Rapid, Randomly Oriented SiC/SiC Composites

Hypersonic vehicles and propulsion systems are anticipated to require improvements to materials and processing to support next-generation air vehicles, such as space planes, long-range munitions, and/or rockets. Though high-speed vehicles already exist and have employed composite matrix composite materials for quite some time, currently not all CMC materials are not able to tolerate the extreme thermal and mechanical stresses associated with these applications, with failure modes commonly associated with oxidation or delamination in the hottest and most stressful applications. Due to the oxidation resistance requirements at high temperatures in service, composites made from SiC matrix surrounding SiC fibers tend to be the most affordable solution, providing better survivability than carbon fiber-based composites, though this leads to fewer and slower options for the complete composite as compared to carbon-carbon solutions. Thus, CRG proposes to address this issue via novel SiC/SiC composite materials, based on technologies that have been incorporated into demonstrations already delivered to DoD agencies primarily geared for conventional rockets. Multiple fiber materials and formats have been demonstrated, along with varying degrees of SiC matrix content that demonstrated the range of ablation resistance achievable, manufacturing process options, and cost implications. This approach will include oxidation resistance provided by the randomly oriented SiC fiber and primary SiC matrix, with manufacturing rate improvements enabled by the high-char carbon matrix scaffold that serves as the initial matrix for supporting SiC through subsequent processing. This is enabled by converting a porous carbon-matrix preform into a SiC matrix composite through a process such as reaction melt infusion (RMI). The primary path for forming the initial composite structure will be via compression molding of resin/fiber combination, leveraging that manufacturing technology for reducing part cost, increasing part repeatability, and increasing fabrication rate. Testing of these approaches will be performed at coupon-scale, with scale-up of part size and testing complexity in future phases, based on application requirements. CRG anticipates the ability to rapidly mature such SiC/SiC material technologies to enable long-term test and operation of components made from these materials and processing, enabling affordable transition of these materials to operational status in current and next-generation vehicles.