Study On Reaction-Sintered Silicon Carbide(RSSiC) Mirror Manufacturing Technology

Reaction sintered silicon carbide (RSS1C) has low thermal distortion, high specific stiffness and excellent dimensional stability, which make it a promissing mirror material, especially for applications such as space-borne optical systems. Accordingly, silicon carbide mirror manufacturing technology has been a focus of attention in optical engineering. Investigation in this program was concentrated on three main parts: (1) mirror greenbody fabricating, (2) reaction sintering. and (3) material properties characterizing. I In the first part. geeenbody molding and carbonizing are stressed. A gelcasting process was devised with non-uniform-phase adhesive being used to decrease greenbody shrinkage. On the other hand, a liquid-phase geeenbody carbonizing process was contrived using inorganic/organic hybrid precursor prepared by sd-gel technology as infiltrant. In addition, a (1) 150 lightweight mirror model has been fabricated to test the feasibility of these process experimentally. 1n the second part, RSSIC sintering process and its microstructure evolution were described, and theoretical investigation on sintering mechanism by means of Si-C phase diagram was conducted. U In the last part. for RSSiC sample prepared in our Laboratory, phases identification and microstructural observation were performed, and besides, properties analysis and characterizing ware carried out. Result shows: (1) The idea of 搉on shrinkage?molding can be realized by regulating adhesive distribution in greenbody. RSSiC greenbody with large dimension and complex shape can be fabricated by the process base an this idea, which suggest a potential solution for RSSiC lightweight mirror manufacturing; (2) Uniform carbon distribution in greenbody can be achieved by liquid-phase carbonizing process; (3) Analysis of reaction sintering process by means of Si-C phase diagram gives another proof of solution-precipitation theory. This is the first researching program on reaction sintered silicon carbide mirror manufacturing technology in China.