The influence of components on the high-temperature performance and cutting performance of Si3N4-based ceramic tools

Three kinds of Si3N4-based ceramic tools (single-phase Si3N4, Si3N4/(W,Ti)C, and Si3N4/(W,Ti)C/Ni) were fabricated by microwave sintering. The phase composition, toughening mechanism, mechanical properties at room and high temperatures (800 degrees C), and cutting performance of Si3N4-based ceramic tool materials with different additives were investigated. The results showed that the addition of (W,Ti)C and Ni had a significant effect on improving the mechanical properties at room temperature, although it reduced the phase transition conversion rate of Si3N4. Si3N4/(W,Ti)C tools had good high-temperature stability, while Si3N4/(W,Ti)C/Ni tools had a decrease of about 31.6% in high-temperature hardness and a decrease of 13.7% in high-temperature flexure strength. Under the premise of ensuring a certain level of fracture toughness, high-temperature hardness is the main influencing factor on the cutting life of cutting tools. The Si3N4/(W,Ti)C tools exhibit superior cutting performance whose cutting life reaches to 50.67 min which was 1.37-3.27 times longer than the other two ceramic cutting tools at the same cutting parameters when continuous dry cutting T10A. In addition, high-temperature flexure strength limits the choice of cutting speed, and lower high-temperature flexure strength can lead to rapid tool failure.