Fabrication technique of large-scale lightweight SiC space mirror

Ge Zhang; Rucheng Zhao; Wenxing Zhao

doi:10.1117/12.782705

21 November 2007 Fabrication technique of large-scale lightweight SiC space mirror

Ge Zhang, Rucheng Zhao, Wenxing Zhao

Proceedings Volume 6721, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes; 67210B (2007) https://doi.org/10.1117/12.782705
Event: 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes, 2007, Chengdu, China

Abstract

Silicon carbide (SiC) is a new type candidate material for large-scale lightweight space mirror. Its low thermal distortion, high stiffness, high optical quality, and its dimensional stability are better than other traditional optical substrate materials such as ULE, Zerodure, Beryllium (Be) and so on. In this paper, the lightweight silicon carbide space mirror blank was fabricated by reaction sintering. As a space born mirror material, silicon carbide must be an optical grade ceramic. So we prepared the silicon carbide green body with gel-casting method. Then some carbon materials were supplemented into the green body which will bring reaction-sintering with silicon in a vacuum furnace during 1500-1600°C, ultimately the reaction bonded silicon carbide was made. The diameter of SiC space mirror blank we have made is 680mm. If expanding the size of the vacuum furnace, bigger mirror blank can be obtained. The test results show that the mechanical and thermal properties of RB-SiC are excellent with bending strength of 350MPa, fracture toughness of 4.1 MPa·m1/2 and coefficient of thermal expansion(CET) of 2.67×10-6/K. The surface roughness(RMS) could be better than 3nm.

Citation Download Citation

Ge Zhang, Rucheng Zhao, and Wenxing Zhao "Fabrication technique of large-scale lightweight SiC space mirror", Proc. SPIE 6721, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Large Mirrors and Telescopes, 67210B (21 November 2007); https://doi.org/10.1117/12.782705

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