High-efficiency tantalum-based ceramic (HETC) composite structures are suitable for use in thermal protection systems. These composite structures have high-efficiency surfaces (low catalytic efficiency and high-emittance), thereby reducing heat flux to a spacecraft during planetary reentry. These low catalytic efficiency and high-emittance ceramic materials were developed in order to increase the capability of a Toughened Uni-Piece Fibrous Insulation (TUFI)-like thermal protection system, with its high-impact resistance, to temperatures above 3,000 °F (≈1,650 °C). These ceramics have been applied to various aerodynamic configurations, such as wedge, wing-leading segment, and conventional tile shapes used on high-speed atmospheric entry vehicles. In addition, this family of tantalum-based ceramics exhibits low catalytic efficiency to atom recombination during exposure to high-energy dissociated hypersonic flow.
The various embodiments of this technology include insulating composites capable of surviving high heating ranges and large thermal gradients in the aero-convective heating environment that entry vehicles are exposed to characteristically. The tantalum-based ceramics contain tantalum disilicide, borosilicate glass, and, optionally, molybdenum disilicide. The components are milled, along with a processing aid to facilitate sintering, then applied to a surface of a porous substrate, such as a fibrous or open-pored silica, carbon, aluminosilicate, silicon carbide, or silicon oxycarbide substrate, as well as other substrates of silicon/carbon compositions. Following application, the coating is then sintered on the substrate. The composite structure is substantially impervious to hot gas penetration, and capable of surviving high heat fluxes.