Silicon Carbide/Boron Nitride Dual In-Line Coating of Silicon Carbide Fiber Tows

This SBIR Phase I project will demonstrate monolayer and dual layer coating of SiC fiber by leveraging Laser Chemical Vapor Deposition techniques developed by Free Form Fibers for direct fiber production. Ceramic fibers, particularly SiC, must be coated in order to protect the fibers from oxidizing environments, and to allow their use in SiC CMC's. FFF's LCVD techniques can be modified for fast, high purity coating. The Phase I effort includes creating a custom reactor that leverages FFF's existing gas precursor delivery infrastructure, and passing existing monofilament SiC fiber through the reactor to coat with BN in real time. Reversing direction and coating the coated fiber with SiC will be done for dual layer coating. Phase II would scale the process to serially dualcoat a unidirectional moving parallel array of hundreds or thousands of moving fibers. If successful, industry would finally have a reliable in-line approach to fiber coating prior to tow production, because spreading and coating already-sized tows is nearly impossible. Based on prior coating experience and other related proposals, Phase I work would take us from TRL3 to TRL4. Phase II could take us to TRL4 or TRL5, either on a FFF or other commercial fiber production facility.