Effect of texture, grain boundary constitution, and molybdenum partitioning on corrosion and hydrogen permeation behavior of pulse electrodeposited Ni-Mo coatings
Sunando Banerjee, Akhand Pratap Singh, G. Mohan Kumar, Chandan Srivastava
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引用次数: 0
Abstract
Microstructural evolution, electrochemical corrosion and hydrogen permeation in pulse electrodeposited Ni-Mo coatings (2, 4, 8, and 11wt% Mo) were investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements revealed improved corrosion resistance at an optimum Mo content. The corrosion current density icorr and polarization resistance Rp values obtained were 13.8 μA/cm2 and 1745 Ωcm2 respectively for pure Ni coating while the icorr and Rp values obtained were 1.7 μA/cm2 and 5406 Ωcm2 respectively for Ni-4wt% Mo coating. Further, increase in the Mo content beyond 4 wt% increased the corrosion rate. Nevertheless, corrosion resistance of Ni-Mo coatings was found to be higher than the pure Ni coating. Ni-Mo coatings contained relatively Mo-enriched clusters in a solid solution matrix. The highest corrosion resistance of Ni-4wt% Mo coating was due to lower energy (001) and (111) textures, lower energy grain boundary constitution, and low coating strain. In Ni-4wt% Mo coating, Mo-enriched Ni-Mo nanoclusters inhibited hydrogen passage by providing a torturous path. In contrast, a high fraction of high-angle grain boundaries (compared to pure Ni coating) facilitated hydrogen permeation leading to a similar extent of hydrogen permeation through pure Ni and Ni-4wt% Mo coatings.
期刊介绍:
Materialia is a multidisciplinary journal of materials science and engineering that publishes original peer-reviewed research articles. Articles in Materialia advance the understanding of the relationship between processing, structure, property, and function of materials.
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