Prediction Of Performance Of Composite Ceramic Tool Materials At Microscopic Scale

The rapid development of modern industry has led to the continuous innovation and rapid development of cutting tools.Nowadays,cutting tools are widely used in aerospace,automotive,medical devices and other fields.Multiphase ceramic tool materials are a kind of materials with high hardness,wear resistance and low thermal expansion coefficient.However,the research and development of new ceramic tools materials has a large investment and a long cycle,and with the help of computer numerical simulation method to predict its macro-mechanical properties from the micro-scale,low cost and high efficiency,it has gradually become a new method to study the properties of ceramic tool materials.Based on the secondary development of ABAQUS,this paper constructed the microstructure model of ceramic tool materials with the help of Voronoi Tessellation.Combined with the meso-finite element and cohesive zone model method,an effective method for systematically predicting the elastic modulus and crack growth of materials was formed,the elastic properties and crack growth resistance of Al₂O₃/TiB₂multiphase ceramic tool materials were predicted,and the effects of microstructure on elastic properties and fracture toughness were revealed.The Al₂O₃/TiB₂ multiphase ceramic tool material was prepared by plasma sintering process,and the rationality of the prediction method was verified.A method of constructing two-dimensional microstructure model of multiphase ceramic tool materials based on Voronoi Tessellation was proposed.Under the set random factor?,the finite element model reflecting the actual microstructure of the material was established on ABAQUS,and the GUI interface was created,which improved the efficiency of modeling.At the same time,based on the set shape factor?,the moving window method was used to determine the reasonable size of the representative volume element.The periodic boundary conditions for the relationship between macro and micro were established,the constraint mode of grid nodes was optimized,and the elastic modulus of ceramic tool materials was predicted by uniaxial tensile simulation.The effects of average particle size,volume fraction of reinforcement phase and porosity on elastic modulus were studied.The results showed that the elastic modulus decreased with the increase of average particle size and porosity,but increased with the increase of volume fraction of reinforced phase.Based on the traction-separation law,the microstructure cohesion model was constructed,and the finite element simulation method of crack propagation in ceramic tool materials was proposed.The effects of grain boundary energy,particle size,volume fraction of reinforced phase and porosity on crack propagation were discussed systematically.The results showed that the stronger the grain boundary energy was,the easier the transgranular phenomenon was;with the decrease of the average particle size,the crack propagation path became more tortuous and the fracture toughness increased gradually;with the increase of the volume fraction of reinforcement phase,the crack growth path became more tortuous,while the fracture toughness increased at first and then decreased;with the increase of porosity,the crack propagation path tended to be consistent and the fracture toughness decreased gradually.The Al₂O₃/TiB₂ ceramic tool material was prepared by plasma sintering process.The effects of sintering temperature,holding time and volume fraction of reinforcing phase on the mechanical properties of the material were studied.The result showed that the comprehensive properties of ceramic tool material was the best when the sintering temperature was 1600?,the holding time was 7 min and the reinforcement phase TiB₂was 20vol%.The fracture toughness,hardness and bending strength were 5.38MPa·m^1/2,18.32 GPa and 601.21 MPa,respectively.