(中南大學(xué) 粉末冶金國(guó)家重點(diǎn)實(shí)驗(yàn)室， 長(zhǎng)沙 410083)
摘 要: 采用定向流動(dòng)熱梯度CVI工藝， 以丙烯作炭源氣， 以針刺炭纖維整體氈作預(yù)制體分別研究了加氫氣和氮?dú)庾鬏d氣對(duì)C/C復(fù)合材料密度和熱解炭結(jié)構(gòu)分布的影響。 結(jié)果表明， 載氣對(duì)熱梯度CVI C/C材料密度和熱解炭結(jié)構(gòu)沿徑向分布的均勻性有重要影響。 當(dāng)其它工藝條件相同時(shí)， 經(jīng)過(guò)400 h的沉積， 采用N2作載氣時(shí)所得炭盤的平均體密度為1.54 g/cm3， 炭盤密度沿徑向分布的偏差Δρ為0.24 g/cm3， 在炭盤的外側(cè)易形成SL結(jié)構(gòu)熱解炭； 而采用H2作載氣時(shí)， 可以得到平均體密度為1.67 g/cm3、 熱解炭結(jié)構(gòu)分布高度均勻的全RL結(jié)構(gòu)PyC基C/C復(fù)合材料， 且炭盤密度沿徑向分布的偏差Δρ僅為0.11 g/cm3, 密度分布均勻性提高一倍以上。 不管是采用N2還是H2作載氣， 炭盤的密度沿周向分布都十分均勻(Δρ≤0.02 g/cm3)， 且炭盤的較低密度部位均位于中間偏內(nèi)側(cè)。
關(guān)鍵字: C/C復(fù)合材料; 化學(xué)氣相滲透; 載氣; 熱解炭
CVI-derived C/C composites
（ State Key Laboratory of Powder Metallurgy, Central South University,
Changsha 410083, China）
Abstract: Needled carbon fibre integrated preforms were densified by directional flow thermal gradient CVI process from carbon source gas C3H6, 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/cm3 after 400 h infiltration, and the density distribution discrepancy (Δρ) of the disk along the radial direction is 0.24 g/cm3. 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/cm3 can be obtained within the same time, and the density distribution discrepancy of the disk along the radial direction is only 0.11 g/cm3 , 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 (Δρ≤0.02 g/cm3) and the lower density zone is found to be the middle position which is adjacent to the inner part of the C/C disks.
Key words: C/C composites; CVI; carrier gas; pyrolytic carbon
