Thermal response, oxidation and ablation of ultra–high temperature ceramics, C/SiC, C/C, graphite and graphite–ceramics

Abstract

• Thermal responses, oxidation, and ablation of ultrahigh temperature ceramics, C/SiC, C/C, graphite, and graphite ceramics were systematically investigated. • These thermal protection materials exhibited remarkably different thermal responses and subsequent oxidation and ablation behaviors under the test conditions. • The comparisons and relationships of the oxidation and ablation behaviors for these thermal protection materials under extreme environments were illustrated. • The mechanisms for thermal responses, oxidation and ablation of these thermal protection materials were provided. Various thermal protection materials exhibit obviously different and complicated thermal response, oxidation and ablation behavior, which are very important for the appropriate design and selection. However, the relative researches are very few currently. In this work, the thermal response, oxidation and ablation behavior of representative thermal protection materials including ultra–high temperature ceramics, C/SiC, C/C, graphite and graphite–ceramic were investigated systematically in strong heat flux, high enthalpy and low-pressure environments. Thermal response of these materials was analyzed based on experimental results and thermal energy balance that accounts for all of the heat transfer processes transporting energy into and out of the surface. Many factors were playing important roles in the thermal response including thermal conductivity, volumetric heat capacity, catalytic efficiency, emissivity and oxidation characteristics of the materials. The importance of each factor not only depends on the material characteristics such as material composition and phase content but also environment parameters including heat flux, enthalpy, pressure and testing time. The comparisons and relationships of oxidation and ablation behaviors for these materials under extreme environments were also illustrated in detail. Furthermore, thermal response and ablation behaviors of pre–oxidized material or repeated tests were also performed to evaluate the effect of pre–treatment on the performance and reusability of thermal protection materials. This work offers guiding significance for the appropriate design and selection of thermal protection materials.