Nickel Electroplating in Post Supercritical CO2 Mixed Watts Bath under Different Agitations
The process of post-supercritical CO2 electroplating uses the electrolyte solution after being mixed with supercritical CO2 and released to atmospheric pressure. It utilizes the microbubbles that form when oversaturated CO2 in the electrolyte returns to gaseous state, which gives the similar effect of pulsed electroplating. Under atmospheric pressure, the CO2 bubbles gradually diffuse. Therefore, the introduction of ultrasound and/or other agitation can potentially excite the CO2 microbubbles to achieve an electroplated surface of even higher quality. In this study, during the electroplating process, three different modes of agitation: magnetic stirrer agitation, ultrasonic agitation and a combined mode (magnetic + ultrasonic) were applied, respectively, in order to obtain an optimal surface morphology and mechanical properties for the electroplated Ni coating. It is found that the combined agitation mode at a current density of 40 A/dm2 achieved the smallest grain size, lower surface roughness, and produced an electroplated Ni layer that achieved hardness of 320 HV, much higher when compared with conventional method, which were usually in the range of 160 to 300 HV. However, at the same time, the electroplating with combined agitation developed a higher internal stress of 320 MPa due to the lower current efficiency of the process and finer grain in the coating. Moreover, a new control methodology for tailoring the coating’s mechanical property through its thickness was demonstrated by the timely introduction of ultrasonic agitation during the electroplating process with post supercritical CO2 mixed electrolyte.
Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1131323Procedia APA BibTeX Chicago EndNote Harvard JSON MLA RIS XML ISO 690 PDF Downloads 613
 S. A. Perusich, and R. C. Alkire, “Ultrasonically Induced Cavitation Studies of Electrochemical Passivity and Transport Mechanisms,” Electrochemical Society, vol. 138, no. 3, 1991, pp. 700-707.
 M. E. Hyde, and R. G. Compton, “How Ultrasound Influences the Electrodeposition of Metals,” Electroanalytical Chemistry, vol. 531, no. 6, 2002, pp. 19-24.
 C. T. Walker, and R. Walker, “Effect of Ultrasonic Agitation on Some Properties of Electrodeposits,” Electrodeposition and Surface Treatment, vol. 1, no. 6, 1973, pp. 457-469.
 D. W. Dini, and H. R. Johnson, “The Influence of Nickel Sulfamate Operating Parameters on the Impurity Content and Properties of Electrodeposits,” Thin Solid Films, 1978, vol. 54, no. 2, pp. 183-188.
 R. Vasudevan, R. Devanathan, K. G. Chidambaram, “Effect of Ultrasonic Agitation During Electroplating of Nickel and Copper at Room Temperature,” Metal Finishing, vol. 90, 1992, pp. 23-26.
 P. B. S. N. V. Prasad, R. Vasudevan, S. K. Seshadri, “The Effect of Ultrasonic Vibration on Nickel Electrodeposition,” Materials Letters, vol. 17, 1993, pp. 357-359.
 K. Kobayashi, A. Chiba, N. Minami, “Effect of Ultrasound on Both Electrolyte and Electroless Nickel Depositions,” Ultrasonics, vol. 38, 2000, pp. 676-681.
 H. Yoshida, M. Sone, A. Mizushima, K. Abe, X. T. Tao, S. Ichihara, S. Miyata, “Electroplating of Nanostructured Nickel in Emulsion of Supercritical Carbon Dioxide in Electrolyte Solution,” Chemistry Letters, vol. 11, 2002, pp. 1086.
 H. Yoshida, M. Sone, A. Mizushima, H. Yan, H. Wakabayashi, K. Abe, X. T. Tao, S. Ichihara, S. Miyata, “Application of Emulsion of Dense Carbon Dioxide in Electroplating Solution with Nonionic Surfactants for Nickel Electroplating,” Surface and Coatings Technology, vol. 173, 2003, pp. 285-292.
 T. F. M. Chang, M. Sone, A. Shibata, C. Ishiyama, Y. Higo, “Bright Nickel Film Deposited by Supercritical Carbon Dioxide Emulsion Using Additive-free Watts Bath,” Electrochimica Acta, vol.55, 2010, pp. 6469-6475.
 H. Yan, M. Sone, A. Mizushima, T. Nagai, K. Abe, S. Ichihara, S. Miyata, “Electroplating in CO2-in-Water and Water-in-CO2 Emulsions Using a Nickel Electroplating Solution with Anionic Fluorinated Surfactant,” Surface & Coatings Technology, vol. 187, 2004, pp.86-92.
 M. S. Kim, J. Y. Kim, C. K. Kim, N. K. Kim, “Study on the Effect of Temperature and Pressure on Nickel-electroplating Characteristics in Supercritical CO2,” Chemosphere, vol. 58, 2005, pp. 459-465.
 T. F. M. Chang, M. Sone, “Function and Mechanism of Supercritical Carbon Dioxide Emulsified Electrolyte in Nickel Electroplating Reaction,” Surface & Coatings Technology, vol. 205, 2011, pp. 3890-3899.
 S. T. Chung, H. C. Huang, S. J. Pan, W. T. Tsai, P. Y. Lee, C. H. Yang, , and M. B. Wu, "Material characterization and corrosion performance of nickel electroplated in supercritical CO2 fluid," Corrosion Science, Vol. 50, No. 9, 2008, pp. 2614-2619.
 C. V. Nguyen, C. Y. Lee, F. J. Chen, C. S. Lin, T. Y. Liu, “Study on the Internal Stress of Nickel Coating Electrodeposited in an Electrolyte Mixed with Supercritical Carbon Dioxide,” Surface & Coating Technology, vol. 206, 2012, pp. 3201-3207.
 C. V. Nguyen, C. Y. Lee, L. Chang, F. J. Chen, C. S. Lin, “The Relationship Between Nano Crystallite Structure and Internal Stress in Ni Electrodeposited Films Pated by the Supercritical CO2 Method,” Journal of The Electrochemical Society, vol. 159, 2012, pp. 393-399.
 C. V. Nguyen, C. Y. Lee, F. J. Chen, C. S. Lin, L. Chang, 2013, “An Electroplating Technique using the Post Supercritical Carbon Dioxide Mixed Electrolyte,” Surface & Coatings Technology, 232, pp.234-239.
 R. Weil, “The Origins of Stress in Electrodeposits, Review of the Literature Dealing with Stress in Electrodeposited Metal”, Plating, vol. 58, 1971, pp. 137-146.