Study On Process And Mechanism Of Laser Cleaning Paint Coating

The original paint layer on the surface of the rail vehicle needs to be removed during the maintenance of rail vehicles.Traditional methods,such as mechanical grinding and sandblasting,will cause environmental pollution and other problems.Under the circumstances that our country's environmental protection requirements are getting higher,laser cleaning,as an emerging surface cleaning technology,has been more and more widely used in paint removal due to its high precision,high efficiency and environmental protection.However,the current research on the process and mechanism of laser cleaning paint is not enough,and the coating adhesion of substrate after laser cleaning also needs further research.In this paper,based on the three factors of laser power,laser repetition frequency,and cleaning speed,the single factor experiment and orthogonal experiment optimization of500 W pulsed laser cleaning paint are carried out,and the composition and generation mechanism of the paint removal product are studied.Subsequently,based on the three factors of laser power,laser line width and cleaning speed,the single factor experiment and orthogonal experiment optimization of 1000 W continuous laser cleaning paint were carried out,and the composition and generation mechanism of the paint removal product were studied.Finally,the surface roughness,corrosion resistance,coating and coating adhesion of the aluminum alloy substrate after repainting were tested,and compared with the traditional mechanical grinding method.The experimental results show that the laser repetition frequency has the greatest impact on the cleaning effect in the process of pulsed laser paint removal,and should be taken as a priority factor.The products of laser cleaning paint mainly have three morphologies:granular products,rod-shaped products and flake products.The generation mechanism of granular products and rod-shaped products is the ablation mechanism,and the generation mechanism of flake products is the vibration mechanism.In the continuous laser paint removal process,the laser power has the greatest impact on the cleaning effect and should be taken as a priority factor.The products of continuous laser cleaning paint mainly have two morphologies,granular product aggregates and flocculent product aggregates.Among them,the granular product is produced under the combined action of ablation mechanism and vibration mechanism,and the flocculent product is mainly produced by the ablation mechanism.In terms of paint removal quality and substrate performance,both laser cleaning and mechanical grinding can completely remove the paint layer on the surface of 5083 aluminum alloy.After laser cleaning,the oxygen content of the substrate surface is lower than that of mechanical grinding,and the surface roughness varies from small to small.The major order is pulsed laser cleaning,mechanical grinding,and continuous laser cleaning.After pulsed laser cleaning,the corrosion resistance of the aluminum alloy substrate increased by 96%.after continuous laser cleaning,the corrosion resistance of the aluminum alloy substrate increased by 23%.After pulsed laser cleaning,the coating adhesion of the substrate coating is increased by 22% compared with mechanical grinding.The performance of the aluminum alloy substrate after pulsed laser cleaning is better than continuous laser cleaning and mechanical grinding,which is the best laser cleaning method for paint coatings.