磨削加工对Al2O3陶瓷表面质量与力学性能的影响

Effect of Grinding Process on Surface Quality and Mechanical Properties of Al2O3 Ceramics

航空航天等领域的快速发展对Al2O3陶瓷表面加工质量的要求越来越高。目前,磨削加工由于精度高、材料去除率高而成为陶瓷表面加工最主要、最常用的方法,因此,建立磨削加工方式、陶瓷表面质量和力学性能之间的联系具有十分重要的意义。本工作利用精密研磨抛光机和磨床对Al2O3陶瓷进行表面加工,探讨了不同磨盘转速、磨盘/磨床砂轮目数、砂轮进刀量、磨床横向平移速度等不同磨削加工条件对陶瓷表面质量(材料表面粗糙度、表面形貌、表面残余应力)和力学性能的影响。研究结果表明:相比于磨盘加工,磨床加工对Al2O3陶瓷表面质量的影响较大,表现为磨床加工后的粗糙度数值较大,且磨削表面产生了较为明显的加工划痕。Al2O3陶瓷在磨削加工中的去除方式主要为脆性去除和延性域去除,加工后其表面残余应力均为压应力。特别地,在高的磨盘或砂轮目数、大的磨盘转速、较小的砂轮进刀量以及大的磨床平移速度情况下,Al2O3陶瓷以延性域去除为主,表面残余压应力最高达到-241 MPa。Al2O3陶瓷的力学性能是由表面粗糙度、表面微观形貌、表面残余应力共同作用的,随着陶瓷表面粗糙度的减小、残余压应力的增大,陶瓷弯曲强度提高,最高可达528 MPa。

A higher requirement for the surface quality of Al2O3 ceramic had been put forward to adapt the rapidly development in the aerospace or other fields.At present,the grinding process was one of the most commonly used methods for ceramic surface processing due to the high precision of grinding and high material removal rate.Therefore,it was greatly significant to clarify the relationship among grinding processing methods,surface quality and mechanical properties.The surface processing of Al2O3 ceramic was performed using the precision grinding/polishing machine and grinding machine.The effect of different grinding conditions involving grinding disc speed,the abrasive grain size of grinding disc or wheel,the longitudinal feed or horizontal translation speed of grinding wheel on the surface quality,surface residual stress and mechanical properties of Al2O3 ceramic were investigated and discussed.The experimental results show that a more rough surface(such as the processing scratches)was observed on the surface of Al2O3 ceramic after the grinding machine processing,indicating that the surface processing used by grin-ding machine had a greater influence on the surface quality of Al2O3 ceramic compared to the grinding disc processing.Furthermore,the removal mechanism of Al2O3 ceramics during grinding processing was a mixture of brittle removal and ductile removal,and the surface residual stresses exhibit compressive stress after processing.Especially,the removal mechanism of Al2O3 ceramics was mainly ductile removal and the surface residual compressive stress was up to-241 MPa in the case of fine abrasive grain size of grinding disc or wheel,large grinding disc rotation speed,small longitudinal feed and large horizontal translation speed of grinding wheel.The surface roughness,microstructure and surface residual stress had a comprehensive effect on the bending strength of Al2O3 ceramics.The bending strength increased to 528 MPa with decreasing the surface roughness and residual compressive stress of Al2O3 ceramic.