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不同分子量聚碳硅烷的性能及对C/ C-SiC 复合材料增密的影响
黄 剑,李 辉,嵇阿琳,王玲玲,刘 博
西安航天复合材料研究所,西安 710025
摘要:
以四种分子量级别聚碳硅烷(PCS)为浸渍剂ꎬ采用CVD 和浸渍-裂解工艺制备了C/ C-SiC 复合
材料ꎬ分析了四种分子量级别PCS 的分子量、软化点ꎬ分子结构和热失重性能ꎬ采用压汞法测试试件的孔隙分
布特性ꎮ 分析表明ꎬPCS 的软化点和800℃转化率都随着分子量的提高而提高ꎻ四种分子量级别的PCS 热分解
过程基本相同ꎬ分子的支化程度差异不大ꎮ 数均分子量为1 178、1 333 的PCS 的整体致密化效率要高于数均
分子量为1 550 的PCSꎬ经过7 个周期致密后ꎬ分子量为1 178 的PCS 所致密试样的累积孔隙容积最高ꎬ分子量
为1 550 的PCS 所致密的试样最低ꎮ 前5 个浸渍裂解致密周期采用分子量为1 550 的PCSꎬ以后周期采用分子
量为1 178 或1 333 的PCSꎬ可以达到较高的致密效率。
关键词:  聚碳硅烷,分子量,C/ C-SiC 复合材料,密度
DOI:
分类号:TB33
基金项目:
Performance of Polycarbosilane With Different Molecular Weigh andIts Effect on Densification of C/ C-SiC Composites
Abstract:
C/ C-SiC composites were prepared by CVD ꎬimpregnation and pyrolysis method using polycarbosilane
(PCS) with four number average molecular weight as impregnant.The molecular weightꎬ softening pointꎬ molecular struc ̄
ture and thermogravimetic performance of PCS were determinedꎬ and the distribution of pores were analyzed by means of
mercury intrusion method .The results showed that the softening point and rate of conversion at 800℃ of PCS increased with
increasing molecular weight of PCS. The pyrolysis process of PCS with four molecular weight grade were identicalꎬ and
branch degree did not have significant difference. The integral densification efficiency of PCS with molecular weight 1 178
and 1 333 was higher than that of PCS with molecular weight 1 550. The cumulative pore content of sample densified by PCS
with molecular weight 1 178 was maximum after seven densification cyclesꎬ and that of sample densified by PCS with molec ̄
ular weight 1 550 was minimum.When PCS with molecular weight 1 178 and 1 333 was used in previous five ̄cycles and mo ̄
lecular weight 1 550 was used in other cyclesꎬ the material could be densified more efficiently.
Key words:  PCSꎬ  Molecular weightꎬ  C/ C-SiC compositesꎬ  Density