Current developments of nanoscale insight into corrosion protection by passive oxide films

Maurice, Vincent; Marcus, Philippe

doi:10.1016/j.cossms.2018.05.004

Cited by 80 publications

(56 citation statements)

References 119 publications

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“…As suggested by recent nanometer scale studies [27,48], the Cr(III) enrichment may not be homogeneous in the passive film, and the Cr enrichment heterogeneities may cause the local failure of the passivity and the initiation of localized corrosion followed by pit growth where the passive film fails to self-repair [49]. The better understanding of the mechanisms governing the Cr (and Mo) enrichment requires to thoroughly investigate the initial stages of oxidation leading to pre-passivation of the SS surface [50,51,52] as well as the alterations brought by electrochemical passivation of the native oxide-covered SS surface [46,47].…”

Section: Introductionmentioning

confidence: 99%

Chloride-induced alterations of the passive film on 316L stainless steel and blocking effect of pre-passivation

Wang

Seyeux

Zanna

et al. 2020

Electrochimica Acta

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Electrochemical polarization measurements were combined with surface analysis by Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), X-Ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) to study the alterations of the passive film on 316L austenitic stainless steel induced by the presence of chlorides in sulfuric acid electrolyte. The work was performed at a stage of initiation of localized corrosion preceding metastable pitting at the micrometer scale as verified by current transient analysis and AFM. The results show that Clions enter the bilayer structure of the surface oxide already formed in the native oxide-covered initial surface state at concentrations below the detection limit of XPS (< 0.5 at%), mostly in the hydroxide outer layer where Fe(III) and Mo(IV,VI) species are concentrated but barely in the oxide inner layer enriched in Cr(III). Their main effect is to produce a less resistive passive state by poisoning dehydroxylation and further Cr(III) and Mo(IV,VI) enrichments obtained in the absence of chlorides. This detrimental effect can be suppressed by pre-passivation in a Cl-free electrolyte, which blocks the entry of chlorides in the passive film, including in the outer exchange layer, and enables the beneficial aging-induced variations of the composition to take place despite the presence of chlorides in the environment.On AISI 316L, recent surface analytical studies performed by Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS) [27,46,47] confirmed the bilayer structure of the passive film previously reported [21,22,27,30,32]. The native oxide film formed in air was found to already develop this bilayer structure with both the hydroxide outer and oxide inner layers enriched in Cr(III) and with Fe(III) more concentrated in the outer layer together with Mo(IV,VI). Electrochemical passivation in chloride-free sulfuric acid solution did not alter the bilayer structure and thickness of the surface oxide but promoted its Cr and Mo enrichments, owing to the lower stability and preferential dissolution of Fe(III) as previously proposed [4,16,53], and thereby increased the corrosion resistance of the passive state.In the present work, we address the alterations of the surface oxide films brought by electrochemical passivation in Cl-containing sulfuric acid solutions. Potentiodynamic and potentiostatic polarization measurements were used to define the electrochemical conditions best suited to alter the passive state without initiating localized corrosion (i.e metastable pitting) at the micrometer scale. ToF-SIMS and XPS were applied to characterize the bilayer structure, thickness and composition of the passive film and the entry of chlorides. Surface morphology was studied by Atomic Force Microscopy (AFM).The results provide new insight on the effect of pre-passivation on the entry of chlorides in the passive film and increased resistance to metastable pitting at the nanometer scale. ExperimentalThe same polycrystalline AISI 316...

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Section: Introductionmentioning

confidence: 99%

Chloride-induced alterations of the passive film on 316L stainless steel and blocking effect of pre-passivation

Wang

Seyeux

Zanna

et al. 2020

Electrochimica Acta

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“…It is now well-established from surface analytical studies of passivity performed on ferritic and austenitic SS at macroscopic level that the key for efficient passivity is a marked Cr(III) enrichment of the passive film, because of the higher stability of Cr(III) compared to Fe(II,III) oxide/hydroxide species [1][2][3][4][5][6][7][8]. For austenitic SS, only very little Ni(II) is present when detected in the passive film and the metallic alloy region underneath the oxide is Ni(0)-enriched [9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Passivation mechanisms and pre-oxidation effects on model surfaces of FeCrNi austenitic stainless steel

Pascalidou

Wiame

et al. 2020

Corrosion Science

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Passivation mechanisms were investigated on (100)-oriented Fe-18Cr-13Ni surfaces with direct transfer between surface preparation and analysis by X-ray photoelectron spectroscopy and scanning tunneling microscopy and electrochemical characterization. Starting from oxide-free surfaces, pre-oxidation at saturation under ultra-low pressure (ULP) oxygen markedly promotes the oxide film Cr(III) enrichment and hinders/delays subsequent iron oxidation in water-containing environment. Exposure to sulfuric acid at open circuit potential causes preferential dissolution of oxidized iron species. Anodic passivation forces oxide film re-growth, Cr(III) dehydroxylation and further enrichment. ULP pre-oxidation promotes Cr(III) hydroxide formation at open circuit potential, compactness of the nanogranular oxide film and corrosion protection.

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“…This corrosion resistance comes from the passive film which is a surface oxide film only a few nanometers thick and strongly enriched in Cr(III) (hydr)oxide species. [1][2][3][4][5][6][7] Even though numerous studies have characterized the passivity of various SS grades at macroscopic level, only recent surface analytical works performed on austenitic SS have suggested that the origin of passivity breakdown, which can lead to the local failure of the corrosion resistance and to localized corrosion by pitting, would depend on the surface heterogeneity at microscopic level. [6][7][8] Hence, the distribution of the chromium enrichment in the passive film at the nanometric scale appears of paramount importance for the stability and barrier properties of the passive film and its resistance to localized corrosion initiation.…”

Section: Introductionmentioning

confidence: 99%

Origin of nanoscale heterogeneity in the surface oxide film protecting stainless steel against corrosion

Wiame

Maurice

et al. 2019

npj Mater Degrad

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Stainless steels are widely used as metal components owing to self-protection in aggressive environments, provided by an extremely thin surface oxide film enriched in chromium oxide. Yet, despite decades of research, the mechanisms distributing the chromium enrichment at small length scale are poorly understood, although it may cause loss of stability and local failure of the corrosion resistance. Here, we apply high resolution surface analysis to investigate at small time and length scales the nucleation and growth mechanisms of the surface oxide on a model stainless steel. Starting from an oxide-free surface, we report the direct observation of the oxide nucleation and local oxidation of chromium, which governs the nanoscale heterogeneity of the growing surface oxide by chromium pumping from the atomic terraces to the steps for preferential Cr(III) oxide nucleation and subsequently by segregation from the atomic planes below to grow the Cr(III) layer incompletely saturating the stainless steel surface. This work provides new insight on corrosion chemistry, by evidencing local chemical and structural defects self-generated at the nanoscale by the building process of the protective oxide barrier, and affecting the passive film stability.

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Current developments of nanoscale insight into corrosion protection by passive oxide films

Cited by 80 publications

References 119 publications

Chloride-induced alterations of the passive film on 316L stainless steel and blocking effect of pre-passivation

Chloride-induced alterations of the passive film on 316L stainless steel and blocking effect of pre-passivation

Passivation mechanisms and pre-oxidation effects on model surfaces of FeCrNi austenitic stainless steel

Origin of nanoscale heterogeneity in the surface oxide film protecting stainless steel against corrosion

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