(中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室, 長沙 410083)
摘 要: 利用TaCl5-Ar-C3H6-H2反應(yīng)體系, 采用化學(xué)氣相滲透（CVI）法在炭氈中沉積TaC, 并研究了CVI工藝參數(shù)如氣體流速、 滯留時(shí)間、 沉積溫度、 沉積壓力和H2的加入等對碳化鉭在炭氈中沉積速率(用炭氈質(zhì)量分?jǐn)?shù)的增加來表示)的影響。 研究表明： CVI-TaC受表面反應(yīng)控制的最大氣體流速為40 cm/s, 最小滯留時(shí)間為1.2 s； 沉積速率與沉積溫度之間的關(guān)系不符合Arrhenius方程, 沉積速率隨沉積溫度的升高先增加后減小, 在950 ℃時(shí)達(dá)到最大值； 在1 000 ℃時(shí),CVI過程受孔隙擴(kuò)散所控制； 沉積速率隨沉積壓力的升高以及H2的加入而急劇增加。
關(guān)鍵字: TaC； 炭氈； 化學(xué)氣相滲透； 擴(kuò)散； 沉積速率
deposition rate of CVI-TaC
ZHANG Hong-bo, YIN Jian, HUANG Bai-yun
（State Key Laboratory of Powder Metallurgy,
Central South University, Changsha 410083, China）
Abstract: TaC was deposited by chemical vapor infiltration(CVI) method with TaCl5-Ar-C3-H6-H2 system in carbon fiber felt. The influences of CVI process parameters, such as gas velocity, residence time, deposition temperature, deposition pressure and the addition of H2, on the deposition rate(expressed by the mass fraction increment of the sample) of TaC were studied. The results show that CVI-TaC process is controlled by surface reaction, the maximum gas velocity is 40 cm/s and the minimum residence time is 1.2 s. The relationship between the deposition rate and the preform temperature do not accord with Arrhenius formula. The deposition rate increases firstly with the increase of temperature, reaches the maximum value at 950 ℃. At 1 000 ℃, the CVI process is controlled by pore diffusion. The deposition rate increases obviously with the increase of deposition pressure and the addition of H2.
Key words: TaC; carbon felt; chemical vapor infiltration(CVI); diffusion; deposition rate
