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为了研究纤维表面状态对C/C-SiC复合材料微观组织和相成分的影响,将T300碳纤维在氮气氛围中进行不同温度的热处理后,采用液硅熔渗法制备了C/C-SiC复合材料。采用光电子能谱(XPS)对纤维表面成分进行了分析。结果表明:未处理纤维表面具有较高的氧含量,随着热处理温度的升高,纤维表面氧含量逐渐降低,导致纤维表面含氧官能团数目减少。扫描电镜(SEM)观察发现:未处理纤维增强的C/C预制体,孔隙尺寸较大且孔隙率低;而经1 500℃热处理纤维增强的预制体,孔隙尺寸较小但孔隙率高。随后对C/C预制体进行液硅熔渗处理,并对熔渗反应过程分析发现:由未处理纤维增强的预制体,液硅熔渗反应主要受溶解-沉淀和界面限制的扩散反应过程控制,获得的C/C-SiC复合材料中SiC基体相分布规则且含量较低,同时含有较高的残留Si;而经1 500℃热处理纤维增强的预制体,熔渗反应则主要受溶解-沉淀过程控制,获得的C/C-SiC复合材料中SiC基体含量多且分布较均匀,残留Si含量较少。
In order to study the effect of fiber surface condition on the microstructure and phase composition of C / C-SiC composites, T300 carbon fibers were heat-treated at different temperatures in a nitrogen atmosphere. The C / C-SiC composites . The fiber surface composition was analyzed by photoelectron spectroscopy (XPS). The results showed that the surface of untreated fiber had higher oxygen content. With the increase of heat treatment temperature, the oxygen content on the surface of fiber decreased gradually, which led to the reduction of the number of oxygen-containing functional groups on the surface of fiber. Scanning electron microscopy (SEM) observation showed that the untreated fiber reinforced C / C preform had larger pore size and lower porosity, while the fiber pretreated by heat treatment at 1 500 ℃ had smaller pore size and higher porosity. Then the C / C preform was infiltrated by liquid silicon, and the infiltration reaction process was analyzed. It was found that infiltration reaction of liquid silicon was mainly controlled by diffusion-reaction process of dissolution-precipitation and interfacial confinement , SiC matrix phase distribution of the obtained C / C-SiC composites is regular and low content, and contains high residual Si; and after heat treatment at 1500 ℃ fiber reinforced preform, the infiltration reaction is mainly affected by dissolution - precipitation In the process control, the content of SiC matrix in C / C-SiC composites is more and more uniform and the residual Si content is less.