マイクロサテライトにおけるトライボロジー技術と宇宙環境からの影響評価に関する研究

本课题研究了二硫化钼(MoS_2)润滑剂的摩擦学性能对空间环境的影响。在以往的研究中，摩擦学试验往往是在后处理过程中进行的，这意味着启动摩擦包括形成磨痕的力。这种现象通常包括原子氧在摩擦力中的作用。本研究进行了现场摩擦学试验，利用XPS、AES、RGA、AFM和摩擦试验研究了原子氧对摩擦磨损的影响。结果表明，摩擦力随原子氧流量的增加而增大，达到普通摩擦力的2.5倍以上。随着原子氧暴露的增加，不仅启动摩擦增加，稳态摩擦也增加。观察到原子氧通量对摩擦系数的依赖关系。XPS结果表明，MoS_2表面的硫原子被去除，钼被原子氧暴露氧化成MoO_3。RGA测量表明，原子氧/MoS_2体系的挥发性反应产物是这样的。从本研究的结果可以看出，MoS_2润滑剂受到近地轨道原子氧暴露的严重影响。微小卫星系统是卫星系统中的一种最新技术发展趋势，其摩擦系统的外加载荷由于质量减小，即惯性较小而减小，因此摩擦表面的分层现象不会发生。结论是原子氧对微小卫星的影响将更加严重。

This project deals with the effect on space environment of tribological properties of molybdenum disulfide(MoS2)lubricants. In the previous researches, tribological testing was always carried out in a post process, which means the start-up friction includes the force of forming a wear track. This phenomenon usually covers the effect of atomic oxygen in a friction force. In this research, in-situ tribological testing was conducted and effect of atomic oxygen was investigated by XPS, AES, RGA, AFM and friction test. The results clearly indicated that the friction force increases with atomic oxygen fluence and it reached more than 2.5 times larger than ordinary friction force. Not only the start-up friction, but also steady-state friction increased with atomic oxygen exposures. The atomic oxygen fluence dependence on a friction coefficient was clearly observed. XPS results were interpreted that sulfur atom was removed from the MoS_2 surface, and molybdenum was oxidized into MoO_3 by the atomic oxygen exposures. RGA measurements revealed that the volatile reactive products of atomic oxygen/MoS_2 system is So. From the results obtained in this study, we concluded that MoS_2 lubricant is severely influenced by the atomic oxygen exposures in low earth orbit. In the case of microsatellite system, which is a recent technological trends in satellite systems, applied load of a friction system will be reduced due to the reduced mass, i.e., low inertia, thus, the delaminating phenomenon at the frictional surface will not be expected very much in such a system. Conclusion is that the microsatellite will be influenced by the atomic oxygen more severely.