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Publications (10 of 132) Show all publications
Liu, M., Jin, Y., Leygraf, C. & Pan, J. (2019). A DFT-Study of Cl Ingress into alpha-Al2O3(0001) and Al(111) and Its Possible Influence on Localized Corrosion of Al. Journal of the Electrochemical Society, 166(11), C3124-C3130
Open this publication in new window or tab >>A DFT-Study of Cl Ingress into alpha-Al2O3(0001) and Al(111) and Its Possible Influence on Localized Corrosion of Al
2019 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 11, p. C3124-C3130Article in journal (Refereed) Published
Abstract [en]

Ingress of chloride into alpha-Al2O3(0001) and Al(111) was calculated by first-principles theory calculations by considering Cl insertion into Al or O vacancies within alpha-Al2O3(0001) or into vacancy or interstitial sites within Al(111). For alpha-Al2O3, the formation of an O vacancy is energetically more favorable than of an Al vacancy. The insertion of Cl into an O vacancy is also more favorable than into an Al vacancy. A high energy-barrier has been derived for Cl transport within the neighboring O vacancies. In addition, the work function decreases with Cl ingress into the interior of the oxide. For Al(111), Cl insertion into either an Al vacancy or an interstitial site is less favorable compared to the insertion into alpha-Al2O3. The work function only changes slightly with Cl insertion into an Al vacancy. Moreover, the pre-inserted Cl reduces the energy-barrier for further Cl ingress into alpha-Al2O3, whereas Cl tends to stay in the sub-surface layer of Al(111), suggesting Cl accumulation at the Al2O3/Al.

Place, publisher, year, edition, pages
ELECTROCHEMICAL SOC INC, 2019
Keywords
LLEY B, 1990, JOURNAL OF CHEMICAL PHYSICS, V92, P508
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:kth:diva-251275 (URN)10.1149/2.0161911jes (DOI)000465526200002 ()
Note

QC 20190515

Available from: 2019-05-15 Created: 2019-05-15 Last updated: 2019-05-15Bibliographically approved
Långberg, M., Örnek, C., Zhang, F., Cheng, J., Liu, M., Granaes, E., . . . Pan, J. (2019). Characterization of Native Oxide and Passive Film on Austenite/Ferrite Phases of Duplex Stainless Steel Using Synchrotron HAXPEEM. Journal of the Electrochemical Society, 166(11), C3336-C3340
Open this publication in new window or tab >>Characterization of Native Oxide and Passive Film on Austenite/Ferrite Phases of Duplex Stainless Steel Using Synchrotron HAXPEEM
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2019 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 11, p. C3336-C3340Article in journal (Refereed) Published
Abstract [en]

A new measurement protocol was used for microscopic chemical analysis of surface oxide films with lateral resolution of 1 mu m. The native air-formed oxide and an anodic passive film on austenite and ferrite phases of a 25Cr-7Ni super duplex stainless steel were investigated using synchrotron hard X-ray photoemission electron microscopy (HAXPEEM). Pre-deposited Pt-markers, in combination with electron backscattering diffraction mapping (EBSD), allowed analysis of the native oxide on individual grains of the two phases and the passive film formed on the same area after electrochemical polarization of the sample. The results showed a certain difference in the composition of the surface films between the two phases. For the grains with (001) crystallographic face // sample surface, the native oxide film on the ferrite contained more Cr oxide than the austenite. Anodic polarization up to 1000 mV/(Ag/AgCl) in 1M NaCl solution at room temperature resulted in a growth of the Cr- and Fe-oxides, diminish of Cr-hydroxide, and an increased proportion of Fe3+ species. 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.

Place, publisher, year, edition, pages
Electrochemical Society, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-254081 (URN)10.1149/2.0421911jes (DOI)000470207900001 ()
Note

QC 20190625

Available from: 2019-06-25 Created: 2019-06-25 Last updated: 2019-07-09Bibliographically approved
Kharitonov, D. S., Sommertune, J., Örnek, C., Ryl, J., Kurilo, I. I., Claesson, P. M. & Pan, J. (2019). Corrosion inhibition of aluminium alloy AA6063-T5 by vanadates: Local surface chemical events elucidated by confocal Raman micro-spectroscopy. CORROSION SCIENCE, 148, 237-250
Open this publication in new window or tab >>Corrosion inhibition of aluminium alloy AA6063-T5 by vanadates: Local surface chemical events elucidated by confocal Raman micro-spectroscopy
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2019 (English)In: CORROSION SCIENCE, Vol. 148, p. 237-250Article in journal (Refereed) Published
Abstract [en]

Chemical interactions between aqueous vanadium species and aluminium alloy AA6063-T5 were investigated in vanadate-containing NaCl solutions. Confocal Raman and X-ray photoelectron spectroscopy experiments were utilised to gain insight into the mechanism of corrosion inhibition by vanadates. A greenish-grey coloured surface layer, consisting of V+4 and V+5 polymerized species, was seen to form on the alloy surface, especially on top of cathodic micrometre-sized IMPs, whereby suppressing oxygen reduction kinetics. The results suggest a two-step mechanism of corrosion inhibition in which V+5 species are first reduced to V+4 or V+3 species above cathodic IMPs, and then oxidized to mixed-valence V+5/V+4 polymerized compounds.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Aluminium, Alloy, Raman spectroscopy, SEM, XPS, Vanadate inhibitor
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-244484 (URN)10.1016/j.corsci.2018.12.011 (DOI)000457950400023 ()2-s2.0-85059158841 (Scopus ID)
Note

QC 20190321

Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-04-04Bibliographically approved
Anantha, K. H., Örnek, C., Ejnermark, S., Thuvander, A., Medvedeva, A., Sjostrom, J. & Pan, J. (2019). Experimental and modelling study of the effect of tempering on the susceptibility to environment-assisted cracking of AISI 420 martensitic stainless steel. Corrosion Science, 148, 83-93
Open this publication in new window or tab >>Experimental and modelling study of the effect of tempering on the susceptibility to environment-assisted cracking of AISI 420 martensitic stainless steel
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2019 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 148, p. 83-93Article in journal (Refereed) Published
Abstract [en]

The resistance to environment-assisted cracking (EAC) of AISI 420 martensitic stainless steel (MSS) was investigated in 0.3 M NaCl solution (room temperature) at constant loads for 30 days. The steel tempered at 250 degrees C was superior to the 500 degrees C-temper, which showed corrosion pits favouring cracking. The fracture surface showed faceted grains, cleavage, striations, and inter- and transgranular cracks, suggesting a mixed stress corrosion cracking (SCC) and hydrogen embrittlement (HE) mechanism as the cause for EAC. Finite element modelling (FEM) indicated strain/stress localization at the mouth of deep pits and at the wall of shallow pits, displaying the favoured locations for pit-to-crack transition.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Martensitic stainless steel, Residual stress, Tempering, Environment-assisted cracking, Pit-to-crack transition
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:kth:diva-244485 (URN)10.1016/j.corsci.2018.12.010 (DOI)000457950400009 ()2-s2.0-85058373436 (Scopus ID)
Note

QC 20190321

Available from: 2019-03-21 Created: 2019-03-21 Last updated: 2019-04-04Bibliographically approved
Örnek, C., Långberg, M., Evertsson, J., Harlow, G., Linpe, W., Rullik, L., . . . Pan, J. (2019). Influence of Surface Strain on Passive Film Formation of Duplex Stainless Steel and Its Degradation in Corrosive Environment. Journal of the Electrochemical Society, 166(11), C3071-C3080
Open this publication in new window or tab >>Influence of Surface Strain on Passive Film Formation of Duplex Stainless Steel and Its Degradation in Corrosive Environment
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2019 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 11, p. C3071-C3080Article in journal (Refereed) Published
Abstract [en]

The effect of surface strain on the passive film evolution of SAF 2507 super duplex stainless steel exposed to ambient air and 0.1 M NaCl solution with varying anodic polarization at room temperature has been investigated using in-situ grazing incidence X-ray diffraction (GIXRD) in combination with electrochemical measurements. Surface strain affected the crystallinity of the passive film as such that the surface oxides/hydroxides were predominantly amorphous, with some minor crystalline CrOOH and FeOOH present in the film. Crystalline CrOOH was seen to diminish in volume upon immersion in the NaCl solution, well-possibly becoming amorphous during anodic polarization, whereas crystalline FeOOH was seen to increase in volume during polarization to the passive potential regime. Strain relaxation, associated with metal dissolution, occurred in both austenitic and ferritic grains during immersion in the electrolyte. Anodic polarization to the transpassive regime led to maximum strain relaxation, occurring more on the austenite than the ferrite. The selective transpassive dissolution nature of the ferrite was significantly reduced due to large strains in the austenite. Passive film breakdown was reflected by enhanced dissolution of Fe, Cr, Mo and Ni occurring simultaneously around 1300 mV vs. Ag/AgCl. 

Place, publisher, year, edition, pages
ELECTROCHEMICAL SOC INC, 2019
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-249787 (URN)10.1149/2.0101911jes (DOI)000463697200001 ()
Note

QC 20190424

Available from: 2019-04-24 Created: 2019-04-24 Last updated: 2019-06-11Bibliographically approved
Zhang, F., Chen, C., Hou, R., Li, J., Cao, Y., Dong, S., . . . Pan, J. (2019). Investigation and application of mussel adhesive protein nanocomposite film-forming inhibitor for reinforced concrete engineering. Corrosion Science, 153, 333-340
Open this publication in new window or tab >>Investigation and application of mussel adhesive protein nanocomposite film-forming inhibitor for reinforced concrete engineering
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2019 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 153, p. 333-340Article in journal (Refereed) Published
Abstract [en]

A mussel adhesive protein based nanocomposite thin film was produced to be applied as surface pre-treatment or primer on rebars of reinforced concrete. The film deposition and drying processes were investigated to enhance the corrosion protection, and facilitate large-scale industrial applications. The morphology, chemical composition and microstructure of the film were characterised with SEM, EDS, Micro-IR and AFM techniques. EIS results suggested the film provides excellent and increased corrosion protection for the carbon steel in mild and extreme concrete pore solutions. In-situ AFM results demonstrated the self-healing ability of the film to the pitting corrosion.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
Mussel adhesive protein, Nanocomposite, Corrosion protection, Self-healing, Film forming, Reinforced concrete
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-252594 (URN)10.1016/j.corsci.2019.03.023 (DOI)000467669300032 ()
Note

QC 20190611

Available from: 2019-06-11 Created: 2019-06-11 Last updated: 2019-06-11Bibliographically approved
Zhang, F., Chen, C., Hou, R., Li, J., Cao, Y., Dong, S., . . . Pan, J. (2019). Investigation and application of mussel adhesive protein nanocomposite film-forming inhibitor for reinforced concrete engineering. Corrosion Science, 153, 333-340
Open this publication in new window or tab >>Investigation and application of mussel adhesive protein nanocomposite film-forming inhibitor for reinforced concrete engineering
Show others...
2019 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 153, p. 333-340Article in journal (Refereed) Published
Abstract [en]

A mussel adhesive protein based nanocomposite thin film was produced to be applied as surface pre-treatment or primer on rebars of reinforced concrete. The film deposition and drying processes were investigated to enhance the corrosion protection, and facilitate large-scale industrial applications. The morphology, chemical composition and microstructure of the film were characterised with SEM, EDS, Micro-IR and AFM techniques. EIS results suggested the film provides excellent and increased corrosion protection for the carbon steel in mild and extreme concrete pore solutions. In-situ AFM results demonstrated the self-healing ability of the film to the pitting corrosion.

Place, publisher, year, edition, pages
Elsevier Ltd, 2019
Keywords
Corrosion protection, Film forming, Mussel adhesive protein, Nanocomposite, Reinforced concrete, Self-healing, Adhesives, Electrochemical corrosion, Molluscs, Morphology, Nanocomposites, Pitting, Proteins, Self-healing materials, Steel corrosion, Surface treatment, Thin films, Concrete pore solutions, Film forming inhibitors, Film-forming, Mussel adhesive proteins, Nanocomposite thin films, Self-healing abilities, Surface pre-treatments, Nanocomposite films
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:kth:diva-252522 (URN)10.1016/j.corsci.2019.03.023 (DOI)000467669300032 ()2-s2.0-85063986188 (Scopus ID)
Note

QC 20190613

Available from: 2019-06-13 Created: 2019-06-13 Last updated: 2019-06-13Bibliographically approved
Örnek, C., Leygraf, C. & Pan, J. (2019). On the Volta potential measured by SKPFM - fundamental and practical pects with relevance to corrosion science. Corrosion Engineering, Science and Technology, 54(3), 185-198
Open this publication in new window or tab >>On the Volta potential measured by SKPFM - fundamental and practical pects with relevance to corrosion science
2019 (English)In: Corrosion Engineering, Science and Technology, ISSN 1478-422X, E-ISSN 1743-2782, Vol. 54, no 3, p. 185-198Article, review/survey (Refereed) Published
Abstract [en]

The Volta potential is an electron-sensitive parameter and describes the ermodynamic propensity of a metal to take part in electrochemical actions. It has found widespread acceptance among corrosion searchers due to its connection to the corrosion potential and its sy measurability in local scale, being often used to study localised rrosion phenomena and micro-galvanic activities. The principle object this paper is to provide a comprehensive, fundamental insight into e meaning of the Volta potential and to define a polarity convention measured potentials by the scanning Kelvin probe force microscopy KPFM) in order to assess local nobilities in microstructures. nditions to relate the Volta potential with the mixed-potential theory e discussed and a possible connection to corrosion phenomena plained. The limitations of the Volta potential as well as the SKPFM chnique are also aimed to be explained, with some practical formation to maximise the output of high quality data.

Place, publisher, year, edition, pages
Taylor & Francis, 2019
Keywords
Volta potential, scanning Kelvin probe force microscopy, Surface potential, Work function, nobility, corrosion
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-248314 (URN)10.1080/1478422X.2019.1583436 (DOI)000461631700001 ()2-s2.0-85063102596 (Scopus ID)
Note

QC 20190405

Available from: 2019-04-05 Created: 2019-04-05 Last updated: 2019-04-05Bibliographically approved
Örnek, C., Leygraf, C. & Pan, J. (2019). Passive film characterisation of duplex stainless steel using scanning Kelvin probe force microscopy in combination with electrochemical measurements. npJ Materials Degradation, 3(1), 1-8
Open this publication in new window or tab >>Passive film characterisation of duplex stainless steel using scanning Kelvin probe force microscopy in combination with electrochemical measurements
2019 (English)In: npJ Materials Degradation, ISSN 2397-2106, Vol. 3, no 1, p. 1-8Article in journal (Refereed) Published
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.

Keywords
Scanning Kelvin probe force microscopy; SKPFM; Volta potential; Duplex Stainless Steel; Corrosion; Electrochemical Nobility; Electrochemical Measurements; Polarization; Electrochemical Impedance Spectroscopy
National Category
Metallurgy and Metallic Materials Materials Engineering Corrosion Engineering Condensed Matter Physics
Research subject
Materials Science and Engineering
Identifiers
urn:nbn:se:kth:diva-248530 (URN)10.1038/s41529-019-0071-8 (DOI)
Note

QC 20190507

Available from: 2019-04-09 Created: 2019-04-09 Last updated: 2019-05-07Bibliographically approved
Li, J., Ecco, L., Ahniyaz, A. & Pan, J. (2019). Probing electrochemical mechanism of polyaniline and CeO2 nanoparticles in alkyd coating with in-situ electrochemical-AFM and IRAS. Progress in organic coatings, 132, 399-408
Open this publication in new window or tab >>Probing electrochemical mechanism of polyaniline and CeO2 nanoparticles in alkyd coating with in-situ electrochemical-AFM and IRAS
2019 (English)In: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 132, p. 399-408Article in journal (Refereed) Published
Abstract [en]

The corrosion protection and electrochemical mechanism of solvent-borne alkyd composite coating containing 1.0 wt.% polyaniline (PANI) and 1.0 wt.% CeO2 nanoparticles (NPs) for carbon steel in 3.0 wt.% NaCl solution were investigated by means of scanning electron microscopy (SEM), ex-situ, in-situ and electrochemical controlled (EC) atomic force microscopy (AFM), open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) methods. The SEM and ex-situ AFM results revealed the micro- and nanostructure of the composite coating. The in-situ sequential AFM images and line profiling analysis indicated electrochemical activity of the NPs and a high stability of the composite coating in NaCl solution. The results of EC-AFM combined with cyclic voltammetry (CV) demonstrated volume change of the PANI NPs upon reduction and oxidation at certain applied potentials on the coating. The redox reactions between the different forms of PANI and the effect of the CeO2 NPs on the polymerization of the composite polymer were further confirmed by infrared reflection absorption spectroscopy (IRAS). The OCP and EIS results revealed that the composite coating provided an improved corrosion protection for carbon steel within several days of exposure, which was attributed to the barrier protection of CeO2 NPs and the passivation ability of PANI.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Alkyd coating, CeO2, Nanoparticles, Polyaniline, In-situ and EC-AFM, EIS, Corrosion mechanism
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:kth:diva-254072 (URN)10.1016/j.porgcoat.2019.04.012 (DOI)000469902800047 ()2-s2.0-85063906914 (Scopus ID)
Note

QC 20190626

Available from: 2019-06-26 Created: 2019-06-26 Last updated: 2019-06-26Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4431-0671

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