Atomic oxygen-induced erosion of fluorinated polymers in LEO: its collapse and new mechnism

2021 Fiscal Year Final Research Report

• Project/Area Number: 18K18912
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 24:Aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: Kobe University
• Principal Investigator: Yokota Kumiko 神戸大学, 工学研究科, 助手 (20252794)
• Co-Investigator(Kenkyū-buntansha): 田川 雅人 神戸大学, 工学研究科, 准教授 (10216806)
• Project Period (FY): 2018-06-29 – 2022-03-31
• Keywords: 宇宙環境 / 原子状酸素 / フッ素系高分子材料 / 高質量分子 / 材料劣化 / 窒素

Outline of Final Research Achievements

It has been widely believed that material degradation in LEO is due to atomic oxygen collision. However, ground based-simulation could not duplicate FEP erosion in LEO. This research proposed a new hypothesis that FEP is eroded mainly by N2 collision in LEO. We performed ground-based experiment using AO+Ar beam which simulates simultaneous AO and N2 collision. It was discovered that FEP is eroded much more than that of hydrocarbon in AO+Ar exposure condition. Since the erosion of hydrocarbon is accelerated by the simultaneous Ar (or N2) collisions, the experimental result implies that effect of Ar (or N2) collision on FEP gave even more acceleration on erosion than that of hydrocarbons. The overall conclusion is that FEP erosion in LEO occurs not only by the atomic oxygen collision, but also N2 collision acts as being accelerative or independent.

Free Research Field

宇宙環境工学

Academic Significance and Societal Importance of the Research Achievements

これまで地球高層大気による材料劣化現象は原子状酸素によるものと信じられてきた。この仮定のもとで全ての材料試験が行われてきたが、フッ素系材料など一部の宇宙用材料では軌道上での劣化現象と地上実験との間に不整合が生ずることが知られている。本研究ではこの未解決の問題が窒素分子等の高エネルギー衝突を考えることにより説明できることを示し、この結果に基づく地上試験方法国際基準の改定の必要性を明らかにした。