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Abstract  

Mössbauer study of the rust formed on SS-304 exposed to sea water for about 30 d indicates that ferrihydrite and -FeOOH are formed as corrosion products, the cause of corrosion being the presence of chloride ions in sea water. Ferrihydrite is found to exhibit two doublets at 300 K while at 80 K it exhibits a doublet and a sextet. This is contrary to earlier studies in which it was reported that at 80 K ferrihydrite is fully magnetically ordered and exhibits a sextet only.

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Abstract  

The corrosion of mild steel as a result of 3 years of immersion in deionized water, using Mössbauer results, indicates that -FeOOH, -FeOOH and Fe3O4 are formed as corrosion products. This study shows that purified water will produce -FeOOH only when the exposure time is long. It is proposed that ferrihydrite, which is formed as an intermediate corrosion product, is converted to -FeOOH, which in turn is converted to -FeOOH and Fe3O4.

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Abstract  

The Mössbauer technique has been used to study the oxidation of alloy 1.4306S (SS-304L) at 1200°C exposed in atmospheres of air and steam, for, 1, 6, 24, 100 and 400 hours. By oxidation in air the major products are -FE2O3, -FE2O3, and Fe3O4 while, during oxidation in steam they are -FeOOH, -Fe2O3 and Fe3O4. A minor phase detected following both kinds of oxidation may be ascribed to MnCrFeO4, Cr2FeO4, -FeOOH and -FeOOH produced in steam only while the base material is found following air oxidation. The proportion of Fe3O4 on the scale remains constant for all exposure durations in air oxidation, while it becomes constant in steam oxidation only in cases where the entire sample has been oxidized.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Siddique, M. Anwar-ul-Islam, N. Butt, N. Hussain, S. Rehman, and M. Arshed

Abstract  

Room temperature corrosion studies have been made on the rust of commercially available mild steel in a simulated acid rain environment using the method of transmission Mössbauer spectroscopy. The main corrosion products identified are α-FeOOH, γ-FeOOH, and a product with unfamiliar parameters which seems to be amorphous in nature (being very large linewidth −2.5 mm/s) and may be considered as an intermediate phase. A small amount of γ-Fe2O3 (6–8%) is also observed.

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Abstract  

Mössbauer measurements have been carried out on Ni-substituted Mn-ferrites, Mn1-xNixFe2O4 (x = 0, 0.25, 0.50, 0.75 and 1.0), at room temperature. The cation distribution at tetrahedral (A) and octahedral (B) sites and its effect on Mössbauer parameters is studied. Mn2+ ions are found to occupy sites A and B both, while Ni2+ ions occupy site B only. It has been observed that the internal magnetic fields (H eff) for all B sites increase and it remains almost constant for site A with increasing Ni concentration. The line widths of the most of B sites are decreased and no significant change is observed in isomer shift with increasing Ni concentration.

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