单向C/C复合材料的液相法制备及其显微结构

Microstructures of unidirectional fibre-reinforced C/C composites fabricated by liquid method

以沥青、沥青加焦炭粉和树脂加焦炭粉 3种预浸料制备纤维预浸体 ,模压成型制备初坯体 ,然后用沥青液相法制备了 3种单向C/C复合材料试样 ,对这些试样的密度、孔隙率和显微结构进行了测试和观察。在热压成型初坯体内 ,收缩微裂纹沿纤维轴向与外界相通 ,可被再浸渍填充 ,而孔洞则大多与外界隔绝 ,不能被再浸渍填充。添加焦炭粉作填料有利于C/C复合材料中纤维体积含量的控制、减少封闭气孔的形成 ,提高材料的密度。但焦炭粉末将扰乱基体层状结构组织 ,甚至使其出现紊乱状态。

Three kinds of unidirectional fibre-reinforced C/C composites were fabricated by the liquid method using pitch, pitch plus coke and resin plus coke during the prepreg. Their densities, porosities and microstructures were tested and observed. In primary green composites, shrinkage cracks are formed mostly along the fibre axial and connected to the outside. They can be easily reimpregnated. However, pores are usually isolated from the outside and cannot be reimpregnated. The coke fillers can modify the microstructures. The use of filler particles facilitates the control of the fibre volume fraction and the reduction of the pores formed during moulding. The composites with coke fillers can be reimpregnated to get higher densities. On the other hand, coke particles interfere with the layer microstructure of the carbon base.