The Formation and Breakdown of Passive Film on Ni Alloys : in situ synchrotron studies
(2023)- Abstract
- Corrosion results in huge annual costs and a large environmental footprint. The corrosion rate of some alloys can be made negligible by the presence of a spontaneously forming oxide film on the surface, a so-called passive film. Famous examples of alloys exhibiting passivity are stainless steels. However, in some demanding applications, stainless steel does not provide significant corrosion resistance. Instead, Ni alloys are used, which are known for their excellent corrosion resistance. The nature, formation, and mechanism of breakdown of the passive films that form on Ni alloys is, however, not well understood.
In this thesis, a combination of in situ synchrotron-based methods has been used to elucidate the chemistry and structure of... (More) - Corrosion results in huge annual costs and a large environmental footprint. The corrosion rate of some alloys can be made negligible by the presence of a spontaneously forming oxide film on the surface, a so-called passive film. Famous examples of alloys exhibiting passivity are stainless steels. However, in some demanding applications, stainless steel does not provide significant corrosion resistance. Instead, Ni alloys are used, which are known for their excellent corrosion resistance. The nature, formation, and mechanism of breakdown of the passive films that form on Ni alloys is, however, not well understood.
In this thesis, a combination of in situ synchrotron-based methods has been used to elucidate the chemistry and structure of the thin oxide films that dictate the corrosion resistance, as well as the chemistry of the electrolyte above the sample surface to probe the concentration of dissolved ions and their chemical state. This was also coupled with the use of optical microscopy to provide a full-field view of the surface in situ.
It was found that the passive film on the studied Ni-Cr-Mo alloys mainly contains Cr oxides and Mo oxides, while Ni does not participate in the oxide film. The film is only one nanometer thick and forms rapidly upon exposure to oxygen. It was shown that even if the initial oxidation kinetics are rapid, it takes time for a true steady-state composition to be reached, and aging of the sample surface in air affects the oxide thickness and composition. It was also found that Ni-Cr-Mo alloys exhibit a transpassive breakdown mechanism that is different from that of typical Cr-containing alloys. This mechanism was also found to be connected to the catalytic activity towards the oxygen evolution reaction, which takes place at increased anodic potentials. Lastly, this thesis also covers some method development of both X-ray-based and optical surface-sensitive methods that were used to study the thin oxide films at the solid-liquid interface in situ.
(Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/dea3e3f0-ff07-4d45-9c7e-6a091015e420
- author
- Larsson, Alfred LU
- supervisor
- opponent
-
- Professor Mol, Arjan, Delft University of Technology.
- organization
- publishing date
- 2023
- type
- Thesis
- publication status
- published
- subject
- keywords
- Passivity, Corrosion, Degradation, Nickel alloys, synchrotron, in situ, Fysicumarkivet A:2023:Larsson
- pages
- 110 pages
- publisher
- Lund University
- defense location
- Rydbergssalen. Join via Zoom: https://lu-se.zoom.us/j/69511786657?pwd=Ym94cVJOWjFoMEZmUlVpaEsrVnZ0QT09
- defense date
- 2023-12-15 13:15:00
- ISBN
- 978-91-8039-845-9
- 978-91-8039-846-6
- language
- English
- LU publication?
- yes
- id
- dea3e3f0-ff07-4d45-9c7e-6a091015e420
- date added to LUP
- 2023-11-10 14:17:39
- date last changed
- 2024-01-31 11:48:39
@phdthesis{dea3e3f0-ff07-4d45-9c7e-6a091015e420,
abstract = {{Corrosion results in huge annual costs and a large environmental footprint. The corrosion rate of some alloys can be made negligible by the presence of a spontaneously forming oxide film on the surface, a so-called passive film. Famous examples of alloys exhibiting passivity are stainless steels. However, in some demanding applications, stainless steel does not provide significant corrosion resistance. Instead, Ni alloys are used, which are known for their excellent corrosion resistance. The nature, formation, and mechanism of breakdown of the passive films that form on Ni alloys is, however, not well understood.<br/>In this thesis, a combination of in situ synchrotron-based methods has been used to elucidate the chemistry and structure of the thin oxide films that dictate the corrosion resistance, as well as the chemistry of the electrolyte above the sample surface to probe the concentration of dissolved ions and their chemical state. This was also coupled with the use of optical microscopy to provide a full-field view of the surface in situ.<br/>It was found that the passive film on the studied Ni-Cr-Mo alloys mainly contains Cr oxides and Mo oxides, while Ni does not participate in the oxide film. The film is only one nanometer thick and forms rapidly upon exposure to oxygen. It was shown that even if the initial oxidation kinetics are rapid, it takes time for a true steady-state composition to be reached, and aging of the sample surface in air affects the oxide thickness and composition. It was also found that Ni-Cr-Mo alloys exhibit a transpassive breakdown mechanism that is different from that of typical Cr-containing alloys. This mechanism was also found to be connected to the catalytic activity towards the oxygen evolution reaction, which takes place at increased anodic potentials. Lastly, this thesis also covers some method development of both X-ray-based and optical surface-sensitive methods that were used to study the thin oxide films at the solid-liquid interface in situ. <br/>}},
author = {{Larsson, Alfred}},
isbn = {{978-91-8039-845-9}},
keywords = {{Passivity; Corrosion; Degradation; Nickel alloys; synchrotron; in situ; Fysicumarkivet A:2023:Larsson}},
language = {{eng}},
publisher = {{Lund University}},
school = {{Lund University}},
title = {{The Formation and Breakdown of Passive Film on Ni Alloys : in situ synchrotron studies}},
url = {{https://lup.lub.lu.se/search/files/164726980/Alfred_Larsson_-_WEBB.pdf}},
year = {{2023}},
}