Effect of Cu in electroless Ni-Cu-P coating on passivation process

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• 作者：Yiwei Gan ; Tingting Zhao ; Zhixin Kang and Jing Sang
• 刊名：Surface and Interface Analysis
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：49
• 期：3
• 页码：190-196
• 全文大小：653K
• ISSN：1096-9918

文摘

Electroless Ni–P and Ni–Cu–P coatings were passivated by chromate conversion treatment respectively. The anticorrosive performances of passivated coatings were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy measurements. The passivated Ni–Cu–P coating exhibited a high corrosion resistance with the i_corr of 0.236 μA/cm,² while the value of passivated Ni–P coating was only 1.030 μA/cm,² indicating the passive film could improve the corrosion resistance of Ni–Cu–P coating to a significant extent. High-resolution X-ray photoelectron spectroscopy was used to determine the chemical states of elements detected in the passive film. Compared with passivated Ni–P coating, the passive film on Ni–Cu–P coating exhibited a higher ratio of Cr₂O₃ to Cr(OH)₃ with the value of 72:28, which was the main factor for passivated Ni–Cu–P coating showing excellent corrosion resistance. The effect of Cu in electroless Ni–Cu–P coating on passivation process was discussed by the contrast experiment. Copyright