Low-Cost Repairable Oxidation Resistant Coatings for Carbon-Carbon Composites via CCVD

摘要

This Phase I project focused on the development of the Combustion Chemical Vapor Deposition (CCVD) thin film process to yield oxidation resistant coatings on carbon-carbon (C-C) composites. Work was on simple coatings at this preliminary stage of investigation, including silicon dioxide, platinum and aluminum oxide. Most coatings were deposited as thin films (< 2 micrometers). Results indicated that various materials could be deposited onto the substrate. However, coating adhesion was found to be closely linked to adhesion of the substrate within itself. Substrate surface integrity was not complete, and some surface material could always be removed with tape adhesion testing. The thinness of the films, which should have been beneficial for any thermal expansion mismatches between coating and substrate, seemed to be detrimental for completely and sufficiently covering all crevices of the composite surface. Full encapsulation of the substrate was not evident from elevated temperature testing, where, in some cases, the coating remained despite substrate degradation and evaporation. The potential of the thin films investigated may be more amenable to individual fibers rather than to complete composite materials at the coating thicknesses considered.