Hard nanocrystalline Ni-Co or Ni-W coatings are receiving a growing interest owing to their premium hardness, wear, and corrosion properties for several industrial applications. Furthermore, surface hydrophobicity greatly improves surface corrosion resistance. In this research, the durability of hydrophobic hierarchical NiW electrodeposited film has been evaluated in a high-speed slurry erosion–corrosion (EC) test rig. Two different coatings have been tested: a rough coating obtained in a chloride-based bath (NiW_chloride) and a smooth coating obtained in a sulfate-based bath (NiW_sulfate). Corrosion behavior over time was evaluated by electrochemical impedance spectroscopy (EIS), while surface hydrophobic performance was determined by the sessile drop method. The morphological features of the coatings were assessed by scanning electron microscopy while roughness modification during the EC tests were identified by means of an atomic force microscopy. During static immersion in the aggressive solution, the impedance modulus of the coatings continuously increased due to an increase in the thickness of corrosion products. During the EC test, the impedance modulus of the smooth NiW coating decreased, losing its barrier property. It was observed that the increase in impedance modulus of the hierarchical structure of the rough NiW coating during EC was far greater than that during static immersion. After 64 min of EC, the NiW_chloride was able to resume its hydrophobicity property by storing in air; nevertheless, the NiW_sulfate, with a loss of approximately 72% in its initial contact angle, was no longer hydrophobic. The results showed improvements in the lifetime of hydrophobic NiW coatings in erosion–corrosion conditions of the hierarchical nanostructure obtained in a chloride-based electroplating bath.

中文翻译：

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表面形貌对高疏水性镍钨电沉积薄膜侵蚀-腐蚀和耐蚀性的影响

硬纳米晶 Ni-Co 或 Ni-W 涂层因其在多种工业应用中的优异硬度、耐磨性和腐蚀性能而受到越来越多的关注。此外，表面疏水性大大提高了表面耐腐蚀性。在这项研究中，在高速浆料侵蚀腐蚀 (EC) 试验台上评估了疏水分层 NiW 电沉积膜的耐久性。已经测试了两种不同的涂层：在氯化物基浴中获得的粗糙涂层（NiW_氯化物）和在硫酸盐基浴中获得的光滑涂层（NiW_硫酸盐）。通过电化学阻抗谱 (EIS) 评估随时间的腐蚀行为，而通过固滴法确定表面疏水性能。通过扫描电子显微镜评估涂层的形态特征，同时通过原子力显微镜确定 EC 测试期间的粗糙度修改。在侵蚀性溶液中静态浸泡期间，由于腐蚀产物厚度的增加，涂层的阻抗模量不断增加。在 EC 测试期间，光滑 NiW 涂层的阻抗模量下降，失去其阻隔性。观察到在 EC 期间粗糙 NiW 涂层的分层结构的阻抗模量的增加远大于静态浸泡期间的增加。EC 64 分钟后，NiW_氯化物通过储存在空气中能够恢复其疏水性；尽管如此，NiW_硫酸盐的初始接触角损失约 72%，不再是疏水的。结果表明，在氯化物基电镀浴中获得的分级纳米结构的侵蚀-腐蚀条件下，疏水性 NiW 涂层的寿命有所改善。