Evolution of corrosion resistance and passive film properties of Ni-Mo alloy coatings during exposure to 0.5 M NaCl solution

Citric acid passivation is an attractive alternative to increase the corrosion resistance of stainless steels. In this work, the correlation of passive film composition and the corrosion properties of citric acid-passivated AISI 316L stainless steel samples was assessed. The concentration of citric acid in the passivating solution was varied from 10 to 30 wt.%. Passive film composition was examined by X-ray photoelectron spectroscopy. The corrosion behavior was investigated by potentiodynamic polarization curves. The citric acid passivation treatment led to Cr 2 O 3 enrichment of the passive film, especially for the 20-wt.% concentration. By increasing the citric acid concentration to 30 wt.%, the corrosion resistance decreased. In addition to chromium compounds, the passivation treatment also affected the relative concentrations of Fe, Mo, and Ni compounds in the passive films. The formation of Mo oxides was triggered at citric acid concentrations of 10 and 20 wt.%, contributing to slower anodic dissolution rate. The corrosion resistance of the passivated samples was favored as the relative concentration of Fe oxides (FeO and Fe 2 O 3) increased with respect to FeOOH.

Section: Resultssupporting

confidence: 90%

“…good agreement with other published data. 32,33 The quantitative results are displayed in Table 4. Because of its lower oxidation susceptibility when compared with chromium and iron, the relative fraction of metallic nickel is higher.…”

Section: Electrochemical Testsmentioning

confidence: 99%

Interplay between the composition of the passive film and the corrosion resistance of citric acid‐passivated AISI 316L stainless steel

Costa

Oliveira

Antunes

2020

“…This indicates that the surface of the Al 85 Ni 9 Ce 6 amorphous ribbon is further oxidized after 48 hours of immersion, as also indicated by the fitting results for the Al2p core levels (Table ). The coexistence of Ni 0 , NiO, and Ni (OH) 2 has been reported for different nickel surfaces.…”

Section: Resultsmentioning

confidence: 99%

Corrosion of Al₈₅Ni₉Ce₆ amorphous alloy in the first hours of immersion in 3.5‐wt% NaCl solution: The role of surface chemistry

Oliveira

Ríos

et al. 2019

The surface chemistry and corrosion behavior of Al 85 Ni 9 Ce 6 melt-spun ribbons were studied after the first hours of immersion in 3.5-wt% NaCl solution at room temperature. X-ray photoelectron spectroscopy (XPS) was used to assess the chemical states of Al, Ce, Ni, and O. Electrochemical impedance spectroscopy was used to assess the corrosion resistance of the Al 85 Ni 9 Ce 6 ribbons. The alloy remained immersed for up to 48 hours. The results showed that hydroxide species in the passive film play a central role in the corrosion behavior of the Al 85 Ni 9 Ce 6 alloy.

“…Corrosion studies were carried out in three media: 0.5 M NaCl, 0.5 M H 2 SO 4 , and 2 M NaOH solutions at room temperature (≈ 20°C‐22°C). Concentrations of these media were selected based on the literature review . Potentiodynamic polarization scans and electrochemical impedance spectroscopy (EIS) tests were performed using an Autolab PGSTAT 302 N potentiostat‐galvanostat (Methrom Autolab, The Netherlands) in a three‐electrode glass cell.…”

Section: Methodsmentioning

confidence: 99%

Corrosion properties of nickel coatings obtained from aqueous and nonaqueous electrolytes

Cruz

Makarova

Kharitonov

et al. 2019

Nickel was deposited on a copper substrate from aqueous and nonaqueous ethanol electrolytes. X‐ray photoelectron spectroscopy, electrochemical impedance spectroscopy and chronovoltametry, scanning electron microscopy, and atomic force microscopy were used to study the effect of the solvent on the surface and corrosion properties of the Ni coatings formed. Unifom and relatively smooth Ni films were obtained as measured with microscopy techniques. The formation of a passive film in acidic, alkaline, and neutral chloride‐containing media was confirmed with X‐ray photoelectron spectroscopy. The water‐based nickel‐plating electrolyte makes it possible to deposit coatings with higher corrosion resistance as compared with coatings deposited from ethanol electrolyte in NaOH and NaCl media. The proposed mechanism of corrosion in a 0.5 M H2SO4 solution involves cycles of active‐passive surface behavior due to its passivation by corrosion products.