Hexavalent chromium-free pre-treatment for galvanized steel Conference Paper

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Overview

abstract

• The corrosion protection provided by an organic inhibitor containing an alkanolamine salt of a polycarboxilic acid that is suggested as non-toxic alternative to chromate and phosphate conversion coatings on galvanized steel was studied. Open circuit corrosion potential evolution, linear polarization, potentiodynamic polarization, electrochemical impedance spectroscopy, x-ray diffraction, salt spray (fog) tests and immersion - weight loss tests were used to evaluate the provided protection in a 0.5 M aerated NaCl solution. All tests gave concordant results, indicating that the chromate-free inhibitor does protect galvanized steel in this environment, even though the provided protection was less than that of the chromate conversion coating. It was observed that after a moderate initial attack, and except for the phosphated samples, the corrosion rate diminishes due to the appearance and growth of passivating corrosion products layers, mainly constituted by zinc hydroxychloride (Zn5(OH)8Cl2•H 2O) and two varieties of zinc hydroxide. copyright The Electrochemical Society.

authors

• Domínguez Espinos Octavio
• Hernandez L.A.
• Hernández Hernández Luis Salvador
• Miranda Vidales Juana María

publication date

• 2008-01-01

published in

• ECS Transactions  Proceedings

Research

keywords

• Alkanolamine; Chromate conversion coatings; Corrosion products; Electrochemical impedances; Electrochemical societies; Galvanized steels; Hexavalent chromiums; Linear polarizations; Nacl solutions; Open circuit corrosions; Organic inhibitors; Phosphate conversion coatings; Salt sprays; Weight loss tests; X-ray diffractions; Zinc hydroxides; Zinc hydroxychloride; Blood vessel prostheses; Chromate coatings; Chromates; Chromium; Corrosion; Corrosion inhibitors; Corrosion protection; Electrochemical corrosion; Electrochemical impedance spectroscopy; Fiber optics; Galvanizing; Growth (materials); Organic coatings; Phosphate coatings; Polarization; Sodium chloride; Steel; Steel corrosion; Zinc; Galvanized metal

Identity

Digital Object Identifier (DOI)

• 10.1149/1.2838452

Additional Document Info

start page

• 37

end page

• 47

volume

• 3

issue

• 43