectively inhibited by adding appropriate amount of TiB₂, and the internal grains of the material can be refined. The TiB₂ has a uniform distribution in the matrix and acts as a diffusion toughening agent. The cutting performance of Al₂O₃/TiC/10 vol.%TiB₂ tool material was further investigated. Experiments conducted on tools made of Al₂O₃/TiC and Al₂O₃/TiC/TiB₂ materials showed that the main forms of wear for both tools were abrasive wear and bonded wear. The friction coefficient of Al₂O₃/TiC/TiB₂ tools was reduced by 10.77% compared to Al₂O₃/TiC tools. [ABSTRACT FROM AUTHOR]