1991 Fiscal Year Final Research Report Summary
Study on Space Tribology Using the Pulsed Oxygen-Atom Source
| Project/Area Number |
02452112
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
機械要素
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| Research Institution | Osaka University |
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Principal Investigator |
OHAME Nobuo Osaka Univ., Dept. of Precision Eng., Associate Professor, 工学部, 助教授 (60029345)
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| Co-Investigator(Kenkyū-buntansha) |
TAGAWA Masahito Osaka Univ., Dept. of Precision Eng., Research Associate, 工学部, 助手 (10216806)
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| Project Period (FY) |
1990 – 1991
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| Keywords | Tribology / Low Earth Orbit / Atomic Oxygen / Solid Lubricants / Surface Degradation |
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| Research Abstract |
Ground-based facilities for generating atomic oxygen (AOX) are essential to investigate tribology in low earth orbit (LEO), where the space station is to be launched. We have developed a new AOX generator utilizing the decomposition of pulsed oxygen molecule gases into AOX with use of Xe arc flash light. The AOX generator was operated at a vacuum of 10^<-6>Pa, which is the vacuum level in LEO. The kinetic energy and flux of AOX beam were set at 5 eV and 10^<16> atoms/m^2s both of which are the typical values in LEO (<similar or equal>500 km). Thus the present AOX generator is able to simulate the LEO environment. Gas breakdown by the Xe arc flash light also was maintained with an auxiliary use of mini-YAG laser.
Molybdenumdisulfide, which has been considered as one of the best materials for space tribology, are attacked by AOX. The desorption of sulfur in the form of SO and SO_2 occurred at first, and the formation of molybdenum oxide, primary MoO_3, followed. HOPG graphite also was severely damaged ; C-O and C=O bonds and subsequent carboxyl formation being recognized. Natural graphite showed the disappearance of characteristic shoulder in the carbon-KLL Auger peak, which implies the deterioration of graphite lamellar structure. Friction coefficient as high as 0.2 was found for molybdenumdisulfide exposed to AOX beam. Therefore, the use of molybdenumdisulfide in LEO is not promising. The development of oxide-based solid lubricants is to be needed.
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Research Products
(28 results)
