C/C-SiC材料的快速制备及显微结构研究

Study of Rapid Fabrication and Microstructure of C/C-SiC Composites

分别以碳毡和二维碳纤维为预制体，采用化学液相气化渗入法结合熔融渗硅反应法快速制备了C／C-SiC陶瓷复合材料。对这种材料的密度和气孔率进行了表征，并通过XRD，OM和SEM等方法对其相组成、显微结构和反应机理进行了研究。结果表明：不同预制体制备的C／C—SiC材料密度和气孔率分别为～2．0g／cm^3和～1．0％。其相组成包括反应生成β-SiC以及未反应的游离Si和C。C／C—SiC中纤维被环状的沉积碳包裹，生成SiC的反应只发生在Si与沉积碳之间，纤维没有损伤。Si，C和SiC各相分布和含量因预制体的不同而有明显差异。

To reduce processing cost and time of C/C-SiC composites, the PAN based felt and the 2-Dimension carbon fibers were chosen as preforms, respectively, and method of chemical liquid-vaporized infiltration combined with reactive melt infiltration was used to fabricate C/C-SiC composites. Densities and open porosities of the composites were investigated by Archimedes method and microstructures were studied by OM and SEM. XRD was used to identify the crystal phase of the composites. The result shows that the densities of the two C/C-SiC composites mentioned above are -2.0 g/cm^3 （with low porosities of-1%）. It is also found that during the processing, β-SiC is formed and some free Si and C still exist in the composites. The contents of different phases depend on the difference of the preform. Microstructural observations of the C/C-SiC composites reveal that the pyrocarbon are concentric around the fibers. The reactions to form SiC only happen between liquid silicon and pyrocarbon, while carbon fibers are not damaged.