The results of studying the density of powder coatings obtained by the electrocontact method are presented. The functional performance of coatings presents the two problems: density and strength of adhesion to the base. Review and analysis of theoretical and practical aspects of producing powder coatings resulted in deciding the prime lines of research on their density, which are related to the mechanics of their compaction on formation, establishment of basic density against pressure relations, micromechanics of the contact interaction of powder particles and surface to be hardened. The three stages of powder coating formation by the electrocontact method are recognized: powder precompaction, second compaction and preheating, sintering. The dominant processes are cold molding (pressing), hot pressing (sintering) or rolling. Cold molding is governed by the density-pressure relation, which was viewed in the context of the discrete powder nature concept, based on the analysis of contact interaction and deformation conditions of single powder particles. Phenomenologically, molding of powder materials under pressure at high temperatures (hot pressing or rolling) results in the change of linear dimensions of a porous powder body, which is appropriate for consideration as a rheological process, i.e., change of the form and volume of the dispersed system with time. The kinetics for powder particles in contact and their interfacial (base) contact is presented. In the coating formation, powder particles are bonded to the base as a result of their deformation, mechanical cohesion, adhesion, and welding in between and with the base. The interpolation equation that describes the powder layer compaction on its formation by the electrocontact method (coating density against pressure whereby the tool electrode compacts the powder layer) is proposed. Theoretical and experimental results for the powder coating density related to the pressure of their formation by the electrocontact method were obtained.
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Translated from Problemy Mitsnosti, No. 4, pp. 94 – 106, July – August, 2023.
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Lopata, L.A., Kulyzhskyi, V.M., Lopata, O.V. et al. Computation-Experimental Evaluation of the Density and Adhesion Strength of Powder Coatings Applied by the Electrocontact Method. Part 1. Coating Compaction. Strength Mater 55, 759–768 (2023). https://doi.org/10.1007/s11223-023-00566-9
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DOI: https://doi.org/10.1007/s11223-023-00566-9