PVD改性RB-SiC表面缺陷研究

为获得高表面质量的PVD改性RB-SiC反射镜，解决实际加工中出现的表面缺陷问题，对缺陷的形成机理及处理方法进行了研究。根据Preston假设设计相关试验，推测表面缺陷是由于PVD改性层中的大颗粒结晶受到较大冲击，从而使大颗粒结晶剥落而非对其产生磨削作用而产生的。试验表明:过高的抛光速度或过高的抛光压力会造成改性层表面缺陷的产生，调整抛光的相对速度及抛光压力等关键工艺参数，可在保持抛光效率的同时有效减少和避免表面缺陷问题的产生。经试验验证，当表面缺陷产生后，通过选择适当的相对速度和抛光压强，改性层去除0.7 m～1 m后，可有效修复缺陷，并且无新的表面缺陷产生。

Surface defects of PVD modified RB-SiC

In order to obtain the high surface quality of physical vapor deposition (PVD) modified RB-SiC mirror and solve the problems of the surface defects in the practical processing, we conducted studies on the forming mechanism and the processing method of defects. According to Preston hypothesis, it was deduced that higher impact on the large rimes in PVD layer could be the main reason which may cause surface defects. The experiment proved that the defects would appear if the polishing speed or the polishing presure was too high. In order to reduce and avoid surface defects effectively, it was reasonable to control the relative polishing speed and polishing pressure, in the meanwhile, the polishing efficiency could be maintained. According to the analysis above, the surface defects could be renovated after 0.7 μm～1 μm of coating material was removed with the proper polishing speed and pressure, while new defects did not appeare any more.