Research on the metamorphic layer of silicon nitride ceramic under high temperature based on molecular dynamics

摘要

The high temperature of the grinding area at the engineering ceramic materials processing is one of the main factors affecting the quality of processing and the performance of parts. In order to reveal the law of temperature distribution of silicon, nitride ceramic grinding and its mechanism of action on surface quality. The process of machining silicon nitride ceramic material is simulated based on the established molecular dynamics model of the nanometric grinding of silicon nitride. The influence of grinding parameters on the nanometric grinding process is studied from the variation law of grinding temperature and the evolution of system energy, as well as the formation of grinding surface and metamorphic layer during machining. And the results of the experiment were compared with the theoretical research. With the increasing of grinding depth and speed of diamond grains, the energy released during the deformation and amorphous phase change of the atomic lattice get increased, and the grinding temperature get increased. The high grinding temperature will cause amorphous phase change in silicon nitride ceramics, and the amorphous atoms are recombined with the atomic bonds of the processed surface to form a metamorphic layer of the processed surface. The effect of grinding parameters on temperature changes from large to small is grinding wheel line speed, workpiece feeding speed, and grinding depth. There is an important effect on improving the surface machining quality and the service life of parts of engineering ceramics such as silicon nitride from the results of this paper, and it also plays an important role in reducing the effect of grinding temperature on the surface quality.