Inhibited protective coatings based on polyurethane
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INHIBITED PROTECTIVE COATINGS BASED ON POLYURETHANE L. М. Bilyi1,2 and Ya. I. Zin’1
UDC 620.197
We establish the synergism of inhibition of the corrosion processes in steel placed in weakly acid corrosive media by compositions of pigments based on zinc/iron phosphate and wollastonite. A mechanism of their protective action is proposed. The influence of filling of a polyurethane primer with a mixture of zinc/iron phosphate and wollastonite on its anticorrosion and physicomechanical characteristics is investigated. On the basis of the results of experimental investigations, we develop a new polyurethaneperchlorovinyl primer for protecting the problem sections of pipelines at the sites of earth–air transitions. Keywords: inhibiting pigments, wollastonite, polyurethane-perchlorovinyl primer, impact resistance, underfilm corrosion, impedance, adhesive strength.
The service life of gas-and-oil mains is mainly determined by their corrosion protection. The rise of the requirements imposed on the efficiency of corrosion protection of pipeline transport is reflected both in the Ukrainian regulating documents [1] and in the standards of the European Union [2] and caused by the intensification of the influence of corrosion factors as a result of the anthropogenic pollution of the environment. The increase in the service life and reliability of corrosion-inhibiting coatings in the open parts of the main pipelines and at the sites of earth–air transitions deserves special attention [3, 4]. In the world practice, it is customary to apply polyurethane coatings characterized by high atmospheric and chemical stability to the indicated sections of pipelines [5, 6]. Thus, coatings based on polyurethane enamel and modified with perchlorovinyl resin [7] have high barrier characteristics in various corrosive media and, hence, prove to be quite promising for this purpose. However, in the case where the coatings have through defects, the medium penetrates to the substrate, and the process of underfilm corrosion of the metal develops fairly intensely. Hence, it is necessary to develop efficiently inhibited primers for application under polyurethane enamel coatings. The analysis of the available patent, scientific, and engineering literature shows that the role of reliable inhibiting pigments for the polyurethane primers on steel can be played by low-cost, environmentally safe, and low-toxicity zinc/iron phosphates combined with appropriate active inorganic compounds capable of strengthening their protective action due to the interaction with components of the mineral filler. The aim of the present work is to develop an efficient synergistically inhibited primer based on polyurethane with elevated mechanical and anticorrosion characteristics. Materials and Methods of Investigation Inhibiting primers were obtained on the basis of a polyurethane enamel with the following composition (wt.%): laprol-1052 (15), PSKh-LS perchlorovinyl resin (7), chromium oxide (12.9), R-5 solvent (a mixture of 1 2
Karpenko Physicomechanical Institute, Ukrainian
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