Ablation regression behaviors of C/C composites under mechanochemical coupling

Abstract

In previous work, a theoretical explanation that stress affected ablation thermochemical reactions was proposed for the formation of the typical steady state ablation morphology of C/C composites. However, the mechanism of mechanochemical coupling is still unclear, and the ablation velocity expression took the first-order Taylor expansion term lacks of precision under extreme load environment. This study proposes a mechanism by which stress affects the rate constant of chemical reactions through modifications in the activation energy. A quantitative relationship between stress and chemical reaction rate constant is derived from thermodynamic equilibrium perspective, leading to a revised expression for ablation velocity. Furthermore, the investigation into the effects of mechanochemical coupling on steady state and transient ablation recession behaviors is conducted through microscopic to mesoscopic scale change. The findings from this research provide valuable theoretical insights into the interactions among various physical fields and their influence on ablation recession behaviors of C/C composites.