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Corrosion Science. 01/2007; 49:2781-2799.
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Corrosion Engineering Science and Technology. 01/2004; 39:301-307.
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ABSTRACT: Researchers’ efforts are focused on understanding how coatings can be tested in order to determine their real capabilities and selected for different purposes. Outdoor exposures are certainly reliable and offer a good representation of the actual service life. However, such tests cannot be considered quick.On the other hand, a quick test, even if reliable, very often disagrees with the actual degradation mechanisms occurring under natural conditions. In fact, in order to determine an acceleration of the natural weathering, it is necessary to increase the effect of natural parameters affecting the protection properties of a coating.The usual modern way to operate is to take advantage of ageing tests where temperature plays a big role in the ageing of the material, permitting to gather faster information for coating corrosion resistance evaluation.Following the recent new experience realised by the Bierwagen group, we carried out different thermal cycling tests consisting in daily series of electrochemical measurements on coated samples, carried out using electrochemical impedance spectroscopy (EIS).The cumulative effects of such a thermal cycling on the film, based on a large variety of theoretical explanations, should permit the ranking of a variety of materials, by constituents, characteristics and application purposes, in a short time while remaining objective and reliable.The used ageing procedure and data evaluation allowed to quickly and precisely obtain information concerning both barrier properties and adhesion properties of the studied materials.
Progress in Organic Coatings.
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ABSTRACT: A variety of methodology which are supposed to accelerate and/or simulate the effects of time and environment, weathering, on organic coatings degradation are under development since long time. Taking into account that no test can duplicate all of the variables associated with a coatings environment, two modern accelerated tests were carried out and their investigation capabilities were compared: the Norwegian Norsok M 501 and the thermal cycling in electrolyte immersion. The first test highlighted the adhesion performances of coatings and the importance of the zinc-rich primers on the scratch protection. The thermal cycling test has lead to a very rapid loss of film properties. Electrochemical impedance measurements associated to this test have shown the relative importance of electrical resistance and capacitance in predicting corrosion protective performance in presence of very thick coatings.
Progress in Organic Coatings.
