化学气相渗积压力对渗积速率和热解炭组织结构的影响(英文)  

Influence of infiltration pressure on the densification rate and microstructure of pyrocarbon during chemical vapor infiltration

作　　者：张云峰[1] 罗瑞盈[1] 

机构地区：[1]北京航空航天大学物理与核能工程学院,北京100191

出　　处：《新型炭材料》2012年第1期42-48,共7页New Carbon Materials

基　　金：National Natural Science Foundation of China(21071011)~~

摘　　要：采用天然气为前躯体在不同压力下使用化学气相渗积法制备炭/炭复合材料。利用甲烷分解热力学与沉积动力学研究了渗积压力对渗积速率和热解炭组织结构的影响。采用偏光显微镜观察热解炭的组织结构。结果表明:随着渗积压力的增加,初始渗积速率增大;但在渗积后期,渗积速率随着渗积压力的增大而降低,导致在高渗积压力下相同时间制备样品的最终密度降低。热解炭组织结构对渗积压力具有很强的依赖性。在低压(1 kPa)下渗积得到的热解炭基体全部为粗糙层结构。在适中的压力(3kPa,5 kPa,10 kPa)下,以炭纤维为圆心由内到外依次得到各向同性和粗糙层热解炭,整个基体以粗糙层为主。在15 kPa下,得到的热解炭组织结构为各向同性和光滑层组织。Carbon/carbon composites were fabricated by chemical vapor infltrafion of needled carbon fiber felts （70% porosity） with natural gas as precursor at different infiltration pressures. The thermodynamics of methane pyrolysis and the densification kinetics were used to investigate the influence of infiltration pressure on the infiltration rate and the microstructure of pyrocarbon. The microstructure of pyrocarbon was examined by polarized light microscopy. Results showed that the initial infiltration rate increased with pressure, whereas it decreased with pressure during the later stages of infiltration, which led to a decrease in the final density of the samples. The pyrocarbon microstructure depended markedly on the infiltration pressure at the given deposition temperature. Rough laminar （RL） carbon is formed as the matrix at the lowest pressure （approximately 1 kPa）. At medium pressures （3, 5, and 10 kPa）, isotropic （ISO） carbon is formed, followed by RL carbon, in the radial direction of the carbon fiber, with RL being the major matrix. Smooth laminar and ISO structures are the maior ohases at hizh oressures （ 15 kPa）.

关 键 词：炭/炭复合材料 化学气相渗积 热解炭 显微结构 

分 类 号：TB332[一般工业技术—材料科学与工程]