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Leygraf, ChristopherORCID iD iconorcid.org/0000-0002-9453-1333
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Publications (10 of 217) Show all publications
Yin, L., Li, W., Wang, Y., Jin, Y., Pan, J. & Leygraf, C. (2019). Numerical simulation of micro-galvanic corrosion of Al alloys: Effect of density of Al(OH)(3) precipitate. Electrochimica Acta, 324, Article ID UNSP 134847.
Open this publication in new window or tab >>Numerical simulation of micro-galvanic corrosion of Al alloys: Effect of density of Al(OH)(3) precipitate
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2019 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 324, article id UNSP 134847Article in journal (Refereed) Published
Abstract [en]

This work is a further step to develop a finite element model to simulate localized corrosion of aluminum alloys driven by micro-galvanic effects. The focus herein is to explore the effect of density (porosity and tortuosity) of Al(OH)(3) precipitates generated both on the electrode surface and in the liquid phase. Two coupled processes are identified and discussed, both influencing the local pH: the Al3+ dissolution from the electrode surface, and the steric hindrance effects on mass transport of species between the bulk solution and the anolyte next to the corroding surface. With the densest precipitate investigated, Al3+ dissolution is more effectively blocked and the mass transport largely hindered of Al3+ ions leaving the electrode surface. With increasing porosity of the precipitate, Al3+ dissolution is enhanced, also the mass transport of species in the electrolyte. The most severe localized acidification inside the occluded volume occurs when the density, namely ascribed by porosity, of precipitate is at an intermediate level with epsilon(c )= 0.01. In qualitative agreement with experimental observations, this work highlights the importance of corrosion product density on the progress of localized corrosion.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2019
Keywords
FEM model, Micro-galvanic corrosion, Al(OH)(3) precipitate, Porosity and tortuosity, Steric hindrance effect
National Category
Corrosion Engineering
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-262932 (URN)10.1016/j.electacta.2019.134847 (DOI)000489840900046 ()2-s2.0-85072305820 (Scopus ID)
Note

QC 20191030

Available from: 2019-10-30 Created: 2019-10-30 Last updated: 2019-12-03Bibliographically 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
Leygraf, C., Chang, T., Herting, G. & Odnevall Wallinder, I. (2019). The origin and evolution of copper patina colour. Corrosion Science, 157, 337-346
Open this publication in new window or tab >>The origin and evolution of copper patina colour
2019 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 157, p. 337-346Article in journal (Refereed) Published
Abstract [en]

The copper patina colour has been systematically explored through a large set of short- and long-term exposed copper metal samples. The initial brown-black appearance is attributed to semiconducting properties of cuprite (Cu2O) and fully attained at thickness 0.8 +/- 0.2 mu m. The characteristic green-blue appearance is due to the colour forming Cu(II)-ion in the outer patina layer which needs to be 12 +/- 2 mu m to fully cover the inner cuprite layer. No significant influence of atmospheric environment on patina colour is discerned. The green-blue patina colour on historic copper was attained after shorter exposures than in modem copper due to more inhomogeneous microstructure.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Copper, SEM, XPS, Atmospheric corrosion
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-257434 (URN)10.1016/j.corsci.2019.05.025 (DOI)000480374200032 ()2-s2.0-85067466175 (Scopus ID)
Note

QC 20190902

Available from: 2019-09-02 Created: 2019-09-02 Last updated: 2019-09-02Bibliographically approved
Chang, T., Herting, G., Goidanich, S., Sánchez Amaya, J. M., Arenas, M. A., Le Bozec, N., . . . Odnevall Wallinder, I. (2019). The role of Sn on the long-term atmospheric corrosion of binary Cu-Sn bronze alloys in architecture. Corrosion Science, 149, 54-67
Open this publication in new window or tab >>The role of Sn on the long-term atmospheric corrosion of binary Cu-Sn bronze alloys in architecture
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2019 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 149, p. 54-67Article in journal (Refereed) Published
Abstract [en]

The role of Sn on the atmospheric corrosion performance of binary Cu-Sn bronze alloys (4–6 wt.% Sn) compared with Cu metal used in outdoor architecture is elucidated in terms of microstructure, native surface oxide composition, patina evolution, corrosion rates, appearance and metal release. Results are presented for non-exposed surfaces and surfaces exposed at different urban and marine sites in Europe up to 5 years and based on multi-analytical findings from microscopic, spectroscopic, electrochemical and chemical investigations. Alloying influenced the corrosion, aesthetic appearance and patina evolution, differently for urban and marine sites, whereas no effects were observed on the release pattern.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Aesthetic appearance, Atmospheric corrosion, Bronze, Metal release, Patina
National Category
Metallurgy and Metallic Materials
Identifiers
urn:nbn:se:kth:diva-246467 (URN)10.1016/j.corsci.2019.01.002 (DOI)000459839700006 ()2-s2.0-85059532533 (Scopus ID)
Note

QC 20190328

Available from: 2019-03-28 Created: 2019-03-28 Last updated: 2019-03-28Bibliographically approved
Chang, T., Leygraf, C., Odnevall Wallinder, I. & Jin, Y. (2019). Understanding the Barrier Layer Formed via Adding BTAH in Copper Film Electrodeposition. Journal of the Electrochemical Society, 166(2), D10-D20
Open this publication in new window or tab >>Understanding the Barrier Layer Formed via Adding BTAH in Copper Film Electrodeposition
2019 (English)In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 166, no 2, p. D10-D20Article in journal (Refereed) Published
Abstract [en]

The influence of surface adsorption of benzotriazole (BTAH) and of chloride ions (Cl-) on the kinetics of copper electrodeposition/dissolution in copper sulfate solutions and on copper deposit characteristics have been investigated using electrochemical quartz crystal microbalance (EQCM) combined with cyclic voltammetry (CV). The addition of BTAH alone increases the overpotential of copper deposition, whereas a Cu(I)BTA complex forms at potentials higher than 0.08 V (vs. SCE) accompanied with the occurrence of copper anodic dissolution. With simultaneous addition of BTAH and Cl-, surface adsorption of Cl- competes with that of BTAH during the initial stage of copper nucleation. Different cuprous reaction intermediates form in the examined potential range -0.4 to 0.3 V (vs. SCE), which partly eliminate the favorable effect of BTAH on the deposited copper. A BTAH-containing adsorbed layer formed on the matte side of electrodeposited copper film in the presence of BTAH with or without Cl-, exhibiting a barrier surface property and an improved corrosion resistance compared with the copper film electrodeposited in the electrolyte without addition of BTAH.

Place, publisher, year, edition, pages
ELECTROCHEMICAL SOC INC, 2019
National Category
Materials Engineering
Identifiers
urn:nbn:se:kth:diva-241310 (URN)10.1149/2.0041902jes (DOI)000455193100001 ()
Note

QC 20190125

Available from: 2019-01-25 Created: 2019-01-25 Last updated: 2019-01-25Bibliographically approved
Zhang, X., Odnevall Wallinder, I. & Leygraf, C. (2018). Atmospheric corrosion of Zn-Al coatings in a simulated automotive environment. Surface Engineering, 34(9), 641-648
Open this publication in new window or tab >>Atmospheric corrosion of Zn-Al coatings in a simulated automotive environment
2018 (English)In: Surface Engineering, ISSN 0267-0844, E-ISSN 1743-2944, Vol. 34, no 9, p. 641-648Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
TAYLOR & FRANCIS LTD, 2018
Keywords
Atmospheric corrosion, NVDA tests, Zn, Al, Galfan, Galvalume, chloride, microstructure
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:kth:diva-232426 (URN)10.1080/02670844.2017.1305658 (DOI)000437723800001 ()2-s2.0-85016451068 (Scopus ID)
Note

QC 20180724

Available from: 2018-07-24 Created: 2018-07-24 Last updated: 2018-07-24Bibliographically approved
Szakalos, P., Åkermark, T. & Leygraf, C. (2018). Comments on the paper "Copper in ultrapure water, a scientific issue under debate" by M. Ottosson, M. Boman, P. Berastegui, Y. Andersson, M. Hahlin, M. Korvela, and R. Berger [Letter to the editor]. Corrosion Science, 142, 305-307
Open this publication in new window or tab >>Comments on the paper "Copper in ultrapure water, a scientific issue under debate" by M. Ottosson, M. Boman, P. Berastegui, Y. Andersson, M. Hahlin, M. Korvela, and R. Berger
2018 (English)In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 142, p. 305-307Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:kth:diva-235892 (URN)10.1016/j.corsci.2018.02.001 (DOI)000444933400029 ()2-s2.0-85044581202 (Scopus ID)
Note

QC 20181022

Available from: 2018-10-22 Created: 2018-10-22 Last updated: 2018-10-22Bibliographically approved
Leygraf, C., Chang, T., Odnevall Wallinder, I., De La Fuente, D., Chico, B., Diaz, I. & Morcillo, M. (2017). Analysis of historic copper patinas 1: Influence of substrate on patina uniformity. In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017: . Paper presented at Joint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017, Prague Congress Centre, Prague, Czech Republic, 3 September 2017 through 7 September 2017. Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers
Open this publication in new window or tab >>Analysis of historic copper patinas 1: Influence of substrate on patina uniformity
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2017 (English)In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017, Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers , 2017Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers, 2017
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-234516 (URN)2-s2.0-85052338861 (Scopus ID)
Conference
Joint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017, Prague Congress Centre, Prague, Czech Republic, 3 September 2017 through 7 September 2017
Note

QC 20180907

Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2018-11-09Bibliographically approved
Chico, B., Fuente, D. D., Jiménez, J. A., Chang, T., Odnevall Wallinder, I., Leygraf, C. & Morcillo, M. (2017). Analysis of historic copper patinas 2: Characterization of 400 year old patina from Royal Summer Palace in Prague. In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017: . Paper presented at Joint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017, Prague Congress Centre, Prague, Czech Republic, 3 September 2017 through 7 September 2017. Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers
Open this publication in new window or tab >>Analysis of historic copper patinas 2: Characterization of 400 year old patina from Royal Summer Palace in Prague
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2017 (English)In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017, Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers , 2017Conference paper, Published paper (Refereed)
Abstract [en]

This paper presents an in-depth characterisation study of the patina formed on a copper tile taken from the roof of Queen Anne's Summer Palace in Prague after close to 400 years of exposure to the action of the atmosphere. A wide variety of techniques have been performed, including metallographic and chemical analysis (electrogravimetry, AAS, XRF) of the copper matrix, and spectroscopic and microscopic investigations (GIXRD, TEM/EDS and SEM/EDS) to determine the composition and structure of the patina. The major conclusions of the study are: (a) the base copper contains abundant inclusions mainly of rosiaite (PbSb2O6); (b) the patina is formed by an inner sublayer of cuprite (Cu2O) and an outer sublayer of brochantite [Cu4SO4(OH)6] and antlerite [Cu3SO4(OH)4] and traces of azurite [Cu3(CO3)2(OH)2]; and (c) the brochantite/antlerite crystals are randomly doped with Fe and C.

Place, publisher, year, edition, pages
Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers, 2017
Keywords
Atmospheric corrosion, Characterization, Copper tile, Patina, Queen Anne's Summer Palace
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-234519 (URN)2-s2.0-85052322168 (Scopus ID)
Conference
Joint European Corrosion Congress 2017, EUROCORR 2017 and 20th International Corrosion Congress and Process Safety Congress 2017, Prague Congress Centre, Prague, Czech Republic, 3 September 2017 through 7 September 2017
Note

QC 20180907

Available from: 2018-09-07 Created: 2018-09-07 Last updated: 2018-11-09Bibliographically approved
Chang, T., Odnevall Wallinder, I., de la Fuente, D., Chico, B., Morcillo, M., Welter, J.-M. -. & Leygraf, C. (2017). Analysis of historic copper patinas. Influence of inclusions on patina uniformity. Materials, 10(3), Article ID 298.
Open this publication in new window or tab >>Analysis of historic copper patinas. Influence of inclusions on patina uniformity
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2017 (English)In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 10, no 3, article id 298Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
MDPI AG, 2017
Keywords
Antlerite, Atmospheric corrosion, Bilayer, Brochantite, Cuprite, Historic copper, Inclusions, Micro-galvanic effect, Patina, Volta potential, Antimony, Copper corrosion, Corrosion, Lead, Metallic matrix composites, Ores, Substrates, Bi-layer, Galvanic effect, Copper
National Category
Corrosion Engineering
Identifiers
urn:nbn:se:kth:diva-207437 (URN)10.3390/ma10030298 (DOI)000400863500081 ()2-s2.0-85015630454 (Scopus ID)
Note

QC 20170523

Available from: 2017-05-23 Created: 2017-05-23 Last updated: 2018-11-08Bibliographically approved
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Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9453-1333

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