Effect of rare earth on microstructure and corrosion behavior of electroless Ni-W-P composite coatings

Purpose This paper aims to research the effect of different concentrations for Nd(NO3)3 and Ce(NO3)3 on the microstructures and corrosion resistance of Ni-W-P composite coatings through electroless plating method. Design/methodology/approach Scanning electron microscope, attached energy dispersive spectroscopy system and X-ray diffraction were used in this work. Meanwhile, the immersion test and electrochemical tests were used to characterize the corrosion behavior of the coating. Findings The coatings prepared at 1.00 g·L−1 Nd(NO3)3 exhibit a dense structure and high phosphorus content (12.38 wt.%). In addition, compared to the addition of Ce(NO3)3, when Nd(NO3)3 was introduced at a concentration of 1.00 g·L−1, the minimum corrosion rate of the coating was 1.209 g·m−2·h−1, with a noble Ecorr (−0.29 V) and lower Icorr (8.29 × 10−4 A·cm−2). Originality/value The effects of rare earths on the deposition and corrosion resistance mechanisms of Ni-W-P composite coatings were explored, with the rare earth elements promoting the deposition of nickel and tungsten atoms. Simultaneously, the amorphization of the coating increases, which excellently enhances the corrosion resistance of the coating.