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Effect of Cu in electroless Ni–Cu–P coating on passivation process
Author(s) -
Gan Yiwei,
Zhao Tingting,
Kang Zhixin,
Sang Jing
Publication year - 2017
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6107
Subject(s) - passivation , coating , corrosion , materials science , x ray photoelectron spectroscopy , chromate conversion coating , dielectric spectroscopy , metallurgy , conversion coating , electrochemistry , chemical engineering , nuclear chemistry , composite material , electrode , chemistry , layer (electronics) , engineering
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 Cr 2 O 3 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 © 2016 John Wiley & Sons, Ltd.