炭素繊維およびC/C複合材料の熱処理によるヤング率の変化

抄録

As one of the most important basic mechanical properties of advanced C/C composites for high temperature structural applications, temperature dependence ofYoung's modulus was precisely studied from room temperature up to 1373K. Materials used were two kinds of unidirectional C/C composites, where the variables were microstructure of carbon fibers in C/C composites introduced by heat treatment prior to composite fabrication (denoted as prior heat treatment).Those composites were, then, heat treated between 1473K and 3073K (denoted as post heat treatment). Microstructural inspections were performed with X-ray diffraction analysis, TEM observation and Raman spectroscopy. The temperature dependence of Young's modulus showed positive and negative trends, i.e. two way temperature dependence, reflecting microstructure changes of carbon fibers by postheat treatments. For all the specimens, these temperature dependence could be written by a liner function of two typical specimens, in which the graphitization of carbon fiber were the lowest and the highest of all specimens. And the temperature dependence of Young's modulus was considered to be predictable from the results of Raman spectroscopy. Also the correlation between microstructure and Young's modulus was discussed together with the TEM results and thermal history during the fabrication of carbon fibers and C/C composites.