Nanocrystalline Ni-Co alloy coatings: electrodeposition using horizontal electrodes and corrosion resistance
Nanocrystalline Ni-Co alloy coatings: electrodeposition using horizontal electrodes and corrosion resistance
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DOI：
10.1007/s11998-012-9437-3
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发表时间：
2013-03-01
影响因子：
2.3
通讯作者：
Akbari, Alireza
中科院分区：
文献类型：
--
作者：
Bakhit, Babak;Akbari, Alireza
在改进的瓦茨镀液中，用水平电极电沉积了含钴0~45wt%的纳米晶Ni-Co合金镀层。采用扫描电子显微镜、能谱仪、X射线衍射仪、微压痕法和动电位极化等技术对合金镀层进行了表征。研究了镀液中钴离子浓度(Co2+)对合金镀层性能的影响。观察到合金共沉积表现出反常行为。随着镀液中Co2+浓度的增加和电解液搅拌的增加，合金镀层中的Co含量增加。Co含量对合金涂层的形貌和晶粒度有很大影响。随着Co含量的增加，合金涂层的表面形貌由金字塔形转变为球形。合金涂层的显微硬度随着Co含量的增加而增加，这主要是由于晶粒尺寸的减小遵循Hall-Petch关系。此外，与纯Ni和其他Ni-Co合金相比，Ni-17wt%Co合金具有更好的耐蚀性。从Ni-17wt%Co涂层的相结构、晶粒度和择优取向等方面讨论了Ni-17wt%Co涂层具有较高的耐蚀性。
Nanocrystalline Ni-Co alloy coatings containing 0-45 wt% Co were electrodeposited using horizontal electrodes in a modified Watts bath. Different techniques including scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, microindentation, and potentiodynamic polarization were used to characterize the alloy coatings. Properties of the alloy coatings were investigated as a function of the cobalt ion concentration (Co2+) in the bath. It was observed that the alloy codeposition exhibits anomalous behavior. Co content in the alloy coatings increases with increasing Co2+ in the bath and with electrolyte agitation. Morphology and grain size of alloy coatings are greatly affected by Co content. By increasing Co content, surface morphology of the alloy coatings changes from pyramidal to spherical. Microhardness of the alloy coatings increases with increasing Co content mainly due to decreasing grain size that follows the Hall-Petch relation. In addition, Ni-17 wt% Co alloy exhibits better corrosion resistance compared to pure Ni and other Ni-Co alloy coatings. The higher corrosion resistance of Ni-17 wt% Co coating is discussed based on its phase structure, grain size, and preferred orientation.