Investigation of paint removal by atmospheric pressure plasma jet

Acrylic polyurethane paint on the surface of 2A12 Al alloy was cleaned utilizing an atmospheric pressure plasma jet in this work. The dynamic evolution of the paint removal process during plasma treatment with time was explored through analysis of morphology and chemical states. The results showed that although the thickness of paint could be reduced effectively with an increase in cleaning time, the removal rate of paint gradually decreased with time. During the initial cleaning process range, its original smooth morphology of paint turned rugged quickly and was almost unchanged with further plasma treatment. Element and chemical state analysis showed that the content of C in the paint layer decreased obviously after plasma treatment. In contrast, the O content increased remarkably. The cleaning mechanism could be mainly attributed to the reaction between active O-containing species in air plasma and organic components in the paint. After removal of superficial organic matter, residue inorganic metal oxide substances aggregated on the base. The exposed metal oxides on the one hand elevated the superficial O content, but on the other hand hindered further plasma penetration, resulting in a gradual decrease in cleaning rate with cleaning time. Therefore, physical wiping was proposed to be incorporated with the plasma method and effective removal of paint was realized.