Selection and evaluation of single-layer coating compositions in corrosive environments

Abstract

HANUŠ, J.: Selection and evaluation of single-layer coating compositions in corrosive environments. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 5, pp. 53-64 The objective of the work was to select a suitable methodology for accelerated corrosion tests of singlelayer coating compositions (hereina er referred to as CC), to assess the condition of coatings during corrosion tests and to evaluate the resistance of the monitored single-layer CCs a er the completion of the tests in selected corrosive environments. The results were used for the determination of the potential use of the selected single-layer coating compositions in agricultural environments. The following single-layer, water-based CCs were applied to sheet steel samples: V 2026, Aquapol_J and Denapox EZ. The following synthetic CCs were selected: AR 40-00, Krahokryl_J and ACS 20-ST. The resistance of these coatings was tested in 5 corrosive environments: in NaCl environment according to CSN EN ISO 7253, in SO 2 environment according to CSN EN ISO 3231 and in the environment of a condensation chamber with de-ionized water according to CSN 03 8131. To simulate agricultural environments, solutions of the Cererit fertilizer and pig semi-liquid manure were selected. The samples were le in the condensation chamber in aqueous environment according to CSN 03 8131 for 8 hours and then soaked in Cererit or semi-liquid manure and le in the laboratory environment for 16 hours. Samples were evaluated according to CSN EN ISO 4628-1, 2, 3. The water-based CC Denapox EZ and the synthetic CC AR 40-00 reached the best results. single-layer coating compositions, evaluation of coatings, protection from corrosion, water-based coating compositions, corrosive tests At present, requirements are put on the development of coating systems that are environmentally friendly and that decrease the costs of production and application of paints while maintaining high corrosion resistance. The CSN EN ISO 11890 -1, 2 standard was passed in the Czech legislation in order to limit the content of volatile organic compounds (VOC) in CCs. Thanks to that the volume of volatile organic compounds is decreased to the minimum or completely banned. Compounds are replaced by other, more environmentally-friendly substances and new directions are developed in the fi eld of coating compositions.Single-layer CCs follow this trend. As the title implies, these CCs only have one layer that fulfi ls the function of the undercoat as well as the topcoat with water being the dissolving agent, or with a limited volume of solvents. Thanks to that these CCs are environmentally friendly. Another advantage is saving time and thus money during the application and subsequent drying of the coating.Single-layer water-based and synthetic CCs were selected on the basis of the aforementioned reasons to determine their resistance in the protection from corrosion and the possibility of use in agricultural environments.

Automatized Approach to Assessment of Degree of Delamination Around a Scribe

“…ISO 4628 is a comprehensive regulation, which provides more than necessary number of tools for every possible type of coating defects. Nevertheless, manual evaluation of samples is implied [2], and, surprisingly, not many methods for automatized application of ISO 4628 have been presented, so far. Whitfield et.…”