Abstract

SUAREZ, O.J.; OLAYA, J.J.  and  RODIL, S.. The effect of operating conditions during plating on the electrochemical behavior and morphology of trivalent solution-derived chromium coatings. Rev. Mex. Ing. Quím [online]. 2013, vol.12, n.1, pp.129-141. ISSN 1665-2738.

Trivalent electrolyte-based chromium plating represents an alternative for the major problems associated with traditional hexavalent plating. Response surface methodology was chosen in this work for designing experiments. Chromium coatings were obtained from trivalent solutions in a chloride-based bath using different operating conditions. Three concentrations (0.19, 0.38 and 0.57 mol L^-1 as Cr(III) ), three pH (2.0, 3.0 and 4.0) and temperature (25°C, 32°C, 40 ^oC) was varied during the experiments. Scanning electron microscopy and energy dispersive X-ray analysis were used for examining the coatings surface morphology and composition; the coulometric method was used for thickness measurement and potentiodynamic and impedance tests on 3% NaCl were made on a three-eletrode cell for studying chromium film electrochemical behavior. Large differences in morphology, thickness and corrosion resistance were observed, mainly due to variations in chromium concentration and pH solution. Crack; patterns were observed on films obtained at high pH values independently of process temperature.

Keywords : trivalent chromium; plating; microstructure; corrosion; electrochemical impedance.

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