Ablation behaviors of carbon/carbon composites with C-SiC-TaC multi-interlayers

Carbon/carbon composites with C-SiC-TaC multi-interlayers were prepared by isothermal chemical vapor infiltration. The ablation behaviors of the composites were tested with an oxyacetylene flame. The mass loss rate increases markedly in the initial 10 s, then reaches a steady state or decreases slightly in 10-40 s; while after 40 s, the mass loss rate increases remarkably. A similar trend is observed in the linear loss rate, except that it begins to increase only after 60 s. After ablation for 5 s, the composite surface consists in black carbon fibers and white ceramic oxides. After 20 s, three different regions with different ablation behaviors are observed: central, transition and border. After 100 s, the composites are severely ablated and the shape is completely destroyed. A cross-section of the composites after ablation for 20 s shows three distinct regions: a rugged oxide layer, a smooth oxide layer and the matrix. The tantalum compounds have not been able to protect efficiently the material from constant oxide evolution, possibly because of a too large pore volume fraction.