Evaluation of Steel Corrosion Products in Tropical Climates

• Published in: Corrosion (Houston, Tex.) Vol. 53; no. 11; pp. 835 - 841
• Main Authors: Rincón, A., de Rincón, O.T., Haces, C., Furet, N.R., Corvo, F.
• Format: Journal Article
• Language: English
• Published: Houston, TX NACE International 01.11.1997; NACE
• Subjects: Analytical methods; Applied sciences; Climate; Contamination; Corrosion; Corrosion environments; Corrosion products; Corrosion rate; Exact sciences and technology; Infrared spectroscopy; Marine environment; Metals. Metallurgy; Meteorological parameters; Mossbauer spectroscopy; Phase composition; Phase variations; Spectroscopy; Spectrum analysis; Steel; Tropical climate; X-ray diffraction; Venezuela; Cuba; Phase composition; Marine atmosphere; Corrosion rate; Carbon steel; Rural atmosphere; Tropical climate; Goethite; Corrosion product; Industrial atmosphere; Atmospheric corrosion
• ISSN: 0010-9312; 1938-159X
• DOI: 10.5006/1.3290268

INTRODUCTIONFactors influencing the acceleration of corrosion in a tropical climate include time of wetness, contamination, and temperature.1 The physical-chemical properties of rust and the phase composition of the oxide layer give information about its protective properties2 and allow recommendation of the most appropriate anticorrosive measures to reduce effects resulting from corrosion.3 The main phases of iron corrosion products reported in the literature are the oxyhydroxides of iron -FeOOH (goethite), -FeOOH (akaganeite), -FeOOH (lepidocrocite) and Fe3O4 (magnetite).4-5 The presence of akaganeite and magnetite in a marine climate was determined by Singh, et al.6 Raman and Kiban found only magnetite, and not the phase, in field tests in Louisiana and Texas climates.7 This result was corroborated in field tests along the northwestern coast of Cuba, where there is a strong influence of marine aerosol.8 Leidheiser and Music studied atmospheric corrosion products of steel and determined the formation of -Fe2O3 (maghemite),9-10 while Johnson, et al., found hydrated maghemites together with goethite in the initial stages of the corrosion process.11 Obviously, there are no uniform criteria regarding formation of the different phases that constitute rust, perhaps because the various analytical techniques used prevent appropriate comparison. The objective of the present paper was to determine phase composition of the corrosion products of steel exposed in the tropical climates of Venezuela and Cuba, using x-ray diffraction (XRD), infrared (IR) spectroscopy, and Mössbauer spectroscopy. Misawa, et al., found truly differentiated layers of corrosion products in low-alloy steel but intermixed amorphous and crystalline phases in carbon steels.12 Okada, et al., examined the cross section of rust