Carbon-Fibre-Reinforced Carbon–Silicon Carbide Composites for Extreme Environments: A Critical Narrative Review of Processing Strategies, Interface Engineering, Oxidation Resistance and Engineering Applications

Abstract

Carbon-fibre-reinforced carbon–silicon carbide (C/C–SiC) and carbon-fibre-reinforced silicon carbide (C/SiC) composites occupy a distinctive position among materials for extreme environments because they combine low density, damage tolerance and thermal-shock resistance with a matrix that forms protective silica at high temperature. Their use in re-entry thermal protection, rocket propulsion and high-energy friction systems has nevertheless remained constrained by an unresolved tension between the carbon reinforcement, which is required for toughness, and its vulnerability to oxidation. This critical narrative review examines how processing strategies, interface engineering and oxidation-protection approaches interact to determine the engineering performance of these composites. Literature was identified through structured searching of multidisciplinary scholarly indexes and specialised technical repositories, supplemented by backward and forward citation tracking, and was appraised for methodological                   adequacy, test realism and consistency with independent evidence. The synthesis indicates that chemical vapour infiltration, polymer infiltration and pyrolysis, and liquid or gaseous silicon infiltration yield materially different phase assemblies, residual-stress states and crack networks, so that properties reported for one route cannot be transferred uncritically to another. Interphase optimisation is supported by consistent evidence that intermediate pyrolytic carbon thicknesses maximise strength and reliability, but the optimum depends on the matrix route and residual stress rather than on a universal value. Oxidation behaviour follows temperature-dependent regimes governed by reaction control, diffusion through matrix microcracks and crack sealing by silica, yet most evidence derives from short, unstressed laboratory exposures. Protective coatings and ultra-high-temperature ceramic modifications improve short-term ablation resistance, whereas evidence for long-duration, multi-cycle durability under combined mechanical, thermal and chemical loading remains limited. Friction applications show the most mature translation, while reusable hot structures remain constrained by environmental durability and manufacturing cost. The review concludes that progress now depends less on incremental compositional modification than on standardised coupled-environment testing, validated life-prediction models and process routes that control residual silicon, porosity and interphase integrity simultaneously.