| Project/Area Number |
03650565
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
HARA Nobuyoshi Tohoku University, Engineering, Associate Professor, 工学部, 助教授 (40111257)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1992: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1991: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Chemical vapor deposition / MOCVD / Artificial passivation film / Corrosion resistance / Ellipsometry / Composite oxide film / エリプソメトリ- |
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| Research Abstract |
Single oxide films of Al_2O_3, TiO_2, Ta_2O_5, ZrO_2 and SiO_2, and composite oxide Films of Fe_2O_3-Cr_2O_3-NiO and Ta_2O_5-ZrO_2 have been formed on Pt substrates by metal organic chemical vapor deposition (MOCVD) technique. The corrosion resistance of these films were examined in 5M-HCl and 5M-NaOH by the measurement of film thickness using ellipsometry and the chemical analysis of test solutions using inductively-coupled plasma-emission spectroscopy.
It was found that the corrosion resistance of the single oxide films increased in the following order: Al_2O_3<TiO_2<SiO_2<ZrO_2<Ta_2O_5 in 5M-HCl, and Al_2O_3<SiO_2<TiO_2<Ta_2O_5<ZrO_2 in 5M-NaOH. Composite oxide films of Ta_2O_5-ZrO_2 having cationic mass fraction of Ta^<5+> ions between 0.3 and 0.5 showed the highest corrosion resistance against both the HCl and NaOH solutions. The dissolution rate of Fe_2O_3-Cr_2O_3 composite films in 5M-HCl decreased exponentially with an increase in the cationic mass fraction of Cr^<3+> ions, X_<cr>, of the films. The same type of changes in the dissolution rate with X_<cr> was also observed for the NiO-Cr_2O_3 composite films. On the other hand, the addition of NiO to Fe_2O_3-Cr_2O_3 composite films containing adequate amount of Cr_2O_3 did not bring an effective improvement in corrosion resistance. The corrosion resistance of SiO_2-coated SUS304 stainless steels increased with increasing thickness and formation temperature of the SiO_2 films.
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