C/C复合材料断口热解炭及其界面形貌SEM分析

采用SEM，以增强体为薄毡叠层、基体分别为光滑层及粗糙层结构化学气相沉积热解炭的2种C／C复合材料为研究对象，了三点弯曲试样断口上热解炭及热解炭／热解炭界面的形貌特征，并分析了其成因。结果表明：在垂直于炭纤维轴向的断面上，光滑层结构热解炭未发生塑性变形，但粗糙层结构热解炭发生了明显的塑性变形；在平行于炭纤维轴向的断面上，光滑层结构热解炭／热解炭界面呈光滑状，而粗糙层结构热解炭／热解炭界面呈鳞片状，鳞片的周边粗糙，内部光滑。认为鳞片结构的产生与化学气相沉积过程相关，并对此提出了假设模型：两相邻热解炭生长到界面时，在鳞片周边部位互生长形成真正的结合，使鳞片内部形成封闭的空隙或使气流无法通过鳞片内部，造成鳞片内部的伪结合。

Analysis of Fracture Morphologies of Pyrocarbons and Their Interface in C/C Composites by SEM

The fracture morphologies of pyrocarbons and the interface between them in two kinds of C/C composites have been analyzed by SEM. The reinforcement of the two composites is laminated carbon felt, and the matrix of the two composites consists exclusively of SL(smooth lamina) or RL(rough lamina) pyrocarbon respectively. Experimental results show that plastic deformation can be observed in RL pyrocarbon in fracture surface vertical to the axis of carbon fiber, whereas no plastic deformation can be observed in SL pyrocarbon. The interface between RL pyrocarbon is scale-like with rough outline and smooth inner face in fracture surface parallel to the axis of carbon fiber, whereas the interface between SL pyrocarbon is smooth. The scale-like structure can be related to CVD process. A model of the CVD process is presented: carbon is deposited at the outline location of the scale, which makes the inner face of the scale become not infiltrated to vapor flow, as a result, really strong interface bonding only occurs at the outline location.