丙烷CVI工艺热解炭沉积非均相反应动力学模拟  

Modeling of carbon deposition from propane in chemical vapor infiltration

作　　者：汤哲鹏 徐伟[1] 李爱军[1] 张中伟[2] 白瑞成[1] 王俊山[2] 任慕苏[1] 

机构地区：[1]上海大学材料复合及先进分散技术教育部工程中心,上海200072 [2]航天材料及工艺研究所先进功能复合材料技术国防科技重点实验室,北京100076

出　　处：《新型炭材料》2016年第1期77-86,共10页New Carbon Materials

基　　金：教育部博士点基金(20113108120019);上海人才发展资金(2011028);航空基金(2013ZFS6001);上海市科委基金(13521101202)~~

摘　　要：分别运用总括非均相反应机理和详细非均相反应机理,结合均相反应机理（包括285种气相组分,1 074个气相可逆基元反应）来模拟C_3H_8在CVI工艺条件下炭纤维表面热解炭的沉积过程,进而对实验中的气相组分和热解炭的形成过程进行预测。总括非均相反应机理对炭沉积反应进行了简化处理,气相中的烃组分直接在表面脱氢沉积为热解炭;而详细非均相反应机理则利用表面基元反应来描述热解炭沉积过程,包括66种表面组分和250个表面基元反应。本文以C_3H_8为炭源,N_2为稀释气体,温度1 173~1 323 K、低压（2.6 kPa）和滞留时间为0.5~4s条件下的连续搅拌釜反应器为模型进行模拟,气相组成和沉积动力学两方面的预测与实验结果都较好吻合。计算表明在该设定条件下热解炭的前驱体主要为不饱和小分子（C_2H_2和C_2H_4）和甲基,进而利用这些组分定量解释热解炭的沉积动力学。A reaction model including global reactions and 1 074 elementary reactions of 285 species in both the gas phase and the solid surface was used to numerically simulate the gas phase composition and the deposition kinetics of pyrocarbon on carbon fibers in chemical vapor infiltration using propane. The global reactions were simplified to be the direct dehydrogenation reactions from the hydrocarbon species in the gas phase while the elementary reactions included 66 surface species and 250 elementary steps. Simulated results were compared with experiments performed in a perfectly stirred reactor at 2.6 kPa from 1 173 to 1 323 K for 0.5 to 4 s, using propane as the carbon precursor and nitrogen as the diluting gas. Excellent agreement between the simulated and the experi- mental results are found for both the gas phase compositions and deposition kinetics at various conditions. The simulation indicates that the pyrocarbon precursors are mostly small unsaturated species （ acetylene and ethylene） and methyl radicals, and the deposition kinetics could be quantitatively described by the deposition of these species.

关 键 词：模拟 热解炭 表面动力学 丙烷 化学气相渗透 

分 类 号：TB332[一般工业技术—材料科学与工程]