Mechanical properties and microstructure of Ti(C5N5)-TiB2-(W7Ti3)C composite cutting tool materials

Abstract

Ti(C5,N5)-TiB2-(W7,Ti3)C composite ceramic cutting tool materials were prepared using the vacuum hot-pressed sintering technology. The effects of the sintering temperature and the heating rate on the mechanical properties and microstructure of different composite materials containing different contents of TiB2 were investigated. The sintering process of a higher temperature with a fast heating rate or a lower temperature with a slow heating rate was found to be beneficial to the mechanical properties of the composites. The better sintering temperature range for fabricating the composites was from 1585 to 1620 °C. The composite material with a content of 30 wt% TiB2 sintered at 1585 °C with either a heating rate of 90 or 50 °C/min had the prominent flexural strength. The composite with a content of 20 wt% TiB2 sintered at 1620 °C with a heating rate of 90 °C/min had the relatively better fracture toughness and hardness than that with a content of 30 wt% TiB2. The two core-rim microstructures were formed inside the TiB2 and Ti(C, N) grains, which further contributed to a compact microstructure and improved the mechanical properties of the composites. The optimum sintering temperature range for the formation of the core-rim microstructures was also from 1585 to 1620 °C.