单向碳/碳复合材料ICVI致密化机理研究  

On the Mechanism of Densifying Unidirectional C/C Composites by Isothermal Chemical Vapor Infiltration

作　　者：侯向辉[1] 李贺军[1] 刘应楼[1] 康沫狂[1] 

机构地区：[1]西北工业大学

出　　处：《西北工业大学学报》1999年第2期221-225,共5页Journal of Northwestern Polytechnical University

基　　金：国家自然科学基金

摘　　要：通过把致密化进程中热解碳作为分散相和连续相两种情况进行统一处理，研究了圆柱形单向碳／碳复合材料的化学气相渗透过程。着重讨论了致密化的均匀性问题，分析了预制体纤维体积分数对致密进程的影响及预制体内贯穿大孔洞对致密化的增进作用。研究结果表明，预制体纤维体积分数越低，致密化后期所能达到的密度越高，致密化的均匀程度也越好；贯穿大孔洞的存在，大大提高了丙烯气体在预制体内的传输能力，使内部的致密化效果有了很大改善。Isothermal Chemical Vapor Infiltration (ICVI) for fabricating C/C composites suffers from two shortcomings: (1) low densification efficiency; (2) densification uniformity not quite satisfactory. We try to overcome these two shortcomings by investigating the mechanism of densifying process of C/C composites. We divide the densifying process into two stages according to the two states of pyrolytic carbon: disperse phase and continuous phase as shown in Fig.2, in order to quantitatively describe the whole CVI process. We prepared preforms for four different fiber volume fractions: V f =45%, 50%, 55%, 60%. We found that, for lower values of V f , the rate of densification and the final density at the end of 350 h of densification are both higher (Fig.3). We found through test observation that penetrate pores in preform larger than 100 μm are conducive to better densification. We calculated the mass transportation of propylene and found that big penetrate pores of around 100 μm are needed for improving such mass transfer to the level helpful to making densifications within preforms better.

关 键 词：碳/碳复合材料 致密化 化学气相渗透 ICVI 

分 类 号：TB332[一般工业技术—材料科学与工程]