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

Ma, Li; Wiame, Frédéric; Maurice, Vincent; Marcus, Philippe

doi:10.1038/s41529-019-0091-4

Cited by 56 publications

(52 citation statements)

References 33 publications

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“…Hydrogen absorption and destructive expansion of steel is well known. As mentioned earlier, it may happen or be enhanced locally, on the microscopic scale, driven by gradients in the electrochemical potential, resulting from local inhomogeneities in steel surface composition . These are—whether they originate from material composition variations, impurities, and specific features from production or processing—generally understood to be the root cause for pitting corrosion .…”

Section: Introductionmentioning

confidence: 99%

Swelling of Steel Film by Hydrogen Absorption at Cathodic Potential in Electrolyte

Garai

Carlomagno

Solokha

et al. 2020

Physica Status Solidi (b)

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An ≈4 nm FeCrNi film, deposited on a Ru/B4C multilayer (ML), is used to study cathodic hydrogen charging in electrolyte. A thin film on a ML allows obtaining precise quantitative information on surface metal composition and oxidation state using the X‐ray standing wave technique combined with near‐edge X‐ray absorption spectroscopy. The metal composition is found being close to the composition of stainless steel (SS) 304, and, as for bulk steel, the outer 2 nm passive layer, consisting of oxidized iron and chromium, is depleted of nickel. Overall, it is found that the film represented a useful replica of the surface of bulk steel. Following exposure to 0.1 m KCl electrolyte at −0.6 V versus Ag/AgCl, 11.3 (±3)% swelling of the film by hydrogen absorption is observed. The estimated absorbed amount is exceeding reported bulk absorption under similar conditions by more than an order of magnitude. Strong hydrogen absorption appears to be enabled by the 2D character of the thin film, i.e., a significantly lower associated strain energy compared with bulk absorption. The strong surface swelling is suggested to be related to the lowering of the pitting corrosion resistance of SS surfaces reported following hydrogen exposure.

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Section: Introductionmentioning

confidence: 99%

Swelling of Steel Film by Hydrogen Absorption at Cathodic Potential in Electrolyte

Garai

Carlomagno

Solokha

et al. 2020

Physica Status Solidi (b)

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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]. successive 1200 and 2400 grades and then with diamond suspensions of successive 6, 3, 1 and 0.25 μm grades.…”

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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“…Hence, a thorough investigation of the Cr(III) enrichment mechanisms is necessary to develop the comprehensive knowledge on how to improve the resistance to local failure of passivity. It must address the initial stages of oxidation leading to pre-passivation of the SS surface (Ma et al, 2018(Ma et al, , 2019 as well as the alterations of the native oxide film brought by immersion in the aqueous environment and by electrochemical anodic polarization in the passive range (Wang et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of Cr and Mo Enrichments in the Passive Oxide Film on 316L Austenitic Stainless Steel

et al. 2019

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An approach preventing contact to ambient air during transfer from liquid environment for electrochemical treatment to UHV environment for surface analysis by X-Ray Photoelectron Spectroscopy and Time-of-Flight Secondary Ion Mass Spectrometry was applied to study the mechanisms of Cr and Mo enrichments in the passive oxide film formed on 316L austenitic stainless steel. Starting from the air-formed native oxide-covered surface, exposures were conducted in aqueous sulfuric acid solution first at open circuit potential and then under anodic polarization in the passive range. At open circuit potential the thickness of the bi-layered oxide film was observed to decrease and the enrichments of both Cr(III) and Mo, mostly Mo(VI), to markedly increase as well as the film hydroxylation. This is due to preferential dissolution of the Fe(III) oxide/hydroxide, not compensated by oxide growth in the absence of an electric field established by anodic polarization. Anodic polarization in the passive domain causes the bi-layered structure of the oxide film to re-grow by oxidation of iron, chromium and molybdenum, without impacting the Cr enrichment and only slightly mitigating the Mo enrichment. De-hydroxylation of the inner layer is also promoted upon anodic polarization. These results show that the treatment of the surface oxide film in acid solution at open circuit potential enhances Cr and Mo enrichments and promotes hydroxylation. Passivation by anodic polarization allows dehydroxylation, yielding more Cr oxide, without markedly affecting the Mo enrichment, also beneficial for the corrosion resistance.

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

Cited by 56 publications

References 33 publications

Swelling of Steel Film by Hydrogen Absorption at Cathodic Potential in Electrolyte

Swelling of Steel Film by Hydrogen Absorption at Cathodic Potential in Electrolyte

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

Mechanisms of Cr and Mo Enrichments in the Passive Oxide Film on 316L Austenitic Stainless Steel

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