热解炭的微观结构及其测试方法

2007年第4期CARBON TECHNIQUES200T№4第26卷炭套技术Vol 26·综合述评·热解炭的微观结构及其测试方法刘立海,黄启忠,谢志勇,王秀飞(中南大学粉末冶金国家重点实验室,湖南长沙410083)摘要:主要介绍了利用正交偏光显微镜(PLM)、X射线射(XRD)透射电镜(TEM)和喇曼光谱(RS)等测试方法对采用化学气相沉积(cD)法制备的c/C复合材料的热解炭的表面微观形貌沉积炭层间距dm微晶尺寸L及其石墨化度等参数进行表征和测量从而判断沉积的热解炭的织构类型(光滑层粗糙层和各向同性炭),并且分析了上述各种测试手段的优缺点关健词:化学气相沉积;C/C复合材料;热解炭;织构中图分类号:TQ127.1·1文獻标识码:A文章编号:1001-3741(2007)04001706MICROSTRUCTURAL CHARACTERIZATIONAND MEASUREMENTS OF PYROLYTICCARBONLIU Li-hai, HUANG Qi-zhong, XIE Zhi-yong, WANG Xiu-feiState Key Laboratory for Powder Metallurgy, Central South University, Changsha410083. ChinaAbstract: In this paper, in order to judge the structure (SL, RL, ISO)of pyrolytic carbons prepared by chemicaldeposition(CVD), the methods for observation and measurement of the surface morphologies and structural paprameterssuch as the interlayer spacing don, crystallite size L and graphitization degree of pyrolytic carbons were introducedwhich includes the polarized light microscopy(PLM), scanning electron microscopy(SEM), tansmission electron mirecopy(TEM), X-ray diffraction (XRD) and Raman spectroscopy. The advantages and disadvantages of each measurement were also analysized.Key words Chemical vapor deposition; carbon/ carbon composites; pyrolytic carbonitexture对于C/C复合材料而言,结构与性能之间的关料;而各向同性结构具有较好的各向同性、生物相系至关重要,化学气相沉积制备的C/C复合材料一容性、密封性,可用于生物材料、密封材料等。热解般由各向同性的炭纤维和各向异性的热解炭组炭是气态碳氢化合物在热基体表面通过脱氢环化成。材料的性能主要取决于基体,即沉积的热解炭作用沉积而形成的炭材料。文献[1~6]研究表明不类型。例如,光滑层结构具有很好的高温力学性能,同类型的热解炭对C/C复合材料的摩擦磨损、力学主要用于高温结构件、抗烧蚀件等;粗糙层结构具性能等影响较大。因此,对热解炭组织结构的类型有较好的摩擦磨损性能,适用于高性能飞机刹车材进行表征和测量是十分重要的。对热解炭织构类型作者简介:刘立海男1981年出生,硕士研究生,E-mil:hiulihaigodc@163.com。收稿日期:2007-02-02炭素技术07年进行表征和测量的方法有多种。例如,采用偏光显起偏器起偏器微镜( Polarized Light Microscopy,PLM)、X射线衍射检偏器(X- Ray diffraction)、透射电镜( Transmission Elec了消光角ron Microscopy,TFM)、喇曼光谱( Raman Spectrum等方法。H前,国内外对热鮮炭织构类型的判别主要基于」述各种方法,但是对上述各种方法综述性的报道尚未见报。本文主要对上述方法作简要的综旋转述性报道,并提出各自方法的优缺点。减偏器1热解炭类型和结构特征E1.1偏光显微镜图2偏光显微镜测量消光角示意图Fig 2 Schematic diagram ot extinction angle measure under热解炭材料最初是采用PLM进行研究的PLMPierson和 Lieberman0等为首的美国 Sadia实验室,对沉积在纤维毡的热解炭进行了深入细致的 Rough laminar,RL)和各向问性热解炭( isotroPic研究。他们将在偏光下观察到的热解炭的微观结构IS0),以及以上三种中任意两者或者两者以上交替划分为三类:光滑层( Smooth laminar,SL)粗糙层组合而形成的带状结构( Banded Structure,Bs),如图1所示1从图1可以看出,其中SL在光学上各向异性,柑位移较低,无生长锥形成,呈现清晰可见的十字消光线且视觉效果光滑、呈灰色、裂纹显著;RL光学活性较高,具有生长锥特征,呈现大量不规则的十字消光线且视觉效果粗糙、呈银灰色、无裂纹;ISO光学各向同性,相位移为零,观察不到十字消光线。随后, Diefendorf和1 okarsky I3基于沉积的炭层关于基面的择优取向程度不同而其在PIM下的旋(a)sL光性不同定义了消光角Aea在PLM屮,当两个棱镜正交时,视场中出现黑十字线,通过逆时针旋转检偏器,第一象限逐渐消失然后又变亮,在即将变亮的那一瞬间,分析器刻度盘上显示的即为消光角数值,如图2所示1各种热解炭的微观结构可以用Ae来表征,Ae的大小与织构的择优取向程度有关,择优取向程度越高,Ae越大,反之亦然:ISO(Ae<4),DL(4°≤A<12°),SL(12°≤Aec≥50乱的堆积状态。aa=180°da=A/(2ein0);g=(0.3340-da)/(0.3440-0.3354);L=(K)/(Bo08)0.340nm≤d≤0.344mmda≈0.343nm≥70%20%≤g<70%23.9mm≤L9.5rm≤L≤16.5nm7mm≤L≤llmmR-= IG/lp2007年2005,5:1201~1207.结论[13] DIEFENDORF R J, TOKARSKY E w. 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