Fabrication of near-net shape graphite/magnesium composites for large mirrors

Robert G. Wendt Jr.; Mohan S. Misra

doi:10.1117/12.21538

1 October 1990 Fabrication of near-net shape graphite/magnesium composites for large mirrors

Robert G. Wendt Jr., Mohan S. Misra

Proceedings Volume 1303, Advances in Optical Structure Systems; (1990) https://doi.org/10.1117/12.21538
Event: 1990 Technical Symposium on Optics, Electro-Optics, and Sensors, 1990, Orlando, FL, United States

Abstract

Successful development of space-based surveillance and laser systems will require large precision mirrors which are dimensionally stable under thermal, static, and dynamic (i.e. structural vibrations and retargeting) loading conditions. Among the advanced composites under consideration for large spe mirrors, graphite fiber reinfced magnesium (Gr/Mg) is an ideal candidate material that can be tailored to obtain an optimum combination ofproperties, including a high modulus of elasticity zero coefficient of thermal expansion, low density, and high thermal condtxtivity In addition, an innovative technique, combining conventional filament winding and vuum casting has been developed to produce near-net shape Gr/Mg composites. This approach can significanfly reduce the cost of fabricating large mirrors by decreasing required machining. However, since Gr/Mg cannot be polished to a reflective surface, plating is required. This paper will review research at Martin Marietta Astronautics Group on GrIMg mirror blank fabrication and measured mechanical and thermal properties. Also, copper plating and polishing methods, and optical surface characteristics will be presented.

Citation Download Citation

Robert G. Wendt Jr. and Mohan S. Misra "Fabrication of near-net shape graphite/magnesium composites for large mirrors", Proc. SPIE 1303, Advances in Optical Structure Systems, (1 October 1990); https://doi.org/10.1117/12.21538

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