中文摘要：

采用高密度3D炭纤维预制体,以丙烯作为碳源,氮气作为载气,利用自制的快速CVI炉制备了板形C/C复合材料.详细分析了压差等工艺参数在CVI制备C/C复合材料过程中对＂封孔＂现象的影响,采用扫描电镜（SEM）和正交偏光显微镜（PLM）对各阶段C/C材料的微观形貌特征作了详细研究,分析了预制体在増密过程中密度的变化,初步探讨了＂封孔＂形成的机理.实验证明：采用多阶段CVI工艺可明显改善板形C/C材料封孔现象,初始密度为0.94g/cm3的高密度预制体经过250h的增密,C/C复合材料密度达到了1.82g/cm3.

英文摘要：

With C3H6 as the precursor,N2 as the carrier gas and high density 3D carbon fiber braided preform,the plate of C/C composites was fabricated by the fast CVI process.Influence of gradient pressure and other factors of process on the sealed pores in C/C composites were analyzed,and the morphologies were characterized by scanning electron microscope（SEM） and polarized light microscope（PLM） in detail.The formation mechanism of sealed pores and the transformation of density in high density preform in the densification process are simply analysized.The experimental results show that the sealed pores can be reduced by multi-stage CVI process and the density of the C/C composite are improved from 0.94g/cm3 to 1.82g/cm3 after 250 h CVI process.