1995 Fiscal Year Final Research Report Summary
Effect of impurity elements in recycled aluminum on corrosion behavior
| Project/Area Number |
06650790
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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 |
Material processing/treatments
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| Research Institution | Muroran Institute of Technology |
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Principal Investigator |
TAGASHIRA Kousuke Muroran Institute of Technology Professor, 工学部, 教授 (10091539)
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| Co-Investigator(Kenkyū-buntansha) |
SERI Osami Muroran Institute of Technology Associate Professor, 工学部, 助教授 (60179356)
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| Project Period (FY) |
1994 – 1995
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| Keywords | aluminum / aluminum alloys / pitting attck / impurity element / surface treatment |
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| Research Abstract |
Investigations have been made the relation between concentration of dissolved oxygen in a beverage solution in Japanese market and pitting attack of aluminum alloy 5182. The value of anodic polarized resistance of 5182 was measured by the area polarization technique in a drink solution environment of which dissolved oxygen concentration was continuously changed from 10ppb to 600ppb. It is electrochemically and metallingically found that the value of more than 40ppb dissolved oxygen in the solution leads to that the occurrence of pitting attack of 5182 aluminum alloy. This expectation value of 40ppb coincides with the realistic rupture condition of beverage solution in a market. Dissolution behavior in a 5% NaOH solution for Al-Fe-Si alloys with various different Fe/Si ratio have been investigated. Weight loss of the alloys decrease with decreasing Fe/Si ratio in the alloys. Dissolution process at the NaOH etching treatment is controlled by the cathodic reaction of water reduction. It i
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s electrochemically found that the intermetallic compounds with lower Fe/Si ratio in the alloys cathodically plays poor role in the etching process. Electrochemical measurements and metallurgical observations have been made to clarify the effect of NaCl concentration on the corrosion behavior of the intermetallic compounds such as FeA13 in aluminum. The autocatalytic nature that are preferential dissolution of iron in the intermetallic compounds and subsequently deposition of ferrous iron to metallic iron occurs in the dilute NaCl solution environment (<1.0M NaCl). The intermetallic compounds in the concentrated NaCl solution environment (>3.0M NaCl), however, always provide the cathodic sites at which the well-known oxygen reduction reaction takes places. It is explained that dissolution possibility of the intermetallic compounds is depend on the variation of the corrosion potentials ; the pitting potentials are equal to the corrosion potentials related to the concentrations of NaCl solutions. Less
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Research Products
(6 results)
