Thermal protection material on the base of silicon-carbide ceramics

Abstract

The results of the thermal tests of silicon carbide ceramics, developed by the authors, intended for prospective use as the outer layer of the combined thermal protection of returnable orbiters and hypersonic aircraft are presented. Tests have shown that the developed silicon carbide ceramics is characterized by high operating temperature (about 2000 °C), resistance to thermal shock (heating rate ~ 65 K/s), and can withstand high thermal loads (~ 7 MW/m2) for a considerable time. Under comparable conditions, the proposed material exceeds by 1.5–2.5 times the WCu pseudo-alloy in terms of the ablation rate of the mass, while it is 5.5 times lighter. Due to the presence of free silicon in the material, the absorption of large heat fluxes can occur due to the melting and evaporation of silicon. This fact has received experimental confirmation. The problem of reducing the catalytic activity of ceramics due to the layer of silicon dioxide formed on its surface is discussed.