化学气相渗透碳化硅增强石墨泡沫的温度效应研究  

The effect of deposition temperature on the properties of the silicon carbide strengthening the graphite foams by chemical vapor infiltration

作　　者：赵俊通 连鹏飞[2,3] 程金星 宋金亮 张俊鹏 赵俊一[1] Zhao Jun-tong;Lian Peng-fei;Cheng Jin-xing;Song Jin-liang;Zhang Jun-peng;Zhao Jun-yi(Wuxing New Material Technology Co.,Ltd.,Henan Pingdingshan 467000,China;Key Laboratory of Carbon Materials,Institute of Coal Chemistry,Chinese Academy of Sciences,Shanxi Taiyuan 030001,China;Beijing High-tech Institute,Beijing 100094,China;Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]五星新材科技有限公司,河南平顶山467000 [2]中国科学院山西煤炭化学研究所,山西太原030001 [3]北京高技术研究院,北京100096 [4]中国科学院上海应用物理研究所,上海201800 [5]中国科学院大学,北京100049

出　　处：《炭素技术》2023年第4期39-43,57,共6页Carbon Techniques

基　　金：国家自然科学基金(52072397,12175323);中国科学院山西煤炭化学研究所创新基金(SCJC-XCL202207,SCJC-XCL202209)。

摘　　要：通过化学气相渗透技术,在中间相沥青基石墨泡沫内部沉积了碳化硅涂层;研究了不同沉积温度对碳化硅形貌、晶体结构和强度的影响。结果表明,1223 K可以制备完整的碳化硅涂层,沉积速率较慢,晶粒尺寸较小;温度超过1423 K,易在石墨表面沉积生成热解炭,比强度开始下降。低温沉积时,临界形核自由能下降,形成的核芯数目增加,有利于形成晶粒细小而连续的SiC涂层组织,1273 K和1373 K温度条件下沉积的SiC涂层较光滑平整,比强度较高。随着沉积温度提高,抗弯强度由1223 K的1.8 MPa提高到1473 K的5.4 MPa,比强度由1273 K的3.40 MPa·cm^(3)/g提高到1373 K温度下的7.31 MPa·cm^(3)/g。沉积温度超过1423 K时,沉积的SiC晶粒粒径增加,热解炭比例升高,无定形碳比例增加,比强度有所下降。The silicon carbide(SiC)coatings were prepared on the mesophase pitch based graphite foams by chemical vapor infiltration(CVI)method based methyltrichlorosilane(CH3SiCl3,MTS).The SiC coating deposition behaviors and the morphology,microstructure,bending strength of the SiC foams have been studied systematically.The results show that the SiC coatings could be prepared at 1223 K with low deposition rate and small crystal grain size and the pyrolytic carbon could be detected at 1423 K on the graphite surface and the specific bending strength of the SiC coating decreased.The critical nucleation free energy of the deposition decreases and nucleation number increases at low deposition temperature,which could be beifitted to form the small SiC crystalline grain size and the compact coatings at 1273 and 1373 K.The bending strength of the SiC foams increases form 1.8 MPa at 1223 K to 5.4 MPa at 1473 K.And the specific bending strength of the SiC foams increases from 3.40 MPa·cm^(3)/g at 1273 K to 7.31 MPa·cm^(3)/g at 1373 K and decreases to 7.01 MPa·cm^3/g at 1473 K.The grain size of the SiC coatings increases and the pyrolytic/ungraphitised carbon ratio in the coatings increased at higher temperature than 1423 K,which led to the low specific bending strength of the SiC foams.

关 键 词：石墨泡沫 碳化硅 化学气相渗透 沉积温度 抗弯强度 

分 类 号：TB333[一般工业技术—材料科学与工程]