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Vol.57, No.10, 641 ~ 648, 2019
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| Title |
| Optimization of Electrochemical Variables of Pulse-Reverse Electroplating in Trivalent Chromium Bath to Enhance the Corrosion Resistance of Chromium Film |
| 임채원 Chaewon Lim , 임동욱 Dongwook Lim , 구본일 Bonil Ku , 심상은 Sang Eun Shim , 백성현 Sung-hyeon Baeck |
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| Abstract |
| Electroplating chromium films in a trivalent chromium bath has been extensively investigated as a replacement for the conventional hexavalent chromium bath. However, commercialization of the trivalent chromium method has been hindered because the resulting chromium films exhibit inferior mechanical properties compared to hexavalent chromium coated film. In this study, we enhanced the properties of trivalent chromium electroplated film using a pulse-reverse (PR) method. Firstly, the cathodic current density needed to produce a shiny surface was optimized using direct current (DC) electroplating. After optimizing the cathodic current density, the appropriate anodic current density for PR electroplating needed to achieve optimum crack density and corrosion resistance was investigated. The chromium coating prepared using PR electroplating exhibited higher corrosion resistance than that prepared by DC electroplating, because it suppressed crack formation. Concerning the electrochemical corrosion behavior in 3.5 wt% NaCl solution, the optimized sample (PR2) electroplated at an anodic current density of 0.04 A cm-2 showed a corrosion potential shift of 129.9 mV to the anodic direction, and an increase in electrochemical corrosion resistance which was bigger than the chromium film prepared using DC electroplating. This optimization of electrochemical variables opens a new way to obtain improved electrodeposited film with low crack density and high corrosion resistance.
(Received May 14, 2019; Accepted August 21, 2019) |
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| Key Words |
| trivalent chromium, crack, pulse-reverse electroplating, anodic current, corrosion resistance |
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