Increased Production Capacity of Cf/ZrC CMCs for Hypersonic and Related Applications, Phase II

Hypersonic weapon flight performance is improved significantly by the drag reduction achieved when thermal protection system (TPS)-related structures remain sharp and shape-stable under all flight conditions. UltrametÆs approach to this design goal is to utilize its carbon fiber-reinforced zirconium carbide (Cf/ZrC) ceramic matrix composite (CMC) material for these applications. Ultramet has developed and established the feasibility of the Cf/ZrC CMC material for hypersonic and other reentry applications through more than 20 years of development, characterization, and testing in relevant environments, during which Cf/ZrC has shown great promise in these types of applications. In the current work, Ultramet is seeking to increase carbon chemical vapor infiltration (CVI) capabilities to enable increased Cf/ZrC CMC production rate. Carbon CVI is a crucial step in UltrametÆs melt infiltration process used for Cf/ZrC fabrication. The initial technical and commercial feasibility of carbon CVI processing scaleup, and the significant cost and lead time advantages of the scaled-up process, were successfully demonstrated in Phase I, providing a viable path forward toward expanding the manufacturing base for UltrametÆs Cf/ZrC CMC for adoption into DoD hypersonic vehicle designs. The Phase II project will build upon the Phase I work and continue with the carbon CVI process scaleup. Phase II will also explore domestically sourced and fabricated carbon fiber preforms for use in CMC fabrication and characterization. These goals will be achieved through carbon CVI process optimization in increased-scale production furnaces and identification of a preferred carbon fiber preform type through CMC fabrication and property characterization. The optimized carbon CVI process will be used to densify and prepare variations (fiber type and fiber architecture) of carbon fiber preforms that will subsequently be processed into Cf/ZrC CMCs. The resultant CMC materials will undergo baseline temperature-dependent thermal and mechanical property characterization. An iterative process will be performed in which material will be fabricated and improvements to preform fabrication and/or CVI processing will be made based on material property characterization. At the conclusion of the project, an optimized carbon fiber preform and carbon CVI process will have been identified, from which a Cf/ZrC CMC material that is equivalent to the existing baseline material can be produced, and a comprehensive temperature-dependent thermal and mechanical properties database will have been collected. The database will provide designers with the necessary material properties for hypersonic vehicle component design. The MRL of the Cf/ZrC CMC manufacturing process will increase to 6+ in key areas, significantly aiding in increasing CMC production capacity within a two-year time frame.