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  • 1. Aastrup, T.
    et al.
    Wadsak, M.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Schreiner, M.
    In situ studies of the initial atmospheric corrosion of copper influence of humidity, sulfur dioxide, ozone, and nitrogen dioxide2000In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 147, no 7, p. 2543-2551Article in journal (Refereed)
    Abstract [en]

    Infrared reflection absorption spectroscopy and quartz crystal microbalance, integrated into a one-surface analytical system, and complemented with tapping mode atomic force microscopy, has been used to explore the metal/atmosphere interfacial region under atmospheric pressure conditions. This unique combination of ill situ techniques, all possessing submonolayer sensitivity, has revealed information on the different accelerating roles of ozone (O-3) and nitrogen dioxide (NO2) on the SO2-induced atmospheric corrosion of copper. The formation of reaction products could be followed quantitatively with respect to chemical identity and kinetics. Exposure in SO2-containing humidified air resulted in CuSO3. xH(2)O-like species, formed atop a cuprous oxide, designated Cu2O, all over the copper surface. O-3 introduction resulted in an accelerated mass gain with an increased formation rate of both Cu2O and of CuSO4. xH(2)O all over the surface. NO2 introduction resulted in less mass gain than observed under SO2 and O-3, with no formation of new Cu2O, an initial oxidation of CuSO3. xH(2)O to CuSO4. xH(2)O, and with sulfite oxidation gradually replaced by copper nitrate formation, possibly as CuNO3(OH)(3) The formation rates of the dominating end products, CuSO4. xH(2)O in SO2/O-3 and Cu2NO3(OH)(3) in SO2/NO2 seemed to be limited by the supply of the gaseous constituents.

  • 2. Aastrup, T.
    et al.
    Wadsak, M.
    Schreiner, M.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Experimental in situ studies of copper exposed to humidified air2000In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 42, no 6, p. 957-967Article in journal (Refereed)
    Abstract [en]

    Three complementary experimental techniques for in situ surface analysis have been combined for the first time in order to explore the chemistry and physics of a copper surface exposed to humidified air. Infrared reflection absorption spectroscopy, quartz crystal microbalance and atomic force microscopy provide a congruent picture of the processes occurring at the surface. At a given relative humidity, cuprous oxide forms according to an approximately logarithmic rate law. In addition, an aqueous adlayer of constant mass physisorbs on the surface. Increased relative humidity stimulates the physisorption of water and enhances the nucleation rate of oxide grains, thereby increasing the formation rate of cuprous oxide.

  • 3.
    Adhikari, Arindam
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Pani, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Deidinaitei, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Blomberg, Eva
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Electrochemical behavior and anticorrosion properties of modified polyaniline dispersed in polyvinylacetate coating on carbon steel2008In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 53, no 12, p. 4239-4247Article in journal (Refereed)
    Abstract [en]

    Conducting polyaniline (Pani) was prepared in the presence of methane sulfonic acid (MeSA) as dopant by chemical oxidative polymerization. The Pani-MeSA polymer was characterized by FT-IR, UV-vis, X-ray diffraction (XRD) and impedance spectroscopy. The polyrner was dispersed in polyvinylacetate and coated oil carbon steel samples by a dipping method. The electrochemical behavior and anticorrosion properties of the coating, oil carbon steel in 3% NaCl were investigated using Open-circuit Potential (OCP) versus time of exposure, and electrochemical techniques including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and cyclic voltammetry (CV). During initial exposure, the OCP dropped about 0.35 V and the interfacial resistance increased several times, indicating I certain reduction of the polymer and oxidation of the steel surface. Later the OCP shifted to the noble direction and remained at a stable value during the exposure up to 60 days. The EIS monitoring also revealed the initial change and later stabilization of the coating. The stable high OCP and low coating impedance Suggest that the conducting polymer maintains its oxidative state and provides corrosion protection for carbon steel through out the investigated period. The polarization curves and CV show that the conducting polymer coating induces a passive-like behavior and greatly reduces the corrosion of carbon steel.

  • 4.
    Alvarez-Asencio, Rubén
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Bettini, Eleonora
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nanotribology and Microstructure of a CoCrMo Alloy: A TribologicalProperties Mapping StudyManuscript (preprint) (Other academic)
  • 5. Bahar, B.
    et al.
    Herting, G.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Hakkila, K.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    Virta, M.
    The interaction between concrete pavement and corrosion-induced copper runoff from buildings2008In: Environmental Monitoring & Assessment, ISSN 0167-6369, E-ISSN 1573-2959, Vol. 140, no 1-3, p. 175-189Article in journal (Refereed)
    Abstract [en]

    Changes in chemical speciation of copper and the capacity of concrete pavement to retain copper in runoff water from external buildings have been investigated at urban field conditions, and in parallel laboratory experiments simulating outdoor scenarios. The research study showed the concrete surface to form a copper rich surface layer (approximate to 50 mu m thick) upon exposure, and a high capacity to significantly reduce the bioavailable fraction of released copper (20-95%). The retention capacity of copper varied between 5 and 20% during single runoff events in the laboratory, and between 10 and 40% of the total copper release during single natural runoff events. The capacity to retain and reduce the bioavailable fraction of non-retained copper increased with increasing wetness of the concrete surfaces, increasing pH of the runoff water and decreasing flow rates. Bioassay testing with bacterial and yeast bioreporters showed the bioavailable fraction of non-retained copper to be significantly lower than the total copper concentration in the runoff water, between 22 and 40% for bacteria and between 8 and 31% for yeast. The application of generated data to simulate a fictive outdoor scenario, suggests a significant reduction of bioavailable and total copper to background values during environmental entry as a result of dilution, and the interaction with solid surfaces, organic matter and complexing agents already in the drainage system.

  • 6.
    Bahar, Babak
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Corrosion-induced copper release from rain gutters2008In: Metall (Berlin. 1947), ISSN 0026-0746, Vol. 62, no 3, p. 129-135Article in journal (Refereed)
    Abstract [en]

    While runoff rates from copper roofs have been extensively studied during the last years, corresponding studies from copper rain gutters have been missing. A laboratory investigation has been undertaken to examine the influence of important runoff water parameters on the copper runoff from rain gutters. At a given rainfall quantity, the release rate of copper increases with decreasing runoff water intensity and decreasing degree of gutter inclination, and with increasing runoff acidity and increasing Cu2+-ion concentration in the runoff water. A comparison of the predicted long-term copper release from the gutter-system compared to the roof on a real building suggests that less than 5% of the total copper runoff originates from the gutter. However, single rain events may result in higher release rates, especially during the initial rain portion.

  • 7.
    Belonoshko, Anatoly B.
    et al.
    KTH, Superseded Departments, Physics.
    Rosengren, Anders
    KTH, Superseded Departments, Physics.
    Dong, Qian
    KTH, Superseded Departments, Materials Science and Engineering.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    First-principles study of hydrogen diffusion in alpha-Al2O3 and liquid alumina2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 69, no 2Article in journal (Refereed)
    Abstract [en]

    We have studied the energetics and mobility of neutral hydrogen in alumina Al2O3 using ab initio density-functional calculations. The mobility of hydrogen was studied in corundum (alpha-Al2O3) as well as in liquid alumina. Using both static as well as molecular-dynamics calculations, and applying classical transition state theory, we derive the temperature-dependent diffusivity of hydrogen in alpha-Al2O3 as D(T)=(21.7x10(-8) m(2)/s)exp(-1.24 eV/kT). The corresponding diffusivity of hydrogen in liquid/amorphous alumina, derived directly from ab initio molecular dynamics calculations, is D(T)=(8.71x10(-7) m(2)/s)exp(-0.91 eV/kT). The computed diffusivity compares very well to experimental data. We conclude that diffusion of neutral hydrogen through the bulk of alumina is a good approximation of the mechanism for hydrogen mobility in corrosion scales. The representation of grain-boundary structures by amorphous alumina is, probably, realistic at higher temperatures.

  • 8.
    Belonoshko, Anatoly B.
    et al.
    KTH, Superseded Departments, Physics.
    Rosengren, Anders
    KTH, Superseded Departments, Physics.
    Dong, Qian
    KTH, Superseded Departments, Materials Science and Engineering.
    Hultquist, Gunnar
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    First-principles study of hydrogen diffusion in α-Al 2O3 and liquid alumina2004In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 69, no 2, p. 243021-243026Article in journal (Refereed)
    Abstract [en]

    We have studied the energetics and mobility of neutral hydrogen in alumina Al2O3 using ab initio density-functional calculations. The mobility of hydrogen was studied in corundum (α-Al2O 3) as well as in liquid alumina. Using both static as well as molecular-dynamics calculations, and applying classical transition state theory, we derive the temperature-dependent diffusivity of hydrogen in α-Al 2O3 as D(T)=(21.7 × 10-8 m 2/s)exp(-1.24 eV/kT). The corresponding diffusivity of hydrogen in liquid/amorphous alumina, derived directly from ab initio molecular dynamics calculations, is D(T)=(8.71 × 10-7 m2/s)exp(-0.91 eV/kT). The computed diffusivity compares very well to experimental data. We conclude that diffusion of neutral hydrogen through the bulk of alumina is a good approximation of the mechanism for hydrogen mobility in corrosion scales. The representation of grain-boundary structures by amorphous alumina is, probably, realistic at higher temperatures.

  • 9. Berggren, D.
    et al.
    Bertling, Sofia
    KTH, Superseded Departments, Materials Science and Engineering.
    Heijerick, D.
    Herting, Gunilla
    KTH, Superseded Departments, Materials Science and Engineering.
    Koundakjian, P.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, Superseded Departments, Materials Science and Engineering.
    Release of Chromium, Nickel and Iron from Stainless Steel Exposed under Atmospheric Conditions and The Environmental Interaction of these Metals: A Combined Field and Laboratory Investigation2004Report (Other academic)
  • 10.
    Bertling, Sofia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Degryse, F.
    Laboratory for Soil and Water Management, Catholic University of Leuven.
    Odnevall Wallinder, Inger
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Smolders, E.
    Laboratory for Soil and Water Management, Catholic University of Leuven.
    Leygraf, Christofer
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Model studies of corrosion induced copper runoff fate in soil2006In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 25, no 3, p. 683-691Article in journal (Refereed)
    Abstract [en]

    Laboratory experiments have been performed with 3-cm soil columns simulating the fate of corrosion-induced copper runoff in contact with soil. The investigation simulates approximately 30 years (assuming an infiltration surplus of 25 cm/year) of continuous percolation of copper containing runoff water of a concentration realistic at the immediate release situation (4.8 mg/L) into four soils representative of urban conditions. Two of the three investigated topsoils reached their breakthrough of copper within the simulated time, while the third topsoil did not show a breakthrough. The subsoil reached a breakthrough after approximately 10 years of simulated exposure. To simulate more realistic outdoor scenarios, the laboratory-obtained breakthrough curves were modeled with Hydrus-1D (R) using a Langmuir-Freundlich model to describe copper sorption, the parameters of which were estimated from soil properties (pH, organic carbon content). The model predicts longer breakthrough times with increasing pH and organic content of the soil and with decreasing concentrations of copper and dissolved organic carbon in the runoff water. The time span for copper in runoff water (at concentrations of 0.01-10 mg/L) to reach a soil depth of 50 cm varied between 170 and more than 8,000 years for the predicted field scenarios.

  • 11.
    Bertling, Sofia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Berggren Kleja, Daniel
    Department of Soil Sciences, Swedish University of Agricultural Sciences, SLU, Uppsala, Sweden.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Long-term corrosion-induced copper runoff from natural and artificial patina and its environmental impact2006In: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 25, no 3, p. 891-898Article in journal (Refereed)
    Abstract [en]

    The overall objective of this paper is to present an extensive set of data for corrosion-induced copper dispersion and its environmental interaction with solid surfaces in the near vicinity of buildings. Copper dispersion is discussed in terms of total copper flows, copper speciation and bioavailability at the immediate release situation, and its changes during transport from source to recipient. Presented results are based on extensive field exposures (eight years) at an urban site, laboratory investigations of the runoff process, published field data, generated predictive site-specific runoff rate models, and reactivity investigations toward various natural and manmade surfaces, such as those in soil, limestone, and concrete. Emphasis is placed on the interaction of copper-containing runoff water with different soil systems through long-term laboratory column investigations. The fate of copper is discussed in terms of copper retention, copper chemical speciation, breakthrough capacities, and future mobilization based on changes in copper concentrations in the percolate water, computer modeling using the Windermere Humic Aqueous Model, and sequential extractions. The results illustrate that, for scenarios where copper comes in extensive contact with solid surfaces, such as soil and limestone, a large fraction of released copper is retained already in the immediate vicinity of the building. In all, both the total copper concentration in runoff water and its bioavailable part undergo a significant and rapid reduction.

  • 12.
    Bertling, Sofia
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Immobilization of copper in runoff water from roofing materials by limestone, soil and concrete2002In: 15th Internatioal Corrosion Conference: Granada, Spain, 2002Conference paper (Refereed)
  • 13.
    Bertling, Sofia
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    The capacity of limestone to immobilize copper in runoff water: a laboratory investigation2002In: 15th International Corrosion Conference: Granada, Spain, 2002Conference paper (Refereed)
  • 14.
    Bertling, Sofia
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Berggren, D.
    KTH, Superseded Departments, Materials Science and Engineering.
    Environmental effects of zinc runoff from roofing materials: a new multidisciplinary approach2002In: Outdoor Atmospheric Corrosion / [ed] Townsend HE, 2002, Vol. 1421, p. 200-215Conference paper (Refereed)
    Abstract [en]

    The objective of this work is to study changes in concentration and bioavailability of zinc-containing runoff water, released from roofing materials, upon passage through soil. The experimental approach is based on simulating the interaction between zinc in artificial runoff water and soil in a column system.

    The total zinc concentration of runoff was substantially reduced when passing through the soil and suggests marked zinc retention, During a constant flow and supply of zinc into the soil, equivalent to three and a half years of precipitation in Stockholm, a zinc retention capacity of approximately 99% was recorded, Not only the total concentration, but also the bio-available portion of the total zinc concentration was reduced after passage through soil, Most of the retained zinc was located in top 3 cm of the soil core and suggests the total capacity for zinc retention of the investigated soil to be about 140 years per kilogram soil in an isolated system in real systems, changes of temperature, pH, microbial activity, weathering of minerals and deposition of new organic material must be considered.

    The results form part of the effect assessment, preceding future risk assessment of the environmental effects of dispersed zinc.

  • 15.
    Bertling, Sofia
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Leygraf, Christofer
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Berggren, Kleja D.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Occurrence and fate of corrosion-induced zinc in runoff water from external structures2006In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 367, no 2-3, p. 908-923Article in journal (Refereed)
    Abstract [en]

    This paper comprises data from an extensive cross-disciplinary research project aiming to elucidate the environmental fate of corrosion-induced zinc release from external structures. It includes an exposure assessment that provide long-term runoff rates, concentrations and chemical speciation of zinc, from 14 zinc-based materials exposed during 5 years in Stockholm, Sweden, and an effect assessment including bioavailability and ecotoxicity measurements, both at the immediate release situation and after soil interaction.Runoff rates of total zinc ranged from 0.07 to 2.5g Znm(-2) yr(-1) with zinc primarily released as the free ion for all materials investigated. The average effect concentration, causing a 50% growth reduction after 72h to the green algae Raphidocelis subcapitata, was at the immediate release situation 69 mu g ZnL-1. Upon interaction of runoff water with soil, which simulated 18 to 34years of exposure, the total zinc concentration was significantly reduced, from milligram per litre to microgram per litre levels. Simultaneously, the most bioavailable fraction of zinc in runoff, the hydrated zinc(II)-ion, decreased from more than 95% to about 30%. The major fraction, 98-99%, of the introduced total zinc concentration in the runoff water was retained within the soil. As long as the soil retention capacity was not reached, this resulted in zinc concentrations in the percolate water transported through the soil layer, close to background values and below growth inhibition concentrations for the green algae investigated. Zinc retained in soil was to a large extent (85-99.9%) extractable with EDTA, and available for plant uptake after 5 to 7months of ageing.

  • 16.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Eriksson, Tom
    Bostrom, Magnus
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Influence of metal carbides on dissolution behavior of biomedical CoCrMo alloy: SEM, TEM and AFM studies2011In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 56, no 25, p. 9413-9419Article in journal (Refereed)
    Abstract [en]

    The influence of precipitate carbides on dissolution tendency and behavior of a biomedical CoCrMo alloy was investigated at microscopic scale. SEM/EDS, TEM/EDS and XRD were performed to characterize crystallographic structure and composition of different precipitate carbides. Scanning Kelvin probe force microscope (SKPFM) was used to evaluate relative nobility of the carbides. In addition to polarization curves, in situ electrochemical AFM (EC-AFM) measurements were performed to investigate the effect of the carbides on local dissolution processes. SEM/EDS, TEM/EDS and XRD characterizations showed non-uniform structure and composition of Cr and Mo carbides. SKPFM analysis suggested the carbide boundaries as preferential sites for corrosion/dissolution process. Cyclic polarization curves of the alloy in phosphate-buffered saline (PBS) solution showed a large current density increase above a certain potential, but only a small hysteresis loop during reverse scan. No noticeable pitting corrosion was observed by SEM after the experiments. In situ AFM images of the sample in PBS showed a stable surface at potentials in the passive region and around the potential corresponding to the current increase and slight etching-like dissolution around the carbides at higher potentials. Carbide boundaries are preferential sites for metal dissolution and carbides with non-uniform composition might exhibit different dissolution rates.

  • 17.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kivisäkk, Ulf
    Sandvik Materials Technology.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Study of corrosion behavior of a 22% Cr duplex stainless steel: influence of nano-sized chromium nitrides and exposure temperature2013In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 113, p. 280-289Article in journal (Refereed)
    Abstract [en]

    Chromium nitrides may precipitate in duplex stainless steels during processing and their influence on the corrosion behavior is of great importance for the steel performance. In this study, the influence of nano-sized quenched-in chromium nitrides on the corrosion behavior of a heat treated 2205 duplex stainless steel was investigated at room temperature and 50 °C (just above critical pitting temperature). The microstructure was characterized by SEM/EDS and AFM analyses, and quenched-in nitrides precipitated in the ferrite phase were identified by TEM analysis. Volta potential mapping at room temperature suggests lower relative nobility of the ferrite matrix. Electrochemical polarization and in-situ AFM measurements in 1 M NaCl solution at room temperature show a passive behavior of the steel despite the presence of the quenched-in nitrides in the ferrite phase, and preferential dissolution of ferrite phase occurred only at transpassive conditions. At 50 °C, selective dissolution of the austenite phase was observed, while the ferrite phase with the quenched-in nitrides remained to be stable. It can be concluded that the finely dispersed quenched-in nitrides do not cause localized corrosion, whereas the exposure temperature has a strong influence on the corrosion behavior of the duplex stainless steel.

  • 18.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Kivisäkk, Ulf
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Study of Corrosion Behavior of a 2507 Super Duplex Stainless Steel: Influence of Quenched-in and Isothermal Nitrides2014In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 9, no 1, p. 61-80Article in journal (Refereed)
    Abstract [en]

    Precipitation of different types of chromium nitrides may occur during processing of super duplex stainless steels, affecting the properties of the material. In this study the influence of quenched-in (size range ca. 50-100 nm) and isothermal (size range ca. 80-250 nm) types of nitrides on the corrosion behavior of a 2507 super duplex stainless steel has been investigated at room temperature and at 90 degrees C (above the critical pitting temperature) in 1 M NaCl solution. The microstructure has been characterized by scanning electron microscopy and magnetic force microscopy. The isothermal nitrides exhibit a higher Volta potential compared to the matrix, but such difference could not be observed for the quenched-in nitrides. In-situ electrochemical AFM measurements at room temperature show stable surfaces for a wide range of applied potentials despite the presence of either type of nitrides. In the transpassive region isothermal nitrides appear to be slightly more deleterious than quenched-in nitrides. At 90 degrees C isothermal nitrides largely reduce the corrosion resistance of the austenite phase, while the quenched-in nitrides reduce the corrosion resistance of the material to a much lesser extent. The size difference between isothermal and quenched-in chromium nitrides may be crucial, in particular above the critical pitting temperature.

  • 19.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lin, Changjian
    Liu, Ping
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Influence of Grain Boundaries on Dissolution Behavior of a Biomedical CoCrMo Alloy: In-Situ Electrochemical-Optical, AFM and SEM/TEM Studies2012In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 159, no 9, p. C422-C427Article in journal (Refereed)
    Abstract [en]

    In this study, preferential sites for metal dissolution during anodic polarization were investigated for a biomedical CoCrMo alloy. As-cast and heat treated materials were compared through a combination of complementary techniques. Scanning Kelvin probe force microscopy mapping suggested the matrix areas adjacent to the carbides to be preferential sites for metal dissolution. By means of in situ electrochemical-optical microscopy it was observed that localized dissolution initiated from the matrix areas adjacent to carbides and grain boundaries in both materials at high anodic potential. By using scanning electron microscopy and transmission electron microscopy/energy dispersive spectroscopy analysis, submicron-sized carbides were found along the grain boundaries, and significant Cr depletion was detected across the grain boundaries for both materials, providing an explanation for the initiation of metal dissolution. A slightly higher metal dissolution was observed for the as-cast sample at high anodic potential, probably due to a more heterogeneous microstructure.

  • 20.
    Bettini, Eleonora
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nature of current increase for a CoCrMo alloy: "transpassive" dissolution vs. water oxidation2013In: International Journal of Electrochemical Science, ISSN 1452-3981, E-ISSN 1452-3981, Vol. 8, no 10, p. 11791-11804Article in journal (Refereed)
    Abstract [en]

    The “transpassive” behavior of a CoCrMo alloy has been investigated to clarify the nature of the current increase at high anodic potential (0.5-0.7 VAg/AgCl). The total amount of released metal ions was determined after the potentiostatic measurements. According to the calculation through Faradays’ law, the metal dissolution only contributes to part of the total current recorded. Electrochemical AFM mapping did not show pronounced topography changes at 0.65 VAg/AgCl, while light optical microscopy observation revealed fast evolution of oxygen bubbles. Evidently water oxidation is another important process largely contributing to the current increase at the high potential.

  • 21.
    Bjorkbacka, Asa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johnson, C. Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Role of the Oxide Layer in Radiation-Induced Corrosion of Copper in Anoxic Water2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 21, p. 11450-11455Article in journal (Refereed)
    Abstract [en]

    The influence of a pregrown copper oxide layer on radiation-induced corrosion of polished copper in pure anoxic water has been explored. The resulting amount of copper oxide formed during corrosion was measured with cathodic reduction, and the concentration of dissolved copper in solution was measured with inductively coupled plasma atomic emission spectroscopy. The identity of corrosion products and their topography was determined with Raman spectroscopy and scanning electron microscopy, respectively. Nonirradiated reference samples were analyzed for comparison. The results show that radiation-induced corrosion of copper in anoxic water is significantly more effective on preoxidized copper compared to polished copper. The total amount of oxidized copper exceeds the amount expected solely from radiation chemistry of water by more than 3 orders of magnitude. To explain this discrepancy a mechanism is suggested where the hydroxyl radical (HO center dot) is the main radiolytic oxidative species driving the corrosion process. If the thermodynamic driving force would be large enough (such as for the hydroxyl radical or its precursor, H2O+), the oxide layer could conduct electrons from the metal to the hydroxyl radicals formed at oxide surfaces. The formation of an oxide layer will then result in an increased reactive surface area partly accounting for the observed discrepancy.

  • 22.
    Björkbacka, Åsa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hosseinpour, Saman
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation induced corrosion of copper for spent nuclear fuel storage2013In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, Vol. 92, p. 80-86Article in journal (Refereed)
    Abstract [en]

    The long term safety of repositories for radioactive waste is one of the main concerns for countries utilizing nuclear power. The integrity of engineered and natural barriers in such repositories must be carefully evaluated in order to minimize the release of radionuclides to the biosphere. One of the most developed concepts of long term storage of spent nuclear fuel is the Swedish KBS-3 method. According to this method, the spent fuel will be sealed inside copper canisters surrounded by bentonite clay and placed 500 m down in stable bedrock. Despite the importance of the process of radiation induced corrosion of copper, relatively few studies have been reported. In this work the effect of the total gamma dose on radiation induced corrosion of copper in anoxic pure water has been studied experimentally. Copper samples submerged in water were exposed to a series of total doses using three different dose rates. Unirradiated samples were used as reference samples throughout. The copper surfaces were examined qualitatively using IRAS and XPS and quantitatively using cathodic reduction. The concentration of copper in solution after irradiation was measured using ICP-AES. The influence of aqueous radiation chemistry on the corrosion process was evaluated based on numerical simulations. The experiments show that the dissolution as well as the oxide layer thickness increase upon radiation. Interestingly, the evaluation using numerical simulations indicates that aqueous radiation chemistry is not the only process driving the corrosion of copper in these systems.

  • 23.
    Björkbacka, Åsa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hosseinpour, Saman
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation Induced Corrosion of Copper in Anoxic Aqueous Solution2012In: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 15, no 5, p. C5-C7Article in journal (Refereed)
    Abstract [en]

    The effect of gamma radiation on corrosion of copper under anoxic conditions in pure water has been studied experimentally. Copper samples submerged in water were exposed to dose rates of 0.37 or 0.77 kGy/h. Reference samples were used throughout. The copper surfaces have been examined using the techniques of SEM-EDS, IRAS, CR spectroscopy and AFM. Dissolution of copper was measured using ICP-OES. The results show that irradiated samples are more corroded than corresponding reference samples. This is also reflected by the increased concentration of copper in water after irradiation. Surface examination also reveals local corrosion features.

  • 24.
    Björkbacka, Åsa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation induced corrosion of copper in humid air and argonManuscript (preprint) (Other academic)
  • 25.
    Björkbacka, Åsa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    The role of the oxide layerin radiation induced corrosion of copper in anoxic waterManuscript (preprint) (Other academic)
  • 26.
    Björkbacka, Åsa
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Yang, Miao
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gasparrini, Claudia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kinetics and mechanisms of reactions between H2O2 and copper and copper oxides2015In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 44, no 36, p. 16045-16051Article in journal (Refereed)
    Abstract [en]

    One of the main challenges for the nuclear power industry today is the disposal of spent nuclear fuel. One of the most developed methods for its long term storage is the Swedish KBS-3 concept where the spent fuel is sealed inside copper canisters and placed 500 meters down in the bedrock. Gamma radiation will penetrate the canisters and be absorbed by groundwater thereby creating oxidative radiolysis products such as hydrogen peroxide (H2O2) and hydroxyl radicals (HO[radical dot]). Both H2O2 and HO[radical dot] are able to initiate corrosion of the copper canisters. In this work the kinetics and mechanism of reactions between the stable radiolysis product, H2O2, and copper and copper oxides were studied. Also the dissolution of copper into solution after reaction with H2O2 was monitored by ICP-OES. The experiments show that both H2O2 and HO[radical dot] are present in the systems with copper and copper oxides. Nevertheless, these species do not appear to influence the dissolution of copper to the same extent as observed in recent studies in irradiated systems. This strongly suggests that aqueous radiolysis can only account for a very minor part of the observed radiation induced corrosion of copper.

  • 27.
    Chang, Tingru
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Univ Sci & Technol Beijing, Peoples R China.
    Jin, Ying
    Wen, Lei
    Zhang, Chensheng
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Zhang, Junping
    Synergistic effects of gelatin and convection on copper foil electrodeposition2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 211, p. 245-254Article in journal (Refereed)
    Abstract [en]

    Copper foil electrodeposition has been explored using a pure titanium rotating disk electrode (RDE) in acidic electrolytes containing gelatin and/or chloride ions under different convection conditions. In the plating bath without gelatin, the results indicate that stronger convection promotes hydrogen evolution, which reduces the current efficiency during copper plating. Gelatin restrains the growth of copper grains in the lateral direction parallel to the surface. This results in grain refinement on the shiny side, an increase in local grain misorientation and in internal stresses on both the shiny and the matte side, and a reduction in their internal stress difference. At strong convection conditions and with gelatin present, copper deposits as strip-like grains along the centrifugal direction of the cross section, and finally forms a spiral-shaped pattern on the matte side. The causes of these features are discussed in detail. The combined influences of hydrogen and gelatin adsorption are further elaborated in a model for a copper deposition. The current investigation suggests that a moderate convection (somewhat lower than 1000 rpm) and a concentration of 2 ppm gelatin in the plating bath are sufficient for copper foil fabrication in the presence of chloride ions (20 ppm).

  • 28.
    Chang, Tingru
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    de la Fuente, D.
    Chico, B.
    Morcillo, M.
    Welter, J. -M
    Leygraf, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Analysis of historic copper patinas. Influence of inclusions on patina uniformity2017In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, no 3, article id 298Article in journal (Refereed)
    Abstract [en]

    The morphology and elemental composition of cross sections of eight historic copper materials have been explored. The materials were taken from copper roofs installed in different middle and northern European environments from the 16th to the 19th century. All copper substrates contain inclusions of varying size, number and composition, reflecting different copper ores and production methods. The largest inclusions have a size of up to 40 μm, with most inclusions in the size ranging between 2 and 10 μm. The most common element in the inclusions is O, followed by Pb, Sb and As. Minor elements include Ni, Sn and Fe. All historic patinas exhibit quite fragmentized bilayer structures, with a thin inner layer of cuprite (Cu2O) and a thicker outer one consisting mainly of brochantite (Cu4SO4(OH)6). The extent of patina fragmentation seems to depend on the size of the inclusions, rather than on their number and elemental composition. The larger inclusions are electrochemically nobler than the surrounding copper matrix. This creates micro-galvanic effects resulting both in a profound influence on the homogeneity and morphology of historic copper patinas and in a significantly increased ratio of the thicknesses of the brochantite and cuprite layers. The results suggest that copper patinas formed during different centuries exhibit variations in uniformity and corrosion protection ability.

  • 29.
    Chen, Zhuo Yuan
    et al.
    Swedish Corrosion Institute.
    Persson, D.
    Swedish Corrosion Institute.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    In situ studies of the effect of SO2 on the initial NaCl-induced atmospheric corrosion of copper2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 12, p. B526-B533Article in journal (Refereed)
    Abstract [en]

    The initial SO2-induced atmospheric corrosion of copper deposited with NaCl has been examined with Fourier transform infrared microspectroscopy under in situ and ex situ conditions in order to reveal the spatial distribution of reaction products. The oxidation of S(IV) turns out to be fast at the area of the NaCl-containing electrolyte droplet, and both sulfate (SO42-) and dithionate (S2O62-) ions form. A copper-catalyzed reaction route for the sulfite oxidation has been suggested, which includes the formation of a Cu(II)-sulfito complex as an important step. The presence of gaseous oxidants such as NO2 and O-3 has previously been considered as an important prerequisite for the oxidation of sulfite on copper. The results obtained here suggest that the formation of local electrochemical cells induced by deposited NaCl particles could be another important route for S(IV) oxidation to sulfate formation. SO2 was found to promote the formation of less soluble paratacamite [Cu-2(OH)(3)Cl] and nantokite (CuCl), which may slow down the atmospheric corrosion rate of copper.

  • 30.
    Chen, Zhuo Yuan
    et al.
    Swedish Corrosion Institute.
    Persson, D.
    Swedish Corrosion Institute.
    Nazarov, A.
    Swedish Corrosion Institute.
    Zakipour, S.
    Swedish Corrosion Institute.
    Thierry, D.
    Swedish Corrosion Institute.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    In situ studies of the effect of CO2 on the initial NaCl-induced atmospheric corrosion of copper2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 9, p. B342-B351Article in journal (Refereed)
    Abstract [en]

    The effect of carbon dioxide (CO2) on the NaCl-induced atmospheric corrosion of copper was studied using in situ Fourier transform infrared microspectroscopy, in situ scanning Kelvin probe, and scanning electron microscopy/energy-dispersive analysis by X-ray. The copper surface was contaminated with a single NaCl particle and then exposed to 80 +/- 2% relative humidity clean humidified air with two concentrations of CO2 (< 5 and 350 ppm). After formation of an electrolyte droplet secondary spreading of electrolyte from the peripherical parts of the droplet was observed. The secondary spreading effect, which was much larger at < 5 ppm CO2 than at 350 ppm, was a consequence of the formation of a galvanic element between a local cathode outside the edge of the droplet and an anode in the droplet. This lead to alkaline conditions in the secondary spreading area and transport of Na+ ions to the local cathode. The large secondary spreading at low CO2 concentration was possible due to lowering of the surface tension of the electrolyte/metal oxide interface at the peripheral parts of the droplet. Carbonate formation lowered the pH when the CO2 concentration was 350 ppm and resulted in a decrease of the pH and inhibition of the secondary spreading.

  • 31.
    Chen, Zhuo Yuan
    et al.
    Swedish Corrosion Institute.
    Persson, D.
    Swedish Corrosion Institute.
    Samie, F.
    Swedish Corrosion Institute.
    Zakipour, S.
    Swedish Corrosion Institute.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Effect of carbon dioxide on sodium chloride-induced atmospheric corrosion of copper2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 12, p. B502-B511Article in journal (Refereed)
    Abstract [en]

    The effect of carbon dioxide (CO2) on sodium chloride (NaCl) induced atmospheric corrosion of copper was studied in laboratory exposures using microgravimetry, ion chromatography, Fourier transform infrared spectroscopy, and scanning electron microscopy with X-ray microanalysis. With lower amount of NaCl particles on the copper surface (< 15 mu g/cm(2)), the corrosion rate was higher with < 1 ppm CO2 than with 350 ppm CO2, and for higher amount of NaCl (> 15 mu g/cm(2)), the corrosion was higher with 350 ppm CO2. With lower amount of NaCl and low CO2 concentration, a secondary spreading of electrolyte occurred from the droplets that formed at the particle clusters. This led to a larger effective cathodic area and a higher corrosion rate. However, at higher surface concentration of NaCl a spatial interaction effect between the local corrosion sites counteracted the increase in the corrosion rate due to overlap of the cathodic areas from the particles. Another factor, which influenced the corrosion process, was the effect of CO2 on the pH of the surface electrolyte. Higher pH (< 1 ppm CO2 concentration) increased the formation of CuO, which improved the corrosion resistance of the corrosion product layer but hindered the formation of insoluble CuCl, whereby more soluble chloride ions were available for triggering localized corrosion and accelerating the initial atmospheric corrosion of copper. Hence, the overall influence of CO2 and NaCl depends on at least three identified mechanisms.

  • 32. Chen, Zhuo Yuan
    et al.
    Persson, Dan
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Initial NaCl- Particle Induced Atmospheric Corrosion of Zinc-Effect of CO2 and SO22008In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 50, no 1, p. 111-123Article in journal (Refereed)
    Abstract [en]

    Initial corrosion and secondary spreading effects during NaCl particle induced corrosion on zinc was explored using in situ and ex situ FTIR microspectroscopy, optical microscopy, and SEM/EDAX. The secondary spreading effect which occurs upon introduction of humid air on NaCl deposited zinc surfaces was strongly dependent on the CO2 and SO2 content of the introduced air. Ambient level of CO2 (350 ppm) resulted in a relatively low spreading effect, whereas the lower level of CO2 (<5 ppm) caused a much faster spreading over a larger area. In the presence of SO2, the secondary spreading effect was absent which could limit the cathodic process in this case. At <5 ppm CO2, the corrosion is more localized, with the formation of simonkolleite (Zn5(OH)8Cl2 · H2O), zincite (ZnO) and sodium carbonate (Na2CO3), and a larger effective cathodic area. At 350 ppm CO2, the corrosion is more general and formation of simonkolleite, hydrozincite (Zn5(OH)6(CO3)2) and sodium carbonate was observed. Sodium carbonate was mainly formed in more alkaline areas, in the inner edge of the electrolyte droplet and in the secondary spreading area. Oxidation of sulphur and concomitant sulphate formation was enhanced in the presence of NaCl particles, due to the formation of a droplet, the separation of the anodic and cathodic areas and the accompanying differences in chemical composition and pH in the surface electrolyte.

  • 33.
    Chen, Zhuo Yuan
    et al.
    Swedish Corrosion Institute.
    Tidblad, J.
    Swedish Corrosion Institute.
    Persson, D.
    Swedish Corrosion Institute.
    Zakipour, S.
    Swedish Corrosion Institute.
    Kucera, V.
    Swedish Corrosion Institute.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    The Effect of Ammonium Sulfate Particles on the Atmospheric Corrosion of CopperManuscript (preprint) (Other academic)
  • 34.
    Chen, Zhuo Yuan
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Zakipour, S.
    Persson, D.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    The Effect of Sodium Chloride Particles on the Atmospheric Corrosion of Pure Copper2004In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 60, no 5, p. 479-491Article in journal (Refereed)
    Abstract [en]

    The atmospheric corrosion of copper has been investigated after deposition of sodium chloride (NaCl) particles and 10 days of subsequent exposure to clean, humidified air below, near, and above the point of deliquescence of NaCl (at around 75% relative humidity (RH), Microgravimetry, Fourier transform infrared (FTIR) microspectroscopy, scanning electron microscopy with x-ray microanalysis, and scanning Kelvin probe were used to identify corrosion processes and products. The NaCl deposition resulted in the evenly distributed NaCl particle clusters with a diameter of approximately 100 μm. The clusters consisted of individual NaCl particles of <10 μm. The mass gain increased linearly with the amount of NaCl particles added in the range of this study (up to 4 μg/cm2). Even at very low RH (55%), which lies far below the point of deliquescence (75%), copper with NaCl particles added suffered from significant corrosion attack and the mass gain of copper with 4 μg/cm2 NaCl added was about 7 μg/cm2 after 10 days of exposure. At 55% RH, the NaCl particles did not dissolve. However, significant chloride-induced corrosion effects were observed after 10 days, both in the original particle cluster and in a 20-μm-wide outer zone into which chloride ions had dffused radially. At 75% RH, the NaCl particles dissolved and chloride ions diffused to cover the whole surface. Chloride-accelerated corrosion effects resulted in the formation of cuprite (Cu2O) and copper carbonate, mainly in the area of the original particle cluster. The corrosion effects accelerated further at 95% PH, resulting in the formation of Cu2O over the whole surface and copper carbonate in a concentric zone outside the original particle cluster. The distribution of the corrosion products was related to the localization of the anodic and cathodic reactions during the corrosion process.

  • 35.
    Chen, Zhuo Yuan
    et al.
    wedish Corrosion Institute, Sweden.
    Zakipur, S.
    Persson, D.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    The Combined Effects of Gaseous pollutants and Sodium Chloride Particles on the Atmospheric Corrosion of Pure Copper2005In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 61, no 11, p. 1022-1034Article in journal (Refereed)
    Abstract [en]

    The atmospheric corrosion of pure copper has been investigated after the deposition of sodium chloride (NaCI) particles and exposure to humid air containing gaseous pollutants. Microgravimetry, Fourier transform infrared (FTIR) micro-spectroscopy, and scanning electron microscopy with x-ray microanalysis were used for the investigation of corrosion processes and products. The effect of NaCl particles on the mass gain was much higher than that of gaseous pollutants. With deposition of NaCl particles on the copper surfaces, the corrosion rate increased significantly, with severe corrosion attack mainly localized to the NaCl particle clusters. A similar corrosion rate was found, however, after exposure to pure humid air and to humid air containing gaseous pollutants, sulfur dioxide (SO2), ozone (O-3), nitrogen dioxide (NO2), and SO2 + NO2. The corrosion rate was not dependent on the concentration of the pollutants. However, this was not the case for the combination of SO2 and O-3, leading to a significantly higher corrosion rate at higher concentrations. Exposure of copper samples with NaCl particles deposited resulted in unevenly distributed corrosion product clusters, with a distribution of corrosion products that could be associated with the locations of the particle clusters. Around the particle clusters, the corrosion resulted in areas with different amounts of corrosion products. After 10 days of exposure to humid air containing 100 ppb SO2 and 100 ppb NO2 + SO2, cuprite (Cu2O), paratacamite (Cu-2[OH](3)Cl), carbonate (CO32-), and sulfate (SO42-) were observed mainly in the area of the original particle cluster, with some sutfate and copper hydroxysulfate also in the areas outside. After 10 days of exposure to humid air containing 100 ppb O-3 + SO2, cuprite (Cu2O), hydroxychloride (maybe paratacamite, Cu-2[OH](3)Cl), carbonate (CO32-), and sutfate (SO42-) were observed in the area of the original particle cluster. A circular zone containing brochantite (Cu-4[OH](6)SO4) was formed around and outside of the original particle cluster, and the formation of this phase was promoted by the presence of NaCl particles on the surface. The location of anodic and cathodic reactions during the corrosion process leads to the distribution of different corrosion products on the surface.

  • 36. Davoodi, A
    et al.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Integration of scanning electrochemical microscopy and atomic force microscopy for in-situ investigation of localized corrosion2005In: Proc. 16th International Corrosion Congress, Beijing, Sept. 19-24, 2005, 2005, p. 19-19Conference paper (Other academic)
  • 37. Davoodi, A.
    et al.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Parvizi, R.
    Norgren, S.
    An insight into the influence of morphological and compositional heterogeneity of an individual intermetallic particle on aluminium alloy corrosion initiation2013In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 64, no 3, p. 195-198Article in journal (Refereed)
    Abstract [en]

    In this work, a multi-analytical in situ and ex situ approach was used to provide information needed to identify the role of an individual heterogeneous intermetallic particle (IMP) in localized corrosion initiation of aluminium alloys. The heterogeneity of the IMP was studied by combining atomic force microscopy (AFM), scanning electron microscopy and energy dispersive spectroscopy (SEMEDS) and scanning electrochemical microscopy (SECM). A complex AlMnFeSi IMP phase with different chemical composition in its inner and outer parts was characterized by SEMEDS analysis. AFM results uniquely revealed a brain-like feature of an IMP with 20nm height variations. Submicron sized galvanic cell induced by morphological and compositional heterogeneity resulted in a localized corrosion attack inside the individual IMP. Various collected current levels measured by SECM were associated to the morphological and compositional heterogeneity of IMPs.

  • 38.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Farzadi, Ali
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Zhu, Y.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    AFM-based SECM for insitu investigation of localized corrosion: Part I: Instrumental set-up and SECM simulationIn: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111Article in journal (Other academic)
  • 39.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Farzadi, Ali
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Zhu, Y.
    Developing an AFM-Based SECM system; Instrumental setup, SECM simulation, characterization, and calibration2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 8, p. C474-C485Article in journal (Refereed)
    Abstract [en]

    An integrated atomic force microscopy/scanning electrochemical microscopy (AFM/SECM) system was developed as an in situ local electrochemical probing technique. It consists of a dual-mode probe acting as an AFM cantilever and SECM microelectrode to simultaneously obtain the topography and electrochemical current map of the same area. Two types of probes with different geometries were used. The scan velocity and concentration profile of the redox mediator during the scan were simulated, using the equations of convection-diffusion mass transport coupled with continuity and momentum in three dimensions under steady-state and transient conditions. The temporal and spatial resolutions of the probes were investigated. It was found that, during a normal scan rate (around 1 Hz), the effect of convective transport is negligible and the SECM lateral resolution depends on the geometrical parameters. With favorable geometry, a probe with a Pt microelectrode of 1 mu m diameter can distinguish two active sites with a distance of at least 3-4 mu m. The paper also reports experiments for characterization and calibration of the AFM/SECM system. Concurrent AFM and SECM images obtained on a gold band calibration sample verify the high-resolution capability of the SECM of one or a few micrometers with optimized conditions.

  • 40.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Farzadi, Ali
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hu, R.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Zhu, Y.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    AFMbased SECM for in-situ investigation of localized corrosion: Part II: Characterization, calibration and verificationIn: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111Article in journal (Other academic)
  • 41.
    Davoodi, Ali
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Pan, Jinshan
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Leygraf, Christofer
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Norgren, S.
    Sapa Technology, Finspång.
    In-situ investigation of localized corrosion of aluminum alloys in chloride solution using integrated EC-AFM/SECM technique2005In: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 8, no 6, p. B21-B24Article in journal (Refereed)
    Abstract [en]

    Scanning electrochemical microscopy (SECM) has been integrated with electrochemical atomic force microscopy (EC-AFM), and applied for in situ studies of localized corrosion of Al alloys in NaCl solution. The instrument utilizes a dual mode probe, which functions both as a normal cantilever and as an ultramicroelectrode. The I-/I3- redox mediator was used for mapping of local electrochemical current. Concurrent topography and electrochemical activity maps have been obtained on the same surface area with micrometer lateral resolution. Preliminary results show ongoing localized dissolution related to intermetallic particles in the Al alloys, which may occur well below the breakdown potential.

  • 42.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Sapa Technology, Finspång.
    Integrated AFM and SECM for in situ studies of localized corrosion of Al alloys2007In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 52, no 27, p. 7697-7705Article in journal (Refereed)
    Abstract [en]

    Rolled 3xxx series Al alloys, e.g., EN AW-3003, are generally used as fin or tube material in heat exchangers for automobiles. With reducing fin thickness, maintaining fin material integrity is of increasing importance. This study aimed at exploring the differences in intrinsic corrosion properties between EN AW-3003 and a newly developed Al–Mn–Si–Zr fin alloy using state-of-the-art local probing techniques. Volta potential mapping of both alloys by scanning Kelvin probe force microscopy (SKPFM) indicates a cathodic behaviour of constituent intermetallic particles (>0.5 μm) relative to the alloy matrix. Compared to EN AW-3003, the Al–Mn–Si–Zr alloy has a smaller number of particles with large Volta potential difference relative to the matrix. In situ atomic force microscopy (AFM) measurements in slightly corrosive solutions showed extensive localized dissolution and deposition of corrosion products on EN AW-3003, and only a small number of corroding sites and “tunnel-like” pits on Al–Mn–Si–Zr. Probing the ongoing localized corrosion process by integrated AFM and scanning electrochemical microscopy (SECM) revealed more extensive local electrochemical activity on EN AW-3003 than on Al–Mn–Si–Zr. In all, the lower corrosion activity and smaller tunnel-like pits resulted in lower material loss of the Al–Mn–Si–Zr alloy, a beneficial property when striving towards thinner fin material.

  • 43.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Sapa Technol, Finspång.
    Multianalytical and in situ studies of localized corrosion of EN AW-3003 alloy: influence of intermetallic particles2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 4, p. C138-146Article in journal (Refereed)
    Abstract [en]

    The influence of intermetallic particles (IMPs) on the localized corrosion behavior of an EN AW-3003 alloy was investigated in situ by conventional electrochemical measurements and high-resolution local probing techniques in chloride solutions with and without acetic acid. The open-circuit potential (OCP) fluctuations indicate local activities on the surface, and electrochemical impedance spectroscopy measurements suggest active dissolution in acidic solutions but a passivelike behavior in near-neutral solutions. Integrated atomic force microscopy/scanning electrochemical microscopy (AFM/SECM) was used to investigate the localized activities on the surface in a diluted chloride solution. The concurrent AFM and SECM images reveal cathodic activity of the IMPs and enhanced anodic current due to localized dissolution adjacent to some large IMPs upon anodic polarization. Moreover, in situ AFM imaging at OCP in solutions containing acetic acid show localized dissolution around the IMPs, leading to formation of deposits of ringlike corrosion products. The in situ observations reveal the microgalvanic effect of the IMPs, and the large IMPs are more prone to initiate localized corrosion compared to submicrometer dispersoids. Infrared absorption spectroscopy measurements after the exposure and thermodynamic calculations suggest the formation of mixtures of aluminum oxihydroxide and acetate on the surface in the presence of acetic acid.

  • 44.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Sapa Technology, Finspång.
    Probing of local dissolution of Al-alloys in chloride solutions by AFM and SECM2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5499-5503Article in journal (Refereed)
    Abstract [en]

    Local dissolution of Al alloys was probed in situ in chloride solutions by using atomic force microscopy (AFM) and scanning electrochemical microscopy (SECM). Preferential dissolution in the boundary region between some intermetallic particles (IMPs) and alloy matrix, and trench formation around large IMPs during free immersion and under electrochemical anodic polarization were observed, which indicate different dissolution behavior associated to different types of IMPs. Moreover, by using an integrated AFM/SECM system with a dual mode cantilever/microelectrode probe, simultaneous probing of electrochemical active sites and topographic changes over the same area was performed with submicron resolution. This allowed the ongoing localized corrosion processes related to the IMP to be revealed.

  • 45.
    Davoodi, Ali
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Norgren, S.
    Sapa Technology, Finspång.
    The role of intermetallic particles in localized corrosion of an aluminum alloy studied by SKPFM and integrated AFM/SECM2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 5, p. C211-218Article in journal (Refereed)
    Abstract [en]

    Aluminum alloy EN AW-3003contains a certain amount of micrometer-sized constituent particles and alarge number of nanometer-sized dispersoids. The practical nobility of intermetallicparticles relative to an alloy matrix was evaluated ex situby scanning Kelvin probe force microscopy (SKPFM), and localized corrosioninitiation of the alloy exposed to chloride solutions was studiedin situ by integrated atomic force microscopy (AFM) and scanningelectrochemical microscopy (SECM). The SKPFM results show a higher Voltapotential for the constituent particles than the matrix, and alarger difference for larger particles. In some cases, the boundaryregion between the large constituents and the matrix exhibits aminimum Volta potential. In contrast, a small Volta potential differencewas measured for the particles less than 1  µm. The SECMmapping of the alloy surface in the solution provided evidenceof a cathodic action of some constituent particles and alocal anodic dissolution adjacent to them. Concurrent AFM and SECMimages indicate that only some of the constituents are proneto initiate localized corrosion. Moreover, in situ AFM observations confirmenhanced localized dissolution in the boundary regions, verifying the cathodiccharacter of the constituent particles and a microgalvanic effect onlocalized corrosion. The fine dispersoids of nanometer size seem tohave no effect on the corrosion initiation.

  • 46. Davoodi, Ali
    et al.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Parvizi, Reza
    Minuscule device for hydrogen generation/electrical energy collection system on aluminum alloy surface2011In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 36, no 4, p. 2855-2859Article in journal (Refereed)
    Abstract [en]

    Cogeneration of hydrogen and electrical energy in a single system is still a challenging issue. In this work, in a micro scale, a novel miniaturized system is introduced to capture the electrical energy of produced hydrogen on aluminum alloy by using an ultra-microelectrode based on scanning electrochemical microscopy (SECM). Sophisticated nanosize atomic force microscopy (AFM) based SECM probe could collect the electrochemical current close proximity distance from the aluminum surface to attain the highest possible current efficiency. Various collected current levels were associated to the aluminum microstructure constituents. It is expected that future development in instrumentation could principally facilitate SECM as a tool for hydrogen economy.

  • 47. Femenia, M.
    et al.
    Canalias, C.
    Pan, Jinshan
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Scanning Kelvin probe force microscopy and magnetic force microscopy for characterization of duplex stainless steels2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 6, p. B274-B281Article in journal (Refereed)
    Abstract [en]

    In this study, the Volta potential distribution over the surface of duplex stainless steels (DSSs) has been mapped for the first time with submicrometer resolution by scanning Kelvin probe force microscopy (SKPFM). The different magnetic properties of ferrite and austenite enable the utilization of magnetic force microscopy (MFM) for visualizing their surface distribution without the need of surface etching. The combined MFM and SKPFM mapping of the same area makes it possible to associate the variation in the Volta potential to the phase distribution and phase boundaries. The difference in potential between the two phases is measurable and significant. Generally, the ferrite phase was associated to regions of lower potential, and the austenite phase to regions of more noble potential. This can be regarded as direct evidence of galvanic interactions between the two phases. The phase boundary regions often exhibited a lower potential in the ferrite phase, indicating a higher tendency to corrosion. The high lateral resolution of SKPFM provides the possibility of comparing these results with those obtained from other localized techniques, a necessary step for a deeper understanding of the local corrosion processes in DSSs.

  • 48. Femenia, M.
    et al.
    Pan, Jinshan
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    In situ local dissolution of duplex stainless steels in 1 M H2SO4+1 M NaCl by electrochemical scanning tunneling microscopy2002In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, no 6, p. B187-B197Article in journal (Refereed)
    Abstract [en]

    Local dissolution behavior of duplex stainless steel UNS S32304, UNS S31803, and UNS S32750 in 1 M H2SO4 + 1 M NaCl was studied in situ by electrochemical scanning tunneling microscopy (STM). Submicrometer features could be resolved and events occurring at phase/grain boundary regions could be monitored in the solution. By STM imaging, severe local dissolution was observed on UNS S32304 in the form of both pitting-like dissolution occurring at the active potential region, and selective dissolution of ferrite phase that already started at the corrosion potential. On UNS S31803, no pitting-like corrosion was observed, but a small amount of selective dissolution occurred at anodic potentials in the active region. The phase boundary region seemed to be prone to local dissolution. No noticeable local dissolution was observed on UNS S32750 in this solution in active and passive potential regions. The results show that a sufficient amount of both Mo and N in duplex stainless steel resulted in more homogeneous dissolution of the two phases and strengthened phase boundaries, and thus decreased the risk for local dissolution.

  • 49. Femenia, M.
    et al.
    Pan, Jinshan
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Luukkonen, P.
    In situ study of selective dissolution of duplex stainless steel 2205 by electrochemical scanning tunnelling microscopy2001In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 43, no 10, p. 1939-1951Article in journal (Refereed)
    Abstract [en]

    Selective dissolution of duplex stainless steel 2205 in acidic chloride solutions was studied in situ by electrochemical scanning tunnelling microscopy (STM). In 0.05 M H2SO4 + 1 M NaCl, no appreciable active dissolution was observed by in situ STM imaging at the corrosion potential (E-corr), but at potentials higher than E-corr + 1000 mV some selective dissolution at the austenite-ferrite boundary region occurred. In 4 M H2SO4 + 1 M HCl, STM images revealed active dissolution of ferrite grains at around E-corr + 50 mV. Dissolution of austenite grains started to occur at around E-corr + 150 mV, exhibiting steps of submicron scale on the edges.

  • 50.
    Femenia, Marc
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Pan, Jinshan
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Characterization of ferrite-austenite boundary region of duplex stainless steels by SAES2004In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, no 11, p. B581-B585Article in journal (Refereed)
    Abstract [en]

    Scanning Auger electron spectroscopy (SAES) has been used to investigate the phase boundary region between ferrite and austenite in three duplex stainless steels. Of the elements investigated Cr and Mo are partitioned to the ferrite phase, while Ni and N are partitioned to the austenite phase. The composition gradient across the phase boundary occurs within a few micrometers. The results are in accordance with previous results of the same phase boundary region obtained with complementary techniques. They form evidence of galvanic interaction between the ferrite and austenite phases and suggest this to be the main cause of the higher initial dissolution rate of ferrite adjacent to the austenite phase. The addition of alloying elements improves corrosion resistance of both the ferrite and austenite phases, the weaker sites are comparatively more strengthened. In the highly alloyed duplex stainless steel, the alloying elements are also partitioned, but in such a way that the corrosion resistance of the two phases is very similar, which results in a homogeneous dissolution behavior.

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