Influence of temperature on passive film properties on Ni–Cr–Mo Alloy C-2000

• Published in: Corrosion science Vol. 76; pp. 424 - 431
• Main Authors: Zhang, Xiangrong, Shoesmith, David W.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-11-2013; Elsevier
• Subjects: A: nickel; Applied sciences; B: SIMS; B: XPS; C: crevice corrosion; C: passive films; Chromium; Chromium oxides; Copper; Corrosion; Corrosion environments; Exact sciences and technology; Metals. Metallurgy; Nickel; Nickel base alloys; Oxides; Passivity; C: passive films; B: XPS; B: SIMS; C: crevice corrosion; A: nickel; Nickel base alloys; Temperature; Surface layer; Secondary ion mass spectrometry; Crevice corrosion; Passivity; Chromium alloy; Photoelectron spectrometry; Passivation
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2013.07.016

•The passive films on Alloy C-2000 were investigated by AR-XPS and ToF-SIMS.•The film consists of an inner Cr2O3, outer Cr/Ni hydroxide and Mo/Cu oxides.•Increasing temperature leads to thickening of both layers which improves passivity.•Increasing temperature leads to loss of Cr2O3 from inner, Mo/Cu from outer layers.•These compensating effects make passive current almost independent of temperature.
The properties of the passive film on a Ni–Cr–Mo alloy, Alloy C-2000 (Ni–23Cr–16Mo–1.6Cu), grown at various temperatures, were investigated by AR-XPS and ToF-SIMS. The presence of a layered structure in the passive film has been demonstrated at low and mild temperatures in neutral solutions, with an inner Cr2O3 layer, outer Cr/Ni hydroxides layer and Mo/Cu oxide in the outermost surface. As temperature increases, the thickness of both layers increase which improves passivity. Increasing temperature leads to a loss of Cr2O3 from the inner and of Mo/Cu from outer layers. These compensating effects make the passive current density almost independent of temperature.