Preparation Of Superhydrophobic Surface And Analysis Of Its Anti-icing Performance On Aluminum Alloy Surface

Under the combined action of the micro-structure and chemical elements on the surface of biological samples,the surface of organisms has superhydrophobic properties.With the in-depth study of superhydrophobic surfaces,researchers have found that they can delay the surface icing of samples.Inspired by this,we successfully fabricated superhydrophobic surface with anti-icing performance by using bionics principle and high-speed WEDM method.In this process,we have mainly completed the following tasks:By comparing the contact angles and slide angles of the stationary droplets and contact time of moving droplets on the surfaces of four biological samples,including lotus leaf,reed leaf,clover leaf and canna leaf,lotus leaf and clover leaf were selected as biological samples on the superhydrophobic surface.Inspired by the bionic structure on the surface of clover sample,we prepared the rough surface on the surface of 7075 Al by double-discharge machining of the highspeed linear cutting machine.The surface prepared by this method has superhydrophobic and anti-icing properties without chemical treatment.In addition,in order to verify the durability of the anti-icing performance of the sample surface,friction and wear experiments were carried out on blank sample surface,chemically modified sample surface,and the surface prepared by double-discharge machining.The freezing time of droplets on the surface of the sample was 177 s and 157 s before and after the experiment,the freezing time of droplets on the blank sample surface was 110 s and 108 s before and after the experiment,and the freezing time of droplets on the surface of the chemically modified sample was 173 s and 130 s before and after the experiment,respectively.The anti-icing property of the superhydrophobic surface prepared by double-discharge machining can not only resist certain mechanical strength,but also keep the anti-icing property at room temperature for a long time.We have successfully prepared a superhydrophobic surface with durable anti-icing performance by using an environmentally friendly,efficient and inexpensive method.Inspired by the surface microstructure of lotus leaf,superhydrophobic surface was prepared by high speed linear cutting.The shapes of ice droplets on the surface of blank sample and lotus leaf bionic sample was spread and spherical,respectively.The surface of bionic sample had freezing delay function,and the freezing delay function increased with the increase of the volume of droplets.The adhesion strength of ice droplets on the surface of blank sample and the bionic sample of lotus leaf was 564±10KPa and 160±7KPa,respectively.The adhesion strength of the bionic sample could be reduced.Based on the VOF and the solidification-melting model,Fluent 15.0 was used to analyze the freezing process of droplets on the surfaces.The results showed that the variation of droplet freezing time with the surface temperature presented an exponential distribution.In addition,combined with the experimental and simulation methods,we analyzed the process of the moving droplets hitting the horizontal lowtemperature surface.Compared with the blank sample surface,the spreading diameter of the droplets on the bionic sample surfaces was smaller and the contact time was shorter.It was proved that the surface of the bionic sample had anti-icing property from two aspects of stationary droplet and moving droplet.Considering the practical application of bionic samples,we simulated the process of liquid droplets hitting 30°,45° and 60° sample surface based on the VOF model.The contact time of droplets on the surface of inclined samples was less than 10 ms,and the spreading diameter was smaller,which further strengthened the anti-icing performance of the sample surface.The superhydrophobic surface prepared based on the surface microstructure of lotus leaf has anti-icing property.In this paper,superhydrophobic surfaces with anti-icing properties were successfully prepared based on the microstructures of two biological samples,lotus leaf and clover.The preparation methods of the two biomimetic structures are simple and efficient,and the preparation methods are green and environmentally friendly without chemical treatment,so they have great potential for popularization and application.