典型碳化硅光学材料的超光滑抛光试验研究

Experimental Research on Super-smooth Polishing Process of Typical Silicon Carbide Materials

研究了三种典型的碳化硅光学材料CVDSiC、HPSiC以及RBSiC的材料去除机理与可抛光性,并对其进行了超光滑抛光试验。在分析各种材料制备方法与材料特性的基础上,通过选择合理的抛光工艺参数,均获得了表面粗糙度优于Rq=2nm(采样面积为0.71mm×0.53mm)的超光滑表面。试验结果表明:研磨过程中,三种碳化硅光学材料均以脆性断裂的方式去除材料,加工表面存在着裂纹以及材料脱落留下的缺陷;抛光过程中,CVDSiC主要以塑性划痕的方式去除材料,决定表面粗糙度的主要因素为表面微观划痕的深度;HPSiC同时以塑性划痕与晶粒脱落的形式去除材料,决定表面粗糙度的主要因素为碳化硅颗粒大小以及颗粒之间微孔的尺寸;RBSiC为多组分材料,决定其表面粗糙度的主要因素为RBSiC三种组分之间的去除率差异导致的高差。

Super-smooth polishing experiments were carried out herein to study the polishing mechanisms and polishability of three types of silicon carbide materials： CVD SiC （chemical vapor deposition silicon carbide）, HP SiC（hot-pressed silicon carbide） and RB SiC（reaction-bonded silicon carbide）. A surface roughness of better than 2nm Rq （0.71mm×0.53mm） was achieved by analyzing the characteristic of each material and selecting processing parameters for each material. The experimental results indicate that during the lapping process, three types of silicon carbide materials are all removed by brittle fracture, and there exist surface cracks and pits caused by materials being pulled out on the surfaces. During the polishing process, CVD SiC is removed mostly by plastic scratches, thus the dominant factor of the surface roughness is the depth of the scratch on the polished surface; HP SiC is removed by plastic scratch and grains being pulled out at the same time, and the dominant factors of the surface roughness are the sizes of the SiC particles and the micropores between the particles; RB SiC is removed mostly by plastic scratches, and the dominant factor of the surface roughness is the height difference between the three components of RB SiC because of their different material removal rates.