Corrosion Resistance Of Passive Film Research Articles

Effect of hydrostatic pressure on the nature of passive film of pure nickel

AbstractThe effect of hydrostatic pressure on the nature of passive film of nickel in 3.5% NaCl solution was investigated by means of polarization curves, electrochemical impedance spectroscopy (EIS), and Mott–Schottky measurement. The experimental results revealed that hydrostatic pressure had two opposite effects on passive film of nickel. On one hand, hydrostatic pressure improved the corrosion resistance of passive film of nickel such as the decreased acceptor density. On the other hand, the passive film became unstable and showed a higher diffusivity of acceptor density with the increasing of hydrostatic pressure, which deteriorated the corrosion resistance of passive film of nickel. The deterioration effect had greater influence on the passive film than the improvement effect, which led to the decreasing corrosion resistance of passive film with the increasing of hydrostatic pressure.

The Semiconductor Character of Passive Film of 304L Stainless Steel(SS), 316L SS and Nickel Alloy 800 Formed in Zinc Contained High-Temperature and High-Pressure Water

The semiconductor properties of passive film formed on 304L stainless steel (SS), 316L SS and Alloy 800HT in high-temperature and high-pressure water with zinc addition have been investigated by using Polarization curve, Mott-Schottky analysis and photocurrent method. The donor density, flat band and band gap of semiconductor behavior are analyzed to investigate the impact of zinc addition to the passive film. Analysis of the experimental results indicated that passive film formed on 316L and 800HT with zinc addition showed different electrochemical, photo-electrochemical and semiconductor properties. The results indicated that corrosion resistance of passive film from in high-temperature and high-pressure water with zinc addition was obviously better than that without zinc addition.

Study on Chromium-Free Color Passivation for Zinc Coating Treated with Silicate

This paper mainly focuses on how the silicate liquid composition of chromium-free color passivation affects on passivation result, and confirmes the optimum passivation conditions, and uses two zinc plating system of alkaline and acid deposition. Silicate passivation system is compared with hexavalent chromium passivation technology and the results showed that: the appearance and corrosion resistance of passive films formed on zinc coatings plated with alkaline system are better than samples plated with acid system, and have the same corrosion resistanc with hexavalent chromium passivation. The silicate passivation films can keep 200 hours with no white rust in neutral salt spray test.

Investigation of the Effect of Hydrogen on the Passive Film on Iron by Surface Analysis Techniques

The effects of dissolved hydrogen on the thickness, structure, and composition of the passive film on iron formed in a boric/borate solution at pH 8.4 were investigated by Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), and nuclear reaction analysis (NRA). AES analysis showed that hydrogen decreases the film thickness and the oxygen content in the film, reduces the valence state of iron, and increases both the iron content in the film and the degree of deviation of the oxide in the passive film from its nominal chemical stoichiometry. The decrease in the oxygen content in the passive film was confirmed by NRA measurements. SIMS results showed that hydrogen charging increases the hydroxyl content in the passive film. These results provide very useful information for elucidating the mechanism by which hydrogen decreases the corrosion resistance of passive films and promotes pitting of iron. © 2003 The Electrochemical Society. All rights reserved.