Preparation Methods And Wetting Properties Of Biomimetic Superhydrophobic Copper Surfaces

In nature,many animals and plants exhibit superhydrophobicity,the most common of which are lotus leaves that are “come out of the dirty mud unsoiled”,rice leaves that condense dew into beads,and butterfly wings that do not wet,and so on.Researchers apply this special wetting property to aspects such as self-cleaning,oil-water separation,frost protection,and corrosion resistance through bionic technology.This article imitates the microstructure of rice leaves and lotus leaf to prepare a superhydrophobic surface.The selected material is copper metal.Due to its excellent electrical and thermal conductivity,corrosion resistance and other excellent properties,copper is widely used in semiconductors,construction and other industrial production,and has broad development and application prospects.Therefore,it is significant and valuable to study the properties of copper surface.At present,there are many methods for preparing superhydrophobic surfaces,such as electrochemical deposition method,template method,sol-gel method,etc.In many methods,basically,a certain roughness is first formed on the surface of the material,and then the material is modified with low surface energy.Modifications,especially for the construction of superhydrophobic surfaces on the surface of metallic materials,due to their higher surface energy and the need for surface treatment with the aid of external modifiers,few people can construct superhydrophobic surfaces directly on metallic surfaces.The method we introduced can directly prepare the copper-based superhydrophobic surface without modification.Therefore,our methods have more theoretical value.The microscopic morphology was observed by a scanning electron microscope,and the structure and composition were examined by X-ray diffractometer and X-ray photoelectron spectroscopy,and the contact angle was measured by an optical contact angle measuring instrument.The effects of the static and dynamic wetting behavior of the superhydrophobic surface,the laser processing parameters and the heat treatment time on the wettability,and the practical application performance of the superhydrophobic surface were investigated.The main work and conclusions are as follows:1)A superhydrophobic surface of directional rice-like structure was prepared by mechanical texturing combined with brush plating and the contact angle of superhydrophobic surface was as high as 157.3°.In the direction of parallel grooves and in the direction of vertical grooves,both the static contact angle and the dynamic contact angle have anisotropy.After brush plating,samples I and II were annealed at 120°C and 180°C for low temperature.samples III and IV were stored at room temperature for 4 months.After testing,all samples had superhydrophobic properties.Therefore,we conclude that heat treatment can effectively shorten the time for preparing superhydrophobic samples.2)In order to further improve the sample preparation rate,laser texturing was used to replace mechanical texturing for forming the rough structure.The surface morphology analysis showed that the sample we prepared had a three-level hierarchical structure lotus-leaf-like.And the contact angle of the sample surface as high as 158.1° and a roll angle as low as 5.6°,which has a typical self-cleaning effect.In addition,the contact angle hysteresis of each sample was also detected by the method of water drop horizontal moving.It was found that as the texturing step size increased,the contact angle hysteresis increased.3)This article also explored the method of preparing superhydrophobic samples directly by laser texturing,and explored the effects of laser texturing parameters on surface morphology,texturing parameters and heat treatment time on superhydrophobic properties.The surface morphology analysis shows that the texturing parameters can control the pattern of the sample surface and the depth of the trench.The best texturing step size is 50 μm and the best texturing rate is 100 mm/s.The best heat treatment time is 4 hours at 130℃.4)Finally,the application performance of superhydrophobic surface was studied.The phenomenon and mechanism of self-cleaning on superhydrophobic surface were analyzed.The melting properties of ice and snow at room temperature,anti-icing performance and corrosion resistance at low temperature were tested.The results of above tests showed that the samples we prepared have excellent self-cleaning,anti-icing and corrosion-resistant application properties.