Research On Surface Texture And Hydrophobic Properties Of Electrochemical Composite Etching Assisted By Laser

Using femtosecond or picosecond lasers to fabricate microtextures on the surface of materials,and strengthening the surface hydrophobicity of materials to obtain superhydrophobic surfaces is one of the hot spots in the research of ultrafast laser processing technology in recent years.Because the surface has many excellent properties such as self-cleaning,corrosion resistance,drag reduction,oil-water separation and anti-icing,it has been widely used in new energy,microelectronics,medical and health,aerospace and other fields.In the laser etching process,the surface of the material sometimes affects the surface quality due to the recast layer,while in the laser-assisted electrochemical etching process,the laser interacts with the dielectric to enhance the etching characteristics and increase the reaction rate with almost no recasting layer is generated.In this paper,the picosecond laser etching method and picosecond laser-assisted electrochemical composite etching method were used to prepare micro-nano structures on the surface of 2024aluminum alloy to prepare superhydrophobic surfaces.The main research contents of the paper are as follows:1.The principle of laser etching and the principle of picosecond laser-assisted electrochemical composite etching are studied.The thermal-mechanical effect of laser on workpiece,the smoothing effect of electrochemical reaction on workpiece and the coupling effect of laser and electrolyte in the composite etching process were analyzed.2.The experimental platform of laser-assisted electrochemical composite etching was built,and introduced the components of laser etching system and laser-assisted electrochemical etching system.The experimental reagents,the cathode and anode materials of the composite etching system,the composition and proportion of the electrolyte were determined.3.Microtextures were prepared on the surface of 2024 aluminum alloy by laser etching.The effects of single pulse energy,laser repetition rate,scan times and scan speed on the surface microstructure morphology and surface contact angle were investigated.The regression model was established by the response surface method,and the analysis shows that the influence factors of each process parameter on the surface contact angle are ranked in descending order:single pulse energy,scanning times,laser repetition frequency,scanning speed;with the maximum surface contact angle as the goal,the optimized The combination of process parameters is:single pulse energy of 14μJ,scanning times of 7 times,scanning speed of 650 mm/s,and laser repetition frequency of 2.2×10~6Hz.Under this parameter combination,high-quality micro-scale structures with multi-scale scales can be obtained on the micro-textured surface,supplemented by stearic acid modification,and the surface contact angle can reach 150.3°.4.Microtextures were prepared on the surface of 2024 aluminum alloy by laser-assisted electrochemical composite etching.The effects of electrolyte concentration,single pulse energy,current,and laser scanning times on the surface microstructure,surface roughness and surface contact angle were investigated.The prediction model was established by the response surface method.The response surface showed that the interaction between the electrolyte concentration and the single pulse energy,the electrolyte concentration and the current,the single pulse energy and the number of scans on the surface roughness was significant;The interaction between concentration and current,single-pulse energy and current on surface contact angle is significant;the order of the influencing factors of each process parameter on the surface roughness is from large to small:single pulse energy,electrolyte concentration,number of scans,and current,and the order of influence factors on surface contact angle is from large to small:single pulse energy,Scan times,electrolyte concentration,current;the optimal process parameters with the largest surface contact angle are:electrolyte concentration 2.0 mol/L,single-pulse energy 20μJ,current 18 m A,and scan times 15 times.Under this combination of parameters,the microtextured surface forms a large number of uniform microscale structures with multi-scale scales,supplemented by stearic acid modification,the surface contact angle can reach a maximum of 157.7°,and the hydrophobic performance is excellent.The results show that,in contrast to the laser etching method,the superhydrophobic surface obtained by the composite etching method further improves the surface contact angle,the overall height of the multi-scale micro-scale structure on the micro-textured surface is lower,the number is more,the distribution is more denser and uniform,and almost no recast layer is produced,allowing air to enter more fully,further enhancing the surface hydrophobicity.