Study On Al₂O₃-Ti（C,N）-cBN Ceramic Tool Materials Sintered By Oscillatory Pressure

Al₂O₃-Ti（C,N）multiphase ceramic is a commonly used black ceramic tool material,which has excellent high-temperature stability,chemical stability,wear resistance,corrosion resistance and other characteristics,but its poor toughness is still the key factor hindering its development.Cubic boron nitride（cBN）,second only to diamond in hardness,as a hard particle toughening phase,has received widespread attention as it can toughen the matrix without reducing the hardness and wear resistance.However,the difficulty in sintering cBN makes it difficult to prepare multiphase ceramics with stable phase and high density.In this paper,high performance Al₂O₃-Ti（C,N）-cBN ceramic tool materials was prepared by oscillatory pressure sintering technology to solve the above problems.Firstly,taking Al₂O₃-Ti（C,N）multiphase ceramics as the research object,the densification process and mechanism are analyzed,providing a reference for optimizing the sintering process of Al₂O₃-Ti（C,N）-cBN multiphase ceramics;Then the evolution of microstructure and mechanical properties of Al₂O₃-Ti（C,N）-cBN ceramic tool materials at different sintering temperatures was studied;Finally,the properties of Al₂O₃-Ti（C,N）-cBN ceramic tool material were further optimized by oscillatory pressure sintering forging process.In this paper,the density of ceramic materials was measured by the Archimedes method,the hardness and fracture toughness of ceramic materials was measured by the indentation method,the flexural strength of ceramic materials was measured by the three-point bending method,and the phase and microstructure evolution of multiphase ceramics was characterized by XRD,SEM,EDS,etc.finally establishing the relationship between oscillatory sintering process,structure and performance.The study found that:Oscillation pressure sintered Al₂O₃-Ti（C,N）complex ceramics did not undergo chemical reactions or phase transitions at 1400℃.The properties of Al₂O₃-Ti（C,N）complex ceramics increased with the increase of oscillation pressure,and when the median oscillation pressure was 70 MPa,its relative density,hardness and flexural strength were 99.99%,22.7 GPa and 693 MPa,respectively.Among the oscillation pressure sintered Al₂O₃-Ti（C,N）-cBN ceramic tool materials,when the sintering temperature is 1500℃,the mechanical properties of Al₂O₃-Ti（C,N）-cBN ceramic tool materials are the best,and their relative density,Vickers hardness,flexural strength and fracture toughness reach 99.43%,21.45 GPa,731 MPa and 5.69 MPa·m^1/2,respectively.The oscillation pressure sintering forging process can improve the thermal stability of Al₂O₃-Ti（C,N）-cBN ceramic tool material to 1600℃,its hardness is 20 GPa,the bending strength is 647 MPa,and the fracture toughness is 5.23 MPa·m^1/2.When the forging temperature reaches 1800℃,the curved grain boundary formed in the multiphase ceramic increases the flexural strength and fracture toughness of Al₂O₃-Ti（C,N）-cBN ceramic tool materials to 877 MPa and 6.59 MPa·m^1/2,respectively.Oscillatory pressure sintering technology can significantly improve the mechanical properties of alumina based ceramic tool materials,which is superior to the properties of hot pressure sintered ceramic materials.Oscillatory pressure sintering forging technology can significantly improve the flexural strength and fracture toughness of alumina based ceramic tool materials.Therefore,oscillatory pressure sintering technology and oscillatory pressure sintering forging technology are expected to produce high-performance alumina based ceramic tools,which can meet the urgent demand for high-performance cutting tools.