Simulation On Microstructure Evolution Of Al₂O₃/SiC Ceramic Cutting Tool Materials

Ceramic material has been widely used in manufacturing industry because of its excellent high hardness, wear resistance and chemical stability. However, the strength and toughness of ceramic material is low which affects the reliability of ceramic cutting tool use and greatly limits its application scope. The microstructure of ceramic materials affects the mechanical properties, so it is very necessary to simulate and optimize the microstructure of ceramic tool materials, to provide a theoretical basis for improving the mechanical properties of ceramic tool material.This paper analyzes the mechanism of grain growth process. An improved Monte Carlo Potts model has been established from grain growth transition rate, growth orientation choice, growth rate control and boundary conditions choice. Through researching the standard and improved Monte Carlo algorithm, this paper proposes the HL Monte Carlo algorithm. In the H-L Monte Carlo algorithm, a grain lattice is chosen in simulation space firstly, and then the grain lattice which lies in the grain boundary is used to attempt another reorientation that is the biggest drop of the total energy conversion. Therefore, the H-L Monte Carlo algorithm has more efficiency than the present simulation algorithm. The H-L Monte Carlo simulation system has been developed with MATLAB software and the microstructure evolution process has been simulated through the system.The Monte Carlo Potts model for simulating the microstructure evolution of the twophase ceramic tool materials has been established based on the H-L Monte Carlo simulation algorithm. The effect of second-phase nano-particles with various sizes, volume fraction and grain boundary energy ratio has been simulated and researched. It is shown that the second-phase nano-particles have a strong inhibition effect on grain growth, can refine the microstructure and inhibit the abnormal grain growth. The inhabitation function will increase with bigger volume fraction and smaller grain size of the second-phase nanoparticles. The matrix phase which has the same grain boundary energy diffuses easily, and the grain grows fast, but the inhabitation function of the second-phase nano-particles becomes weak. When the grain boundary energy radio between the matrix and the second phase nano-particles is different, the inhabitation function of the secondphase nano-particles becomes strong. The simulation results are consistent with the analysis theory of the second-phase particle inhibition to the matrix. It is proved that the Monte Carlo Potts model is accurate. And this paper researches the relationship between the fabrication parameters and the material microstructure evolution, and simulates the effect of sintering temperature on the microstructure evolution. It shows that the average grain radius increases with an increment in sintering temperature.A hot-pressing sintering experiment on Al₂O₃/SiC nano-composite ceramic has been prepared. Testing mechanics properties and observing microstructure images of the ceramic samples through experiments. The comparison between the experimental results and simulation results verifies the accuracy of the Monte Carlo model and simulation results. The simulation of the ceramic tool materials lays a foundation for designing the new ceramic tool materials, optimizing the sintering process parameters and mechanical properties of the cutting tool materials.