Micro Re-entrant Sturcture Fabricated By Laser Etching And Electrochemical Deposition

A superamphiphobic surface refers to a surface with a contact angle larger than 150 °,which can simultaneously repel both water and oily liquids.The superhydrophobic surface only has a contact angle with water larger than 150 °,while the superoleophobic surface has a contact angle with water and oily liquids than 150 °.Superhydrophobic surface has broad application prospects in self-cleaning,anti-icing,corrosion resistance,etc.However,most superhydrophobic surfaces are easily contaminated by oily liquids and then lose use value.Compared with superhydrophobic surfaces,superoleophobic surfaces would be more promising in practical applications.At present,studies have shown that constructing re-entrant structure arrays with the characteristics of broad at upper part and narrow at lower part is an effective method to obtain a superoleophobic surface.However,the existing processing methods generally have disadvantages such as complicated process and high cost,and cannot be applied to common engineering metals.Therefore,this paper proposes to divide the re-entrant structure into two parts: the lower micro-pillar structures and the upper overhang structures,which are fabricated by a combination of laser etching and electrochemical deposition.The micro-pillar arrays were fabricated by nanosecond laser etching on copper plate,after low surface energy modification,the top overhang structures were constructed by liquid/gas interface shape regulated electrochemical deposition.At the same time,the effects of laser parameters on the size of the micro-pillar structure,the wetting properties of the micro-pillar structure,the distribution of the electric field between two electrodes during the electrochemical deposition process,and the influence of liquid/gas interface shape on the growth direction of the micro re-entrant structure,and the influence of the electrochemical deposition parameters on the size of the micro re-entrant structure and the influence of micro re-entrant structure size parameters on its wettability are also explored.The copper micro-pillar arrays obtained by nanosecond laser etching have a contact angle of 161 ° to water after after low surface energy modification.The height of the micro pillar increases with the increase of the power P of the laser,and gradually decreases with the increase of the speed v,frequency f,and line spacing d.The taper of the micro pillar remains basically the same.The simulation software COMSOL was used to analyze the electric field between the two electrodes during the electrochemical deposition process.The simulation results show that the electric field lines are concentrated along the edges during the electrochemical deposition process,and the current density at the edges is larger.In the initial stage of deposition,the overhang structure is deposited at a faster rate.As the deposition progressed,the diameter of the overhang structure grows lower.The local geometric angle of the overhang structure from upward 5 ° to 59 ° on the micro pillar top could be obtained by regulating the iquid/gas interface shape,and the overhang structure with different diameters could be obtained by controlling the deposition parameters.After low surface energy modification,the micro re-entrant structure has a contact angle of 160 ° for water and 158 ° for peanut oil.Even when the diameter of the overhang structure is 70 ?m,and the center distance is 240 ?m,the structure is still superoleophobic.Further reducing the diameter of the overhang structure and increasing the array center distance are not conducive to its superoleophobicity.