Black Trivalent Chromium Electrodeposit

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The objective of this work is the development of advanced black chromium coatings by electroplating fromtrivalent chromium solutions. This project will be focused on active collaboration of Kuntz Electroplating Inc.(KEI) and McMaster University. KEI is working on the development of new technology for electroplating ofblack Cr protective coatings for applications in automotive industry. KEI is interested in the solving of aproblem of replacement of a Cr plating process from the hexavalent Cr solutions for a new plating processfrom the trivalent Cr solutions. The company has a problem of low electrodeposition yield of Cr coatings fromCr3+ solutions and significant cathodic gas evolution, which result in low adhesion, poor mechanicalproperties, low thermal shock resistance and poor corrosion resistance. KEI was not able to achieve black colorof the coatings, which varied from gray to brown. The use of efficient complexing agents is of criticalimportance for electroplating from Cr3+ solutions. KEI is interested in new complexing agents and surfacemodification techniques, which are currently under development in the electrochemical laboratory of McMasterUniversity. The unique features of new complexing agents are: good chelation of Cr3+ and other metal ions,which are used as plating additives, strong adsorption on Cr and Cr oxide additives, ability to facilitate ionreduction in solutions and improve charge transfer. Moreover, new chelating agents can impart black color tothe coatings and hydrophobic properties. It is expected that the application of new chelating agents will resultin the development of black Cr coatings with enhanced corrosion protection and mechanical properties,improved adhesion and thermal shock resistance. The development of black Cr coatings from Cr3+ solutionsmeets interests of Canadian automotive industry and offers many environmental benefits. The benefits of thisproject will include the generation of new technological solutions, technology transfer to KEI and HQPtraining. The resolution of the problem will result in job growth at KEI and increased revenue.