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O Hudak, E. Aschauer, V. Dalbauer, O Hunold, M. Arndt, P. Polcik, P. Felfer, H. Riedl:
"Corrosion induced diffusion pathways in thin film materials investigated by atom probe tomography";
Talk: AVS 67 Virtual Symposium, Virtual Symposium; 2021-10-25 - 2021-10-28.

Corrosion phenomena have a large impact in almost all of today´s technological fields. A ubiquitous interplay between material and its environment challenges material-engineers in selecting materials that provide a safe and work effective implementation. In this regard, protective thin films and surface modifications have opened up new avenues in aviation and power generation sectors. In particular, physical vapor deposited (PVD) coatings have been specifically developed to elicit superior material properties, as well as extend the longevity and work performance of machining components. Unfortunately, due to a deficient understanding of corrosion related processes in PVD coatings, industrial demands for high performance corrosion resistant thin films remain sparse.
This study intends to take a closer look at corrosion driven diffusion pathways in aqueous solutions at an atomic scale. As many technical alloys used in marine environments, aviation and energy sectors are prone to pitting corrosion, a demand for tailored corrosion protective coatings seems quite overdue. A three electrode cell potentiostat was utilized for conducing potentiodynamic polarization measurements, and enabled precise control over the corrosion test parameters. With a systematic approach on highlighting preferred diffusion pathways, this study displays a thorough exploration of the effect of grain size, macro-particle formation and crystallinity on the diffusion mechanism in arc-PVD thin films. For better tracing the corrosive species, a novel marker architecture was developed for eliciting chemical and structural changes upon arrival of the diffused media. Consequently, this allows for improved application of high-resolution analytical methods, such as APT and TEM, to help identify preferential diffusion paths.

Corrosion resistance; PVD coatings; Diffusion pathways; Atom probe tomography; pitting corrosion

Project Head Helmut Riedl:
CDL-SEC