Accelerated ageing of organic coating systems by thermal treatment A. Miszczyk * , K. Darowicki Faculty of Chemistry, Department of Anticorrosion Technology, Technical University of Gdansk, 11/12 Narutowicza St., 80-952 Gdansk, Poland Received 7 January 2000; accepted 28 September 2000 Abstract The accelerated laboratory ageing of coated steel by multiple thermal shock has been proposed. Three polyvinyl coated steel panels exposed to natural weathering for dierent periods 0, 3 and 6 years) were thermally treated from temperatures of 20±65°C. A new epoxy coating for tank protection was treated by multiple thermal shock. Observed changes were interpreted as a protective system degradation and explained on the basis of analysis of stresses within the coating system. It was concluded that the proposed procedure allows to distinguish the performance of dierent coatings in a shorter time compared to traditional laboratory exposition. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: Organic coatings; EIS; Thermal cycling; Paint coatings 1. Introduction Internal and external stresses have been constantly associated with coating life, ®lm formation, service and breakdown either as a cause or as an eect [1]. Coating systems in natural conditions undergo temperature and humidity changes according to the short-term day±night and long-term spring±summer±autumn±winter periods. Due to the dierent thermal expansion coecients of a coating and its metal sub- strate considerable stress imparts to the interface. Perera and Eynde report that the history of temperature changes in the initial service life period has an eect on the durability of the coating [2±4]. Multiple repeated inducted stresses in weather www.elsevier.com/locate/corsci Corrosion Science 43 2001) 1337±1343 * Corresponding author. Tel.: +48-58-347-2483; fax: +48-58-347-1092. E-mail address: misa@chem.pg.gda.pl A. Miszczyk). 0010-938X/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII:S0010-938X00)00156-6