密度和纤维取向对炭/炭复合材料烧蚀性能的影响(英文)

采用不同的预制体和致密化方法制备了密度不同的5种炭/炭复合材料(密度范围1.77g/cm3～1.85g/cm3)。用氧-乙炔焰对试样进行了烧蚀试验,并用SEM表征了烧蚀后材料的形貌。结果表明:烧蚀后,与乙炔焰成30o角的纤维变成楔形,而与火焰平行的纤维变成直径为3.5μm～4.5μm的针状,针状纤维更易被火焰烧蚀而钝化。部分宏观孔(直径为1.0mm～1.26mm)、针状微孔及界面裂纹等缺陷处更易被烧蚀而变成烧蚀坑。包裹纤维的沥青炭层由于热解炭基体的不连续而出现了严重的剥蚀。高密度材料(1.85g/cm3)具有良好的抗烧蚀性能。

Effect of density and fibre orientation on the ablation behaviour of carbon-carbon composites

Five carbon-carbon composites were prepared with different fibre orientations in the preform and were densified by different methods. Their ablation behaviour was examined by an oxy-acetylene test and scanning electron microscopy. The densities of the composites were in the range of 1.77 to 1.85g/cm3. Fibres having an angle of 30° with the oxy-acetylene flame turned into a sharp wedge shape, whereas fibres parallel to the flame had a needle-like shape with diameter up to 3.5-4.5μm after ablation. The needled fibres were easily attacked and ultimately became blunt. Partially filled macropores with sizes of 1.0-1.26mm, needle pores, interfacial cracks and gaps in non-woven cloth were easily attacked by the flame, resulting in macroscopic ablation pits that decreased with increasing density of the composites. The needled fibres around pitch carbon layers were severely denuded due to their discontinuity with the pyrolytic carbon matrix. A high density (1.85g/cm3) composite had an excellent ablation resistance.