Preparation And Application Of Al₂O₃-based Composite Ceramic Cutting Tools Machinability Study

The extensive use of difficult-to-machine materials has put higher requirements on the cutting performance of the tool.As one of the modern mainstream tool materials,ceramic tool materials have good heat resistance and chemical stability.Al₂O₃ceramics have high hardness,but poor flexural strength and fracture toughness affect their development.Adding carbides and other enhancements to Al₂O₃will significantly improve the performance of the relative ceramic materials.Adding Si C nanoparticles to the Al₂O₃material can refine the grains and reduce defects,thereby improving the properties of the material;c BN is a superhard material with good thermal stability,wear resistance,thermal conductivity and chemical stability,which greatly improves the cutting performance of tool materials.1)Firstly,the matrix phase and reinforcing phase of composite ceramic tool material are selected,and the preparation technology and sintering technology of composite tool material powder are studied.The tool materials with different reinforced phase ratios were prepared by SPS spark plasma hot pressing sintering furnace;the sintering temperature and holding time were selected by optimizing the sintering process parameters.The study found that when the sintering pressure of Al₂O₃-Si C-c BN composite ceramic tool material is 32MPa,the sintering temperature is 1500?,and the holding time is 30min,the bending strength,Vickers hardness,fracture toughness and relative density of the tool material were 746MPa,18.8GPa,6.35MPa·m^1/2and 99.3%.Due to the synergistic toughening,grain refinement and fracture mode change of Si C nanoparticles and c BN,the comprehensive properties of the tool material are effectively improved.2)Secondly,the cutting experiment of ceramic tool cutting quenched 45 steel is carried out,the wear pattern of the tool,the temperature of the tool surface and the surface quality of the workpiece under different cutting parameters were studied,and the failure mechanism of the tool cutting quenched 45 steel was analyzed.The research found that the tool life is longest when the cutting speed is 150m/min;the main wear mechanism of the tool during high-speed cutting is adhesive wear.The finite element simulation model of Al₂O₃-Si C-c BN tool cutting quenched 45 steel is established,and the feasibility of the simulation experiment is verified.3)Finally,a simulation model of Al₂O₃-Si C-c BN tool for high-speed cutting of quenched 45 steel was established,and the simulation results of cutting temperature and Miss stress were analyzed,and the geometry of the tool was optimized.Appropriate blunt radius(r=0.05mm),rake angle(-6°)and fillet radius(r=0.6mm)are selected to improve the machining conditions of the tool.