INFLUENCE OF REPAINTING ON THE MECHANICAL PROPERTIES, SURFACE TOPOGRAPHY AND MICROSTRUCTURE OF POLYESTER POWDER COATINGS

摘要

The literature does not provide a systematic analysis of the effect of electrostatic powder coating repainting of structural and constructional aluminum elements on their technological parameters. It is industrial practice that worn or damaged coatings be repainted. It is crucial to determine the effect of electrostatic sprayed coatings repainting on their microstructure, roughness and mechanical properties. The aim of the work is to determinate the influence of repainting of powder deposited polyester coatings on their mechanical properties, roughness and microstructure.This study examined three different electrostatic spray epoxy coatings with matt, silk gloss and fine structure-matt finish. Test panels were prepared as single- and double-layer paint coatings on the aluminum alloy 6060 substrate. Hence, six test sets of coatings were deposited. Each set contained six samples. The microstructure of the cross section of coating was investigated by scanning electron microscopy (SEM) and light optical microscopy (metallographic and stereoscopy microscope). The chemical composition of coating was analyzed by the SEM-EDS method. The 2D surface roughness of single- and double-layer coatings and 3D surface topography maps were examined using a profile measurement gauge. The mechanical properties of coatings were measured by cupping, bending, impact, adhesion to substrate tests run according to standard procedures. As a result, the influence of repainting of polyester powder coatings on their properties was determined. The results demonstrate that repainting has no effect on the microstructure and coating adhesion to substrate as well as the bending test results and roughness of matt and silk gloss coatings. It has been found that repainting affects the results of impact and cupping tests as well as the roughness of samples with fine structure surface finish.