Electrochemical corrosion behavior of electroless Ni–P coating in NaCl and H₂SO₄ solutions

Abstract

Electrochemical corrosion behavior of electroless Ni-P coating in NaCl and H 2 SO 4 solutions were studied by potentiodynamic polarization curves and electrochemical impedance spectra techniques, as well as the corrosion morphology was characterized. The results indicate that electroless Ni-P coating with about 25 mm is stable in 30 days immersion in NaCl solution.Although it was corroded with prolonged immersion days, the corrosive medium has not penetrated through the coating. During the H 2 SO 4 concentration ranging from 5 to 10%, the corrosion current density of electroless Ni-P coating increased due to the intensified anodic dissolution process; in 15% H 2 SO 4 solution, electroless Ni-P coating shows obvious anodic passivation effect.

Development of electroless Ni–P/nano-WC composite coatings and investigation on its properties

“…The coating was then corroded to form the soluble NiCl 2 , over time, more and more nickel was dissolved. This behaviour is similar to previous results reported [39]. Fig.13 shows that the R p of the substrate changed significantly over the course of the immersion test while the R p of the coated sample changed considerably less.…”

Improvement of AZ91 Alloy Corrosion Properties by Duplex NI-P Coating Deposition

“…The following corrosion is even accelerated due to the magnesium alloy revealing to the corrosion environment. This mechanism was observed also in [47] and [48].…”

“…Afterward, Tafel plot was obtained by carrying out partial potentiodynamic polarization in the potential range from −100 mV to 200 mV from OCP at the potential scan rate of 1 mV/s. Electrochemical impedance spectroscopy (EIS) measurements were performed in 0.1 M NaCl solution at room temperature for 5 min, 1,2,4,8,12,24,48,72,96 and 168 h within the frequency range from 100 kHz to 10 mHz. The perturbation amplitude was set up to 5 mV.…”

Full Optimization of an Electroless Nickel Solution: Boosting the Performance of Low-Phosphorous Coatings

“…Significant variations were observed in the corrosion potential (E corr ) values, with differences higher than 100 mV, suggesting the possibility to prepare coatings with variable noble character depending on the experimental conditions. Nevertheless, E corr values do not give by itself information about the kinetics of the corrosion phenomena and, therefore, the corrosion rate obtained from i corr by Tafel extrapolation is regarded as a better indicator [ 37 ]. In this sense, coatings obtained from experiments 2, 5 and 8 showed the lowest corrosion rate among all the samples ( Table 4 ).…”