Atmospheric air plasma jet for improvement of paint adhesion to aluminium surface in industrial applications

Abstract Improvement of paint adhesion to aluminium surfaces is one of the main challenges in many industrial applications. In this paper, we introduce the atmospheric pressure air plasma jet as an appropriate candidate for preparation of 5052 aluminium surface alloy to improve paint adhesion in the industrial level. The employed plasma jet can promote paint adhesion to aluminium surface at the treatment velocity of 2m/min and plasma size of 10mm. Based on the cross-cut test, adhesion of polyurethane paint to the surface greatly increases from 1B to 5B level due to the plasma treatment. According to the results, the surface wettability increases under the influence of the plasma treatment so that water droplet contact angle reduces from 79.0°±2.0° to 27.5°±2.0° after the treatment. Dyne test ink also denotes the increment of surface energy to the greater than 72 mN/m. Besides, we employ various analytical methods to investigate the physical and chemical changes arise from the plasma processing to the surface. Atomic force microscopy (AFM) results show a twofold increase in the roughness parameters of plasma treated surface which can result in a stronger paint and surface interlocking. Chemical analysis of the surface reveals that plasma treatment of the aluminium surface leads to the surface cleaning and formation of hydrophilic functional groups that attract much more water towards the surface and improves the paint adhesion.