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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    KTH, Superseded Departments, Materials Science and Engineering.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.
    Abbasi, M.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Backstrom, J.
    Mid Sweden Univ, FSCN Mat Phys, Dept Nat Sci, SE-85170 Sundsvall, Sweden..
    Cornell, Ann M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Fabrication of Spin-Coated Ti/TiHx/Ni-Sb-SnO2 Electrode: Stability and Electrocatalytic Activity2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, no 9, p. H568-H574Article in journal (Refereed)
    Abstract [en]

    A novel three-layer anode having the composition Ti/TiHx/Ni-Sb-SnO2 (Ti/TiHx/NATO) was successfully prepared by a spin-coating and pyrolysis process aiming at a long service lifetime and good electrocatalytic properties for ozone formation. The TiHx as an interlayer was produced by electrochemical cathodic reduction of a coated layer of the TiOx on the titanium substrate. Spin coating and thermal decomposition were used to deposit the Sn-Sb-Ni precursor on the surface of the prepared Ti/TiHx electrode. Cyclic and linear scanning voltammetry, Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to reveal the electrode performance and morphology. Results show that the onset potential for the oxygen evolution reaction (OER) of Ti/TiHx /NATO is higher than for Ti/NATO. They also indicate that the service lifetime of the Ti/TiHx/NATO is twice as long as the Ti/NATO at a current density of 50 mA.cm(-2) at room temperature. Electrochemical ozone generation and degradation of the methylene blue were investigated to confirm selectivity and activity of the electrodes. After 5 min electrolysis, a current efficiency for ozone generation of 56% was obtained the electrode with TiHx while 38% was obtained on Ti/NATO under same conditions. The results also confirm that the Ti/TiH x /NATO has a higher kinetic rate constant and decolorization efficiency for removal of the methylene blue compare to the Ti/NATO. The rate constant for the pseudo-first ordered reaction of methylene blue degradation showed high values of 350 x 10(-3) min(-1) for Ti/NATO and 440 x 10(-3) min(-1) for Ti/TiHx/NATO. 

  • 3.
    Anantha, Krishnan Hariramabadran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Örnek, Cem
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ejnermark, S.
    Medvedeva, A.
    Sjöström, J.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    In situ AFM study of localized corrosion processes of tempered AISI 420 martensitic stainless steel: Effect of secondary hardening2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 13, p. C810-C818Article in journal (Refereed)
    Abstract [en]

    The effect of secondary hardening of tempered AISI 420 martensitic stainless steel on the corrosion behavior in aqueous 0.01 M NaCl has been studied, in-situ, using atomic force microscopy (AFM) to monitor real-time localized corrosion processes. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses confirmed the presence of undissolved and secondary carbides (Cr23C6, Cr7C3, Cr3C2, Cr3C, Cr2C, and CrC) as well as retained austenite, all finely dispersed in the tempered martensitic matrix. Electrochemical measurements, consisted of monitoring of the open-circuit potential vs. time and cyclic polarization in 0.01 M NaCl solution, were performed to evaluate the passivity and its breakdown, and it was seen that initiation sites for localized corrosion were predominantly peripheral sites of carbides. In-situ AFM measurements revealed that there was a sequence for localized corrosion in which the neighboring matrix next to secondary carbides dissolved first, followed by corrosive attack on regions adjacent to undissolved carbides. Tempering at 500◦C reduced the corrosion resistance and the ability to passivate in comparison to tempering at 250◦C.

  • 4.
    Anantha, Krishnan Hariramabadran
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Örnek, Cem
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ejnermark, Sebastian
    Medvedeva, Anna
    Sjöström, Johnny
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Correlative Microstructure Analysis and In Situ Corrosion Study of AISI 420 Martensitic Stainless Steel for Plastic Molding Applications2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 4, p. C85-C93Article in journal (Refereed)
    Abstract [en]

    In this work, the corrosion behavior of tempered AISI 420 martensitic stainless steel (MSS) was studied by in-situ atomic force microscopy (AFM) in 0.1M NaCl and correlated with the microstructure. Thermocalc simulation, dilatometry, and X-ray diffraction (XRD) were performed to investigate phase transformation which showed the formation of M3C, M7C3, and M23C6 type of carbides and also retained austenite. Optical microscopy, scanning electron microscopy (SEM), and AFM characterization revealed undissolved carbides and tempering carbides in the martensitic matrix. Volta potential mapping measured by scanning Kelvin probe force microscopy (SKPFM) indicated higher electrochemical (practical) nobility of the carbides with respect to the martensitic matrix whereas regions adjacent to carbides showed lower nobilities due to chromium depletion. Open circuit potential and cyclic potentiodynamic polarization measurements showed metastable corrosion activities associated with a weak passive behavior and a risk for localized corrosion along certain carbide boundaries. In-situ AFM measurements revealed selective dissolution of certain carbide interphases and martensitic inter-lath regions indicating higher propensity to localized corrosion.

  • 5.
    Auvinen, Sonja
    et al.
    VTT.
    Tingelöf, Thomas
    VTT.
    Ihonen, Jari
    VTT.
    Siivinen, Jarmo
    VTT.
    Johanson, Max
    Åbo Akademi.
    Cost effective in-situ characterization of coatings for PEFCbipolar plates demonstrated with PVD deposited CrN2011In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 158, no 5, p. B550-B556Article in journal (Refereed)
    Abstract [en]

    The corrosion and contact resistances of coated and uncoated stainless steel grades were studied. The coatings studied were PVD CrN and arc discharge deposited Au. The samples were aged in long steady-state experiments using a multisinglecell device. MEAs and exhaust water were analyzed for accumulated iron after measurements. Iron accumulation was measured from MEAs, exhaust water and gas outlet pipes from the cells. The interfacial contact resistances were measured before and after the fuel cell experiments. Low contact resistance was achieved with all coated samples. The main accumulation site of dissolved iron was found to be the MEA and GDLs. A large variation in the corrosion results due to differences in the coating quality was observed. Some coatings with low interfacial contact resistance were found to be prone to corrosion. The CrN coating was also tested in a stack, and it performed well. It was concluded that the multisinglecell is a useful tool for screening different coatings reliably and cost-effectively.

  • 6.
    Badel, Xavier
    et al.
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Domeij, Martin
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Information Technology, IMIT.
    Doping of electrochemically etched pore arrays in n-type silicon: processing and electrical characterization2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 4, p. G252-G258Article in journal (Refereed)
    Abstract [en]

    Silicon p-n diodes formed in the walls of deep pores have been electrically characterized. The pores were electrochemically etched in low-doped n-type silicon substrates, and the entire pore array was doped p(+) by boron diffusion at 1050 degrees C. Two different process flows were investigated to disconnect the p(+) layers from one pore to another. The first consists of removing a few micrometers of silicon at the top of the sample using reactive ion etching after diffusion while the second enables the prevention of doping at the top of the pore walls with an oxide, acting as a barrier during diffusion. Current-voltage and capacitance-voltage characteristics of p-n junctions are presented and related parameters, such as the serial resistance and the ideality factor are discussed. The results show good rectifying behavior of the diodes with a reverse current about four to five decades smaller than the forward current. Measurements with two pores connected in a transistor-like configuration (p(+)/n(-)/p(+)), were also performed. Device simulations were used to examine the device behavior. Finally, our results demonstrate that pores could work as individual detector pixels for moderate reverse voltages, suitable for radiation imaging applications.

  • 7. Bergman, B.
    et al.
    Lagergren, Carina
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Schwartz, S.
    Zhu, B. H.
    Contact corrosion resistance between the cathode and current collector plate in the molten carbonate fuel cell2001In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, no 1, p. A38-A43Article in journal (Refereed)
    Abstract [en]

    The corrosion layer Formed in the contact between the cathode and the current collector is one factor limiting the cathode performance in molten carbonate fuel cells (MCFC). In order to investigate the contribution to the total polarization of the contact resistance, electrochemical experiments were performed in a laboratory-scale fuel cell unit with a specially designed current collector. Two cathode materials, NiO and LiCoO2, were investigated to elucidate the impact of the cathode material on the formed corrosion layer. Polarization measurements as well as electrochemical impedance spectroscopy were used. The method works well for NiO electrodes. However, due to the poor electronic conductivity in the LiCoO2 electrode, the experimental results become difficult to evaluate due to a nonuniform potential distribution. The contact resistance between the cathode and the current collector contributes with a large value to the total cathode polarization. The corrosion layer in case of the LiCoO2 cathode was iron-rich and has a thickness of about 20 mum after 8 weeks operation of the fuel cell. Ln the case of the NiO cathode, a nickel-rich corrosion layer of about 15 mum was formed after 5 weeks operation of the fuel cell.

  • 8.
    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.

  • 9. Birgersson, E.
    et al.
    Nordlund, J.
    Ekstrom, H.
    Vynnycky, M.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Reduced two-dimensional one-phase model for analysis of the anode of a DMFC2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 10, p. A1368-A1376Article in journal (Refereed)
    Abstract [en]

    An isothermal two-dimensional liquid phase model for the conservation of mass, momentum, and species in the anode of a direct methanol fuel cell (DMFC) is presented and analyzed. The inherent electrochemistry in the DMFC anode active layer is reduced to boundary conditions via parameter adaption. The model is developed for the case when the geometry aspect ratio is small, and it is shown that, under realistic operating conditions, a reduced model, which nonetheless describes all the essential physics of the full model, can be derived. The significant benefits of this approach are that physical trends become much more apparent than in the full model and that there is considerable reduction in the time required to compute numerical solutions, a fact especially useful for wide-ranging parameter studies. Such a study is then performed in terms of the three nondimensional parameters that emerge from the analysis, and we subsequently interpret our results in terms of the dimensional design and operating parameters. In particular, we highlight their effect on methanol mass transfer in the flow channel and on the current density. The results indicate the relative importance of mass-transfer resistance in both the flow channel and the adjacent porous backing.

  • 10.
    Birgersson, Erik
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Noponen, M.
    Vynnycky, Michael
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Analysis of a two-phase non-isothermal model for a PEFC2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 5, p. A1021-A1034Article in journal (Refereed)
    Abstract [en]

    A non-isothermal, two-phase model for a polymer electrolyte fuel cell (PEFC) is presented, analyzed, and solved numerically under three different thermal, and two hydrodynamic, modeling assumptions; the consequences of these are then discussed in terms of thermal and water management and cell performance. The study is motivated by recent experimental results that suggest the presence of previously unreported, and thus unmodeled, thermal contact resistances between the components of PEFCs and the discrepancy in the value for the capillary pressure that is used by different authors when modeling the two-phase flow in PEFCs. For the three different thermal assumptions (assuming effective heat conductivities, isothermal flow, and interfacial and bulk conductivites), liquid saturations of around 10% are obtained at the cathode active layer for 1000 mA cm(-2) and a cell voltage of 0.6 V. When lowering the capillary pressure (hydrodynamic assumption), liquid saturations of almost 30% and locally up to 100% are observed at the active layer of the cathode. At this current density and voltage, temperature differences across the cell of around 9 degrees C are predicted. In addition, the effect of varying clamping pressure within the framework of the model is touched upon. The benefits of the scaling analysis conducted here, to predict correctly, prior to numerical computations, important characteristic cell performance quantities such as current density and temperature drop are also highlighted.

  • 11.
    Birgersson, Erik
    et al.
    KTH, Superseded Departments, Mechanics.
    Nordlund, Joakim
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Vynnycky, Michael
    KTH, Superseded Departments, Mechanics.
    Picard, Cyril
    KTH, Superseded Departments, Mechanics.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Reduced two-phase model for analysis of the anode of a DMFC2004In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 151, no 12, p. A2157-A2172Article in journal (Refereed)
    Abstract [en]

    An isothermal two-phase ternary mixture model that takes into account conservation of momentum, mass, and species in the anode of a direct methanol fuel cell (DMFC) is presented and analyzed. The slenderness of the anode allows a considerable reduction of the mathematical formulation, without sacrificing the essential physics. The reduced model is then verified and validated against data obtained from an experimental DMFC outfitted with a transparent end plate. Good agreement is achieved. The effect of mass-transfer resistances in the flow field and porous backing are highlighted. The presence of a gas phase is shown to improve the mass transfer of methanol at higher temperatures (>30 degreesC). It is also found that at a temperature of around 30 degreesC, a one-phase model predicts the same current density distribution as a more sophisticated two-phase model. Analysis of the results from the two-phase model, in combination with the experiments, results in a suggestion for an optimal flow field for the liquid-fed DMFC.

  • 12.
    Björkbacka, Åsa
    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.
    Radiation Induced Corrosion of Copper in Humid Air and Argon Atmospheres2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 4, p. C201-C206Article in journal (Refereed)
    Abstract [en]

    Corrosion of copper is a key-issue in the safety assessment of deep geological repositories for spent nuclear fuel utilizing copper coated canisters to isolate the spent nuclear fuel from the surrounding environment. Of particular interest is the radiation induced corrosion attributed to the inherent radioactivity of the spent nuclear fuel. In this work we have studied the radiation induced corrosion of copper in humid air and argon atmospheres. Polished copper cubes were gamma irradiated in the environments mentioned above at ambient temperature. Reference samples, not irradiated but otherwise treated under the exact same conditions as the irradiated samples, were used throughout the study. The oxide layers formed during radiation exposure were studied using cathodic reduction, infrared reflection/absorption spectroscopy, and the surfaces were examined using scanning electron microscopy. When possible, the concentration of copper in solution was measured using inductively coupled plasma atomic emission spectroscopy. The experimental results clearly show that radiation induced corrosion of copper in humid air as well as in humid argon is significantly more extensive than the corresponding process in anaerobic water. This is well in line with the recently proposed mechanism for radiation-induced corrosion of copper in anaerobic water. The very similar behavior of copper irradiated in humid air and in humid argon implies that the radiolytically formed HNO3 in the case of humid air has negligible impact on the radiation-induced corrosion compared to the radiolytically formed hydroxyl radical.

  • 13. Blucher, D. B.
    et al.
    Lindström, Rakel
    Svensson, J. E.
    Johansson, L. G.
    The effect of CO2 on the NaCl-induced atmospheric corrosion of aluminum2001In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, no 4, p. B127-B131Article in journal (Refereed)
    Abstract [en]

    A laboratory study of the effect of CO2 and NaCl on the atmospheric corrosion of aluminum is reported. The samples were exposed to pure air with 95% relative humidity and the concentration of CO2 was <1 and 350 ppm, respectively. Sodium chloride was added before exposure (0, 14, and 70 g/cm(2)). The main result is that the NaCl-induced atmospheric corrosion of aluminum is about 10 to 20 times faster in CO2-free humid air compared to air containing ambient levels of CO2. It is suggested that the rapid corrosion of aluminum coated with NaCl in humid CO2-free air is connected to high-pH areas in the surface electrolyte that develop due to the cathodic reduction of oxygen. The anodic dissolution of aluminum is known to be enhanced by high pH. The unexpected corrosion-inhibitive effect of CO2 is explained by the neutralization of the surface electrolyte. In the absence of CO2, bayerite, Al(OH)(3), forms. Only minute amounts of carbonate were found on the surface after exposure to CO2-containing air.

  • 14.
    Bodén, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    A Model for Mass Transport of Molten Alkali Carbonate Mixtures Applied to the MCFC2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 11, p. A2111-A2119Article in journal (Refereed)
    Abstract [en]

    A one-dimensional model based on the Stefan-Maxwell formulation for mass transfer of the main components of a binary molten carbonate electrolyte, including all of the nonidealities, was formulated and applied to the molten carbonate fuel cell (MCFC). The Stefan-Maxwell diffusion coefficients were determined from literature transport data; still, a narrow parameter window in electrolyte composition and temperature had to be used to keep the integrity of the fits. The model for calculation of the electrolyte composition was combined with equations describing the current distribution in the electrodes and the electrolyte. The calculated results of the electrolyte composition changes show that they depend predominantly on the current density and the total electrolyte filling degree. It was also concluded that the electrolyte composition changes are less then two percent for Li/K and five percent for Li/Na. This model demonstrates how experimental data measured at equilibrium conditions may be used to determine Stefan-Maxwell diffusion coefficients and then applied to a transport model for the electrolyte, in this case an MCFC.

  • 15.
    Bodén, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yoshikawa, Masahiro
    Central Research Institute of Electric Power Industry, Energy Conversion Engineering Sector, Kanagawa Japan.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Influence of the anode pore-size distribution and total electrolyte filling degree on the MCFC performance2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 2, p. B172-B179Article in journal (Other academic)
    Abstract [en]

    Experimental data of the total cell reaction resistance as a function of the total electrolyte filling degree was measured to investigate how more electrolyte initially may be added to get as long a cell lifetime as possible. The reaction resistance of each electrode was also measured using two gas compositions and various total electrolyte filling degrees. A theoretical model for the distribution of electrolyte between the anode and the cathode as a function of the total electrolyte filling degree was used to compare the experimental data in this study with data from a symmetrical cell setup. The model takes into account the electrode pore-size distributions and considers two cases for the contact angle between the electrode and the electrolyte for the anode: a zero wetting angle (fully wetted) or reported experimental values for the wetting angle on pure Ni. It was concluded that after the cathode initially has been sufficiently filled with electrolyte the anode pores have to be smaller than the remaining ones of the cathode to allow having the anode act as a reservoir to prolong cell lifetime. The results from the experimental data and the theoretical model for electrolyte distribution were compared with results from a symmetrical setup.

  • 16. Boschloo, Gerrit
    et al.
    Fitzmaurice, D.
    Electron accumulation in nanostructured TiO2 (anatase) electrodes2000In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 147, no 3, p. 1117-1123Article in journal (Refereed)
    Abstract [en]

    The potential-dependent optical-absorption spectroscopy of nanostructured TiO2 (anatase) is most fully accounted for by two processes, band-filling and intercalation. Under weak-accumulation conditions, occupation of surface and conduction-band states by electrons dominates with the accumulated charge being compensated by adsorbed protons or cations. Under strong-accumulation conditions, however, intercalation of protons or cations may take place with a fraction of the accumulated electrons being localized at Ti-IV sites.

  • 17.
    Brown, Shelley
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Mellgren, Niklas
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Vynnycky, Michael
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Impedance as a Tool for Investigating Aging in Lithium-Ion Porous Electrodes: II. Positive Electrode Examination2008In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 155, no 4, p. A320-A338Article in journal (Refereed)
    Abstract [en]

    High-power positive LixNi0.8Co0.15Al0.05O2 composite porous electrodes are known to be the main source of impedance increase in batteries based on GEN2 chemistry. The impedance of positive electrodes, both fresh and harvested from coin cells aged in an accelerated EUCAR hybrid electric vehicle lifetime matrix, was measured in a three-electrode setup and the results fitted with a physically based impedance model. A methodology for fitting the impedance data, including an optimization strategy incorporating a global genetic routine, was used to fit either fresh or aged positive electrodes simultaneously at different states of charge down to 0.5 mHz. The fresh electrodes had an exchange current density of approximately 1.0 A m(-2), a solid-phase diffusion coefficient of approximately 1.4 x 10(-1)5 m(2) s(-1), and a log-normal active particle size distribution with a mean radius of 0.25 mu m. Aged electrode impedance results were shown to be highly dependent on both the electrode state of charge and the pressure applied to the electrode surface. An aging scenario incorporating loss of active particles, coupled with an increase both in the local contact resistance between the active material and the conductive carbon and the resistance of a layer on the current collector, was shown to be adequate in describing the measured aged electrode impedance behavior.

  • 18.
    BURSELL, Martin
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    BJÖRNBOM, Pehr
    KTH, Superseded Departments, Chemical Engineering and Technology.
    A METHOD FOR STUDYING MICROELECTRODES BY MEANS OF MICROMANIPULATORS AS APPLIED TO CARBON AGGLOMERATES FROM OXYGEN REDUCTION ELECTRODE CATALYST1990In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 137, no 1, p. 363-365Article in journal (Refereed)
  • 19. Byrne, P.
    et al.
    Fontes, E.
    Parhammar, O.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    A simulation of the tertiary current density distribution from a chlorate cell - I. Mathematical model2001In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 148, no 10, p. D125-D132Article in journal (Refereed)
    Abstract [en]

    Numerical modeling is becoming an integral part of all research and development within the field of electrolytic systems. A numerical model that calculates the current density distribution and concentration profiles of a chlorate cell is presented here, The results are shown as functions of electrolyte velocity and exchange current density. The model takes into account the three transport mechanisms; diffusion, migration, and convection by considering the development of the flow velocity vector through the channel. It was seen that the developing velocity profile influences the concentration overpotentials, which in turn influences current density distributions. Results from the model show that the total current density decreased along the length of the anode, and that this distribution varied more at lower velocities. In addition, it was seen that migration contributes significantly to species transport, even within the diffusion layer. Finally, the model indicates that the hypochlorite ion is the main participant in the principal side reaction producing oxygen, and not the hypochlorous acid molecule. The results are useful as they increase knowledge of the chlorate process, and can be used to simulate future systems with a wide range of varying parameters such as cell geometry, flow, electrolyte composition, and electrode materials. The aim of the model is to use it as a tool for identifying the sources that contribute to the overpotential in the cell. This article concentrates on the concentration overpotential, which is one of the phenomena that can actually be influenced,

  • 20.
    Chen, Chengdong
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hou, Ruiqing
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dong, Shigang
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lin, Changjian
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Heating-Induced Enhancement of Corrosion Protection of Carbon Steel by a Nanocomposite Film Containing Mussel Adhesive Protein2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 4, p. C188-C193Article in journal (Refereed)
    Abstract [en]

    Application of protective coatings on metals may involve a thermal treatment process. In this study, the effect of thermal treatment up to 200 degrees C on the corrosion protection was investigated for nanocomposite films composed of mussel adhesive protein (MAP), CeO2 nanoparticles and Na2HPO4 deposited on carbon steel. The morphology and microstructure of the pre-formed nanocomposite film were characterized by scanning electron microscopy/energy dispersive spectroscopy and atomic force microscopy (AFM). The changes in the chemical structure of the nanocomposite film due to the thermal treatment were investigated by infrared reflection absorption spectroscopy. The corrosion protection of the unheated and heated nanocomposite films on carbon steel was evaluated by electrochemical impedance spectroscopy and details of the corrosion process were elucidated by in-situ AFM measurements in 0.1 M NaCl solution. The results show a certain increase in the corrosion protection with time of the nanocomposite film for carbon steel. The analyses reveal that thermal treatment leads to a reduction of water molecules in the nanocomposite film, and an enhanced cross-linking and cohesion of the film due to oxidation of catechols to o-quinones. As a result, the film becomes more compact and gives improved corrosion protection for carbon steel.

  • 21.
    Chen, Chengdong
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Xiamen University, China.
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lin, C.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Xiamen University, China.
    Corrosion protection and self-healing of a nanocomposite film of mussel adhesive protein and CeO2 nanoparticles on carbon steel2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 9, p. C545-C552Article in journal (Refereed)
    Abstract [en]

    A nanocomposite film composed of mussel adhesive protein (MAP) and CeO2 nanoparticles has been explored as a 'green' alternative for corrosion protection of carbon steel. In this work, the nanocomposite film of sub-micron thickness was deposited on carbon steel surface by one-step-dipping method. The film was characterized by using scanning electron microscope/energy dispersive spectroscopy and atomic force microscope (AFM). The measurements of scanning reference electrode technique and in-situ AFM were performed to investigate the initial localized corrosion process at defects and self-healing ability of the nanocomposite film. The results demonstrate that the nanocomposite film possesses a certain self-healing ability and provides excellent corrosion protection for carbon steel in neutral 0.1 M NaCl solution. The self-healing ability is attributed to the functional group (catechol) of the MAP, and the healing process is explained by the fact that Fe ions released from the surface defects promote the formation of Fe-catecholato complexes in the nanocomposite film, which retards the localized corrosion at these defects.

  • 22.
    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.

  • 23.
    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.

  • 24.
    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.

  • 25.
    Cornell, Ann
    et al.
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Håkansson, Bo
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Ruthenium-based dimensionally stable anode in chlorate electrolysis - Effects of electrolyte composition on the anode potential2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 1, p. D6-D12Article in journal (Refereed)
    Abstract [en]

    In this work the anodic reactions taking place on a dimensionally stable anode (DSA) in chlorate electrolyte have been investigated. Rotating disk electrodes were made from commercial RuO2-catalyzed DSAs and studied in steady-state polarization measurements, mainly IR-corrected polarization curves. Effects of varying pH and electrolyte concentrations of chloride, chlorate, chromium(VI), hypochlorite (ClO- + ClOH) as well as mass transport were studied. The kinetics for the chlorine evolution reaction, with a Tafel slope of 40 mV/decade of current, was not dependent on pH in the region 2-8, at potentials lower than 1.2 V vs. Ag/AgCl. The slope of the polarization curves increased at about 1.2 V vs. Ag/AgCl, a pH-dependent bend not due to mass-transport limitations in the electrolyte. At a pH of 6.5, typical for the chlorate process, oxygen evolution is an important side reaction favored by the dichromate buffer and by increased mass transport, both keeping down the pH at the anode. In the chlorine evolution region the potentials increased when adding Cr(VI) to the electrolyte, whereas no major effect was seen from additions of NaClO. (C) 2002 The Electrochemical Society.

  • 26.
    Danielsson, Carl-Ola
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Dahlkild, Anders
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Velin, Anna
    Behm, Mårten
    KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Nitrate Removal by Continuous Electropermutation Using Ion-Exchange Textile: I. Modeling2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 4, p. D51-D61Article in journal (Refereed)
    Abstract [en]

    This paper presents a steady-state model of the feed compartment of an electropermutation cell, used for nitrate removal, with ion exchange textiles incorporated as a conducting spacer. In the model the ion-exchange textile is treated as a porous medium and volume averaging is applied to obtain a macrohomogeneous two-phase model. The ion-exchange between the two phases is modeled assuming that the rate-determining step is the mass-transfer resistance on the liquid side of the phase interface. Analysis of the model equations reveals appropriate simplifications. The influence of the governing dimensionless numbers is investigated through simulations based on the model.

  • 27.
    Danielsson, Carl-Ola
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Velin, Anna
    Behm, Mårten
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology. KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Dahlkild, Anders
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Faxén Laboratory.
    Nitrate Removal by Continuous Electropermutation Using Ion-Exchange Textile: II. Experimental Investigation2006In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 153, no 4, p. D62-D67Article in journal (Refereed)
    Abstract [en]

    Water with nitrate concentrations above 100 ppm has been treated with continuous electropermutation which partially substitutes the nitrate with chloride. The performance of a textile anion exchanger as conducting spacer in the feed compartment of an electropermutation cell was investigated. Experiments with and without textile are compared and the influence of the textile is discussed. The process could, using the textile, successfully treat feed water with 105 ppm nitrate to produce a water with less than 25 ppm nitrate. The importance of establishing a good contact between the membranes and the textile spacer was pointed out. The experimental results were compared to model predictions and a good agreement was found.

  • 28.
    Darab, Mahdi
    et al.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Syvertsen, Guttorm Ernst
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Nanoengineered BSCF Cathode Materials for Intermediate-Temperature Solid-Oxide Fuel Cells2009In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 156, no 8, p. K139-K143Article in journal (Refereed)
    Abstract [en]

    A recently reported promising cathode material for solid-oxide fuel cells (SOFCs), namely, BaxSr1-xCoyFe1-yO3-delta (BSCF) is fabricated in nanocrystalline form by a chemical alloying approach. The approach is comprised of solution chemical synthesis of a precursor and its thermochemical processing toward the desired phase. All the constituent elements, Ba, Sr, Co, and Fe, were coprecipitated from an aqueous solution of their salts to produce a precursor with a well-defined composition, fine particle size, high homogeneity, and high reactivity. After calcining and sintering at 1000 degrees C, the individual oxides were alloyed into nanostructured perovskite (with x=0.5 and y=0.2) Ba0.5Sr0.5Co0.2Fe0.8O3 of high purity. Spark plasma sintering was used for compaction to preserve the material's nanostructure, and sintered compacts demonstrated a significant increase in electrical conductivity values at temperatures up to 900 degrees C, compared to the earlier reports. The measured conductivity values are sufficiently high for cathode applications with a maximum of about 63 S cm(-1) at 430 degrees C in air and 25 S cm(-1) at 375 degrees C in N-2, respectively. These values are about twice as high as conventional BSCF mainly due to the reduction in interfacial resistance, implying a high promise for nanoengineered BSCF as cathode material at low or intermediate-temperature SOFCs.

  • 29.
    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)
  • 30.
    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.

  • 31.
    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)
  • 32.
    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.

  • 33.
    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.

  • 34.
    Dentoni Litta, Eugenio
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Hellström, Per-Erik
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Henkel, Christoph
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Valerio, Sven
    KTH, School of Information and Communication Technology (ICT).
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Östling, Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    High-Deposition-Rate Atomic Layer Deposition of Thulium Oxide from TmCp3 and H2O2013In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 160, no 11, p. D538-D542Article in journal (Refereed)
    Abstract [en]

    A novel process for atomic layer deposition of thulium oxide (Tm2O3) has been developed, employing TmCp3 as metal precursor and H2O as oxidizing agent. The use of a highly reactive oorganometallic precursor eliminates the need for a strong oxidizing agent (such as O-3) and provides a high deposition rate of similar to 1.5 angstrom/cycle. A thorough characterization of the process has been performed, identifying true ALD-type film growth in the temperature range 200-300 degrees C. The ALD process has been further investigated by extensive physical and electrical characterization of the deposited films in terms of-composition, crystalline phase, surface roughness and extraction of the dielectric constant. The films were found to be oxygen-rich Tm2O3, with low carbon impurity content at low deposition temperature and after annealing at 600 degrees C. The developed process produced polycrystalline films, with a surface roughness <1 nm RMS. Integration in MOS capacitors demonstrated well-behaved CV curves after annealing at 600 degrees C, with a relative dielectric constant of similar to 16.

  • 35.
    Ekström, Henrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    A model for predicting capacity fade due to SEI formation in a commercial graphite/LiFePO4 cell2015In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 162, no 6, p. A1003-A1007Article in journal (Refereed)
    Abstract [en]

    An aging model for a negative graphite electrode in a lithium-ion battery, for moderate currents up to 1C, is derived and fitted to capacity fade experimental data. The predictive capabilities of the model, using only four fitted parameters, are demonstrated at both 25°C and 45°C. The model is based on a linear combination of two current contributions: one stemming from parts of the graphite particles covered by an intact microporous solid-electrolyte-interface (SEI) layer, and one contribution from parts of the particles were the SEI layer has cracked due to graphite expansion. Mixed kinetic and transport control is used to describe the electrode kinetics.

  • 36. Enback, S.
    et al.
    Lindbergh, Göran
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Experimentally validated model for CO oxidation on PtRu/C in a porous PEFC electrode2005In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 152, no 1, p. A23-A31Article in journal (Refereed)
    Abstract [en]

    Carbon monoxide oxidation in a porous polymer electrolyte fuel cell (PEFC) electrode with PtRu/C catalyst was studied with steady-state polarization curves and open- circuit decay measurements. The Tafel slope was about 210 mV/decade and the reaction order for CO was about 0.45 at 0.4 V vs. RHE. This experimental behavior is explained with a mathematical model with CO adsorbing on Pt and water adsorbing on Ru. Kinetic parameters are determined from a fitting of the model to both the steady-state and the transient measurements. A single rate-determining step cannot account for the polarization curves over the whole potential range. At mid-range potentials the oxidation step is rate-determining but at lower potentials the water adsorption might be rate-determining. The open- circuit decay measurements gave noise-free measurements and confirmed the accuracy of the steady-state measurements. The obtained model for CO oxidation where the coverage of COads on Pt is determined can be used together with a model for H-2 oxidation.

  • 37. Eriksson, T.
    et al.
    Hjelm, A. K.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Gustafsson, T.
    Kinetic study of LiMn2O4 cathodes by in situ XRD with constant-current cycling and potential stepping2002In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, no 9, p. A1164-A1170Article in journal (Refereed)
    Abstract [en]

    The structure and kinetics of LiMn2O4 electrodes have been investigated by in situ X-ray diffraction (XRD) measurements using a novel three-electrode in situ XRD cell, where the reference electrode is sited on the reverse side of the working electrode to facilitate accurate determination of the electrode potential. The use of ballmilling during electrode preparation resulted in a high level of utilization at high charge/discharge rates of LiMn2O4-based electrodes in both structural and electrochemical studies. No evidence of Li concentration gradients in the solid material could be observed from XRD, thus excluding solid-phase diffusion and also phase boundary movement, as described by Fick's law, as the rate-limiting step.

  • 38. Esmaily, M.
    et al.
    Blücher, D. B.
    Wreland Lindström, Rakel
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Applied Electrochemistry.
    Svensson, J. -E
    Johansson, L. G.
    The influence of SO2 on the corrosion of Mg and Mg-Al alloys2015In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 162, no 6, p. C260-C269Article in journal (Refereed)
    Abstract [en]

    The SO2-induced atmospheric corrosion of some magnesium-aluminum (Mg-Al) alloys, including Mg alloy AZ91D, and commercially pure Mg (CP Mg) was investigated using well-controlled laboratory exposures and included real-time measurements of SO2 deposition. The influence of SO2 concentration, alloy composition, humidity, and ppb level additions of O-3 or NO2 on the rate of SO2 deposition was investigated. SO2 accelerates the corrosion of Mg and Mg alloys causing localized corrosion, MgSO(3)6H(2)O being the dominant corrosion product. At 60% RH, traces of O-3 or NO2 strongly increased both the SO2 deposition and the corrosion rate. The rate of SO2 deposition was strongly dependent on humidity; at 70% RH and higher the SO2 deposition rate was very rapid and constant in time while it was transient below 50% RH. At 60% RH, a change from transient to rapid, steady-state, SO2 deposition occurred. The sudden activation is explained by the onset of electrochemical corrosion. The activation behavior was shown to depend on SO2 concentration, the thickness of the surface film and by the presence of ambient O-2. (C) The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

  • 39.
    Esteve, Romain
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Reshano, S.A.
    Savage, S.
    Bakowski, M.
    Kaplan, W.
    Persson, S.
    Schöner, A.
    Zetterling, Carl-Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Toward 4H-SiC MISFETs Devices Based on ONO (SiO2-Si3N4-SiO2) Structures2011In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 5, no 158, p. 496-501Article in journal (Refereed)
    Abstract [en]

    The electrical properties of metal-insulator-semiconductor (MIS) devices based on ONO (SiO2-Si3N4-SiO2) structures fabricatedon n-type 4H-SiC (0001) epilayers have been investigated. Three different combinations of low-pressure chemical vapordeposition (LPCVD), plasma-enhanced chemical vapor deposition (PECVD) and thermal oxidations (TO) in N2O and wet oxygenH2O:O2 were studied for the formation of the ONO stack. In addition, the influence of the thickness of SiO2and Si3N4 layers were considered and recommendations for optimal ONO structure are given. Oxide characterization tests and reliability investigations have been performed at room and high temperatures. This comparative study resulted in the development of ONO structuresdescribing low oxide/near interface/interface defects and high reliability of the devices even at high temperature.

  • 40. 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.

  • 41. 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.

  • 42.
    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.

  • 43. Forsberg, J.
    et al.
    Hedberg, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Nordgren, J.
    Duda, L. C.
    The Initial Stages of Atmospheric Corrosion of Iron in a Saline Environment Studied with Time-Resolved In Situ X-Ray Transmission Microscopy2010In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 3, p. C110-C115Article in journal (Refereed)
    Abstract [en]

    We have investigated atmospheric corrosion of a 50 nm layer of iron covered with a thin layer of NaCl by in situ X-ray transmission spectromicroscopy. We find that upon its deliquescence, a small part of the NaCl layer is rapidly transformed into a sodium oxide (NaOH) species. A large part of the sodium and chlorine ions forms a concentrated solution on the iron surface and becomes segregated, whereby the sodium ions appear stationary and passive during further corrosion progression. In contrast, the chlorine ions appear highly mobile and become concentrated at and travel with the corrosion front, apparently acting as a corrosion catalyst. The corrosion front progression is partly of filiform and partly of radial type. The early iron corrosion products (chloride-containing oxyhydroxides) are short-lived (for some hours) and undergo a transformation as the corrosion front sweeps by from a chlorinated species to a less chlorinated species.

  • 44.
    Forslund, Mattias
    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.
    Claesson, Per M.
    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.
    Octadecanethiol as Corrosion Inhibitor for Zinc and Patterned Zinc-Copper in Humidified Air with Formic Acid2014In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 161, no 6, p. C330-C338Article in journal (Refereed)
    Abstract [en]

    The corrosion inhibition efficiency of octadecanethiol (ODT) for zinc and a zinc-copper patterned model sample (Zn-Cu) has been explored during exposure in an atmosphere that mimics indoor atmospheric corrosion containing humidified air (80% relative humidity at 20 degrees C) and formic acid (around 100 ppb). The corrosion kinetics were monitored in situ with infrared reflection absorption spectroscopy, and the local nature of corrosion effects post-analyzed with complementary scanning electron microscopy, atomic force microscopy and confocal Raman spectroscopy. ODT shows initially a corrosion inhibiting ability both on zinc and on Zn-Cu. This ability decreases with time due to local removal of ODT, which causes micro-galvanic effects that eventually result in corrosion rates that exceed those for the uncovered samples. On bare and ODT-covered samples, the presence of a copper-zinc junction results in both accelerated corrosion and in structurally more developed corrosion products. Overall, the results suggest that ODT can function as a temporary corrosion inhibitor in representative indoor environments on zinc and zinc with zinc-copper junctions.

  • 45.
    Forslund, Mattias
    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.
    Claesson, Per Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lin, C.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Micro-galvanic corrosion effects on patterned copper-zinc samples during exposure in humidified air containing formic acid2013In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 160, no 9, p. C423-C431Article in journal (Refereed)
    Abstract [en]

    Corrosion in indoor atmospheric environments is often triggered by carboxylic acids, especially at higher relative humidity. Microgalvanic effects can lead to severe corrosion, particularly important in miniature devices with small-sized metallic components. To elucidate the mechanism of micro-galvanic corrosion effects, well-defined zinc-copper patterned samples were investigated during exposure to 100 ppb formic acid (HCOOH) and 80% relative humidity at 20°C. The corrosion effects were monitored quantitatively with in situ infrared absorption spectroscopy, and the corrosion products characterized with scanning electron microscopy, confocal Raman microscopy, and atomic force microscopy. The nature of corrosion on zinc on the patterned samples was compared with that on pure zinc and turned out to result, not only in several times higher corrosion kinetics, but also in different corrosion products with respect to distribution, morphology, and composition. Local electrochemical and chemical gradients across the copper-zinc borders resulted in characteristic hemispherically shaped corrosion products at the zinc-copper junction, and in the formation of zinc formate dihydrate (Zn(HCOO)2 · 2H 2O) and crystalline zinc oxide (ZnO), phases not identified on pure zinc. In all, the micro-galvanic effects on the patterned samples resulted in accelerated corrosion kinetics and in structurally more developed corrosion products.

  • 46.
    Fuertes, Nuria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Rachel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Review—Passive Film Properties and Electrochemical Response of Different Phases in a Cu-Alloyed Stainless Steel after Long Term Heat Treatment2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 7, p. C377-C385Article in journal (Refereed)
    Abstract [en]

    In this work the influence of copper (0–4 wt%) on the microstructure, passive film properties and local electrochemical response of 25Cr7Ni-type duplex stainless steel is investigated after long term heat-treatment at 800◦C for 6 months. This heat-treatment was done to promote the formation of different phases which could be studied in terms of passive film properties and electrochemical response. The unique microstructures of the alloys comprise austenite, sigma phase, Cr2N nitrides and, for the 2 wt% and 4 wt% Cu alloys, epsilon-Cu phase. The results show that alloying with Cu increases slightly the amount of isothermal Cr2N nitrides and epsilon-Cu phase, but decreases the sigma phase fraction. The location of pitting corrosion as well as the Electrochemical Potential (EP), or electron work function, measured with Scanning Kelvin Probe Force Microscopy (SKPFM) show that the epsilon-Cu phase has the lowest corrosion resistance. The EP appears to depend more on the composition of the underlying phase than on the thickness of the passive film. Cr-nitrides have the highest EP followed by sigma phase, austenite and epsilon-Cu phase. There is a clear decrease of EP of the austenitic phase when 2 wt% Cu is added in the alloy.

  • 47.
    Fuertes, Nuria
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pettersson, Rachel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Nazarov, Andrej
    French Corrosion Institute.
    Thierry, Dominique
    French Corrosion Institute.
    Vucko, Fabien
    French Corrosion Institute.
    Influence of Mechanical Stress on the Potential Distribution on a 301 LN Stainless Steel Surface2015In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, p. C465-C472Article in journal (Refereed)
    Abstract [en]

    The aim of the present work was to study the influence of the stress on the electrode potential of the austenitic stainless steel301LN using Scanning Kelvin Probe (SKP). It was found that elastic deformation reversibly ennobles the potential whereas plasticdeformation decreases the potential in both tensile and compressive deformation mode and this decrease is retained even 24 h afterremoval of the load. To interpret the stress effects, different surface preparations were used and the composition and thickness ofthe passive film were determined by GDOES. Slip steps formed due to plastic deformation were observed using AFM. The effect ofplastic strain on the potential is explained by the formation of dislocations, which creates more a defective passive film.

  • 48. Georen, P.
    et al.
    Adebahr, J.
    Jacobsson, P.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Concentration polarization of a polymer electrolyte2002In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 149, no 8, p. A1015-A1019Article in journal (Refereed)
    Abstract [en]

    In this study, the salt concentration in a concentrated binary polymer electrolyte was measured in situ by means of confocal Raman spectroscopy during galvanostatic polarization experiments. The electrolyte studied was 0.8 M lithium bis(trifluoromethanesulfone)imide in a copolymer of ethylene- and propylene oxide at 25degreesC. Recent work with a transport model and characterization of the transport properties, for the same electrolyte, was verified with the spectroscopic results of this study. A good agreement between modeled and measured results was found. The spectroscopic method suited well for these studies. The possibilities of using a transport model are briefly demonstrated and discussed.

  • 49. Georen, P.
    et al.
    Hjelm, A. K.
    Lindbergh, Göran
    KTH, Superseded Departments, Chemical Engineering and Technology.
    Lundqvist, A.
    An electrochemical impedance spectroscopy method applied to porous LiMn2O4 and metal hydride battery electrodes2003In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 150, no 2, p. A234-A241Article in journal (Refereed)
    Abstract [en]

    An electrochemical impedance spectroscopy method utilizing the signals from reference electrodes positioned in front of and behind a porous electrode is investigated. The basis for the method is illustrated theoretically, and limiting values under different assumptions are presented. The method was applied to a porous metal hydride and a LiMn2O4 battery electrode. It was concluded that the method facilitates the separation of local impedance effects from the effects of the potential distribution in the porous electrode. Consequently, a more accurate determination of local kinetic parameters and the effective conductivity in the pore electrolyte could be obtained.

  • 50.
    Gil, Harveth
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Quantitative in situ analysis of initial atmospheric corrosion of copper induced by acetic acid.2007In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 154, no 5, p. 272-278Article in journal (Refereed)
    Abstract [en]

    The initial atmospheric corrosion of copper was investigated by means of a quantitative in situ analysis in an atmospherecontaining 120 ppb of acetic acid and 95% relative humidity using a quartz crystal microbalance (QCM) integrated with infraredreflection absorption spectroscopy (IRAS). Crystalline cuprous oxide (various structural forms of Cu2O) and hydrated copperacetate were detected as corrosion products during up to 100 h of exposure. The quantification of data was made possible throughan observed linear relationship between the absorbance of vibrations (IRAS)of both phases and the corresponding mass (QCM).The quantification of cuprous oxide was further supported by ex situ coulometric reduction of the corrosion products. The growthrate of cuprous oxide was initially very fast but almost zero after 20 h exposure where it reached an average thickness of13 ± 1 nm. Copper acetate exhibited a more constant growth rate. Atomic force microscopy showed a uniform growth of cuprousoxide with surface roughness that increased with time and localized formation of copper acetate. The quantified data are consistentwith a previously proposed model that involves proton- and acetate-induced dissolution of copper and subsequent precipitation ofcuprous oxide and copper acetate.

1234 1 - 50 of 173
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