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提出了一种用分形理论研究炭/炭(C/C)复合材料制备过程中孔隙演化特征的新方法.基于压汞测试数据,根据海绵分形模型及热力学关系模型导出的多孔介质分形维数计算公式,计算了致密化各阶段C/C复合材料孔隙的分形维数,并研究了分形维数随孔隙演化过程的变化规律.结果表明C/C复合材料属于多孔分形介质,孔隙分形维数随孔隙率的减小而增大,但同时受到热解炭织构形态的影响,从各向同性到高织构热解炭,分形维数减小.分形维数综合反映了C/C复合材料内部孔隙的复杂程度和热解炭的形貌特征,是监控C/C复合材料致密化过程中孔隙演化的一个有效参数.
A new method for studying the evolution of pores in C / C composites by fractal theory is proposed. Based on the mercury intrusion test data, the fractal dimension of porous media derived from the model of sponge fractal and the thermodynamic model The fractal dimension of C / C composites at various stages of densification was calculated, and the variation of fractal dimension with pore evolution was studied. The results show that C / C composites belong to porous fractal medium and the fractal dimension Porosity decreases, but the fractal dimension decreases from isotropic to highly textured pyrolytic carbon, which is affected by the texture morphology of pyrolytic carbon. The fractal dimension reflects that the C / C composites The complexity of the internal pores and the pyrolytic carbon topography is an effective parameter for monitoring the evolution of porosity in the C / C composites during densification.