We investigate the passivation of functional metal surfaces in reactive environments (e.g. aqueous and electrolytic solutions, controlled atmospheric environments) by in-situ electrochemical analysis techniques (e.g. polarisation measurements, impedance spectroscopy, environmental AFM and photo-electrochemistry).

Mechanistic models are developed to describe the (inter)relationships between the microstructure (e.g. thickness, phase constitution and defect structure) of the oxy-hydroxide thin films (thickness < 10 nm) and the material surface properties (e.g. corrosion resistance, adhesive strength, electrical and tribological properties). Of particular interest is the effect of the defect distribution in the oxide film on the initiation of localized corrosion processes.

At present, our research is mainly focussed on surficial oxide films on Al- and Mg-based alloys (see figure: surface-orientation-dependent passivation behaviour of Al-Cr-Fe complex metallic alloys), as well as the controlled growth of functional ultrathin oxide films for applications in microelectronics and energy-related technologies.

Your contacts: Patrik Schmutz, Lars Jeurgens

Nanomaterials with their characteristically high surface-to-volume (or interface-to-volume) ratio are generally very prone to degradation under ambient conditions. Our research on the environmental sustainability of nanomaterials therefore aim at the identification and tailoring of the local surface reactions and degradation mechanisms of small-size engineered structures during the early stages of exposure to ambient (atmospheric) and aqueous (electrolytic) conditions.

To this end, a state-of-the-art environmental AFM setup has been especially developed (see figure), which can be operated in a broad range of controllable environmental conditions (up to 250°C, from high vacuum to ambient pressures under controlled humidity, in aqueous solutions). It offers unique capabilities to characterize the characterization of the topography, surface forces, surface charges and surfaces potentials (by Kelvin Probe) of reaction products (e.g. passive oxides) on nano-architectured surfaces and nano-particles in controlled `aggressive` environments.

Your contacts: Patrik Schmutz, Alessandra Beni

Fundamental knowledge on the surface reactivity, biocompatibility and toxicity of metallic particles and implants in biological environments is of crucial importance for biomedical applications.

To develop and refine reaction models, we perform in-vitro electrochemical characterizations of the surface reactivity of permanent implants of e.g. stainless steel, Co-Cr-Mo and Ti-Al-Nb alloys in simulated aggressive “biological” environments, focussing on the effects of crevices and galvanic coupling on localized corrosion and dissolution rates of metallic species.

We also consider the positive use of corrosion processes in medical applications, targeting at the controlled (electrochemical) dissolution of degradable Mg-based implants and the production of functionalized core-shell nanoparticles (see figure) for medical treatments.

Your contacts: Patrik Schmutz, Giancarlo Pigozzi