Ultra-precision manufacturing of silicon carbide mirrors with additive manufacturing

The physical characteristics of silicon carbide materials, such as brittle texture and high hardness, make it very difficult to form complex structures. Additive manufacturing can realize the direct molding of complex structure silicon carbide mirrors, improve processing efficiency, and reduce processing costs. In this paper, an additive silicon carbide mirror substrate is processed by the combined process of grinding, lapping, and polishing with a small grinding head. After obtaining a certain surface shape accuracy, the surface was modified to obtain a silicon modified layer with a thickness of 10 μm. After two times of magnetorheological modification of the modified layer, the surface shape converged to 17.313nm RMS. After a conformal smoothing, the surface quality was 1.109nm Ra, which verified the machinability of the additively manufactured silicon carbide mirror.