Ändra sökning
Avgränsa sökresultatet
2345 201 - 220 av 220
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Träffar per sida
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
  • Standard (Relevans)
  • Författare A-Ö
  • Författare Ö-A
  • Titel A-Ö
  • Titel Ö-A
  • Publikationstyp A-Ö
  • Publikationstyp Ö-A
  • Äldst först
  • Nyast först
  • Skapad (Äldst först)
  • Skapad (Nyast först)
  • Senast uppdaterad (Äldst först)
  • Senast uppdaterad (Nyast först)
  • Disputationsdatum (tidigaste först)
  • Disputationsdatum (senaste först)
Markera
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 201.
    Weissenrieder, Jonas
    et al.
    KTH, Tidigare Institutioner, Fysik. KTH, Tidigare Institutioner, Materialvetenskap.
    Leygraf, Christofer
    KTH, Tidigare Institutioner, Materialvetenskap.
    Göthelid, Mats
    KTH, Tidigare Institutioner, Fysik.
    Karlsson, Ulf O.
    KTH, Tidigare Institutioner, Fysik.
    Photoelectron microscopy of filiform corrosion of aluminum2003Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 218, nr 1-4, s. 154-161Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aluminum samples have been investigated during and after exposure to well-controlled amounts of NaCl and humidified air. With infrared reflection absorption spectroscopy the deliquescence of NaCl crystallites could be followed in situ at high relative humidity (RH), as well as the growth of different aluminum oxide, hydroxide and chloride corrosion products. Investigations with scanning electron microscopy and energy dispersive X-ray analysis after exposure revealed the growth of filaments representative of filiform corrosion and chlorine enrichment in the filament heads. The exposed samples were further investigated with synchrotron based photoelectron microscopy/spectroscopy. Spectra taken of the Al 2p core level showed an intricate structure with multiple components in the core level. By means of mapping the intensity of the different chemical states within the core level the distribution of compounds over the surface could be determined. An enrichment of aluminum chloride containing compounds was found in the heads of the filaments, whereas aluminum oxides or hydroxides were observed both inside and outside the filaments.

  • 202.
    Weissenrieder, Jonas
    et al.
    KTH, Tidigare Institutioner, Fysik.
    Leygraf, Christofer
    KTH, Tidigare Institutioner, Materialvetenskap.
    Österman, John
    KTH, Tidigare Institutioner, Mikroelektronik och informationsteknik, IMIT.
    In-Situ Studies of the Initial Atmospheric Corrosion of Iron: Influence of SO2, NO2 and NaCl2001Ingår i: Corrosion and corrosion protection: proceedings of the international symposium, 2001, s. 733-740Konferensbidrag (Refereegranskat)
  • 203.
    Yin, Litao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. Univ Sci & Technol Beijing, Peoples R China.
    Jin, Ying
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Birbilis, Nick
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Numerical Simulation of Micro-Galvanic Corrosion in Al Alloys: Effect of Geometric Factors2017Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, nr 2, s. C75-C84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A finite element model for simulating the propagation of intermetallic particle driven micro-galvanic corrosion in an Al-matrix model system is presented. The model revealed dynamic changes related to localized corrosion, including the moving dissolution boundary, the deposition of reaction products (Al(OH)(3)), and their blocking effect. Modelling was focused on the effects of key geometric parameters, including the radius of cathodic particle (range 0.5 to 4 mu m) and the width of an assumed anodic ring surrounding the particle (range 0.1 to 2 mu m). Simulations revealed the dynamic flow of molecular and ionic species, along with influence of geometrical constraints. For ring widths below 0.5 mu m, deposition of Al(OH)(3) inside the dissolving volume was inhibited due to limited transport of OH- and O-2 into a constrained volume - resulting in local acidification. An increase in cathodic particle radius at given ring width resulted in a greater dissolution by providing a larger cathodic area for O-2 reduction, quantifying the effect of cathode/anode ratio. The model was also developed to include two cathodic particles to explore any interaction. The present study reveals a physicochemical model that contributes toward a framework for multi-process localized corrosion systems, which can be further adapted to commercial alloy systems.

  • 204.
    Yin, Litao
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap. Univ Sci & Technol Beijing, China.
    Jin, Ying
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    A FEM model for investigation of micro-galvanic corrosion of Al alloys and effects of deposition of corrosion products2016Ingår i: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 192, s. 310-318Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A finite element method model has been elaborated aiming at a deeper insight into the influence of microstructure on micro-galvanic corrosion of Al alloys. The model considers a dynamic corroding surface and takes into account kinetic data from local electrochemical reactions, transport of O-2 and ionic species (e.g., Al3+, H+, Cl-), homogeneous reactions in the electrolyte, deposition of reaction products and its influence on both anodic and cathodic reactions. As a first step, an Al matrix with a micrometer-sized cathodic intermetallic particle exposed in 0.1 M NaCl has been considered. The simulation predicts the dynamic changes of the corroding surface, and the flow and distribution of ionic species and of O-2 in space and time. The calculated pH of the electrolyte inside and nearby the occluded corroding volume suggests the formation of insoluble Al(OH)(3) on both the cathodic and anodic areas. This results in blocking effects of anodic and cathodic reactions and in eventual termination of the micro-galvanic corrosion. The predicted deposition of corrosion product is in good agreement with in-situ atomic force microscopy measurements.

  • 205. Zhang, X. Y.
    et al.
    He, W. L.
    Odnevall Wallinder, Inger
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Pan, Jinshan
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Leygraf, Christofer
    KTH, Tidigare Institutioner                               , Materialvetenskap.
    Determination of instantaneous corrosion rates and runoff rates of copper from naturally patinated copper during continuous rain events2002Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 44, nr 9, s. 2131-2151Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Instantaneous corrosion rates of naturally patinated copper of varying age (16 months, 138 and 145 years) have been determined during continuous rain events in the laboratory with electrochemical impedance spectroscopy using a two-electrode cell. The two-electrode cell was found to yield the same information in bulk rainwater as a conventional three-electrode cell. Relatively constant corrosion rates, between 0.2 and 0.6 mum/y, were determined for samples having a two-layer structure with an inner brownish layer of cuprous oxide and an outer greenish layer of basic copper salts (138, 145 years). Samples with cuprous oxide as the dominating phase of the patina (16 months) showed higher and somewhat increasing corrosion rates during a rain event (from 0.6 to 1.2 mum/y). During a continuous rain event, corrosion rates were found to be approximately 10 (brownish patina) and 25 times (greenish patina) lower than corresponding instantaneous runoff rates. The first flush phenomena of the runoff process, with an increased concentration during first flush and a relatively constant concentration during steady state, was indirectly seen as an increase in solution conductivity during the first rain volume followed by relative constant value. The contribution of the concentration in the first flush to the total annual runoff rate was significant for panels having a greenish layer (138, 145 years) whereas it was negligible for panels having a brownish layer (16 months).

  • 206.
    Zhang, Xian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Atmospheric corrosion of Galfan coatings on steel in chloride-rich environments2013Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 73, s. 62-71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Galfan coatings on steel in laboratory exposures with predeposited NaCl and cyclic wet/dry conditions exhibit nearly the same corrosion products as after 5 years of marine exposure. A general scenario for corrosion product evolution on Galfan in chloride-rich atmospheres is proposed. It includes the initial formation of ZnO, ZnAl2O4 and Al2O3 and subsequent formation of Zn6Al2(OH)(16)CO3 center dot 4H(2)O, and Zn2Al(OH)(6)Cl center dot 2H(2)O and/or Zn5Cl2(OH)(8)center dot H2O. An important phase is Zn6Al2(OH)(16)CO3 center dot 4H(2)O, which largely governs the reduced long-term zinc runoff from Galfan. A clear influence of microstructure could be observed on corrosion initiation in the slightly zinc-richer eta-Zn phase adjacent to the beta-Al phase.

  • 207.
    Zhang, Xian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Selected area visualization by FIB-milling for corrosion-microstructure analysis with submicron resolution2013Ingår i: Materials letters (General ed.), ISSN 0167-577X, E-ISSN 1873-4979, Vol. 98, s. 230-233Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report the successful use of focussed ion beam (FIB) milling of trenches in a material of complex microstructure in order to visualize a selected area (32×32 μm) for further multi-analysis with submicron resolution. This capability is demonstrated for a Zn-5 wt% Al coating Galfan™ on steel. The very same eutectic surface area was analyzed by three complementary and independent techniques providing consistent information on the lateral distribution of morphology and elemental composition (scanning electron microscopy with x-ray microanalysis, SEM/EDS), topography and Volta potential (scanning Kelvin probe force microscopy, SKPFM) and oxide composition (confocal Raman microspectroscopy, CRM). The approach enables a straightforward way to explore the interplay between microstructure and local corrosion of metallic materials.

  • 208.
    Zhang, Xian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Liu, Xiaoyan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    The protective role of hydrozincite during initial corrosion of a Cu40Zn alloy in chloride-containing laboratory atmosphere2016Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 103, s. 20-29Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrozincite, Zn-5(CO3)(2)(OH)(6), was recently found to play a key role in reducing corrosion product flaking on Cu-Zn alloys. A fundamental study was undertaken to explore the underlying mechanisms, in particular why hydrozincite can suppress the interaction between chlorides and the alloy surface. Hydrozincite could be formed by exposure of Cu40Zn to air at 70% relative humidity and 1000 ppm of CO2 resulting in a surface of decreased wettability. Its presence reduces the initial spreading ability of NaCl-containing droplets and lowers the overall initial corrosion rate when the alloy is exposed to pre-deposited NaCl and wet/dry cycles.

  • 209.
    Zhang, Xian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Mechanistic studies of corrosion product flaking on copper and copper-based alloys in marine environments2014Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 85, s. 15-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mechanism of corrosion product flaking on bare copper sheet and three copper-based alloys in chloride rich environments has been explored through field and laboratory exposures. The tendency for flaking is much more pronounced on Cu and Cu-4 wt%Sn than on Cu-15 wt%Zn and Cu-5 wt%Al-5 wt%Zn. This difference is explained by the initial formation of zinc and zinc-aluminum hydroxycarbonates on Cu15Zn and Cu5Al5Zn, which delays the formation of CuCl, a precursor of Cu-2(OH)(3)Cl. As a result, the observed volume expansion during transformation of CuCl to Cu-2(OH)(3)Cl, and concomitant corrosion product flaking, is less severe on Cu15Zn and Cu5Al5Zn than on Cu and Cu4Sn.

  • 210.
    Zhang, Xian
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. Wuhan Univ Sci & Technol, State Key Lab Refractory Mat & Met, Hubei Prov Key Lab Syst Sci Met Proc, Int Res Inst Steel Technol, Wuhan 430081, Hubei, Peoples R China..
    Odnevall Wallinder, Inger
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christopher
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Atmospheric corrosion of Zn-Al coatings in a simulated automotive environment2018Ingår i: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 34, nr 9, s. 641-648Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accelerated NVDA (VDA 233-102) tests were performed on bare Zn and Al sheets, Galfan coating (Zn-5 wt-% Al) and Galvalume coating (Zn-55 wt-% Al) on steel. ZnO, Zn(OH)(2) and Zn-5(OH)(8)Cl-2 center dot H2O were the main corrosion products identified on both bare Zn sheet and Galfan. AlOOH and Al(OH)(3) were preferentially formed on bare Al sheet and Galvalume. In addition, Zn-Al-containing corrosion products, Zn6Al2(OH)(16)CO3 center dot 4H(2)O and/or Zn2Al(OH)(6)Cl center dot 2H(2)O were identified on both Galfan and Galvalume. Corrosion products of Zn6Al2(OH)(16)CO3 center dot 4H(2)O with a platelet morphology were preferentially formed in the zinc-rich interdendritic regions of the Galvalume surface. Galfan revealed a similar corrosion behaviour as bare Zn sheet, whereas Galvalume exhibited similar behaviour as bare Al sheet. Deposition of chlorides highly influenced the corrosion of both Galvalume and Al rather than Galfan and Zn due to the rapid local damage of the compact native thin film of Al2O3.

  • 211.
    Zhang, Xian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Qiu, Ping
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Surface structure of 55% Al-Zn alloy coating and corrosion product distribution after exposure in chloride-containing electrolytes2011Ingår i: Proceedings The 10th International Conference on the Structure of Surfaces (ICSOS-10), 2011Konferensbidrag (Refereegranskat)
  • 212.
    Zhang, Xian
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Vu, Thanh-Nam
    Laboratoire de Physico-chimie des Surfaces, ENSCP-CNRS, Ecole Nationale Supérieure de Chimie de Paris, Paris, France.
    Volovitch, P.
    Laboratoire de Physico-chimie des Surfaces, ENSCP-CNRS, Ecole Nationale Supérieure de Chimie de Paris, Paris, France.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    Ogle, K.
    Laboratoire de Physico-chimie des Surfaces, ENSCP-CNRS, Ecole Nationale Supérieure de Chimie de Paris, Paris, France.
    Odnevall Wallinder, Inger
    KTH, Skolan för kemivetenskap (CHE), Kemi, Yt- och korrosionsvetenskap.
    The initial release of zinc and aluminum from non-treated Galvalume and the formation of corrosion products in chloride containing media2011Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, nr 10, s. 4351-4359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study explores the initial release of zinc and aluminum from non-treated Galvalume and the parallel formation of corrosion products when exposed to synthetic seawater and rainwater of different chloride content. Comparisons were made with long-term field exposures at non-sheltered marine conditions. Observed release rates from short-term conditions agree qualitatively with the long-term findings with a selective release of zinc over aluminum. The release and corrosion processes were intertwined through the formation of corrosion products with properties that influence the long-term release process. Prior to exposure, Al2O3 dominated the entire surface, and was subject to local destruction upon interaction with chloride ions. As a consequence Al2O3 was gradually replaced and covered by zinc-rich corrosion products primarily in interdendritic areas during the first year of marine exposure. This was followed by the gradual formation and integration of aluminum-rich corrosion products, reflected by an increased zinc release rate during the first year, followed by a gradually decreased rate during subsequent years. The importance of Al2O3 was also evident in deaerated synthetic rainwater or seawater, where the formation of Al2O3 was presumably hindered. In synthetic rain water this resulted in a higher ratio between released aluminum and zinc compared with non-deaerated conditions.

  • 213.
    Öhman, Maria
    et al.
    Kimab.
    Persson, Dan
    KIMAB.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    A spectroelectrochemical study of metal/polymer interfaces by simultaneous in situ ATR-FTIR and EIS2007Ingår i: Electrochemical and solid-state letters, ISSN 1099-0062, E-ISSN 1944-8775, Vol. 10, nr 4, s. C27-C30Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Buried aluminum/polymer interfaces were studied using a spectroelectrochemical experimental setup based on simultaneous in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and electrical impedance spectroscopy (EIS). Transport of water and electrolyte through the polymer film to the aluminum/polymer interface and oxidation/corrosion of aluminum was followed by ATR-FTIR, while the impedance behavior of the system was simultaneously studied by EIS. As the ATR-FTIR technique is specific for the aluminum/polymer interfacial region while EIS takes into account alterations of both the polymer bulk and the interface, the combined setup provides complementary information of the system investigated.

  • 214.
    Öhman, Maria
    et al.
    Kimab.
    Persson, Dan
    Kimab.
    Leygraf, Christofer
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    In situ ATF-FTIR studies of the aluminium/polymer interface upon exposure to water and electrolyte2006Ingår i: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 57, nr 1, s. 78-88Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with the Kretschmann configuration was applied for in situ studies of the transport of water and ionic species through a polymer film to an aluminium/polymer interface. The time dependent intensity changes of the infrared bands of water were used to follow the transport of water to the aluminium/polymer interfacial region and a NaSCN solution was employed as model electrolyte to follow the transport and accumulation of thiocyanate ions. Apart from water sorption and ion transport, the main processes identified were corrosion/oxidation of the aluminium surface and swelling of the polymer film. The method proved to be useful for detailed in situ studies of changes at a polymer coated metal surface, such as oxidation and surface film formation on the metal. It should also be possible to study the effects of defects and pores in the polymer film on the transport properties of water and ions to the metal/polymer interface, as well as adsorption and other chemical reactions and physical interactions in the metal/polymer interfacial region.

  • 215.
    Öijerholm, Johan
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Pan, Jinshan
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Leygraf, Christofer
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    In-situ measurements by impedance spectroscopy of highly resistive alpha-alumina2006Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 48, nr 1, s. 243-257Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In-situ impedance spectroscopy has been used for characterisation of oxides at elevated temperatures. However, for highly resistive oxides, the influence of electrode contact and leakage currents due to gas phase and surface conduction needs to be taken into account. In this study, IS measurements of pure and dense alpha-alumina (alpha-Al2O3) samples were performed in the temperature range 400-1000 degrees C with different types of electrode contact, in air and in nitrogen. The results show that above 700 degrees C the influence is negligible, whereas at lower temperatures the surface leakage current was substantial, and a so-called guard electrode recommendable.

  • 216.
    Öijerholm, Johan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära (stängd 20081231).
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära (stängd 20081231).
    Lu, Q.
    Kanthal AB, Hallstahammar.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära (stängd 20081231).
    In-situ impedence spectroscopy study of electrical conductivity and ionic transport in thermally grown oxide scales on a commercial FeCrA1 alloy2007Ingår i: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 68, nr 5-6, s. 253-269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In-situ impedance-spectroscopy measurements were performed at temperatures between 600 and 1,000 degrees C to investigate ionic transport in oxide scales formed on Kanthal AF alloy. The samples were pre-oxidized at 800, 900 and 1,000 degrees C in air. The impedance spectra of the oxide formed at 1,000 degrees C exhibited essentially one semicircle, whereas samples oxidized at lower temperatures showed an additional semicircle at high frequencies suggesting a more heterogeneous oxide. The ionic-transference number, derived by measuring the voltage across the oxide scale, indicates that the oxide is a predominant electronic conductor. Ionic diffusivity in the oxide scales formed at different pre-oxidizing temperatures was calculated, using the ionic-transference number. The ionic diffusivities obtained in this way are in reasonable agreement with literature data acquired by other methods. The oxide-formation temperature has a significant influence on the conductivity and ionic-transport properties of the oxide scale.

  • 217.
    Örnberg, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Herstedt, M.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Corrosion resistance, chemical passivation and metal release of 35N LT and MP35N for biomedical material application2007Ingår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 154, nr 9, s. C546-C551Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Co-based special wire alloys 35N LT and MP35N are used for biomedical applications. The corrosion resistance of the two alloys, chemical passivation, and metal release of 35N LT were studied by electrochemical measurements, surface analysis, and solution analysis. The results show no significant difference in the corrosion resistance between 35N LT and MP35N. Preferential dissolution of Co and Ni occurs during chemical passivation of 35N LT in an HNO3 solution, which results in enrichment of oxidized Cr and depletion of oxidized Co in the passive film. The passivation treatment leads to an increased corrosion resistance in a phosphate-buffered saline solution, even with addition of 100 mM H2O2 simulating an inflammatory response. A further effect of the passivation treatment is a significantly reduced metal release, especially Co, from 35N LT during exposure to the synthetic biological medium.

  • 218.
    Örnberg, Andreas
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Pan, Jinshan
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Leygraf, Christofer
    KTH, Skolan för kemivetenskap (CHE), Kemi, Korrosionslära.
    Electrochemical study of tantalum as substrate for pacemaker electrodesIngår i: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111Artikel i tidskrift (Övrigt vetenskapligt)
  • 219.
    Örnek, Cem
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Leygraf, Christopher
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Pan, Jinshan
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Passive film characterisation of duplex stainless steel using scanning Kelvin probe force microscopy in combination with electrochemical measurements2019Ingår i: npJ Materials Degradation, ISSN 2397-2106, Vol. 3, nr 1, s. 1-8Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The characterisation of passive oxide films on heterogeneous microstructures is needed to assess local degradation (corrosion, cracking) in aggressive environments. The Volta potential is a surface-sensitive parameter which can be used to assess the surface nobility and hence passive films. In this work, it is shown that the Volta potential, measured on super duplex stainless steel by scanning Kelvin probe force microscopy, correlates with the electrochemical properties of the passive film, measured by electrochemical impedance spectroscopy and potentiodynamic polarisation. Natural oxidation by ageing in ambient air as well as artificial oxidation by immersion in concentrated nitric acid improved the nobility, both reflected by increased Volta potentials and electrochemical parameters. Passivation was associated with vanishing of the inherent Volta potential difference between the ferrite and austenite, thereby reducing the galvanic coupling and hence improving the corrosion resistance of the material. Hydrogen-passive film interactions, triggered by cathodic polarisation, however, largely increased the Volta potential difference between the phases, resulting in loss of electrochemical nobility, with the ferrite being more affected than the austenite. A correlative approach of using the Volta potential in conjunction with electrochemical data has been introduced to characterise the nobility of passive films in global and local scale.

  • 220.
    Örnek, Cem
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap. Swerea KIMAB AB, Isafjordsgatan 28A, Kista, 164 40, Sweden.
    Liu, Min
    Univ Sci & Technol Beijing, Natl Ctr Mat Serv Safety, Xueyuan Rd 30, Beijing 100083, Peoples R China..
    Pan, Ying
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Jin, Y.
    Univ Sci & Technol Beijing, Natl Ctr Mat Serv Safety, Xueyuan Rd 30, Beijing 100083, Peoples R China..
    Leygraf, Christopher
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemi, Yt- och korrosionsvetenskap.
    Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study2018Ingår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 61, nr 9-11, s. 1169-1182Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, first-principle density functional theory (DFT) was used to calculate the work function and Volta potential differences between aluminum alloy matrix and two intermetallic phases (Mg2Si and Al2Cu) with varying surface terminations as a function of adhering monolayers (ML) of water. The calculated data were compared with experimental local Volta potential data obtained by the scanning Kelvin probe force microscopy (SKPFM) on a commercial aluminum alloy AA6063-T5 in atmospheric environments with varying relative humidity (RH). The calculations suggest that the surface termination has a major effect on the magnitude and polarity of the Volta potential of both intermetallic phases (IMP's). The Volta potential difference between the IMP's and the aluminum matrix decreases when the surface is gradually covered by water molecules, and may further change as a function of adhering ML's of water. This can lead to nobility inversions of the IMP's relative to the aluminum matrix. The measured Volta potential difference between both IMP's and their neighboring matrix is dependent on RH. Natural oxidation in ambient indoor air for 2 months led to a nobility inversion of the IMP's with respect to the aluminum matrix, with the intermetallics showing anodic nature already in dry condition. The anodic nature of Al2Cu remained with the introduction of RH, whereas Mg2Si became cathodic at high RH, presumably due to de-alloying of Mg and oxide dissolution. The DFT calculations predicted an anodic character of both IMP's in reference to the oxidized aluminum matrix, being in good agreement with the SKPFM data. The DFT and SKPFM data were discussed in light of understanding localized corrosion of aluminum alloys under conditions akin to atmospheric exposure.

2345 201 - 220 av 220
RefereraExporteraLänk till träfflistan
Permanent länk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf