Study of the ablation of a carbon/carbon composite at ∼25 MW/m2 with a nitrogen plasma torch

Ablation of carbon/carbon (C/C) composites was investigated in a nitrogen plasma torch with a heat flux of ∼25 MW/m2. The reaction products of carbon in C/C composites and nitrogen plasma jet were calculated based on the principle of free energy minimum. The calculated results show that the thermal chemical ablation and sublimation of carbon occur and Cn(g) (n = 1–3), CN(g), C2N(g) and C2N2(g) may be the major reaction products consuming carbon. Ablation is apt to begin at the interfaces, especially the fibre-matrix interface and interfaces inside the matrix. Ablation of C/C composites is mainly controlled by the thermal chemical ablation, sublimation of carbon, and mechanical breakage. The formation of needle-shaped fibres and shell-shaped matrices is attributed to both the thermal chemical ablation and sublimation of carbon, while carbon fragments and fractured fibres or matrices result from the mechanical breakage.