1990 Fiscal Year Final Research Report Summary
Studies on the Improvement of High-Temperature Corrosion Resistance of Ni_3Al Base Alloys
| Project/Area Number |
01550552
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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 | Osaka University |
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Principal Investigator |
TANIGUCHI Shigeji Osaka Univ., Faculty of Engineering Associate Professor, 工学部, 助教授 (50029196)
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| Co-Investigator(Kenkyū-buntansha) |
SHIBATA Toshio Osaka Univ., Faculty of Engineering Professor, 工学部, 教授 (90001205)
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| Project Period (FY) |
1989 – 1990
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| Keywords | Ni_3Al / High Temperature / Oxidation Resistance / Surface Treatment / Laser Glazing / Vacuum Annealing / Ion Beam |
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| Research Abstract |
Ni_3Al, Ni_3Al-0.1B, and Ni_3Al-1b-0.42Hf specimens were prepared and then subjected to the following surface treatments.
(1) laser glazing using a CO_2 laser,
(2) annealing under a very low oxygen pressure or in hydrogen, and
(3) surface treatments using ion beam techniques
After each treatment the specimens were oxidized in a flow of purified oxygen under atmospheric pressure in a temperature range 1100 to 1400 K. Metallographic examinations were carried out for the specimens before and after the treatment and also after the oxidation under specified conditions.
The laser surface treatments at the powers of 490 to 2000 W showed that the increase in the laser power resulted in the formation of more protective alumina scales leading to enhanced oxidation resistance. This was considered to be due to the grain refining effect brought about by the treatment which would have enhanced the diffusion of Al.
The annealing in a vacuum resulted in the formation of thin Al_2O_3 scales, which were very protective to suppress the subsequent oxidation. The annealing in hydrogen atmosphere showed very similar results as those for the annealing in the vacuum.
Implantation of Mg or Ta ions to the specimen surfaces resulted in the formation of very protective Al_2O_3 scales during the initial periods of oxidation without consuming Ni of the base alloy. The ion mixing treatment of the alloy formed a surface layer containing Si. This treatment also enhanced the growth of very protective of Al_2O_3 scales. A Cr_2N film of 0.5 micron meter thickness and a Si_3N_4 film of (1 micron meter) formed by ion beam enhanced deposition decreased the oxidation rate significantly.
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Research Products
(4 results)
