Fracture-tough Reaction Bonded SiC Composites for Monolithic SiC Optical Instrum

SSGPO proposes the development of a fracture tough reaction bonded silicon carbide (RB SiC) composite for lightweight space-based optical instruments. The combination of visible quality SiC optics and a fracture tough SiC structure will result in athermal operation for demanding environments. The new structural composite has material properties approaching those of reaction bonded SiC (high specific stiffness and thermal stability), ability to be formed into near-net shapes and the durability of a composite. Phase I showed the viability of a composite that combines a novel, low-cost fiber coating process developed in conjunction with the University of Illinois-Chicago and Drexel University with our reaction bonded SiC. This combination provides three critical discriminators for SiC structural materials: (1) low-cost fabrication (fraction of the cost of CVI process) and scaleability, (2) the ability to achieve complex shapes using the inherent near net shape forming of RB SiC and (3) material properties that are well matched to RB SiC while providing increased durability. In Phase II SSGPO will optimize the SiC/SiC composite process and demonstrate this process by building an optical bench for delivery to NASA.