氮化硅陶瓷球研磨去除机制试验与仿真研究

Experiment and Simulation Study on the Material Removal Mode of Si 3N 4 Ceramic Balls in Lapping Process

为研究研磨过程中氮化硅陶瓷球的材料去除形式及磨损行为,结合陶瓷材料动态压痕断裂力学理论,进行陶瓷球研磨加工试验,采用超景深三维显微镜和扫描电镜对研磨后陶瓷球表面进行观察,同时建立单颗金刚石磨粒冲击作用有限元模型并进行仿真研究。试验结果表明:氮化硅陶瓷球表面材料去除以脆性断裂去除和粉末化去除为主,陶瓷球表面残留有大量贝壳状缺陷和呈簇状随机分布的粉末化材料区域;研磨过程中,陶瓷球表面存在擦伤、划伤和凹坑等缺陷;磨粒冲击作用时,表面材料会受微切削作用产生破碎去除,同时也会受挤压作用产生脆性断裂去除,当磨粒以滚动方式作用在陶瓷球表面时,陶瓷球表面更容易形成粉末化去除,且材料去除率更高。仿真结果表明:各磨粒冲击作用方式产生的最大等效应力由大到小的顺序为滚动磨粒变切深、滚动磨粒定切深、磨粒挤压、滑动磨粒定切深,其中,滚动磨粒变切深产生的亚表面裂纹最深。

To explore the mechanism of material removal mode and the wear behaviour of Si 3 N 4 ceramic balls in lapping process,the lapping process experiment was carried out based on the theory of dynamic indentation fracture mechanics of ceramic materials,and the surface morphology was examined using SEM and 3D optical microscopy.The finite element model for the impact of single diamond grain was established,and the simulation was carried out.The experimental results indicate that the main material removal mode is brittle fracture and powder removal.A large number of shell-like defects and clusters of randomly distributed powdery material areas remains on the surface of ceramic spheres.Ceramic ball surface has some defects such as wears,scratches and pits during the grinding process.Under the impact of abrasive particles,the surface material will be crushed and removed by micro-cutting,and brittle fracture will be removed by extrusion.When the abrasive particles act on the surface of ceramic ball in a rolling manner,the ceramic ball surface is more prone to powder removal,and the material removal rate is higher.The simulation results show that the order of maximum equivalent stress generated by the impact mode of each abrasive particle is as follows:rolling grinding grain variable cutting depth,rolling grinding grain fixed cutting depth,grinding grain extrusion,sliding grinding grain fixed cutting depth,among which,rolling grinding grain variable cutting depth produces the deepest sub-surface crack.