We offer unique and state-of-the-art local electrochemical characterizations of the surface reactivity and chemical durability of high-performance materials, coatings and technological components, as applied in civil engineering, medical implants, automotive industry, aviation, machine tooling, power generation, packaging, watches, microelectronics and sensing devices.
To this end, in-house developed micro- and nano-capillary setups are used, which can be operated in (aggressive) liquid environments, as well as in defined gas mixtures at elevated temperatures (up to 1200ºC) on a local scale down to the nanometer range. Such localized electrochemical characterizations at selected heterogeneities on the material’s surface can be combined with ex-situ investigations of the surface and bulk microstructure of the material by conventional analytical techniques (e.g. SEM/EDX, XRD, XPS, AES, Impedance Spectroscopy and environmental AFM).
The principle of the electrochemical capillary technique consists of a tapered glass micro-capillary (with a ground tip diameter in the range of 0.2 - 1000 µm), which acts as a miniaturized electrochemical cell. The micro-capillary electrochemical cell can be positioned at selected locations on a solid surface with the help of an optical microscopic system. Since the electrolyte is directly inside the thin-walled capillary tip, the exposed (analysis) area is approximately equal to the contact area of the capillary tip on the material’s surface. To enable the detection of initial reaction stages at such a local scale, specially modified high-resolution potentiostats with a current detection limit as high as 20 fA are used.
Modified micro-capillary setups allow local electrochemical measurements in liquids and gas mixtures at elevated temperatures with applied mechanical stress, additional friction or with electrolyte flow. These capillary electrochemical sensing techniques have been successfully applied to determine, e.g.
- Role of microstructural heterogeneities (e.g. precipitates, impurities, grain boundaries, micro-cracks, pores) on the reactivity and degradability of high-performance materials, joint assemblies and coating systems
- Chemical stability and biocompatibility of medical implants in bio-environments with simultaneous monitoring of local ionic dissolution processes.
- Altering behavior (deterioration or degradation) of the functional properties of electronic devices and sensors.
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