Simulation Study On Microstructure Of Nano-ceramic Tool Materials

Modern nano-ceramic tool materials with excellent mechanical properties and cutting performance increase the metal-cutting ability to a new high level. Although the mechanical properties of nano-ceramic materials have been enhanced, the fracture toughness of nano-ceramic tool material is still low. Now the development method of ceramic tool material is a "trial-error method", so that the development process of a new ceramic tool materials is very long. Because the mechanical properties of materials depend on the material microstructure, it is significant to simulate the microstructure of ceramic tool materials, which can guide the research of nano-ceramic tool materials and shorten the development cycle.In this paper, the microstructure influencing on its mechanical properties, grain growth theory, Monte Carlo Potts model and the Monte Carlo simulation algorithm have been analyzed, and the three-dimensional Monte Carlo Potts model and Monte Carlo simulation algorithm have been established on the basis of two-dimensional Monte Carlo Potts model and the Monte Carlo simulation algorithm. Three-dimensional simulation software for microstructure of ceramic tool materials has been developed on the basis of Microsoft Visual C++ 6.0 compiler, using C++ language and the OpenGL graphics interface. The software developed in the present thesis can accomplish the three-dimensional simulation for microstructure of ceramic tool materials during fabricationg, the outputs of three-dimensional simulation results at any time, at any two-dimensional cross-section which is perpendicular to simulation area and simulation data, and the quantitative analysis of various factor during fabrication of ceramic tool materials.The grain orientation number Q, the lattice size, real duration time, fabrication temperature and fabrication pressure influencing on simulation results have been studied. It is shown that the appropriate grain orientation number of three-dimensional simulation is 200. Owing to the boundary conditions of simulation model is periodical, the influence of lattice size is small. The relationship between simulation time and real duration time, the relationship between fabrication temperature and grain growth velocity, and the relationship between fabrication pressure and grain growth velocity have been establishied, which have been incorporated into three-dimensional simulation model. So that three-dimensional simulation physical model in accordance with practical situation has been establishied. The microstructure of ceramic tool materials is simulated allowing for the fabrication parameters. It is shown that grain radius increases by the way of parabola with an increment in simulation time, and grain radius also increases with an increment in fabrication temperature and fabrication pressure, which prove that three-dimensional simulation model in this paper is correct and reasonable.The relationship between grain growth index and simulation time, and the relationship between the number of grain and simulation time have been studied. It is shown that grain growth index is 0.4623 when simulation time reaches steady growth state, which is almost equal to the theoretical value 0.5. The relationship between the number of grain and simulation time is hyperbolic, and the number of grain reduces by the way of hyperbolic form with an increment in simulation time. Simulation results have proved that three-dimensional simulation model in this paper is correct and reasonable.Three-dimensional simulation model for microstructure of two-phase ceramic tool materials have been established and simulated. It is shown that the second particles can inhibit the matrix grain from growing, and the inhabitation function increases with an increment in the content of the second particles or a decrescence in the size of the second particles. However, when the boundary energy of the matrix phase, the boundary energy of the second phase, and the boundary energy between the matrix and the second phase are more similar, and the inhabitation by the second phase particles is becoming weaker.Three-dimensional simulation model for microstructure of ceramic tool materials containing pores have been established and simulated. It is shown that the inhabitation by pores is very obvious. At the same simulation time, the simulated mean grain radius without the pores is larger than that with the pores.