| Project/Area Number |
13450296
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | Osaka Kyoiku University |
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Principal Investigator |
ISHIKAWA Tatsuo Osaka Kyoiku University, Faculty of Education, Professor, 教育学部, 教授 (30009055)
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| Co-Investigator(Kenkyū-buntansha) |
KANDORI Kazuhiko Osaka Kyoiku University, Faculty of Education, Associate Professor, 教育学部, 助教授 (70177765)
YASUKAWA Akemi Osaka Kyoiku University, Faculty of Education, Assistant, 教育学部, 助手 (70243285)
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| Project Period (FY) |
2001 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥15,200,000 (Direct Cost: ¥15,200,000)
Fiscal Year 2004: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2003: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2002: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2001: ¥11,800,000 (Direct Cost: ¥11,800,000)
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| Keywords | steel / corrosion / weathering steel / colloid Chemistry / alloy / rust / ferric oxyhydroxide / galvanized steel / 合金元素 / 大気腐食 / 吸着 / 比表面積 / 相転移 / マグネタイト / 鉄鋼 / α-FeOOH / β-FeOOH / γ-FeOOH / アニオン / クラスター / ナノ粒子 / 金属イオン添加 / 非晶質酸化物 / Fe_3O_4 / 非晶失酸化物 |
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| Research Abstract |
1)Synthesized rusts
The aim of this research project is to elucidate the mechanism s of corrosion and corrosion resistance of steels, such as weathering steels.. The structures and formation of the rusts artificially synthesized were irvestigated by various techniques. Including in a point of colloid chemistry. To clarify the role of alloying metals in corrosion resistance of weathering steels, the rusts are synthesized from aqueous Fe salt solutions containing various metal ions. The influences of metal ions strongly depend on the kinds of metal ions and rust components. Most of metals added to weathering steels interfered with the crystalization and particle growth of rusts. It was shown that alloying with more than two kinds of metals is shown to be effective. Especially, the addition of Ti(IV) effectively controlled the formation of β-FeOOH which is formed in Cl^- environment, indicating that the alloying with Ti effectively reduces the corrosion of steels in marine and coastal dist
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ricts. The influences of anions such as chloride, sulfate, and phosphate on the formation and structure of rusts were also studied to investigate the effects of corrosion environment. The formation of β-FeOOH was markedly influenced by the presence of the anions.
2)Rusts of weathering steels
The rusts formed in different situations were characterized by nitrogen adsorption. The rusts on weathering steels exposed in different environments for 17 years were examined by nitrogen adsorption. The specific surface area of the rusts determined by nitrogen adsorption decreased with decreasing the air-born salinity, which means that the rust particles grow with the increase of environmental Cl^- and the corrosion resistance of steels is lowered in marine and coastal districts. The corrosion rate of the steels was increased with decrease of specific surface area, that is, increase of particle size. This result reveals that the compactness of rust layers relating to corrosion resistance of steels is lowered by the particle growth of rusts. It was shown that the rust particles grow with the progress of corrosion. The similar results were obtained on t the rusts on various steels exposed to different situations. Consequently, the adsorption method is useful for characterization of rusts, expecially particle size of rusts which can not be estimated by the other techniques.
3)Rusts of galvanized steels
The steel galvanized by Zn-alloys is an important material in various industries. The corrosion resistance of the galvanized steels is still not thoroughly explored. The mechanism of high corrosion resistance of the galvanized steels was investigated by using the synthesized rusts of Zn-alloys. The rusts of Zn-Al alloys which are widely used for galvanizing steels were sheet particles of simonkoleite on adding a small amount of Al(III) in ZnCl_2 solution. The sheet particles form the compact rust layers by preferred orientation. This fact well accords to a high corrosion resistance of steels plated with Zn-Al alloy in Cl^- environment. It is known that the steels galvanized by Zn-Al-Mg alloys show a high corrosion resistance in the presence of Cl^-. The rusts of Zn-Al-Mg alloys prepared from solutions of Zn-Al-Mg salts were fine sheet particles and formed more compact layers than those of Zn-Al alloys as confirmed by measuring the permeability of air into the rust layers. Less
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