Advanced materials for thermal protection system

Abstract

Reticulated open‐cell ceramic foams (both vitreous carbon and silicon carbide) and ceramic composites (SiC‐based, both monolithic and fiber‐reinforced) were evaluated as candidate materials for use in a heat shield sandwich panel design as an advanced thermal protection system (TPS) for unmanned single‐use hypersonic reentry vehicles. These materials were fabricated by chemical vapor deposition/infiltration (CVD/CVI) and evaluated extensively for their mechanical, thermal, and erosion/ablation performance. In the TPS, the ceramic foams were used as a structural core providing thermal insulation and mechanical load distribution, while the ceramic composites were used as facesheets providing resistance to aerodynamic, shear, and erosive forces. Tensile, compressive, and shear strength, elastic and shear modulus, fracture toughness, Poisson’s ratio, and thermal conductivity were measured for the ceramic foams, while arcjet testing was conducted on the ceramic composites at heat flux levels up to 5.90 MW/m2 (520 Btu/ft2⋅sec). Two prototype test articles were fabricated and subjected to arcjet testing at heat flux levels of 1.70–3.40 MW/m2 (150–300 Btu/ft2⋅sec) under simulated reentry trajectories.