Corrosion Failure Mechanisms of Low‐Hydrogen‐Embrittlement Zn‐Ni Coatings for Engineering Applications: Localized Pitting and Galvanic Effect With Aluminum Alloy
Ying He, Yunhu Ding, Yuxin Li, Yipin Wang, Chaozhi Huang, Zhen Wan, Wenli Xu, Guangyao He, Kangle Ren, Tiansui Zhang, Hongfang LiuABSTRACT
This study systematically investigates the localized and galvanic corrosion failure mechanisms of low‐hydrogen‐embrittlement Zn‐Ni alloy coatings, a promising eco‐friendly alternative to toxic Cd plating for protecting high‐strength steel. The Zn‐Ni coating prepared at 2 A/dm 2 exhibited the best corrosion resistance, with a dense morphology and a higher charge transfer resistance, and its corrosion rate was 65% lower than that at 5 A/dm 2 . Hilbert‐Huang Transform analysis of electrochemical noise revealed that the 5 A/dm 2 Zn‐Ni coating was more susceptible to localized corrosion than the 2 A/dm 2 coating. However, the coating deposited at 5 A/dm 2 possesses a moderately porous structure that facilitates hydrogen release from the substrate. Furthermore, a galvanic potential reversal with 6062 aluminum alloy was identified, with the 2 A/dm 2 Zn‐Ni coating showing the weakest galvanic effect. This work provides crucial insights for the design and application of Zn‐Ni coatings in engineering structures.