Microstructure and ablation mechanism of C/C-ZrC-SiC composite in the solid scramjet plumes environment

Abstract

This study offered a new ablation test environment encountered in the solid scramjet, highlighted by ultra-high temperature, strong oxidation, and supersonic gas-solid two-phase flow. In this environment, microstructure and ablation mechanism of C/C-ZrC-SiC composite was studied. Initially, oxidation and thermal-shock generated a loose surface that would be exfoliated by the flow and then successively caused grooves, humps, and pulled-out fibers. Finally, evaporation and oxidation intensified with increasing temperature. Notably, for one thing, particles in the flow imposed severe mechanical denudation on the composite. For another, some particles, such as B2O3 and Fe2O3, could also induce oxidation at high temperatures. Moreover, different oxidation behavior of ceramics in the thickness direction aggravated the degradation. The abovementioned reasons caused the highest mass ablation rate (MAR) compared with other test environments. For example, the MAR was almost six times the average value in an oxyacetylene torch. This work aims to provide the basis for improving materials for application in solid scramjet.