A Study on Degradation of Carbon-based Materials due to Atomic Oxygen in Space

随着近地轨道结构使用的材料种类越来越多，暴露在空间中的结构材料的降解成为一个新问题。本文进行了地面降解实验和分子动力学模拟。在实验中，等离子炬产生的氧原子被工作气体动态加速。石墨，碳/碳复合材料和硅-碳。（：硅浸渍C/C复合材料）作为靶材料。单位面积的质量损失近似与曝光时间成正比，并与材料表面温度密切相关。利用扫描电镜（SEM）和电子能谱（EPMA）对材料的侵蚀表面进行了观察。在C/C复合材料中，基体区域的侵蚀比碳纤维严重得多。si - cc的质量损失。小于相应的C/C复合材料，只有C/C复合材料区域侵蚀较深，Si和SiC区域几乎没有侵蚀。为了研究高能原子氧对石墨的降解作用，采用分子动力学方法对石墨进行了数值模拟。仿真模型解释了暴露时间对材料降解的影响。

The degradation of structurl material exposed in space is a new problem, since various kinds of materials have been used for structures in low earth orbit (LEO). This study presents an experiment of degradation on the ground and a simulation by the molecular dynamics. In the experiment, atomic oxygen produced at a plasma torch is accelerated fluid dynamically with working gas. Graphite, C/C composite and Si-C.C.( : Sillicon impregnated C/C compsite) were used as the target materials. The mass loss per unit area is approximately proportional to the exposure time and depends strongly on the temperature of material surface. The eroded surface of materials were observed with SEM and EPMA.In case of C/C composit, the matrix region erodes substantially more than carbon fiber. The mass loss of Si-C.C.is less than that of corresponding C/C composite and only the C/C composite region erodes deeply with almost no erosion in Si and SiC regions. In order to investigate the degradation caused by high-energy atomic oxygen, numerical simulation was conducted for graphite using the molecular dynamics method. The simulation model explains tlxe influence of exposure time on the degradation of material.