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An approach for the identification of the origin of iron sulfides formation on iron surfaces using Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS) is reported here in. Two different sulfidation processes of iron surfaces are presented (both at room temperature): the first abiotic procedure was carried out using chronoamperometry (E = −0.8 V/SCE) of pure iron in 10 mM of Na 2 S,9H 2 O (pH = 11) while the second biotic procedure was accomplished by immersing a pure iron sample in a medium containing HS− ions produced by a sulfate-reducing bacterium (SRB) of the genus Desulfovibrio at an open circuit potential (OCP). A surface analytical method using Time-of-Flight Secondary Ions Mass Spectrometry (ToF-SIMS) coupled with ToF-SIMS spectra peak-fitting and data processing was developed to calculate an accurate sulfur isotopic fractionation δ34S V-CDT on iron sulfide layers formed on iron surfaces, thus allowing to discriminate between abiotically versus biotically generated sulfides. This approach contributes to a better understanding of iron surface interactions with sulfur containing environmental species of abiotic or biotic origin. • ToF-SIMS is used to study abiotically and biotically (from SRB) generated iron sulfide layers formed on iron surfaces. • A peak-fitting method and data processing was developed and applied on ToF-SIMS spectra. • Different sulfur isotopic fractionations δ34S (-0.23 ‰ and -13.69 ‰) were obtained for abiotic and biotic iron sulfide layers. • The ToF-SIMS approach presented allows the identification of bacterial contribution in sulfur corrosion products. • The ToF-SIMS approach allows a better understanding of biocorrosion to sulfur originated from abiotic and biotic sources in aqueous medium. [ABSTRACT FROM AUTHOR]

The depth profiling of hydrogen and deuterium in polycrystalline and monocrystalline Nickel-base alloys (Ni-16Cr-8Fe, wt%) was performed by Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) and Elastic Recoil Detection Analysis (ERDA) after oxidation in simulated primary medium conditions containing 9 at.% D 2 O. The use of deuterium isotopic tracer in ToF-SIMS has demonstrated the presence of deuterium in the oxide layer for oxidation times of 300 min and 100 h. The quantities of deuterium were determined by ERDA using a 2 MeV 4 He ion beam. Finally, the penetration coefficient α was calculated, and ranged from 0.01 to 0.04. [ABSTRACT FROM AUTHOR]

Surface spectroscopy analysis and electrochemistry were applied to study the effects of surface preparation by vibratory polishing on the passivity of stainless steel 304L surfaces. Compared to grinding by traditional mechanical polishing, vibratory polishing promotes the enrichment of Cr(III) oxide and hydroxide species in the duplex chemical structure of the surface native oxide film by enhancing selective Fe oxidation and dissolution. As a result, spontaneous passivity, tested in aggressive sulphuric acid electrolyte, is enhanced. However, in the absence of enrichment in Mo(IV) and Mo(VI) species in the passive film, the Cr enrichment does not enhance passivity upon anodic polarisation nor increase the resistance to Cl-induced passivity breakdown and initiation of localised corrosion in accelerated testing conditions. The results provide comprehensive insight into the mechanisms underlying the passivity enhancement of stainless steel by surface engineering. [ABSTRACT FROM AUTHOR]

The oxidation of chromium at 300 °C was investigated in situ by ToF -SIMS for three different oxygen pressures ( $$P_{{{\text{O}}_{2} }} = 2.0 \times 10^{ - 7}$$ , 6.0 × 10 and 2.0 × 10 mbar). Sequential exposure to the O isotopic tracer was performed to reveal the governing transport mechanism in the oxide film. The evolution of the oxide thickness was monitored. Volatilization of CrO was evidenced. A model was used to describe the kinetics resulting from the measurements. Both the parabolic and volatilization constants showed a dependence on oxygen partial pressure like $$P_{{{\text{O}}_{2} }}^{ - 1/n}$$ , with n = 1.9 ± 0.1, indicating a defect structure mainly consisting of oxygen vacancies. The re-oxidation in O shows a growth of the oxide layer at the metal/oxide interface, demonstrating an oxidation process governed by anionic transport via oxygen vacancies. The diffusion coefficient of oxygen in the oxide was determined by fitting the ToF -SIMS depth profiles. It is 2.0 × 10 cm s. [ABSTRACT FROM AUTHOR]

Ion transport mechanisms in growing oxide films on Ni-20Cr and Ni-20Cr-10Mo alloys have been investigated by ToF-SIMS with in situ re-oxidation using 18O isotopic tracer. Whereas the growth is controlled by pure anionic diffusion on Ni-20Cr alloy, the behavior is drastically modified by Mo addition. A mixed cationic and anionic growth mechanism and a reduced diffusion rate of moving species are observed on the alloy containing molybdenum. The passivation in sulfuric acid, which increases the inner Cr oxide barrier layer thickness, also reduces the diffusion rate of the moving species for both Ni-20Cr and Ni-20Cr-10Mo alloys. Significantly higher re-oxidation temperatures are needed to observe the ion transport mechanisms in passive oxides formed on Ni-20Cr and Ni-20Cr-10Mo alloys, as compared to native oxides. Mo addition and electrochemical passivation have synergistic effects that reduce the diffusion rate of moving species through the surface oxide films and thus reinforce the corrosion resistance of the oxide films formed on Ni alloys. [ABSTRACT FROM AUTHOR]

Abstract: Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) was used to examine the film formed on pure magnesium by immersion for 2min in ultra pure water. The ToF-SIMS data indicates that there is magnesium hydride within the surface film. The presence of MgH2 is a result of the Mg corrosion mechanism. [Copyright &y& Elsevier]

Abstract: The structural modifications of Ni(111) single-crystal surfaces induced by prolonged polarization at the onset of the active/passive transition have been studied at the (sub-)nanometer scale by in situ electrochemical STM (EC-STM) in 0.1M NaOH(aq). The results evidence the effect of the structural order in the passivating monolayer on the corrosion resistance properties and the initiation of localized corrosion. 2D pits are initiated by dissolution on the terraces covered by disordered islands of nickel hydroxide particles and at the boundaries of the crystalline Ni(OH)2(0001) islands. The pits propagate preferentially in the disordered areas. Dissolution is blocked in the well-ordered islands of the passivating monolayer and by the 3D nuclei of the passive film formed at the pre-existing step edges of the nickel substrate. This competitive mechanism of dissolution and passivation, repeated on the terraces newly formed by local dissolution, initiates the growth of 3D pits of nanometer dimensions, i.e. localized corrosion at the nanoscale. A tip effect, promoting the dissolution reaction by a mechanical and/or chemical interaction with the passivating particles, contributed to reveal these local properties. This fundamental understanding of the depassivation/repassivation at the nanoscale opens the way to the search for functional surfaces with self-repair properties. [Copyright &y& Elsevier]

A new strategy of utilizing mixtures of ethanol and complexing agents on Mg-air battery is investigated systematically. The presence of ethanol promotes formation of a dense inner layer with a high portion of oxide in the discharge film, leading to significantly enhanced utilization efficiency. The highest utilization efficiency of Mg anode has been increased from 53.6 % to 85.7 % and the discharge potential is decreased 300 mV, when discharges in mixed electrolyte. The adsorption/deposition of S-like species on metal surface is evidenced in ethanol and 5-sulfosalicylate acid containing solution, resulting in inhibition of the hydroxide-rich outer layer growth. • Mixtures of complexing agents and ethanol are adopted as electrolytes for Mg-air battery. • 85.7 % of utilization efficiency is achieved in 3,4-DHB and ethanol containing solution. • Ethanol facilitates the formation of oxide-rich inner surface layer. [ABSTRACT FROM AUTHOR]

• Passivity of CoCrFeMnNi high entropy alloy surfaces investigated by ToF-SIMS. • Bilayer structure formed in aqueous acid solution thermally stable in vacuum. • Further oxidation in low pressure O 2 gas studied in situ with isotopic 18O tracing. • Outward cation diffusion faster than inward oxygen diffusion at 170 °C. • Parabolic law of re-oxidation established and parabolic constant determined. The ion transport mechanisms in passive films pre-formed on CoCrFeMnNi high entropy alloy surfaces in acid solution were studied in-situ by time-of-flight secondary ion mass spectrometry upon oxidation in 18O 2 gas. The bilayer structure of the passive film, with outer Fe, Co-rich and inner Cr, Mn-rich layers, is thermally stable, but with reduction of Fe and Co oxides and formation of Mn oxide in the outer layer above 150 °C. At 170 °C, the transport mechanism is mainly outward cation diffusion with slower inward oxygen diffusion. The re-oxidation growth rate follows a parabolic law and the value of parabolic constant was determined. [ABSTRACT FROM AUTHOR]

• Cl, OH enrichment in the pits showing Cu, Fe presence in AA2050 exposed to NaCl. • LiO dissolution from the surface oxide layer induced by immersion in NaCl. • No modification of metallic Li present in the alloy matrix. • Enhanced corrosion and pitting at the boundary of Al-Cu-Fe-Mn IMP and matrix. • Different and/or higher thickness of oxide-hydroxide layer over IMP than matrix. The pitting corrosion and surface modifications of aluminium alloy AA2050-T8 (Al-Cu-Li) resulting from immersion in 0.1 M NaCl at open circuit potential were studied by time-of-flight secondary ion mass spectrometry (ToF-SIMS). ToF-SIMS chemical mapping showed a local distribution of chlorides and hydroxides in the pits enriched in Cu and Fe. Preferential sites of corrosion initiation were evidenced in the alloy matrix close to Al-Fe-Cu-Mn intermetallic particle. A formation of an oxide-hydroxide layer with different composition and/or higher thickness was evidenced over IMP than the alloy matrix. LiO dissolved from the oxide layer but metallic lithium was still present in the matrix. [ABSTRACT FROM AUTHOR]

• XPS and ToF-SIMS techniques were applied to understand biofilm-surface interaction. • The effect of Escherichia coli on the passive film composition has been explored. • Escherichia coli adhesion leads to a Cr enrichment of the passive film. • A mechanism involving bacterial metabolism explains passive film modifications. Modifications of the passive film on stainless steel (316 L) after Escherichia coli adhesion in the early stage of biofilm formation were investigated by XPS (X-ray Photoelectron Spectroscopy) and ToF-SIMS (Time-of-Flight Secondary Ions Mass Spectrometry). This work evidences an enrichment in Cr(III) in the presence of bacteria, which is known to improve corrosion resistance. The iron depletion is assigned to synthesis by bacteria of organic molecules (siderophore) that specifically chelate Fe3+ ions from the passive layer, followed by the reduction of Fe3+ into Fe2+ ions by the bacterium and finally release of these reduced species into the aqueous solution. [ABSTRACT FROM AUTHOR]

• Thermal stability of the passive film on 316 L stainless steel is investigated in situ by ToF-SIMS. • A step by step heating in ultra-high vacuum is applied. • The modifications of thickness, composition and layered structure on the passive film during stepwise heating are studied. • The changes in the passive film in the temperature range 25–300 °C are discussed. The modifications of the passive film formed on 316 L stainless steel surface during stepwise heating in ultra-high vacuum up to 300 °C have been studied in situ by ToF-SIMS. The pre-formed passive film (in 0.05 M H 2 SO 4) has a bilayer structure, comprising Fe-rich, Mo-rich (outer) and Cr-rich (inner) layers. Below 100 °C, the passive film is stable. At 100 °C–250 °C, dehydroxylation and dehydration is observed. Above 250 °C, the main modification in the film is formation of chromium oxide at the expense of oxidized iron. At higher temperature, thicker Cr-rich inner layer with sharper inner/outer oxide interface is formed. [ABSTRACT FROM AUTHOR]

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 316 L 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 Cl− ions 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. [ABSTRACT FROM AUTHOR]

Effect of silicate sealing on tartaric sulphuric acid anodized 7010-T7451 and 7175-T6 alloys with different distributions of intermetallics (IMPs) in aluminum substrates was studied. Surface characterisations evidenced similar morphology and chemical composition of the sealed layers on both substrates. Electrochemistry and time-lapse microscopy demonstrated the layer's stability under anodic polarization and its localized pitting under cathodic polarization in NaCl electrolyte. No chemical or morphological modifications were detected outside of the pits. The number and size of the pits depended on the IMPs distribution in the alloy, buried under 6 µm thick oxide. A degradation mechanism explaining these observations was proposed. [Display omitted] • Procedure for intelligent ranking of sealants for anodized Al alloys is proposed. • In studied sealant/substrate systems, sealing improves immersion stability. • All studied systems show similar degradation mode (localized pitting). • Pits distribution depends on the alloy process (machining/rolling) for all sealants. • Pits size/number correlates with intermetallics distribution in the substrate alloy. [ABSTRACT FROM AUTHOR]

• The air-formed oxide on Hastelloy BC-1 contained Cr- and Mo- rich regions in the inner and outer oxide, respectively. • Empirical evidence shows O atom incorporation at the outer interfaces of both the Cr- and Mo-rich regions of the oxide. • Heating the air-formed oxide to 300 °C did not increase its thickness, but, further heating to 500 °C led to the thickening. • In all cases, temperature increases induced structural modification to the oxides which then reverted during oxidation. This paper presents insight into the structure and transport mechanisms involved in the surface oxidation of Hastelloy BC-1, gained by means of in situ time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy. The native, air-formed oxide, comprising Cr-rich (inner) and Mo-rich (outer) layers, was found to be on the order of 1–2 nm thick. Oxide thickness did not change when the temperature was increased to 300 °C in oxygen atmosphere but increased to ˜10 nm after exposure at 500 °C. The mechanisms of oxide growth/maintenance as well as observations on the effect of elevated temperatures on oxide structure are discussed. [ABSTRACT FROM AUTHOR]

• Formation of bi-layered films with physisorbed outer and chemisorbed inner layers. • 2-MBI bonding by N to metallic and oxidized Cu, S also involved on metallic Cu. • Formation of Cu(I)−2-MBI complex promoted by cathodic conversion of native Cu oxide. • Increased complex formation owing to Cu(I) ions generated by anodic oxidation. • Cu dissolution inhibited depending on pre-treatment used for interface formation. The interfacial bonding and the layered structure of 2-mercaptobenzimidazole (2-MBI) organic films adsorbed on electrochemically controlled copper surfaces and their corrosion inhibition effects in acidic chloride aqueous solution were investigated using an integrated approach of electrochemical methods and advanced surface analyses by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. It is shown that organic films formed on the copper surfaces are bi-layered with a chemisorbed inner layer and a physisorbed outer layer. In the chemisorbed inner layer, 2-MBI is bonded primarily by its nitrogen atoms with metallic and oxidized copper surfaces. Sulphur atoms are also involved in the bonding mechanism when metallic copper is directly accessible to the 2-MBI molecules. The initial presence of native copper oxides at the interface promotes the formation of Cu(I)-2-MBI metal-organic complexes in the chemisorbed inner layer using cathodic reduction to dissociate the oxide. Metal-organic complexes also form upon anodic polarisation due to Cu(I) ions generated by oxidation of the copper metal. 2-MBI effectively inhibits copper anodic dissolution in varying degrees, between 84% and 93%, depending on the pre-treatment used for the formation of the organic bi-layers. An enhanced protection of the substrate is obtained by adsorbing the 2-MBI inhibitor on an initially oxide-free surface, which is achieved by cathodic pre-treatment in absence of the inhibitor followed by 1 hour exposure to the inhibitor. [ABSTRACT FROM AUTHOR]

Advanced surface analytical techniques were used to study 2-mercaptobenzothiazole (2-MBT) adsorption and interfacial oxide effects on copper, and cyclic voltammetry was used to characterize corrosion inhibition in NaCl solution. 2-MBT adsorbs on metallic copper by its sulphur atoms along with a small fraction of nitrogen atoms. The 2-MBT film formed is thicker when the interfacial oxide is less. Upon anodic polarisation, a direct correlation between the thickness of 2-MBT layer and protection against corrosion initiation is observed. The metal-organic complexes, formed by an interaction between 2-MBT and Cu(I) ions, do not offer additional protection to the substrate. • 2-MBT inhibition of copper initial corrosion in NaCl studied by surface analysis. • 2-MBT adsorption mostly by sulphur atoms and partially by nitrogen atoms. • Thickness of 2-MBT layer dependent on quantity of interfacial oxides present. • Superior protection against corrosion offered by thicker 2-MBT barrier layer. • Metal-organic Cu-2-MBT complexes do not aid in corrosion protection of substrate. [ABSTRACT FROM AUTHOR]

• Surface oxide layers formed on 2304 duplex stainless steel are investigated. • The native surface and the passivated surface are compared. • An innovative coupling of XPS and ToF-SIMS is used. • The oxide layers formed on austenite and ferrite phases are locally characterized. • The effect of passivation on the surface oxide layer is discussed. This work reports an innovative methodology based on the coupling of XPS and ToF-SIMS in order to study the surface oxide layer formed on austenite and ferrite phases of duplex stainless steels. The native oxide film obtained after mechanical polishing and the passive film obtained after electrochemical passivation in 0.05 M H 2 SO 4 were investigated. Chromium and molybdenum contents were found to be higher in the oxide layer formed on ferrite phase. Nickel and nitrogen enrichments were found to be more pronounced under the oxide layer formed on austenite phase. The effect of passivation on the surface oxide layer is discussed. [ABSTRACT FROM AUTHOR]

Highlights • Duplex stainless steel and corresponding single phase alloys are compared. • The native oxide films formed after mechanical polishing are studied. • A coupling of XPS and ToF-SIMS is used. • The thickness, composition and chemical states of the oxide layer are investigated. • The link between the chemical compositions of the bulk and the surface is discussed. Abstract The surface oxide films formed after mechanical polishing on duplex stainless steel and corresponding single phase alloys were characterized by XPS and ToF-SIMS. The native oxide films are mixtures of oxides and hydroxides composed of Fe(III), Mo(IV) and Mo(VI) in the outer region and Cr(III) in the inner region. Nickel, molybdenum and nitrogen are enriched in the underlying metal while chromium and molybdenum are enriched in the oxide layer. The contents of alloying elements in the oxide layer and/or in the underlying metal are found to be directly related to their content in the bulk of the alloys. [ABSTRACT FROM AUTHOR]

The oxidation behaviours of polycrystalline and monocrystalline Ni-base alloys (Ni-16Cr-8Fe (wt%)) were investigated in situ by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The oxide layer formed is duplex: an inner chromium-rich layer and an outer layer which is rich in nickel and iron. Time evolution of the composition of inner layer from pure Cr 2 O 3 towards spinel (NiCr 2 O 4 ) was observed. The oxidation kinetics was accelerated by alloy grain boundaries, which can favour the diffusion of chromium. Both the parabolic and volatilization constants increased with increasing temperature, with k p varying from 1.9×10 −3 to 1.6×10 −2 nm 2 .s −1 , and k v from 1.0×10 −3 to 2.9×10 −3 nm.s −1 . [ABSTRACT FROM AUTHOR]

The role of the SiC substrate surface on the resistance to the local initiation of tarnishing of thin-layered silver stacks for demanding space mirror applications was studied by combined surface and interface analysis on model stack samples deposited by cathodic magnetron sputtering and submitted to accelerated aging in gaseous H 2 S. It is shown that suppressing the surface pores resulting from the bulk SiC material production process by surface pretreatment eliminates the high aspect ratio surface sites that are imperfectly protected by the SiO 2 overcoat after the deposition of silver. The formation of channels connecting the silver layer to its environment through the failing protection layer at the surface pores and locally enabling H 2 S entry and Ag 2 S growth as columns until emergence at the stack surface is suppressed, which markedly delays tarnishing initiation and thereby preserves the optical performance. The results revealed that residual tarnishing initiation proceeds by a mechanism essentially identical in nature but involving different pathways short circuiting the protection layer and enabling H 2 S ingress until the silver layer. These permeation pathways are suggested to be of microstructural origin and could correspond to the incompletely coalesced intergranular boundaries of the SiO 2 layer. [ABSTRACT FROM AUTHOR]

In this work, we addressed the local degradation mechanisms limiting the prelaunch environmental durability of thin-layered silver stacks for demanding space mirror applications. Local initiation and propagation of tarnishing were studied by combined surface and interface analysis on model stack samples consisting of thin silver layers supported on lightweight SiC substrates and protected by thin SiO2 overcoats, deposited by cathodic magnetron sputtering and submitted to accelerated aging in gaseous H2S. The results show that tarnishing is locally initiated by the formation of Ag2S columns erupting above the stack surface. Ag2S growth is promoted at high aspect ratio defects (surface pores) of the SiC substrate as a result of an imperfect protection by the SiO2 overcoat. Channels most likely connect the silver layer to its environment through the protection layer, which enables local H2S entry and Ag2S growth. The silver sulfide columns grow in number and size eventually leading to coalescence with increasing H2S exposure. In more advanced stages, tarnishing slows down owing to saturation of all pre-existing imperfectly protected sites of preferential sulfidation. However, it progresses radially at the basis of the Ag2S columns underneath the protection layer, consuming the metallic silver layer and deteriorating the protecting overcoat. [ABSTRACT FROM AUTHOR]

X‐ray photoelectron spectroscopy analysis was applied to investigate the thermal stability under ultra‐high vacuum environment of the surface oxide film formed by electrochemical passivation of a newly designed Cr15Fe10Co5Ni60Mo10 (at.%) multi‐principal element alloy and providing the alloy superior localized corrosion resistance compared to conventional stainless steels and alloys. A spectral decomposition methodology involving the subtraction of Auger peaks overlapping the Fe 2p and Co 2p core level regions was applied for quantification of the oxide film composition and thickness. The results show that, at 100°C, the passive oxide film is mainly dehydrated and dehydroxylated. Obvious loss of Ni hydroxide and conversion of Mo (VI) to Mo (IV) species are observed at 200°C, with further reduction of Mo species to Mo (III) observed at 300°C. In this temperature range, the total cation quantity in the oxide film remains stable despite the compositional alteration. At 400°C, Cr (III) oxide forms at the expense of Fe and Mo oxides, resulting in an oxide film essentially consisting of chromium oxide. At 500°C, Cr (III) oxide is eliminated, making the passive film unstable at this temperature. Possible Cr oxide removal mechanisms are discussed. [ABSTRACT FROM AUTHOR]

The effects of surface pretreatments (degreasing and pickling) on the characteristics of the Trivalent Chromium Process (TCP) coating on pure aluminum and on AA2024-T351 aluminum alloy were investigated here by means of surface sensitive techniques: X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The XPS and ToF-SIMS results evidence that the TCP coating homogeneity is strongly dependent on the pretreatment process used. The TCP coverage factor, calculated from XPS results, is significantly lower, on both pure aluminum and AA2024-T351 alloy surface, when a pickling step is applied. One of the main effects of pickling pretreatment is strong metallic copper enrichment at the surface of the 2024 alloy, associated with chemical dissolution of Al-Cu intermetallic particles. However, it is evidenced here, that the copper enrichment is not detrimental for the quality of the TCP coating. The coating failure, observed when the pickling step is applied, can be assigned to a faster kinetics of the coating growth leading to formation of thicker conversion coating more susceptible to cracking or to the localized presence of aluminum fluoride species leading to the appearance of coating defects or detachment. [ABSTRACT FROM AUTHOR]

ToF-SIMS and XPS are combined to study the adsorption of tetradecyl-benzyldimethyl-ammonium (BDA-C14) bromide corrosion inhibitor on carbon steel surface. BDA-C14 forms a protective layer with N-containing polar head group interacting with carbon steel surface. The adsorbed inhibitor surface coverage strongly depends on immersion time and inhibitor concentration. A maximum and uniform coverage is found for sufficiently long exposure times at a critical inhibitor concentration of about 25 ppm w. The uniform adsorbed inhibitor layer formed on the surface mitigates the formation of iron chloride/hydroxide intermediates and thus enhances the corrosion protection of carbon steel in aggressive environment. • The adsorption of BDA-C14 corrosion inhibitor on carbon steel surface was studied by ToF-SIMS and XPS. • The inhibitor forms a protective layer with N-containing polar head group interacting with carbon steel surface. • The adsorbed inhibitor surface coverage strongly depends on immersion time and inhibitor concentration. • The critical concentration for a maximum and uniformed inhibitor coverage on carbon steel is determined. • The uniform adsorbed inhibitor layer on carbon steel can mitigate the formation of iron chloride/hydroxide intermediates. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ions mass spectrometry (ToF-SIMS) analyses were performed to characterize the interaction of Cu with mercaptobenzothiazole (MBT) in aqueous solution for 1 h and 24 h in absence and presence of NaCl. The fingerprints of the molecules are identified with XPS (S, N and C signals). The analysis of the Cu 2p core level and Auger Cu peaks allow us to show that the Cu metal is covered by a Cu 2 O oxide layer whose thickness increases with exposure time in the absence of MBT. It is found that MBT forms multilayers on Cu oxide and inhibits the oxide layer growth. The XPS data are consistent with MBT adsorbed on oxide in multilayers, with a small fraction adsorbed on metallic Cu. These interactions are then further characterized using ToF-SIMS. The results suggest adsorption of the MBT molecules in a strongly bonded layer through both S atoms of the organic molecule oriented towards the surface, covered by a weakly bonded multilayer. Quantitative treatments of XPS intensities allows us to evaluate a layer thickness of 23 Å and 32 Å after 1 h and 24 h, respectively. Co-adsorbed water is also identified. The presence of water in the organic layer (ratio H 2 O/MBT = 0.28) may explain the orientation of the molecules with S directed towards the surface and N interacting through H bonds with water molecules, as suggested by complementary DFT calculations. The adsorption of MBT is similar in presence of NaCl and in pure water, and also inhibits the oxide growth. In addition, MBT adsorption inhibits the adsorption of Cl on the Cu surface. Inductively Coupled Plasma Optical Emission Spectrophotometry (ICP OES) experiments demonstrate that MBT adsorption inhibits Cu dissolution, even after 20 days immersion in NaCl. Thus, we demonstrated that MBT, by adsorbing and forming a full monolayer at the Cu surface, inhibits further oxide growth, Cl adsorption and copper dissolution in NaCl. [Display omitted] • MBT adsorbs on Cu immersed in water and forms multilayers with thicknesses of 2.3–3.2 nm. • Adsorbed MBT inhibits the copper oxide growth, Cl adsorption and copper dissolution in NaCl. • The first MBT layer close to the substrate is bonded to copper via the two S atoms oriented towards the surface. • Water is present in the organic film in a ratio H 2 O/MBT = 0.28. • Water in the organic film has a determinant role in molecule orientation, as shown by DFT calculations. • A fraction of MBT is adsorbed on metallic copper, healing some depassivated areas. [ABSTRACT FROM AUTHOR]

• 5-sulfosalicylate as an inhibitor in 0.6 M NaCl electrolyte is used for Mg-air battery. • Upon the inhibitor application the improved discharge voltage and battery lifetime are observed. • Almost a four-fold reduction of the hydrogen evolution and a reduced Mg corrosion are noticed. • A modified structure and composition of the surface layer is observed. This work aims at employing sodium 5-sulfosalicylate (5-S-Sal) corrosion inhibitor into aqueous NaCl electrolyte to improve the discharge performance of Mg-air battery and decrease the side reactions of Mg anode. The corrosion tests at open circuit potential show a four-fold decrease of hydrogen evolution when 5-S-Sal inhibitor is added. X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry analyses show that due to the presence of 5-S-Sal inhibitor, a corrosion resistant layer has a lower quantity of Mg(OH) 2 (by ∼15%) than that formed in NaCl electrolyte. The surface enrichment in S-like species originating from inhibitor molecule could have an important effect on a decreased corrosion and slow down the H 2 evolution. Within a range of concentrations of 5-S-Sal in NaCl electrolyte (0.05 to 0.15 M), the best discharge performances are achieved with 0.1 M inhibitor. The discharge voltage of full Mg-air battery improves from ∼1.58 to ∼1.82 V at 0.5 mA/cm2 and the discharge lifetime is extended from around 12.5 to around 80 h. Scanning electron microscopy and 3D topography laser microscopy indicate that during the discharge tests much smaller surface degradation occurs and a more uniform surface layer is formed in the presence of inhibitor in the NaCl-based electrolyte. [ABSTRACT FROM AUTHOR]

Abstract: Copper alloys often used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation. The objective of this work was to study the influence of protein adsorption, which is the first step in biofilm formation, on the electrochemical behavior of 70Cu–30Ni (wt.%) alloy in static artificial seawater and on the chemical composition of oxide layers. For that purpose, electrochemical measurements performed after 1h of immersion were combined to surface analyses. A model is proposed to analyze impedance data. In the presence of bovine serum albumin (BSA, model protein), the anodic charge transfer resistance deduced from EIS data at Ecorr is slightly higher, corresponding to lower corrosion current. Without BSA, two oxidized layers are shown by XPS and ToF-SIMS: an outer layer mainly composed of copper oxide (Cu2O redeposited layer) and an inner layer mainly composed of oxidized nickel, with a global thickness of ~30nm. The presence of BSA leads to a mixed oxide layer (CuO, Cu2O, Ni(OH)2) with a lower thickness (~10nm). Thus, the protein induces a decrease of the dissolution rate at Ecorr and hence a decrease of the amount of redeposited Cu2O and of the oxide layer thickness. [Copyright &y& Elsevier]

Abstract: Sn–Co alloy films were prepared by electroplating on copper and used as anode material of lithium ion battery. Cyclic voltammetry and galvanostatic discharge/charge measurements were combined with surface analysis by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results show the buildup of a solid electrolyte interphase (SEI) layer formed by reductive decomposition of electrolyte during the first Li–Sn alloying cycle. The layer is constituted of a mixture of Li2CO3, ROCO2Li, lithium oxalates, and/or ROLi, and its chemical composition is modified during the electrochemical multi-cycling process with increase of the Li2CO3 content. Multi-cycling also fractures the SEI layer. ToF-SIMS results revealed an incomplete initial alloying process of lithium ion with Sn, limited by mass transport through a Co layer and dividing the Sn–Co layer alloy into a fully lithiated outer part and an essentially non-lithiated inner layer during the first discharge. The volume expansion/shrink associated with the alloying/dealloying reaction irreversibly cracks and splits up the Sn–Co alloy into particles with interstitials voids filled by the SEI layer. Multi-cycling amplifies this division of the Sn–Co layer without material loss and stabilizes discharge/charge capacity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal stability of Ni20Cr and Ni20Cr10Mo is investigated by XPS and in situ ToF-SIMS • The chemical modifications are studied during heating of surface oxides in vacuum • The highest thermal stability is observed for the pre-passivated Ni20Cr10Mo alloy. • The findings are useful to improve corrosion protection strategies. Thermal stability of surface oxides on Ni-20Cr and Ni-20Cr-10Mo alloys, including air formed native oxides and passive films formed by electrochemical passivation, was investigated by stepwise heat treatments in ultra-high vacuum up to 300 °C. The modifications of the surface oxides were analyzed by XPS and in situ ToF-SIMS. The analytical surface characterization at the nanoscale revealed modifications of the protective surface oxides that depend on temperature and nature of the alloy. A loss of Ni(OH) 2 in the outer hydroxide layer and a decrease of film thickness are observed on both alloys above 100 °C. At 200 °C, Ni hydroxide in the outer layer is no longer stable while MoO 3 decreases and MoO 2 increases in the oxide film. At 300 °C no native oxide film remains at the surface of Ni-20Cr alloy, whereas a thin Cr oxide film partially covering the surface remains on passivated Ni-20Cr and for both native and passivated surfaces of Ni-20Cr-10Mo alloy. It is shown that the thermal stability of the surface oxide is significantly improved by electrochemical passivation on both alloys and is further enhanced by the presence of Mo in the oxide on the Mo-containing alloy. Such findings are useful for the development of corrosion protection strategies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemical speciation of buried interface on rough substrates. • Sputtering by GD-OES and ToF-SIMS to access interfaces for XPS analysis. • GD-OES homogenous sputtering of thin conversion coating on rough substrate. • Application of Auger nanoprobe for characterization of local coating distribution. • Homogenous in-depth distribution of Cr in conversion coating. In order to describe the chemical composition and the distribution of a thin trivalent chromium conversion coating on rough electrodeposited Zn-based alloy substrate, a methodology combining surface analytical and sputtering techniques was used. A sputtering by argon in glow discharge optical emission spectrometry (GD-OES) and by oxygen using time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to monitor the in-depth chemical composition evolution of the conversion coating and define the metal-conversion coating interface. Surface topography measurements were performed by high resolution 3D optical microscope. The chemical characterization of the conversion coating on the top surface and near the rough metal-oxide interface inside the craters was performed by X-ray photoelectron spectroscopy. The local depth and composition of the conversion layer inside and outside the craters were performed by Auger electron spectroscopy nanoprobe equipped with coaxial detector to prevent from shadowing effect during measurement. The results indicated inhomogeneous sputtering inside the ToF-SIMS craters, which was attributed to the shadowing effect, caused by the roughness of the substrate and the 45° incidence angle ion gun. GD-OES sputtering appeared homogeneous in different areas inside the crater despite the roughness of the substrate, which was attributed to the perpendicular incidence angle of the sputtering. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interfacial passivation mechanisms studied on Cr- and Mo-containing alloy surfaces. • D 2 O labelling applied to study the growth of nanometer-thick passive oxide film. • D-labelled species mostly detected in outer hydroxide layer of passive film. • Minor inward hydroxyl diffusion from electrolyte during anodic passivation. • Key role of hydroxyls initially in native oxide in forming Cr hydroxide. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) combined with deuterium labelling (D 2 O), and X-ray photoelectron spectroscopy (XPS) were applied to investigate the interfacial transport mechanisms of hydroxyls between aqueous electrolyte and outer part of the protective oxide film during passivation of Cr 15 Fe 10 Co 5 Ni 60 Mo 10 multi-principal element alloy surfaces. A ToF-SIMS signal treatment methodology was developed to retrieve the in-depth distribution of deuterated hydroxides in the nanometer-thick surface oxide film. After immersion at free potential or anodic passivation in acidified D 2 O, the initial bilayer structure is retained. The use of heavy water electrolyte has no effect on the composition alterations induced by passivation. Deuterated species were detected mostly in the outer layer of the surface oxide film. Pure inward hydroxyl diffusion from electrolyte/oxide to oxide/metal interface is excluded from being primarily responsible for oxide film growth induced by anodic passivation. The hydroxyls from the dissolving hydroxide species are retained in the oxide film and participate in forming Cr hydroxide, thus reducing the hydroxyl surface uptake from the electrolyte. This work provides deeper insight into the mechanisms of oxide growth and corrosion protection induced by anodic passivation. [ABSTRACT FROM AUTHOR]

2,6-pyridinedicarboxylate (2,6-PDC) was studied as corrosion inhibitor for pure magnesium. The surface was prepared either by polishing or polishing followed by treatment with 1 M NaOH solution. The results show that 2,6-PDC promotes the formation of a denser protective oxide/hydroxide layer poor in PDC. The mechanism proposed includes forming weak PDC-Mg complexes that lower the free Mg2+ concentration available for the formation of Mg(OH) 2. This leads to growth of smaller Mg(OH) 2 platelets that are more densely packed and hence form a more protective layer. The highest inhibition efficiency of 2,6-PDC was achieved for samples with surface hydroxylated by NaOH treatment. • 2,6-PDC could effectively inhibit the corrosion of pure magnesium. • 2,6-PDC promotes the dissolution of pure magnesium during the initial phase of immersion. • 2,6-PDC promotes the formation of a denser Mg(OH) 2 /MgO on CP Mg samples. • The corrosion inhibition effect of 2,6-PDC is slightly improved by NaOH treatment on pure magnesium. [ABSTRACT FROM AUTHOR]

To investigate the origin of the protection effect of zinc salts against glass atmospheric alteration, the speciation of Zn2+ ions on glass according to the deposit protocol and the Zn2+ surface concentration, and its change over time, was investigated in the light of the respective performances of the treatments. In that respect, a combination of various characterization methods of the glass surface and near‐surface was used before and after aging experiments (temperature, relative humidity (RH) control) of the Zn‐treated glass. Different Zn‐species could be observed on the surface of the treated glass: chemisorbed species, physisorbed species and precipitated hydroxide phases, their respective distribution being highly dependent on the nature of the treatment and on the Zn2+ surface concentration. GI‐XAS (Zn K‐edge) and ToF‐SIMS experiments pointed out the conversion by thermal activation of these surface species into chemisorbed species inserted in the glass network in the near‐surface. The chemisorbed species appear to be the most effective ones for the glass protection, possibly by making the surface less soluble, less hydrophilic and even by acting as a diffusion barrier. [ABSTRACT FROM AUTHOR]

Following an industrial process to protect manufactured glass windows against atmospheric corrosion during their storage and transport, this research is focused on the possibility that a surface deposit of a small amount of zinc salts may efficiently reduce the atmospheric alteration kinetics of ancient glasses (soda, potash, and mixed alkali silicates). To this end, the chemical action of zinc salts was investigated by means of aging experiments (with temperature and relative humidity (RH) control) on three glass models, of which compositions are representative of the cultural heritage. When the treatment was performed on pristine glass (about 1 μg/cm2 of deposited Zn2+ ions), treated glass plates developed a significantly thinner hydrated layer than the untreated ones at 80°C or at 40°C (85 RH%). The formation of alkali and Ca‐carbonates salts on the surface was also considerably reduced. The state of the glass surface undergoing the Zn treatment and the temperature of the treatment seem critical regarding the efficacy of the protection. [ABSTRACT FROM AUTHOR]

• Thermal oxidation of Al-Cu-Li alloy is studied by in situ XPS & ToF-SIMS 3D mapping. • Li & Ag surface enrichment during annealing then Li oxidization during oxidation. • 2-step oxide growth: fast Al-Li oxide growth, slow Li-Mg surface oxide enrichment. • Li, Cu, Ag surface homogenous distribution & Mg enrichment at the grain boundaries. The thermal stability of Al-Cu-Li alloys is critical for the extreme working conditions in the aircraft industry. The initial stages of thermal oxidation of an industrial AA 2050-T8 Al-Cu-Li alloy were investigated by in situ XPS and ToF-SIMS. Annealing the sample at 200 °C leads to a surface enrichment in metallic Li and Ag. When exposed to oxygen at low pressure (P O 2 < 10−6 mbar) a mixed Li-Al oxide layer is formed. Photoemission intensities (recorded at 45° and 90° relative to the surface) are consistent with the formation of a continuous oxide layer for oxygen exposure from 0 to 5000 langmuirs (L). Assuming a homogeneous composition of the oxide layer, its thickness was 9 ± 1 Å at 5000 L. The relative content of Li and Al in the oxide layer evolves from an initial value of 50% to stabilize at 70% of Li above 100 L of oxygen exposure. Simultaneously, the content of Li at the alloy substrate surface is reduced from 10% to 0%. Moreover, specific segregation sites are evidenced by ToF-SIMS three-dimensional chemical mapping. For Li, a homogenous surface distribution while for Mg the accumulation at the grain boundaries were observed. The segregation of Ag at the oxide/alloy interface was confirmed by ToF-SIMS ion depth profiles. [ABSTRACT FROM AUTHOR]

• Ion transport in pre-formed passive film on 304L stainless steel is investigated in situ by ToF-SIMS. • The pre-formed passive film has a duplex structure with outer iron oxide and inner chromium oxide layers. • Exposure to isotopic 18O 2 at 300 °C of the pre-formed film reveals cation diffusion is governing the oxidation process. • The apparent diffusion coefficients are determined. • The cation diffusion coefficient is found to be markedly higher than the oxygen diffusion coefficient. The ion transport in the pre-formed passive film on 304L stainless steel surface has been investigated by in situ ToF-SIMS with isotopic tracer. The passive film, formed electrochemically in sulfuric acid, has a bilayer structure with outer iron oxide and inner chromium oxide layers. Further exposure of the passive film to 18O 2 gas (isotopic tracer) at 300 °C reveals that outward cation diffusion is the governing ion transport mechanism for the oxide growth. The parabolic rate constant for the oxide growth was determined. The cation diffusion coefficient is found to be markedly higher than the oxygen diffusion coefficient. [ABSTRACT FROM AUTHOR]

Low corrosion protection performances of Trivalent Chromium Process (TCP) coatings with reference to Chromium Conversion Coatings (CCC) deposited on aluminium alloys can be overcome by application of post-treatment processes. This work shows the effect of post-treatment bath (containing hydrogen peroxide and lanthanum salt) on the chemical composition, structure and the corrosion performances of TCP coating deposited on AA 2024-T3 aluminium alloy. Different times of post-treatment bath were applied on the TCP coating and the samples were analyzed by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and Glow Discharge-Optical Emission Spectrometry (GD-OES). The ToF-SIMS and GD-OES depth profiles show that the post-treatment time has no influence on the thickness of the TCP coating and on its bi-layered structure. It is composed of an outer layer, rich in zirconium and chromium oxides and an inner layer rich in aluminium oxides and oxy-fluorides. 3D ToF-SIMS images reveal an enrichment of Cr and Zr-like species over the surface of intermetallic particles with reference to alloy matrix, whereas a homogenous distribution of La is observed. The analysis of in-depth distribution shows that La is present principally in the outer part of the TCP coating. The La concentration increases with increasing post-treatment time. The effect of post-treatment time on protection was evaluated by Electrochemical Impedance Spectroscopy (EIS) and Linear Sweep Voltammetry (LSV) in a 0.001 M NaCl + 0.1 M Na 2 SO 4 electrolyte. The increased post-treatment time enhances the cathodic inhibition against oxygen reduction. The post-treatment provides improved coating homogeneity and sealing properties. • No thickness and structure modification of TCP coating induced by post-treatment • Significant inhibition of the cathodic oxygen reduction induced by post-treatment • Increase of La and decrease of Cr in TCP with higher post-treatment time • Homogenous surface distribution of La responsible for sealing coating defects [ABSTRACT FROM AUTHOR]

Fe-based air alkaline batteries are promising candidates for large scale energy storage due to their low cost, eco-friendliness and high energy density. In this work, pure iron was studied as negative electrode of Fe-air batteries with and without Na 2 S added to the KOH alkaline electrolyte in order to bring new insight on the mechanisms of inhibition of the hydrogen evolution reaction (HER) and improvement of the electrochemical performances of the Fe electrode. Electrochemical (CV, galvanostatic discharge), spectroscopic (XPS, ToF-SIMS) and microscopic (SEM) analysis were applied to characterize the effect of the sulfide additive (Na 2 S) on the electrochemical behavior of Fe electrodes and their chemical and morphological modifications. Surface analysis performed by XPS and ToF-SIMS revealed the formation of a markedly thicker oxide/hydroxide layer. The mechanism of formation of this thick oxide/hydroxide layer is initiated by the adsorption of sulfur (S ads ) at the oxide/metal interface that inhibits the HER during the first stages of electrochemical process and promotes subsequent anodic oxidation. With the Na 2 S electrolyte additive, Fe(0)/Fe(II) conversion/deconversion is suppressed and charge/discharge proceeds mostly by Fe(II)/Fe(III) conversion/deconversion with improved capacity owing to the porous morphology of the oxide/hydroxide layer. [ABSTRACT FROM AUTHOR]

• Investigation of native and passive surface films formed on Ni-20 at.% Cr alloy surfaces. • Surface analysis by in situ electrochemical measurements combined with advanced ex situ surface analysis. • Mechanistic understanding of the effects of high-temperature hydrogen annealing pretreatment. • Enhanced corrosion resistance of electrochemically passivated surface by high-temperature hydrogen annealing pretreatment. • Increase in Cr enrichment of initially weakly protected sites of the inner barrier layer. The effect of high-temperature annealing under hydrogen gas (H 2) surface preparation on a binary polycrystalline Ni-20 at.% Cr alloy was investigated in comparison with conventional mechanical grinding surface preparation. Duplex surface films with inner Cr(III) oxide and outer Ni(II) and Cr(III) hydroxide layers natively formed before and after H 2 annealing were characterized by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. A thinner and less homogeneous inner barrier layer formed after H 2 annealing caused an oxidation peak at the active/passive transition in the linear sweep voltammetry measurement in a 0.5 M H 2 SO 4 solution. Despite this high oxidation peak, passivation of the H 2 annealed surface resulted in the formation of a more corrosion resistant inner layer than on the mechanically ground surface, as demonstrated by electrochemical impedance spectroscopy. The corrosion resistant passive film formation of the H 2 annealed surface is attributed to the increased Cr enrichment of the inner layer caused by the selective Ni dissolution providing corrosion resistance to the initially weakly protected sites of the natively formed surface film. [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids (RTILs) attract much attention as a new type of environmentally benign electrolytes for Li-ion batteries due to their numerous interesting physicochemical properties. Here, in this paper, Li intercalation/deintercalation in presence of the N -butyl- N -methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (PYR 14 TFSI) and N -methyl- N -propylpyrrolidinium bis(fluorosulfonyl)imide (PYR 13 FSI) containing 0.3 M LiTFSI, was evaluated in a thin 100 nm layer of V 2 O 5 deposited on Al substrate by atomic layer deposition. Potentiodynamic tests performed in LiTFSI/Pyr 14 TFSI show a quasi-reversible Li intercalation during 10 cycles (between 2.4 and 5 V) with an average coulombic efficiency of 99%. The capacity, calculated from the 1st cycle, is found to be 182 mAh g −1 , about 19% (±2%) higher than the theoretical capacity reported for V 2 O 5 (147 mAh g −1 ). X-ray photoelectron spectroscopy analysis confirms that the intercalation of more than 1 mol of Li + per V 2 O 5 is achieved as also the possible presence of a solid permeable interface (SPI) layer on the V 2 O 5 surface. Likewise, the Li + in-depth distribution on the V 2 O 5 layer after intercalation in RTILs measured by time-of-flight secondary ion mass spectrometry ion depth profiles, show small irreversible electrode modifications with the presence of lithium through the entire V 2 O 5 layer with significant lithium trapping at the V 2 O 5 layer/Al substrate interface. [ABSTRACT FROM AUTHOR]

• Corrosion inhibition and interfacial bonding of 2-MBT studied on copper. • Electrochemistry combined with advanced surface analysis by XPS and ToF-SIMS. • Inhibition enhanced by cathodic reduction of interface before 2-MBT adsorption. • 2-MBT bonded to metallic copper and copper oxide islands via the S atoms. • Exo- and endocyclic S atoms released by dissociation and bonded to metallic Cu. Electrochemistry along with advanced surface analyzes (X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry) were implemented to investigate copper corrosion inhibition by 2-mercaptobenzothiazole (2-MBT) in hydrochloric aqueous solution and the effects of electrochemical control on the formation of the inhibiting interface. It is shown that reducing the native surface oxide by cathodic reduction prior to exposure to the inhibitor drastically decreases the rate of anodic dissolution. Additionally, increasing the exposure time of the metal surface to the inhibitor results in even better protection against dissolution. 2-MBT adsorbs as multilayers and bonds to both metallic copper and residual copper oxide islands via its sulphur atoms. Partial dissociation of the molecule, releasing the exocyclic sulphur, which then bonds to metallic Cu, is observed. Further dissociation of the molecule, releasing the endocyclic sulphur, is induced by anodic polarization, forming defects in the organic layer and thus compromising the barrier properties of the organic layer. [ABSTRACT FROM AUTHOR]

The high self-corrosion rate of Mg in aqueous electrolyte generates H 2 , which is the main impediment to restrict the utilization of Mg-air batteries. However, organic/inorganic hybrid electrolyte is prone to reduce the Mg degradation. Herein, the effect of different ethanol fractions in water with 0.6 M NaCl on corrosion behavior of Mg and battery discharge performances is demonstrated. The significant corrosion inhibition in a high content of ethanol (≥20 vol%) in electrolyte is attributed to the formation of a thinner, more corrosion protective layer enriched in magnesium oxide as demonstrated by scanning electron microscopy, X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Contrarily, in water-based electrolyte a thick, porous and rough layer principally composed of magnesium hydroxide is formed. By varying the ethanol to water fraction in the electrolyte in full battery cell, it is shown that even a small ethanol content (≤ 5 vol%), can greatly enhance the electrochemical performances of Mg anode. Within several ethanol content, 0.5 vol% demonstrates the best performances with a limited corrosion rate and greatly improves the discharge performance and the battery lifetime. It is demonstrated here that application of inorganic/organic dual electrolyte is a promising and easy way towards a well-controlled Mg anode reactivity and improved performances of Mg-air battery. [Display omitted] • Significant corrosion inhibition in high content of ethanol (≥ 20 vol%). • Formation of a thinner, more corrosion protective layer enriched in MgO in presence of ethanol. • Growth of a thick, porous and rough layer composed of Mg(OH) 2 in water-based electrolyte. • The best discharge performance and battery lifetime in 0.5 vol% ethanol content. [ABSTRACT FROM AUTHOR]

Surface smoothening by substrate annealing was studied as a pre-treatment for improving the corrosion protection provided to copper by 10, 20 and 50 nm thick alumina coatings deposited by atomic layer deposition. The interplay between substrate surface state and deposited film thickness for controlling the corrosion protection provided by ultrathin barrier films is demonstrated. Pre-annealing at 750 °C heals out the dispersed surface heterogeneities left by electropolishing and reduces the surface roughness to less than 2 nm independently of the deposited film thickness. For 10 nm coatings, substrate surface smoothening promotes the corrosion resistance. However, for 20 and 50 nm coatings, it is detrimental to the corrosion protection due to local detachment of the deposited films. The weaker adherence of the thicker coatings is assigned to the stresses accumulated in the films with increasing deposited thickness. Healing out the local heterogeneities on the substrate surface diminishes the interfacial strength that is bearing the stresses of the deposited films, thereby increasing adhesion failure for the thicker films. Pitting corrosion occurs at the local sites of adhesion failure. Intergranular corrosion occurs at the initially well coated substrate grain boundaries because of the growth of a more defective and permeable coating at grain boundaries. [ABSTRACT FROM AUTHOR]

Electrochemical and surface analyses were applied to study the corrosion mechanisms of aluminium protected by ultra-thin (≤50 nm) alumina coatings grown by atomic layer deposition. Corrosion takes place via residual channel defects connecting the substrate to the electrolyte through the insulating coating. The data evidence the growth of a spurious aluminium oxide film at the substrate/coating interface in the reactor, that is beneficial to the sealing performance of the thinner films (10 nm). The resistance to the initiation of localized corrosion by pitting is increased with thicker films (20 and 50 nm) owing to improved sealing and barrier properties. [ABSTRACT FROM AUTHOR]

The effect of the interfacial air-formed native copper oxide layer on the corrosion protection of copper with 20 nm Atomic Layer Deposited (ALD) alumina was investigated in 0.5 M NaCl using electrochemical and surface analysis techniques. The results show that dissolution of the interfacial native oxide by a pre-treatment of the copper substrate with phosphoric acid is beneficial to the sealing property of the coating and to the corrosion resistance of the substrate exposed through channel defects. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) elemental depth profiling evidenced the modifications of the interfacial copper oxide on a pre-treated substrate including cleaning from organic contaminants. The beneficial effects of the pre-treatment include improved ALD nucleation and growth due to interface cleaning and decreased cathodic electrochemical activity (assigned to oxygen reduction) at the end of the channel defects exposing the substrate to the environment. Electrochemical Impedance Spectroscopy (EIS) analysis revealed a remarkably lower porosity of the bulk of the ALD alumina layers as compared to the coating/substrate interface, suggesting interfacial trenching as a major failure mechanism for the corrosion protection. Interfacial trenching can be reduced with a freshly re-grown interfacial oxide on the pre-treated substrate surface. The necessity for better controlling the interface chemistry for improved corrosion protection by ALD alumina is demonstrated. [ABSTRACT FROM AUTHOR]

The oxidation of Cu 0.7 Zn 0.3 (111) exposed to O 2 at low pressure (7.0 × 10 − 7 mbar) and higher pressure (1 mbar) both at 400 K has been investigated by photoelectron spectroscopy. The results evidenced a preferential oxidation of Zn at the surface in agreement with the literature and Zn segregation to the surface. Moreover, a systematic fitting procedure of high-resolution spectra enabled us to decompose the Zn 2p core-level peak into metallic and oxide components in order to follow the growth of the oxide. By combining these results with careful analysis of the Zn L 3 M 45 M 45 Auger transition, we evidenced the formation of a discontinuous ZnO layer (3D ZnO islands) in both pressure conditions. Measurements of the O 1s peak for two photon energies using synchrotron radiation allowed us to identify interface and bulk components. Changes in the Zn 3d level and valence band during the initial steps of oxidation were also followed. We show that not only thermodynamics but also kinetic effects have to be considered to describe this complex oxidation process. The importance of the role played by the structural quality of the sample on the composition, growth kinetic and structure of the surface oxide layer is evidenced. [ABSTRACT FROM AUTHOR]

(Fe,Cr)-binary oxide thin film electrodes were prepared as negative electrode material for lithium-ion micro-batteries by thermal growth on a stainless steel (AISI 410, FeCr 12.5 ) current collector. The mechanisms of lithiation/delithiation were investigated by means of electrochemical (CV, galvanostatic cycling), spectroscopic (XPS, ToF-SIMS) and microscopic (SEM, AFM) analytical techniques. The as-prepared (Fe, Cr)-binary oxide electrodes exhibit a good cycling performance except the first discharge/charge cycle where a high irreversible capacity is observed due to formation of a solid electrolyte interphase (SEI) layer. The influence of substituting an oxidized iron by an oxidized chromium (Cr x Fe 2− x O 3 phase) was evaluated. The data show that the inferior electrochemical conversion activity of substituted oxidized chromium results in hindering lithium transport in the bulk thin film electrode. It was observed that the irreversible morphology modifications together with SEI evolution are critical to capacity degradation while retaining good coulombic efficiency. [ABSTRACT FROM AUTHOR]

Silicate glasses are durable solids, and yet they are chemically unstable in contact with aqueous fluids-this has important implications for numerous industrial applications related to the corrosion resistance of glasses, or the biogeochemical weathering of volcanic glasses in seawater. The aqueous dissolution of synthetic and natural glasses results in the formation of a hydrated, cation-depleted near-surface alteration zone and, depending on alteration conditions, secondary crystalline phases on the surface. The long-standing accepted model of glass corrosion is based on diffusion-coupled hydration and selective cation release, producing a surface-altered zone. However, using a combination of advanced atomic-resolution analytical techniques, our data for the first time reveal that the structural and chemical interface between the pristine glass and altered zone is always extremely sharp, with gradients in the nanometre to sub-nanometre range. These findings support a new corrosion mechanism, interfacial dissolution-reprecipitation. Moreover, they also highlight the importance of using analytical methods with very high spatial and mass resolution for deciphering the nanometre-scale processes controlling corrosion. Our findings provide evidence that interfacial dissolution-reprecipitation may be a universal reaction mechanism that controls both silicate glass corrosion and mineral weathering. [ABSTRACT FROM AUTHOR]

Copper alloys, often used in cooling circuits of industrial plants using seawater as coolant, can be affected by biocorrosion induced by biofilm formation. Extracellular polymeric substances (EPS) produced by bacteria play a fundamental role in the different stages of biofilm formation, maturation and maintenance. The influence of loosely bound (LB) and tightly bound (TB) EPS, extracted from marine Pseudomonas NCIMB 2021, on the electrochemical behaviour of 70Cu–30Ni (wt.%) alloy in static artificial seawater (ASW) and on the chemical composition of oxide layers was studied by combined electrochemical measurements (polarization curves, EIS) and surface analysis (XPS, ToF-SIMS). Results were compared with those obtained in the presence of bovine serum albumin (BSA), a model protein. Compared to 70Cu–30Ni alloy in static ASW without biomolecules, for which a thick duplex oxide layer (outer redeposited Cu 2 O layer and inner oxidized nickel layer) is shown, the presence of BSA, TB EPS and LB EPS leads to a mixed oxide layer (oxidized copper and nickel) with a lower thickness. In the biomolecules-containing solutions, this oxide layer is covered by an adsorbed organic layer, mainly composed of proteins. A model is proposed to analyse impedance data obtained at the corrosion potential. The fitting procedure of impedance diagrams allows extracting the anodic charge transfer resistance, from which the corrosion current density can be calculated. The results show a slow-down of the anodic reaction in the presence of biomolecules (BSA, TB EPS and LB EPS), and a corrosion inhibition effect by LB EPS and to a lesser extent by BSA. No detrimental effect is evidenced with TB EPS. [ABSTRACT FROM AUTHOR]