The present work deals with the galvanostatic fabrication of Ni–Fe nanostructured composition-modulated multilayer alloy (CMMA) coatings on steel panel from the newly optimized acid-sulphate bath solution. The recurring cathode current density combination (RCCC) and the number of layers have been optimized for enhanced performance of the coatings against corrosion. Corrosion behaviour of the nanostructured multilayered coatings was evaluated by Tafel extrapolation and electrochemical impedance spectroscopy (EIS) methods in 3.5% NaCl solution. Under optimal conditions, the CMMA coatings developed were more corrosion-resistant than the monolithic alloy coatings obtained from the same bath. Least corrosion rate (CR) was witnessed at 300 layers, above which saturation of corrosion resistance at a high temperature was found, which is attributed to a shorter relaxation time for redistribution of metal ions during multilayer deposition. Hardness and roughness of the coatings were evaluated using Vickers hardness test and atomic force microscope, respectively. Phase structure of the coatings was discussed using X-ray diffraction technique. The cross-sectional view of the coatings was characterized by scanning electron microscope. CR analysis and the surface morphology of the optimized coatings exposed to high temperature revealed the better performance of CMMA coatings at the elevated temperatures compared to the monolithic coatings.

中文翻译：

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纳米晶多层 Ni-Fe 合金涂层的开发：表征及其在高温下的腐蚀行为

目前的工作涉及从新优化的硫酸盐浴溶液在钢板上恒电流制造 Ni-Fe 纳米结构成分调制多层合金 (CMMA) 涂层。循环阴极电流密度组合 (RCCC) 和层数已经过优化，以提高涂层的抗腐蚀性能。通过塔菲尔外推法和电化学阻抗谱 (EIS) 方法在 3.5% NaCl 溶液中评估纳米结构多层涂层的腐蚀行为。在最佳条件下，开发的 CMMA 涂层比从同一浴中获得的整体合金涂层更耐腐蚀。在 300 层处看到的腐蚀速率 (CR) 最小，高于该层数时发现高温下的耐腐蚀性饱和，这归因于在多层沉积过程中金属离子重新分布的弛豫时间较短。涂层的硬度和粗糙度分别使用维氏硬度测试和原子力显微镜进行评估。使用X射线衍射技术讨论涂层的相结构。通过扫描电子显微镜表征涂层的横截面图。暴露于高温下的优化涂层的 CR 分析和表面形貌表明，与整体涂层相比，CMMA 涂层在高温下具有更好的性能。使用X射线衍射技术讨论涂层的相结构。通过扫描电子显微镜表征涂层的横截面图。暴露于高温下的优化涂层的 CR 分析和表面形貌表明，与整体涂层相比，CMMA 涂层在高温下具有更好的性能。使用X射线衍射技术讨论涂层的相结构。通过扫描电子显微镜表征涂层的横截面图。暴露于高温下的优化涂层的 CR 分析和表面形貌表明，与整体涂层相比，CMMA 涂层在高温下具有更好的性能。