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针对常用恒密度预制体在C/C复合材料制备过程中容易表面孔隙堵塞现象,沿着厚度方向将预制体设计成密度梯度变化,并通过化学气相渗透法制备C/C复合材料。研究了密度梯度变化的预制体结构对C/C复合材料的结构和弯曲力学性能的影响。结果表明:变密度预制体改变了碳纤维在预制体内的分布,导致C/C复合材料内部孔隙结构的变化,形成了细小的闭孔,从而提高了C/C复合材料的力学性能。
Aimed at the prevalently used constant density preform, it is easy to clog the surface pores in the preparation process of C / C composites. The preform is designed to have the density gradient along the thickness direction, and the C / C composites are prepared by chemical vapor infiltration. The effect of preform structure with density gradient on the structure and bending mechanical properties of C / C composites was studied. The results show that the variable density preform changes the distribution of carbon fibers in the preform, which leads to the change of the pore structure in the C / C composites and the formation of small closed cells, which improves the mechanical properties of the C / C composites.