Microstructural interpretation of the effect of various matrices on the ablation properties of carbon-fiber-reinforced composites

This paper presents an extensive study of the ablation properties, microstructural behavior of ablation and thermal stability of various carbon-fiber-reinforced composites composed of four different matrices, a phenolic matrix, a carbonaceous matrix, a carbonaceous matrix containing impregnated resin and a carbonaceous matrix containing pyrocarbon. The ablation properties of the composites used were quantitatively evaluated by performing ablation tests with a plasma torch. The ablation behavior of both the carbon fibers and the composite matrix has been qualitatively interpreted through a scanning-electron-microscopy approach. The thermal stability of the composites was also examined by using a thermogravimetric analyzer both in air and nitrogen gas. The ablation test results reveal that composites with a carbonized matrix only (1C/C) and these with a carbonaceous matrix (1C/C+CVI) containing pyrocarbon infiltrated by a CVI process have the highest ablation resistance. In particular, the ablation resistances of 1C/C and 1C/C+CVI composites are improved by about 61 and 67% on the basis of weight change, respectively, in comparison with carbon/phenolic green composite.