北米走行車体の鉄錆の組成と生成機構

概要

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Quantitative analyses of crystalline compositions have been performed on the rusts which formed on the outer panel surface and in the crevice of the lapped portion on vehicles used in North America. X-ray diffraction using the internal standard technique was employed to analyze the rust composition quantitatively. Characteristic regions of the rust compositions were found in the α-FeOOH/(Fe_3O_4+γ-FeOOH)/(β-FeOOH+amorphous rust) ternary diagram that we proposed in the present study. The rust from the crevice in the lapped portion contained more (γ-FeOOH+Fe_3O_4) than that from the outer steel panels. The composition of rusts which formed in the accelerated corrosion tests indicated that the high content of (Fe_3O_4+γ-FeOOH) in the crevice rust of the lapped portion is caused by the high wetness. The rust on galvanized parts was mostly amorphous at the initial corrosion stage and then β-FeOOH in crystalline appeared characteristically. The composition of iron rust on galvanized parts moves towards the regions of steel parts at the following stage. A ternary diagram that we proposed in the present study is useful in correlating the results obtained in accelerated corrosion tests with those found on automobiles under service conditions.
社団法人日本鉄鋼協会の論文
1995-12-01