| 1. |
- Bender, R., et al.
(författare)
-
Corrosion challenges towards a sustainable society
- 2022
-
Ingår i: Materials and corrosion - Werkstoffe und Korrosion. - : Wiley. - 0947-5117 .- 1521-4176. ; 73:11, s. 1730-1751
-
Tidskriftsartikel (refereegranskat)abstract
- A global transition towards more sustainable, affordable and reliable energy systems is being stimulated by the Paris Agreement and the United Nation's 2030 Agenda for Sustainable Development. This poses a challenge for the corrosion industry, as building climate-resilient energy systems and infrastructures brings with it a long-term direction, so as a result the long-term behaviour of structural materials (mainly metals and alloys) becomes a major prospect. With this in mind “Corrosion Challenges Towards a Sustainable Society” presents a series of cases showing the importance of corrosion protection of metals and alloys in the development of energy production to further understand the science of corrosion, and bring the need for research and the consequences of corrosion into public and political focus. This includes emphasis on the limitation of greenhouse gas emissions, on the lifetime of infrastructures, implants, cultural heritage artefacts, and a variety of other topics.
|
|
| 2. |
|
|
| 3. |
- Chang, Tingru, et al.
(författare)
-
A mechanistic study of stratified patina evolution on Sn-bronze in chloride-rich atmospheres
- 2020
-
Ingår i: Corrosion Science. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0010-938X .- 1879-0496. ; 166
-
Tidskriftsartikel (refereegranskat)abstract
- The complex stratified patina formed on Sn-bronze in chloride-rich atmospheres has been explored through long-term field exposures and short-term laboratory investigations using a multi-analytical approach. The stratified patina is composed of Cu2O- and Cu-2(OH)(3)Cl-rich sublayers intercalated by Sn-oxides, mainly SnO2. The stratification is triggered by events of high chloride deposition, resulting in repeated dissolution and solidification of sublayers, whereby redox reactions between the intermediate products of Sn- and Cu-chlorides play a crucial role. Sn-induced patina stratification is a major reason for enhanced patina flaking on Sn-bronze and its accelerated corrosion rate compared to Cu metal in marine environments.
|
|
| 4. |
- Chang, Tingru, et al.
(författare)
-
A novel methodology to study antimicrobial properties of high-touch surfaces used for indoor hygiene applications-A study on Cu metal
- 2021
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 16:2
-
Tidskriftsartikel (refereegranskat)abstract
- Metal-based high-touch surfaces used for indoor applications such as doorknobs, light switches, handles and desks need to remain their antimicrobial properties even when tarnished or degraded. A novel laboratory methodology of relevance for indoor atmospheric conditions and fingerprint contact has therefore been elaborated for combined studies of both tarnishing/corrosion and antimicrobial properties of such high-touch surfaces. Cu metal was used as a benchmark material. The protocol includes pre-tarnishing/corrosion of the high touch surface for different time periods in a climatic chamber at repeated dry/wet conditions and artificial sweat deposition followed by the introduction of bacteria onto the surfaces via artificial sweat droplets. This methodology provides a more realistic and reproducible approach compared with other reported procedures to determine the antimicrobial efficiency of high-touch surfaces. It provides further a possibility to link the antimicrobial characteristics to physical and chemical properties such as surface composition, chemical reactivity, tarnishing/corrosion, surface roughness and surface wettability. The results elucidate that bacteria interactions as well as differences in extent of tarnishing can alter the physical properties (e.g. surface wettability, surface roughness) as well as the extent of metal release. The results clearly elucidate the importance to consider changes in chemical and physical properties of indoor hygiene surfaces when assessing their antimicrobial properties.
|
|
| 5. |
- Chang, Tingru, et al.
(författare)
-
Analysis of historic copper patinas. Influence of inclusions on patina uniformity
- 2017
-
Ingår i: Materials. - : MDPI AG. - 1996-1944. ; 10:3
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 6. |
- Chang, Tingru, et al.
(författare)
-
Effect of blue light illumination on atmospheric corrosion and bacterial adhesion on copper
- 2024
-
Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 230
-
Tidskriftsartikel (refereegranskat)abstract
- The effect of blue light on atmospheric corrosion of Cu and on the antimicrobial properties was explored upon exposure mimicking the condition of hygienic surface disinfection. The results show that blue light illumination enhanced the formation of Cu2O, resulting in a slightly increased corrosion resistance of Cu without pre-deposited NaCl, whereas the enhanced formation of Cu2O, CuCl and/or Cu(OH)3Cl on copper with pre-deposited NaCl caused concomitant corrosion product flaking and a reduced corrosion resistance. The blue light induced enhancement of Cu corrosion led to increased surface roughness and more pronounced integration of bacteria within the corrosion products.
|
|
| 7. |
- Chang, Tingru, et al.
(författare)
-
The role of Sn on the long-term atmospheric corrosion of binary Cu-Sn bronze alloys in architecture
- 2019
-
Ingår i: Corrosion Science. - : Elsevier Ltd. - 0010-938X .- 1879-0496. ; 149, s. 54-67
-
Tidskriftsartikel (refereegranskat)abstract
- 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. © 2019 The Authors
|
|
| 8. |
- Chang, Tingru, et al.
(författare)
-
Understanding the Barrier Layer Formed via Adding BTAH in Copper Film Electrodeposition
- 2019
-
Ingår i: Journal of the Electrochemical Society. - : ELECTROCHEMICAL SOC INC. - 0013-4651 .- 1945-7111. ; 166:2, s. D10-D20
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 9. |
- Chen, Shuhui, et al.
(författare)
-
First-principles analysis of the stability and hydrogen adsorption properties of the α-Ti/α2-Ti3Al interface towards clarified hydrogen embrittlement mechanism of titanium alloys
- 2024
-
Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 72, s. 338-348
-
Tidskriftsartikel (refereegranskat)abstract
- First-principles calculations were employed to investigate the adsorption and diffusion energy of hydrogen (H) in the Ti/Ti3Al binary system, along with the evolution of the interfacial stability induced by the presence of H. The penetration energy barrier indicates that H can more easily penetrate the substrate through the Ti/Ti3Al interface. The formation energy of H increases with distance from the interface and the Ti/Ti3Al interface acts as a sink for trapping hydrogen interstitials. When all interstitial sites are completely occupied by H, the cleavage energy along the interface decreases from 1.935 to 1.094 J/m2, suggesting that H doping significantly reduces the strength of the Ti-Ti3Al (01–10) interface. When the area density of H-doping at the interface exceeds 0.37 atoms/Å2, the α-Ti lattice expands. Consistent with experimental observations, this triggers atomic migration and the generation of Ti-hydrides. Further analysis of the atomic structure and Bader charge transfers indicate that the interaction of Ti and H can alter the localized electronic structure of Al, leading to a weakened interface due to loss of interface bond strength. In summary, the theoretical calculations have provided new insights into possible hydrogen embrittlement (HE) mechanism in titanium alloys.
|
|
| 10. |
- Chico, B., et al.
(författare)
-
Analysis of historic copper patinas 2 : Characterization of 400 year old patina from Royal Summer Palace in Prague
- 2017
-
Ingår i: 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.
-
Konferensbidrag (refereegranskat)abstract
- 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.
|
|
| 11. |
- Halldin Stenlid, Joakim, et al.
(författare)
-
Computational Analysis of the Early Stage of Cuprous Oxide Sulphidation : A Top-Down Process
- 2017
-
Ingår i: Corrosion Engineering, Science and Technology. - 1478-422X .- 1743-2782. ; 52:S1, s. 50-53
-
Tidskriftsartikel (refereegranskat)abstract
- The initial steps of Cu2O sulphidation to Cu2S have been studied using plane-wave density functional theory at the PBE-D3+U level of sophistication. Surface adsorption and dissociation of H2S and H2O, as well as the replacement reaction of lattice oxygen with sulphur, have been investigated for the most stable (111) and (100) surface facets under oxygen-lean conditions. We find that the (100) surface is more susceptible to sulphidation than the (111) surface, promoting both H2S adsorption, dissociation and the continued oxygen–sulphur replacement. The results presented in this proceeding bridge previous results from high-vacuum experiments on ideal surface to more realistic corrosion conditions and set the grounds for future mechanistic studies. Potential implications on the long-term final disposal of spent nuclear fuel are discussed.
|
|
| 12. |
|
|
| 13. |
- Hägg Mameng, Sukanya, et al.
(författare)
-
Atmospheric Corrosion Resistance of Stainless Steel : Results of a Field Exposure Program in the Middle-East
- 2016
-
Ingår i: Berg- und Huttenmännische Monatshefte (BHM). - : Springer. - 0005-8912 .- 1613-7531. ; 161:1, s. 33-43
-
Tidskriftsartikel (refereegranskat)abstract
- Stainless steels have been widely used as architectural and construction materials because of their high degree of corrosion resistance, unique aesthetic quality, and stability in an unpolluted atmosphere. Although stainless steel is highly corrosion resistant, localized corrosion can occur in certain environments, especially in marine atmospheric conditions if the appropriate grade is not used. Exposure of stainless steel to an environment more aggressive than the limiting conditions may be harmful to its aesthetic appearance and ultimately even to its load-bearing capacity. Selecting a suitable stainless steel grade requires knowledge of the actual location of the application and the atmospheric conditions. In terms of materials selection, the austenitic stainless steel grade 316/316L has proved a very popular choice for architectural applications in many locations, but it is not always suitable at demanding sites such as marine environments in the Middle-East. In such cases the use of a higher-performance grade, often in combination with a good surface finish and established cleaning routines, is required to maintain pristine surfaces.The main objective of this paper is to present information about the atmospheric corrosion resistance of a number of stainless steels in the Middle-East at a marine site. The results obtained are analysed and discussed in terms of factors affecting atmospheric corrosion of stainless steel such as the, alloying element level, surface roughness, surface treatment, and microclimate.
|
|
| 14. |
- Hägg Mameng, Sukanya
(författare)
-
Localised corrosion and atmospheric corrosion of stainless steels
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This research is focused on defining limiting conditions for corrosion of stainless steels. The aim of the first part (Papers I-IV) was to understand the role of alloying level and environmental parameters on localised corrosion in aqueous conditions. Testing was done with a combination of short-term electrochemical and long-term immersion experiments. Results show that the chloride ion concentration and temperature are the main factors that affect the localised corrosion resistance. The presence of residual chlorine is also significant, since it leads to the ennoblement of the corrosion potential. If the corrosion potential exceeds the breakdown potential, the stainless steel will suffer from localised corrosion. Oxygen content and pH were identified as additional factors influencing the corrosivity of the environment.The aim of second part (Papers V-VIII) was to present information about the effect of alloying level, surface condition and environmental conditions on atmospheric corrosion resistance in Middle-East environments. Field exposure tests were performed and supplemented by laboratory aqueous corrosion tests. Results demonstrate that a higher alloying level (in both the bulk material and the surface), plus a smoother and cleaner surface gave an improvement in the corrosion performance and resistance to aesthetic degradation. Chloride and sulphate are the main surface contaminants found in the Middle East atmosphere. Stainless steels exposed in sheltered conditions showed a better atmospheric corrosion resistance than in open conditions. Three factors are considered to contribute to this difference: a very low rainfall, more condensation leading to corrosion in the open conditions and a higher level of beneficial sulphate in the deposits in sheltered conditions. The results showed a reasonable correlation between laboratory pitting corrosion tests and atmospheric field tests.The results from this thesis provide reference data to aid selection of appropriate stainless steel grades. Results can also be used to help understand the limits for use of stainless steels in different conditions in both aqueous environments and in the atmosphere.
|
|
| 15. |
- Leygraf, Christopher, 1946-, et al.
(författare)
-
Analysis of historic copper patinas 1 : Influence of substrate on patina uniformity
- 2017
-
Ingår i: 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.
-
Konferensbidrag (refereegranskat)
|
|
| 16. |
- Leygraf, Christopher, 1946-
(författare)
-
Atmospheric corrosion
- 2011
-
Ingår i: Corrosion Mechanisms in Theory and Practice: Third Edition. - : CRC Press. - 9781420094633 - 9781420094626 ; , s. 669-704
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 17. |
- Leygraf, Christopher, 1946-, et al.
(författare)
-
The origin and evolution of copper patina colour
- 2019
-
Ingår i: Corrosion Science. - : Elsevier. - 0010-938X .- 1879-0496. ; 157, s. 337-346
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 18. |
- Liu, Min, et al.
(författare)
-
Density Functional Theory Study of Influence of Oxide Thickness and Surface Alloying on Cl Migration within alpha-Al2O3
- 2021
-
Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 168:8
-
Tidskriftsartikel (refereegranskat)abstract
- Insertion and migration of chlorine atoms (Cl) in alpha-Al2O3 were studied by density functional theory calculations focusing on the influence of oxide thickness and doping by Mg, Cu and Si. Work function, electronic band gap, and insertion energy were calculated to explore thermodynamics of Cl migration. Partial density of state (PDOS) calculations revealed the role of dopants in the electronic character of metal-O and Al-Cl bonds. Work function data showed the effect of Cl insertion into the oxide film on the corrosion resistance. Cl can locate at an O vacancy (V-O) with a large exothermic insertion energy, independent of oxide thickness, but can only locate at superficial Al vacancy (V-Al) exothermically. The energy barrier for Cl migration via neighboring V-O increases with oxide thickness, and is 2 similar to 2.5 eV for thicker oxides. Cl insertion causes a work function reduction exceeding 2 eV, implying a decreased corrosion resistance. The inhibition of Cl migration by Si-doping can be explained by a more intense hybridization peak of Si-O over Al-O in the PDOS profile, while the reduction of energy barrier by Mg-/Cu-doping probably is due to the deviation of metal-s state from the Fermi energy, thus facilitating Cl movement within the oxide.
|
|
| 19. |
- Mameng, Sukanya Hagg, et al.
(författare)
-
Effect of Stainless Steel Composition on Atmospheric Corrosion Resistance at a Marine Site in Dubai
- 2017
-
Ingår i: Corrosion. - : National Assoc. of Corrosion Engineers International. - 0010-9312 .- 1938-159X. ; 73:7, s. 880-891
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of the composition of stainless steels on atmospheric corrosion resistance in a marine environment in Dubai was investigated after 2 y and 4 y of exposure. Different stainless steel grades with different surface finishes were included in the investigation: three ferritic stainless steels, five austenitic stainless steels, and four duplex stainless steels. The alloying elements chromium (Cr) and molybdenum (Mo) both had a beneficial influence on the corrosion resistance. The pitting resistance equivalent number (PREN =%Cr + 3.3%Mo + 16%N) and the (%Cr + 3.3%Mo) content in the surface film correlated well to the atmospheric corrosion resistance. An increased Cr content both in the bulk material and in the passive film improved the atmospheric corrosion resistance and the additional presence of Mo was effective in preventing red rust and also reduced the depth of pits. The depth of the pitting attack and the degree of aesthetic degradation were both influenced by alloying level, surface finish, and exposure conditions (open and sheltered). In the severe marine environment in Dubai, it is necessary to use Mo-bearing high-Cr stainless steel for adequate atmospheric corrosion resistance. The most resistant stainless steel grades were the high alloyed grades which ranked in the order UNS S31254 similar to UNS S3750 < UNS S34565 < UNS S32654. The duplex stainless steel grade S32205 may be considered for construction and architectural materials in Dubai but is likely to require more maintenance.
|
|
| 20. |
- Mameno, Sukanva Hägg, et al.
(författare)
-
Atmospheric corrosion resistance of stainless steel : Results of a field exposure program in the middle-east
- 2015
-
Ingår i: European Corrosion Congress, EUROCORR 2015. - : Austrian Society for Metallurgy and Materials (ASMET). ; , s. 1244-1254
-
Konferensbidrag (refereegranskat)abstract
- Stainless steels have been widely used as architectural and construction materials because of their high degree of corrosion resistance, unique aesthetic quality, and stability in an unpolluted atmosphere. Although stainless steel is highly corrosion resistant, localized corrosion can occur in certain environments, especially in marine atmospheric conditions if the appropriate grade is not used. Exposure of stainless steel to a more aggressive environment than the limiting conditions may be harmful to its aesthetic appearance and ultimately even to its load-bearing capacity. Selecting a suitable stainless steel grade requires knowledge of the actual location of the application and the atmospheric conditions. In terms of materials selection, the austenitic stainless steel grade 316/316L has proved a very popular choice for architectural applications in many locations but it is not always suitable at demanding sites such as marine environments in the Middle-East. In such cases the use of a higher-performance grade, often in combination with a good surface finish and established cleaning routines, is required to maintain pristine surfaces. The main objective of this paper is to present information about the atmospheric corrosion resistance of a number of stainless steels in the Middle-East at a marine site. The results obtained are analysed and discussed in terms of factors affecting atmospheric corrosion of stainless steel such as the, alloying element level, surface roughness, surface treatment and microclimate.
|
|
| 21. |
- Morcillo, M., et al.
(författare)
-
Characterisation of a centuries-old patinated copper roof tile from Queen Anne's Summer Palace in Prague
- 2017
-
Ingår i: Materials Characterization. - : ELSEVIER SCIENCE INC. - 1044-5803 .- 1873-4189. ; 133, s. 146-155
-
Tidskriftsartikel (refereegranskat)abstract
- 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 > 300 years of exposure to the action of the atmosphere. A wide variety of techniques have been used, including metallographic and chemical analysis (electrogravimetry, AAS, XRF) of the copper matrix, and spectroscopic and microscopic investigations (GIXRD, FTIR, 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 [Cu-3(CO3)(2)(OH)(2)]; and (c) the brochantite/antlerite crystals are randomly doped with Fe and C.
|
|
| 22. |
- Morcillo, M., et al.
(författare)
-
On the Mechanism of Rust Exfoliation in Marine Environments
- 2017
-
Ingår i: Journal of the Electrochemical Society. - : ELECTROCHEMICAL SOC INC. - 0013-4651 .- 1945-7111. ; 164:2, s. C8-C16
-
Tidskriftsartikel (refereegranskat)abstract
- Based on exposures in chloride-rich field and laboratory atmospheres, a mechanism of rust exfoliation of carbon steel is proposed. Key ingredients are structural transformations between main rust phases (goethite, lepidocrocite, spinel oxides and akageneite) during varying exposure conditions and their large difference in molar volume with a factor of five between the most compact and least compact rust phase. Akaganeite transformed to spinel results in volume contraction, lepidocrocite to spinel in volume expansion and in both cases stresses are introduced in the rust multilayer. At sufficiently high chloride deposition rates (similar to 300 mg/m(2).d), the rust multilayer eventually detaches resulting in rust exfoliation.
|
|
| 23. |
|
|
| 24. |
- Ratia-Hanby, V., et al.
(författare)
-
Characterization of surface films that develop on pre-oxidized copper in anoxic simulated groundwater with sulphide
- 2023
-
Ingår i: Colloids and Surfaces A. - : Elsevier BV. - 0927-7757 .- 1873-4359. ; 676
-
Tidskriftsartikel (refereegranskat)abstract
- Surface films formed on pre-oxidized copper in anoxic simulated groundwater with sulphide were characterized by field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FT-IR), open circuit potential (OCP) measurements, and via analysing the water chemistry and weight changes in the specimens. Additionally, films developed under identical conditions on pre-oxidized and ground copper specimens were characterized by glow discharge optical emission spectroscopy (GDOES). The results revealed that the sulphide content in the groundwater significantly influences the morphology, composition and thickness of the surface film. The build-up of Cu2S was evidenced at the sulphide contents of 32 mg/L and 320 mg/L. GDOES depth profiling revealed that sulphur and oxygen coexisted in the film all through its thickness, yet the surface was essentially rich in sulphur. The results from characterization are presented in detail in this paper and discussed from the perspective of capabilities of the used methods.
|
|
| 25. |
- Szakalos, Peter, et al.
(författare)
-
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
-
Ingår i: Corrosion Science. - : Elsevier. - 0010-938X .- 1879-0496. ; 142, s. 305-307
-
Tidskriftsartikel (refereegranskat)
|
|
| 26. |
|
|
| 27. |
- Yin, Litao
(författare)
-
FEM Modelling of Micro-galvanic Corrosion in Al Alloys Induced by Intermetallic Particles : Exploration of Chemical and Geometrical Effects
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Localized corrosion, such as pitting, crevice corrosion or galvanic corrosion, is a long-standing phenomenon that can greatly limit the life of metallic materials. For decades experimental methods have been used to try to understand the underlying physical, chemical and electrochemical processes that control localized corrosion in order to find effective protection methods against its propagation. The complexity of the phenomenon and its small geometric size have often severely restricted the basic understanding of local corrosion. In recent decades, computational methods have been developed as an alternative to the experimental methods. Compared to experimental methods, modeling and numerical simulation enable complicated systems to be systematically investigated without considering the inherent constraints of experimental methods. In the current Doctoral thesis, advanced calculation methodology has been used to study galvanic corrosion of an aluminum alloy with geometric resolution at micrometer level. The computational platform has been a commercial FEM-based software, COMSOL Multiphysics, which was combined with another software, Matlab. The current model system consists of a semi-spherical intermetallic particle, surrounded by a pure aluminum matrix. The aluminum surface is covered by an inert passive film, except for a ring-shaped surface around the particle itself. By assuming that the particle is electrochemically more noble than aluminum, it acts as a cathode and the surrounding aluminum ring as anode. By utilizing the FEM-based software, it has been possible to incorporate important physicochemical reactions, including the electrochemical anode and cathode reactions of the individual phases, mass transport of various chemical compounds formed during ongoing electrochemistry, homogeneous reactions in the electrolyte, as well as deposition of corrosion products consisting of Al(OH)3 along parts of the anodic area. What has made this study a significant step forward is that not only chemical changes but also geometrical changes have been taken into consideration in the simulation of ongoing micro-galvanic corrosion. Particularly challenging has been to mathematically master the gradual deposition of compact Al(OH)3 on an aluminum surface which gradually dissolves anodically. In the initial modeling work, the deposition of Al(OH)3 was assumed to occur only on the electrode surface, resulting in a gradual blockage of surface activity. In an even more advanced stage, the modeling has also sought to simulate the effect of a deposited porous film of Al(OH)3, formed through homogeneous reactions in the electrolyte. By taking into account inhibited diffusion and migration of chemical products that the porous film causes, its sterically inhibiting effect has for the first time been quantitatively interpreted. The porous corrosion product can most closely resemble the lid experimentally observed above local corrosion attacks, which leads to an even more diminished surface activity in electrochemical reactions compared with the deposition of only compact corrosion products on the anode surface. The kinetic model has resulted in a significantly deeper insight into the mechanism of micro-galvanic corrosion of the investigated system. The simulation has been shown to predict the time-dependent geometric changes of the anodically dissolved aluminum surface as well as the flow and distribution of generated chemical products. Contrary to the widely accepted perception that Al(OH)3 is not stable in the occluded acidified electrolyte environment, the calculations predict a higher local pH in the occluded electrolyte. This means that insoluble Al(OH)3 can be deposited on the electrode surface, the blocking effect of which may lead to a termination of the micro-galvanic corrosion. If the ring width is initially 0.5 μm or less, transport of OH- ions from the cathode surface to the occluded electrolyte environment is limited, leading to a local acidification within the occluded dissolving volume. At a given anodic ring width, an increased radius of the cathodic particle instead leads to an increased anodic dissolution rate by formation of a larger area for the cathode reaction. Variation of the chemical parameters in the electrolyte also shows that the simulated micro-galvanic corrosion rate of aluminum has a minimum at pH = 6. Both more acidic and more alkaline conditions result in an elevated anodic dissolution of aluminum. When pH ≤ 4, the deposition of Al(OH)3 becomes negligible, and the micro-galvanic corrosion will continue uninterrupted, completely in accordance with experimental data.
|
|
| 28. |
- Yin, Litao, et al.
(författare)
-
Numerical simulation of micro-galvanic corrosion of Al alloys : Effect of density of Al(OH)(3) precipitate
- 2019
-
Ingår i: Electrochimica Acta. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0013-4686 .- 1873-3859. ; 324
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 29. |
- Yue, Xiaoqi, et al.
(författare)
-
Penetration of corrosive species into copper exposed to simulated O 2 -free groundwater by time-of-flight secondary ion mass spectrometry (ToF-SIMS)
- 2023
-
Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 210
-
Tidskriftsartikel (refereegranskat)abstract
- ToF-SIMS analysis of copper samples after exposures to simulated groundwater with and without sulfide addition was performed to investigate the penetration of corrosive species containing H, S, O, and Cl, into copper. Depth profiles show extent of penetration and 2D/3D images reveal local elemental distribution of the corrosive species at different depths inside copper. Pre-oxidation did not reduce the penetration while sulfide additional in groundwater and exposure at 60 °C significantly promoted the penetration. The extent of penetration of the corrosive species into copper demonstrates the need for risk assessment of complex corrosion forms such as sulfide-induced embrittlement and cracking.
|
|
| 30. |
- Zhang, Hongbo, et al.
(författare)
-
The formation of hydride and its influence on Ti-6Al-4V alloy fracture behavior
- 2023
-
Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 48:92, s. 36169-36184
-
Tidskriftsartikel (refereegranskat)abstract
- The fracture mechanism of hydrogen charged Ti-6Al-4V has been investigated through a multianalytical approach. The difference in hydrogen solubility between 13 phase (high solubility) anda phase (low) governs the formation and growth pattern of titanium hydrides, and determine the fracture mode of Ti-6Al-4V. Depending on the hydrogen charging extent, the penetration of hydrogen and distribution of hydrides can be divided into three stages. In the initial stage hydrogen diffuses mainly into the 13 phase, as judged from its increase in Volta potential, and with no hydrides formed. Failure analysis after tensile tests exhibits plastic behavior and a fracture surface with mainly dimples. In the subsequent transition stage, hydrides are formed at the a/13 interfaces and along a grain boundaries. More initial cracks occur in the brittle hydrides and the fracture surface transforms from dimple to quasi-cleavage. In the final stage a layer of uniformly distributed hydride is produced on the surface and within the a phase. Supported by nanoindentation measurements, the plasticity of the charged sample diminishes with hydrogen charging time, and an intergranular-transgranular mixed fracture is observed. Overall, the study forms clear evidence that the distribution and cracks of hydrides influence the fracture mode of the Ti-6A-4V alloy.
|
|
| 31. |
- Zhang, Xian, et al.
(författare)
-
Atmospheric corrosion of Zn-Al coatings in a simulated automotive environment
- 2018
-
Ingår i: Surface Engineering. - : TAYLOR & FRANCIS LTD. - 0267-0844 .- 1743-2944. ; 34:9, s. 641-648
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 32. |
- Zhao, Weijie, et al.
(författare)
-
Corrosion inhibition of copper with octadecylphosphonic acid (ODPA) in a simulated indoor atmospheric environment
- 2021
-
Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 192:109777
-
Tidskriftsartikel (refereegranskat)abstract
- The corrosion inhibition of self-assembled octadecylphosphonic acid (ODPA) layers on non-oxidized and pre-oxidized copper and Langmuir-Blodgett deposited ODPA layers on pre-oxidized copper was investigated under a simulated indoor atmospheric corrosion environment containing 80% RH and 100 ppb formic acid. The corrosion process was monitored in-situ with infrared absorption/reflection spectroscopy, and the corrosion products were further characterised by grazing incidence X-ray diffraction. Nano-FTIR microscopy was used to reveal the nature, size, and distribution of the corrosion products on the nanoscale. The combination of pre-formed cuprite and ODPA layers, both with only some nanometres thickness, provided an excellent protection under this environment.
|
|
| 33. |
|
|
| 34. |
- Zhao, Weijie, et al.
(författare)
-
The nature of self-assembled octadecylphosphonic acid (ODPA) layers on copper substrates
- 2021
-
Ingår i: Journal of Colloid and Interface Science. - : Academic Press Inc.. - 0021-9797 .- 1095-7103. ; 581, s. 816-825
-
Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: The self-assembly of amphiphilic molecules onto solid substrates can result both in the formation of monolayers and multilayers. However, on oxidized and non-oxidized copper (Cu), only monolayer formation was reported for phosphonic acids possessing one phosphate head group. Here, the adsorption of octadecylphosphonic acid (ODPA) on Cu substrates through a self-assembly process was investigated with the initial hypothesis of monolayer formation. Experiments: The relative amount of ODPA adsorbed on a Cu substrate was determined by infrared reflection/absorption spectroscopy (IRRAS) and by atomic force microscopy (AFM) investigations before and after ODPA deposition. X-ray photoelectron spectroscopy (XPS) with sputtering was used to characterize the nature of the layers. Findings: The results show that the thickness of the ODPA layer increased with deposition time, and after 1 h a multilayer film with a thickness of some tens of nm was formed. The film was robust and required long-time sonication for removal. The origin of the film robustness was attributed to the release of Cu ions, resulting in the formation of Cu-ODPA complexes with Cu ions in the form of Cu(I). Preadsorbing a monolayer of octadecylthiol (ODT) onto the Cu resulted in no ODPA adsorption, since the release of Cu(I) ions was abolished.
|
|
| 35. |
- Örnek, Cem, et al.
(författare)
-
Passive film characterisation of duplex stainless steel using scanning Kelvin probe force microscopy in combination with electrochemical measurements
- 2019
-
Ingår i: npJ Materials Degradation. - : Springer Science and Business Media LLC. - 2397-2106. ; 3:1, s. 1-8
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
