Comparison of Aqueous and Non-Aqueous Deposition of Cobalt Via Electroplating Method

Abstract

The purpose of this study is to compare the deposition of cobalt onto a copper substrate from aqueous and non-aqueous cobalt chloride solutions. The aqueous solution had a pH of 2 and had an equal concentration of cobalt as the non-aqueous. The non-aqueous solution consisted of a 2:1 molar ratio ethylene glycol to choline chloride solution. Deposition was performed for 10, 15 and 30 minute intervals with both solutions at 3 volts potential difference between the copper plate and reference. The suitable electroplating temperatures were found to be 70° C for the non-aqueous solution and 22° C for the the aqueous. The aqueous was initially run at 70° C to keep the temperature variable constant, but was found incapable of producing consistent films and was run at a lower temperature of 22° C. The coating deposited by the non-aqueous solution was black of color and had controllable thickness based on time. The aqueous coating was shiny silver, and was measured to be thinner than that of the non-aqueous films, but still had controllable thickness. The black cobalt thin films could have applications in optical systems to reduce parasitic light. Also the non-aqueous has applications in thermal active solar cells as they are conductive and absorb a wide range of the electromagnetic spectrum emitted by the sun, converting it to applicable thermal energy. The metallic looking cobalt thin films could be applied as mirrors in x-ray optics systems after polishing, as they may have different angles of diffraction. Referencies: 1Florea, A.; Anicai, L.; Costovici, S.; Golgovici, F.; Visan, T. 2010, Surf. Interface Anal, 42, 1271-1275 2Abdel-Fattah, T.M.; Crooks, R. SurfaceCharacterization of High Purity Niobium Electropolished with an Ionic Liquid. 2010, ECS Trans, 33, 571 3Abdel-Fattah, T.M.; Loftis, J.D. Surface Characterization of High Purity Metals of Silver and Nickel Electropolished with an Ionic Liquid. 2010, ECS Trans, 25, 57 4Ionic Liquid Electropolishing of Metal Alloys for Biomedical Applications. Abdel-Fattah, T.M.; Loftis, J.D.; Mahapatro, A. 2010, ECS Trans, 25, 57 5Abdel-Fattah, T.M.; Loftis, J.D. Comparison of the Electrochemical Polishing of Copper and Aluminum in Acid and Acid-free Media. 2009, ECS Trans. 25, 327 6Damiano, B.; Wixtrom, A.; Abdel-Fattah, T. Electrochemical Deposition of Cobalt onto the Surface of Copper Using a Choline Chloride-Based Ionic Liquid. 2012, ECS Trans. 50(11) 277-281