JAXA Repository / AIREX 未来へ続く、宙(そら)への英知
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Other TitleMechanical Properties Degradation and its Prediction Methods of Polyimide Films Exposed to Space Environment
Author(jpn)島村, 宏之; 中村, 孝
Author(eng)Shimamura, Hiroyuki; Nakamura, Takashi
Author Affiliation(jpn)宇宙航空研究開発機構研究開発本部電子部品・デバイス・材料グループ; 北海道大学大学院工学研究科機械宇宙工学専攻
Author Affiliation(eng)Electronic Devices and Materials Group, Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency (JAXA); Division of Mechanical and Space Engineering, Graduate School of Engineering, Hokkaido University
Issue Date2011-01-14
PublisherJapan Aerospace Exploration Agency (JAXA)
Publication titleJAXA reseach and development report
Publication date2011-01-14
AbstractThe mechanical properties of polyimide (PI) films, which were exposed to the space environment in the SM/SEED (Service Module/Space Environment Exposure Device) experiment, were evaluated with tensile tests. Additionally, PI films irradiated by atomic oxygen (AO), ultraviolet, and electron beam using ground facilities were similarly evaluated. Through comparison of these PI films' results, it was revealed that AO was the main space environmental factor degrading the mechanical properties of the PI films. Tensile strength and elongation of the PI films reduced concomitantly with increased AO fluence (F(sub AO)). The PI films expressed rough surfaces because of AO erosion and ruptured from the rough surfaces. In addition, their surface roughness increased as the F(sub AO) increased. These facts suggest that the degradation of mechanical properties is attributable to the increase in surface roughness. The mechanical properties of ITO (Indium Tin Oxide)-coated PI films (ITO/PI films) irradiated by AO were also evaluated. Generally, ITO/PI films have a high durability to AO erosion because ITO coating blocks AO. Therefore, ITO/PI film surfaces remain smooth even after AO irradiation. Tensile strength and elongation of the ITO/PI films, however, reduced with FAO increasing, marking higher degradation than the case of non-coated PI films. The AO-irradiated ITO/PI films have many undercut cavities at defect sites of their ITO coatings and ruptured from the undercut cavities. The undercut cavity developed as F(sub AO) increased, leading to significant degradation of the mechanical properties. The relationship between F(sub AO) and tensile strength in PI and ITO/PI films was predicted with fracture mechanics. The predicted results almost corresponded with the experimental results. The evaluation indicated that fracture mechanics is an effective approach for strength deterioration analysis of PI films exposed to the space environment.
SM/SEED(Service Module/Space Environment Exposure Device)実験により実宇宙環境に曝露したポリイミド(PI: Polyimide)フイルムの機械特性を引張試験により評価した。また、地上設備を用いて原子状酸素(AO: Atomic Oxygen)、紫外線、電子線を照射したPIフイルムについても同様の評価を行った。これら評価結果の比較から、PIフイルムの引張強さ・伸びに影響を与える宇宙環境因子はAOであり、AOフルエンス(F(sub AO))の増加に伴いPIフイルムの引張強さ・伸びは低下することが明らかとなった。この結果は、AOの浸食により形成された粗い面が破壊の起点となり、F(sub AO)の増加に伴いその表面粗さが大きくなるためだと考えられる。さらに、本研究では、AOに対する耐性の高いITO(Indium Tin Oxide)コーティング付PIフイルム(ITO/PIフイルム)に対しても同様の評価を実施した.ITOコーティングがAOをブロックすることにより、ITO/PIフイルム表面ではAOによる侵食が生じない。そのため、AO照射後においても、ITO/PIフイルムは平坦な面を維持している。しかし、ITO/PIフイルムの引張強さ・伸びはF(sub AO)の増加に伴い低下し、その低下の程度はコーティングのないPIフィルムと比較して大きかった。これは、ITOコーティングの欠陥部に形成されたUndercut cavityが破壊の起点として作用し、その深さがF(sub AO)の増加に伴い大きくなることが原因だと考えられる。破壊力学を用いて、PIフイルム及びITO/PIフイルムにおける引張強さの低下とF(sub AO)の関係を予測したところ、予測結果は実験値とほぼ一致した。すなわち、PIフイルムの宇宙環境曝露による強度劣化評価に対する破壊力学的手法の有効性が示された。
DescriptionOriginal contains color illustrations
形態: カラー図版あり
KeywordsSM/SEED、原子状酸素 ポリイミドフィルム、機械特性、破壊力学
Document TypeTechnical Report
JAXA Category研究開発報告
Report NoJAXA-RR-10-009

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