Effect of incorporation of graphene oxide (GO) on the evolution of morphology, phase constitution, microstructure and corrosion properties of SnCo-GO composite coating was investigated. SnCo-GO composite coatings containing different amounts of graphene oxide were electrodeposited over mild steel substrate using electrolyte with different concentrations of dispersed graphene oxide (0.0625, 0.125, 0.1875, 0.25, 0.3125, 0.5, 0.625 g/L). Morphological examination revealed that lesser additions of GO increased the coating compactness and uniformity whereas higher amounts of GO produced surface defects in the composite coatings. Structural characterization revealed the presence of primarily two different intermetallic phases in the coating microstructure: Co₂Sn phase and Co₃Sn₂ phase. It was observed that the phase fraction of the relatively more inert Co₃Sn₂ phase increased monotonically with increase in the amount of GO in the coatings. Microstructural investigations revealed that in the pristine SnCo coating the Co₂Sn phase is present at the grain boundaries of the Co₃Sn₂ phase grains. Incorporation of GO altered the coating microstructure considerably leading to the formation of a layered microstructure where the elongated Co₂Sn phase grains were present beneath laterally elongated grains of the Co₃Sn₂ phase. Electrochemical analysis performed using the Tafel polarization and impedance spectroscopy measurements showed that the corrosion properties of the coating were highly sensitive to the amount of GO present in the coating. Initial addition of GO increased the corrosion resistance till an optimum GO concentration for which highest corrosion resistance was achieved. Further addition of GO beyond the optimum lead to monotonic decrease in the corrosion resistance to values which were lower than the pristine SnCo coating. Initial increase in the corrosion resistance was attributed to uniform distribution of GO in the coating, increase in the uniformity and compactness of the coatings, increase in the fraction of the relatively more inert Co₃Sn₂ phase in the coating microstructure and formation of a layered microstructure in which the exposed coating surface contained the relatively more inert Co₃Sn₂ phase. Decrease in the corrosion resistance beyond the “optimum” was due to increase in the coating surface defects due to the deposition of agglomerated GO and galvanic coupling due to increase in the cathodic (GO) to anodic (metal) phase area.

研究了掺入氧化石墨烯（GO）对SnCo-GO复合涂层的形貌，相组成，显微组织和腐蚀性能的影响。使用具有不同浓度的分散氧化石墨烯（0.0625、0.125、0.1875、0.25、0.3125、0.5、0.625 g / L）的电解质，将含不同氧化石墨烯含量的SnCo-GO复合涂层电沉积在低碳钢基材上。形态学检查表明，加入较少的GO会增加涂层的致密性和均匀性，而大量的GO会在复合涂层中产生表面缺陷。结构表征表明涂层微观结构中主要存在两种不同的金属间相：Co ₂ Sn相和Co ₃ Sn₂阶段。观察到，相对惰性的Co ₃ Sn ₂相的相分数随着涂层中GO量的增加而单调增加。显微组织研究表明，在原始的SnCo涂层中，Co ₂ Sn相存在于Co ₃ Sn ₂相晶粒的晶界处。GO的掺入极大地改变了涂层的微观结构，导致形成了分层的微观结构，其中在Co ₃ Sn _2的横向细长晶粒下方存在细长的Co ₂ Sn相晶粒。相。使用Tafel极化和阻抗谱测量进行的电化学分析表明，涂层的腐蚀性能对涂层中存在的GO量高度敏感。最初添加GO可以提高耐腐蚀性，直至达到最佳的GO浓度，以获得最高的耐腐蚀性。超出最佳范围进一步添加GO会导致耐蚀性单调降低至低于原始SnCo涂层的值。最初的耐蚀性提高归因于GO在涂层中的分布均匀，涂层的均匀性和致密性提高，相对惰性的Co ₃ Sn ₂的分数增加涂层微结构中的Al ₂ O ₃相形成层状微结构，其中暴露的涂层表面包含相对较惰性的Co ₃ Sn ₂相。超过“最佳”值的耐蚀性降低是由于团聚的GO的沉积导致涂层表面缺陷的增加，以及由于阴极（GO）与阳极（金属）相面积的增加而引起的电偶合。