Abstract This work aimed to investigate the corrosion mechanisms of Ni Cr electroplated coatings in HBF4 aqueous solution, using electrochemical impedance spectroscopy (EIS) and electrochemical noise analysis (EN). Among coatings with various Cr content, the polarization resistance of Ni-19 wt% Cr electrodeposited at 0.3 A cm−2 was three times higher than that of pure Ni, and its localization index was 0.06 compared to 0.36 for pure Ni coating. These results, together with the cumulative probability plots of event frequency, according to Shot noise theory, indicated the effective presence of Cr in diminishing both uniform and localized corrosion. Also, using stochastic theory, it was revealed that by introducing Cr up to 19 wt% into the coatings, the initiation rate of the pitting nuclei could be reduced to one-sixth value compared to that of pure Ni coating. Subsequently, the propagation probabilities of the metastable pits were considerably decreased.

中文翻译：

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电镀镍铬镀层在HBF4水溶液中腐蚀的电化学噪声和阻抗研究

摘要 本工作旨在利用电化学阻抗谱（EIS）和电化学噪声分析（EN）研究镍铬电镀涂层在HBF4水溶液中的腐蚀机理。在不同铬含量的镀层中，在 0.3 A cm-2 下电沉积的 Ni-19 wt% Cr 的极化电阻是纯 Ni 的三倍，其定位指数为 0.06，而纯 Ni 镀层为 0.36。根据散粒噪声理论，这些结果与事件频率的累积概率图一起表明 Cr 的存在有效地减少了均匀腐蚀和局部腐蚀。此外，使用随机理论表明，通过在涂层中引入高达 19 wt% 的 Cr，与纯镍涂层相比，点蚀核的引发率可以降低到六分之一。随后，亚稳态坑的传播概率大大降低。