密度梯度变化预制体对C/C复合材料结构和力学性能的影响

Effect of carbon fiber preform with variable density on the structure and mechanical property of C/C composites

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。

In the preparation of C/C composites,the surface pores of preform are easy to jam. In order to prevent this phenomenon, the preform were designed to variable density needle carbon fiber preform along the thickness. Then C/C composites were obtained by chemical vapor infihration（CVI）. The influence of preform on the structure and mechanical properties of C/C composites was studied. The results showed that the distribution of carbon fiber was changed in variable density needled carbon fiber preform,which leaded to the pore structural change of the C/C composites. And the mechanical properties of C/C composites was improved during to the forming of the thin closed-pore and the change of the fiber containing.