1987 Fiscal Year Final Research Report Summary
Influence of the Surface-Laver Structure in Outgassing and Photo-Irradiation Effect
| Project/Area Number |
61470060
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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 |
金属材料(含表面処理・腐食防食)
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| Research Institution | Institute of Industrial Science,University of Tokyo |
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Principal Investigator |
HOMMA Teiichi Professor, Institute of Industrial Science, University of Tokyo, 生産技術研究所, 教授 (20013112)
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| Co-Investigator(Kenkyū-buntansha) |
FUJITA Daisuke Research Assistant, Institute of Industrial Science, University of tokyo, 生産技術研究所, 助手 (00190041)
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| Project Period (FY) |
1986 – 1987
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| Keywords | Aluminum / Surface layer / Outgassing / Photo-Irradiation / Vacuum / 昇温脱離 |
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| Research Abstract |
1. SURFACE LAYER STRUCTURE
The surfacw layer structure of aluminum alloys which are main constructional materials of large accelerators and storage rings has been investigated. The following results have been obtained. (1) In case of electrochemical polishing, an initial oxide layer formed on a magnesium-containing aluminum alloy has an amorphous hydroxide, and it dehydrates during vacuum heating. Radial distribution function obtained from electron diffraction revealed the structure being <gamma>-Al_2O_3. (2) Short-circuit diffusion of magnesium through the oxid occured and MgO phase appeared at the top surface at a low temperature of 150゜C as the baking temperature.
2. INFLUENCE OF THE SURFACE LAYER STRUCTURE ON OUTGASSING
Thermal desorption spectrum was measured to investigate an influence of the surface layer structure on outgassing characteristic and a baking effect. The results obtained are as follows. (1) When the surface polished electrochemically was heated, rapid gas evolution occured due to thermal decomposition of the surface layer. (2) The oxidized surface of a 2.3% aluminum-magnesium alloy may adsorb gases(H_2O,H_2,CO_2) except for CO when exposed to air. (3) A correlation between the surface layer structure and outgassing characteristic has been observed.
characteristic has been observed.
3. OUTGASSING DURING PHOTO-IRRADIATION AND A ROLE OF THE SURFACE LAYER STRUCTURE
A photo-irradiation experiment was undertaken to investigate a mechanism of outgassing and to find an influence of the surface layer structure. The following results were obtained. (1) Outgassing rate depends on the surface which was prepared with different treatments,that is, anodic oxidation,electrochemical polishing, and thermal oxidation (500゜C,10 Torr pure oxygen,1h). Desorption yield normalized by photon number changes in order of the above order. (2) Effect of the surface layer structure and a chemical nature(a degree of hydrate) on outgassing character has been found experimenally.
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Research Products
(6 results)
