Ĭhromium metal cannot be directly obtained from a solution of Cr+ 3 sulfates or chlorides since they form stable and inert complexes with OH -, SO 4 -2 and Cl - ions and oxides during deposition which interfer with the cathodic reaction. Such processes have not been fully implemented in an industrial environment because of their higher maintenance costs and incomplete technological knowledge. Alternatively trivalent chromium chemistry-based processes have been developed to reduce the problems associated with hexavalent chromium. Keywords: Trivalent chromium, plating, microstructure, corrosion resistance.Ĭhromium deposits obtained by electrolysis are of great importance in the field of decorative and industrial coatings however, conventional hexavalent chromium solutions raised serious drawbacks from an environmental and occupational health point of view. Bright chromium films were obtained from all baths however, differences were observed concerning morphology, thickness and corrosion resistance depending on the composition of the forming solution. Electrochemical impedance spectroscopy (EIS) was done using 3% NaCl as electrolyte and using a three-electrode cell with a standard calomel electrode (SCE) as reference. The coulometric method was used for measuring coating thickness. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) were performed to examine the coatings surface morphology and composition respectively. UV-vis spectroscopy was carried out on all solutions before and after plating to observe changes in the chromium complexes chemical state due to the plating process. The chromium coatings were obtained from trivalent solutions in a chloride-based bath with different complexing agents adding also sodium hypophosphite and aluminum chloride. In this work, the resistance to corrosion of chromium films obtained from trivalent chromium solutions of different compositions and the influence of solution compounds on the coatings electrochemical behavior and the microstructure were studied. Bogotá-Colombia.* e-mail: Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, México D.F.-Mexico. Ciudad universitaria edificio de posgrado de materiales. RODIL 2ġ Universidad Nacional de Colombia, Bogotá, Colombia. O.J SUAREZ* 1, J.J OLAYA 1, M.F SUAREZ 1, S.E. Soc, 57, N o 1 (2012) págs.: 977-982ĬORROSION RESISTANCE OF DECORATIVE CHROMIUM FILMS OBTAINED FROM TRIVALENT CHROMIUM SOLUTIONS
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