Optimization Effects of Cr Additives on the Microstructure and Property of Ni-Graphene Composite Coatings

MENG Liang, HU Qin-you, SHI Chao-jian, HUANG Chang-hai

Surface Technology ›› 2020, Vol. 49 ›› Issue (5) : 259-268.

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Surface Technology ›› 2020, Vol. 49 ›› Issue (5) : 259-268. DOI: 10.16490/j.cnki.issn.1001-3660.2020.05.031
Surface Failure and Protection

Optimization Effects of Cr Additives on the Microstructure and Property of Ni-Graphene Composite Coatings

  • MENG Liang1, HU Qin-you2, SHI Chao-jian2, HUANG Chang-hai2
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Abstract

The Ni-Cr-graphene composite coatings were successfully synthesized by the electrodeposition technique. The effects of the Cr concentration on the microstructure and property of the Ni-Cr-graphene coatings were comprehensively investigated. The X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Raman spectroscopy (Raman) were used to characterize the morphology, composition and microstructure (crystallite size, crystallite shape and texture) of the Ni-Cr-graphene coatings. A micro-hardness tester and an electrochemical workstation were used to evaluate the micro-hardness and corrosion behaviors of the Ni-Cr-graphene coatings, respectively. The results showed that with the co-deposition of 4 g/L graphene particles, the Ni crystallite size (175.3 nm) of the pure Ni coating was reduced to 60.5 nm of the Ni-0Cr-4graphene coating. When the Cr concentration in electrolyte increased from 0 g/L to 100 g/L, the Cr content in Ni-Cr-graphene coating increased from 0 wt% to 23.8wt% and the Ni crystallite size further decreased to 29.1 nm of the coating electrodeposited at Cr concentration of 100 g/L, and the Ni[200] texture was gradually eliminated. The micros?tructure evolution contributed to the enhancement in surface micro-hardness of the coatings with increasing Cr concentration. The surface micro-hardness of the coating electrodeposited at Cr concentration of 100 g/L was 489.8HV0.2, which was much higher than that of the pure Ni coating (260.1HV0.2). Besides, the graphene and Cr particles improved the corrosion resistance of the Ni-Cr-graphene coatings in 3.5wt%NaCl solution. The coating electrodeposited at 100 g/L Cr concentration possessed the best corrosion resistance with the maximum Ecorr (-0.21 V) and the minimum Jcorr (0.25 μA/cm2), which was reduced by an order of magnitude comparing to Jcorr of the pure Ni coating (7.01 μA/cm2). The enhancements in the micro-hardness and corrosion resistance of the Ni-Cr-graphene coatings were induced by the microstructure evolution of the Ni deposits.

Key words

electrodeposition; graphene; Ni based composite coating; microstructure; corrosion resistance

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MENG Liang, HU Qin-you, SHI Chao-jian, HUANG Chang-hai. Optimization Effects of Cr Additives on the Microstructure and Property of Ni-Graphene Composite Coatings[J]. Surface Technology. 2020, 49(5): 259-268

Funding

Supported by National Natural Science Foundation of China (51909156), Shanghai Commission of Science and Technology (18DZ1206300), China Postdoctoral Science Foundation (2016M591651)
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