载气对CVIC/C材料密度和热解炭结构分布的影响  

Effects of carrier gas on density and microstructure distribution of CVI-derived C/C composites

作　　者：熊翔[1] 汤中华[1] 张红波[1] 熊杰[1] 浦继强[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083

出　　处：《中国有色金属学报》2006年第3期385-391,共7页The Chinese Journal of Nonferrous Metals

基　　金：国家重点基础研究发展规划资助项目(2005CB600903)

摘　　要：采用定向流动热梯度CVI工艺,以丙烯作炭源气,以针刺炭纤维整体毡作预制体分别研究了加氢气和氮气作载气对C/C复合材料密度和热解炭结构分布的影响。结果表明,载气对热梯度CVI C/C材料密度和热解炭结构沿径向分布的均匀性有重要影响。当其它工艺条件相同时,经过400 h的沉积,采用N2作载气时所得炭盘的平均体密度为1.54 g/cm3,炭盘密度沿径向分布的偏差Δρ为0.24 g/cm3,在炭盘的外侧易形成SL结构热解炭;而采用H2作载气时,可以得到平均体密度为1.67 g/cm3、热解炭结构分布高度均匀的全RL结构PyC基C/C复合材料,且炭盘密度沿径向分布的偏差Δρ仅为0.11 g/cm3,密度分布均匀性提高一倍以上。不管是采用N2还是H2作载气,炭盘的密度沿周向分布都十分均匀(Δρ≤0.02 g/cm3),且炭盘的较低密度部位均位于中间偏内侧。Needled carbon fibre integrated preforms were densified by directional flow thermal gradient CVI process from carbon source gas C3 H6, and the effects of introducing active carrier gas （H2） and inert carrier gas （N2） on the bulk density and microstructure distribution of C/C composites obtained were investigated, respectively. The results show that the type of carrier gases has noticeable influences on the radial distribution of density and microstructure of C/C composites. When N2 is used as carrier gas, the average bulk density of the resultant disk is 1.54 g/cm^3 after 400 h infiltration, and the density distribution discrepancy （△ρ） of the disk along the radial direction is 0.24 g/cm^3. Furthermore, the smooth laminar pyrolytic carbon is subjected to form at the exterior part of the C/C disks. Unlike N2, when H2 is used as carrier gas, a complete rough laminar pyrolytic carbon matrix and C/C disks with average bulk density of 1.67 g/cm^3 can be obtained within the same time, and the density distribution discrepancy of the disk along the radial direction is only 0.11 g/cm^3 , which means the density homogeneity of the radial distribution of C/C disks is more than doubled. It is also shown that no matter what type of carrier gas is employed, the circumferential density profile is very homogeneous （△ρ≤0.02 g/cm^3） and the lower density zone is found to be the middle position which is adjacent to the inner part of the C/C disks.

关 键 词：C/C复合材料 化学气相渗透 载气 热解炭 

分 类 号：TB332[一般工业技术—材料科学与工程]