Characterisation of Organic Coatings with Impedance Measurements: A Study ofCoating Structure, Adhesion and Underfilm Corrosion

摘要

Organic coatings of many different types and formulations are frequently employedto protect metal structures against corrosion and to simultaneously provide them with almost any color and gloss required. Obviously the matter of selecting the optimum coating for a specific substrate to be exposed to a specific environment from the multitude of different commercially available coatings, requires a thorough characterization of the most important coating properties. Furthermore a detailed characterization is a vital step in the development of new types of coatings, and new formulations. This is especially important as the use of a large number of proven types of coatings and components is soon to be prohibited under the new and very strict environmental legislations world-wide. In the thesis the possibilities for a successful application of impedance measurements for the broad characterization of coated metals are investigated in depth. Important in the study is the consideration that a successful data interpretation is possible only if the experimental conditions are highly optimized. This has resulted in the development of a novel cell design, optimization of noise reducing facilities, the optimization of a new technique to produce extremely well defined defects in coatings by laser ablation, and a large number of measurements on extremely well controllable model coatings.