Gas leakage through C/C composite and its suppression technology

碳纤维加固碳基质复合材料（C/Cs）是纤维和基质之间的多孔材料，包括空隙、裂纹和接口。Hence，在C/C的应用中，将空气热结构作为热交换器，气体泄漏成为严重的问题。However，在作者最好的知识中，一些研究已经解决了这个问题，而且基本上没有讨论已经对气体泄漏的机制和措施进行了性能，以尽量减少气体泄漏率。在目前的研究中，下面的讨论得到了性能;1.对气体泄漏率的高温度测量能力的测试固定装置是设计和制造的。按顺序填充C/Cs中的缺陷，熔化硅被填充，填充硅被碳化硅转化为C/Cs中碳的化学反应。C/C的裂缝倾向于关闭温度上升，因此，在低温度环境受到影响的情况下，可以采取额外的措施。目前的研究中获得的结果如下;1.一个测试固定装置，可将高温气体泄漏率测量提高到800 ° C的气体泄漏率是设计和制造的。在气体泄漏率下降至1/10.3的情况下，硅渗透结果。作为低温度方法，通过HIP （热稳态压力）进行碳渗透，通过溶胶-凝胶方法进行玻璃形成，以及在硅渗透后通过溶胶-凝胶方法进行玻璃涂层。第一种方法是在较低的气体泄漏率下得出的，第二和第三种处理方式的较低气体泄漏率超过1/10，与硅抑制的C/Cs相比较。因此，本研究已建立了一种技术，其气体泄漏率低于C/Cs的1/1000，与非处理的C/Cs相比。

Carbon fiber reinforced carbon matrix composites (C/Cs) are porous materials including voids, cracks, and interfacial debonding between the fiber and matrix. Hence, in applications of C/Cs to airtight hot structures such as heat exchangers, the gas leakage becomes serious problem. However, within author's best knowledge, few studies has treated this problem, and essentially no discussion has been performed on gas leak mechanisms and measures to minimize gas leak rate.In the present study, the following discussion was performed ;1. A test fixture capable of high temperature measurement of gas leak rates was designed, and fabricated.2. In order to fill the defects in C/Cs, molten Si was infiltrated, and filled Si was converted to SiC by chemical reaction with carbon in C/Cs.3. Cracks in C/Cs have tendency to be closing with temperature rise, so that additional measures which can be done under low temperature environment were attempted.The results obtained in the present research were as follows ;1. A test fixture capable of high temperature gas leak rate measurements up to 800゜C of gas leak rates was designed, and fabricated.2. The Si impregnation resulted in decreasing gas leak rate to 1/10.3. As low temperature methods, carbon infiltration by HIP (hot isostatic pressure), glass formation by the sol-gel method, and glass coating by the sol-gel method were examined after the Si impregnation. The first method resulted in slight lowering of gas leak rate, the second and third treatments yielded less gas leak rates over 1/10 compared with Si impregnated C/Cs. Thus, this study established technology lowering gas leak rate through C/Cs less than 1/1000 compared with non-treated C/Cs.