Electrodeposition of High-bright and Hard Cr-C Layers with High-current Efficiency from Chromium(III) Sulfate/Organic Additives Aqueous Baths

This study was conducted to improve four characteristics as objectives:（1） high current efficiency, （2） surface brightness, and （3） hardness of chromium-carbon （Cr-C） alloy layers during electrochemical deposition from Cr（III） ions, （4） reproducibility the Cr-C layer formation repeated plating with a electroplating bath. A malonic-acid-containing sulfuric acid bath （sulfuric II） prepared by adding an arrangement conventional I）. The II achieves objectives. Optimizing composition conditions containing malonic accomplished 0.2 M added concentration, 1.5 pH bath, 33.4 dm－2 density. efficiency under these optimized 55.9%. Also, C co-deposition percentage 39.7%. Using acid, testing for performed repeatedly when plating: both continued be greater than 55% 39%, respectively. However, uniformity tended decrease after fifth plating. Comparison brightness that achieved using baths demonstrated able maintain brightness.