Investigation of Rust Formed on Steel Surfaces and Related Oxyhydroxides

摘要

In order to indentity the corrosion products formed on steel surfaces from ~(57)Fe Moessbauer spectroscopy, detailed Moessbauer parameters have been determined for various kinds of iron-oxyhydroxides: α -FeOOH, β-FeOOH, γ-FeOOH and δ'-FeOOH. ~(57)Fe Moessbauer measurements of the iron oxyhydroxides indicate the following results. Fe occupies a single site in α -FeOOH, but below the Neel temperature as at e.g., 300 K the Moessbauer spectrum is always broad, showing a distribution of the strength of the magnetic exchange interactions. Its shape depends on the grain-size and synthetic methods of the specimen. Fe occupies 3 sites in β-FeOOH. High-purity reagents of γ-FeOOH always contain small amounts of α-FeOOH and their Neel temperatures depend on the synthetic methods of the specimen. Moessbauer spectroscopy of the synthetic δ'-FeOOH shows very broad distribution of the hyperfine magnetic fields.