Mössbauer studies of the corrosion products of iron formed in aqueous ammonium nitrate solution

Bhat, Pushpalatha C and Sathyavathiamma, MP and Puttaswamy, NG and Mallya, RM (1983) Mössbauer studies of the corrosion products of iron formed in aqueous ammonium nitrate solution. In: Corrosion Science, 23 (7). pp. 733-752.

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Abstract

The products of corrosion reaction of electrolytic iron in 45% ammonium nitrate solution formed under various conditions of time, temperature and pH have been analysed mainly by Mössbauer spectroscopy, in combination with X-ray diffraction, infrared absorption and electron microscopy techniques. γ-Fe00H is found to be the major product of hydrolytic precipitation at pH > 5.6 while only α-FeOOH is formed at pH < 3.0. In the pH range 3.0 < pH < 5.0, α-Fe00H and ferrihydrite are both formed. However, once the nuclei of α-Fe00H are formed under low pH conditions, their growth is favoured even in the otherwise unfavourable slightly acidic medium, resulting in a hydrous α-Fe00H which has two distinct hyperfine fields at the 57Fe nucleus. Magnetite is always formed in the vicinity of the metal and its rate of formation on the surface increases with temperature. α-Fe203 is the major product of hydrolytic precipitation at temperatures >80C. The possible mechanisms for the formation of each of the corrosion products are discussed.

Item Type:	Journal Article
Publication:	Corrosion Science
Publisher:	Elsevier Science
Additional Information:	Copyright of this article belongs to Elsevier Science.
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	16 Nov 2009 11:53
Last Modified:	19 Sep 2010 05:33
URI:	http://eprints.iisc.ac.in/id/eprint/20586

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