Preparation And Properties Of Anisotropic Wetting Surface By Combining Laser Ablation And Electrodeposition

Surface wetting is very common in nature,and various biological surfaces gradually produce wetting properties beneficial to themselves through evolution and species selection.Inspired by the wetting properties of biological surfaces,artificial functional wetting surfaces of these biological surfaces have been developed,such as anisotropic wetting surfaces and superhydrophobic surfaces.At present,anisotropic wetting surface and superhydrophobic surface can be realized on various materials by various processing methods,but the preparation of anisotropic wetting superhydrophobic surface mostly uses organic materials as substrates,while the preparation of metal surfaces with both anisotropic wetting and superhydrophobic properties is relatively less studied.In this paper,the process of preparing anisotropic wetting superhydrophobic surface by laser and electrodeposition is described in detail.Groove array structures and micro-nano structures are successively prepared on stainless steel surface,and the wettability of anisotropic surfaces at different processing stages and the corresponding droplet contact model are analyzed.The combined process of laser and electrodeposition proposed in this study includes laser ablation,degreasing and electrochemical deposition.Firstly,the groove array structures were fabricated on stainless steel surfaces by using the characteristic that laser ablation can rapidly fabricate micron structure on the metal surface.Then,in order to improve the bonding force between the electrodeposited coating and the substrate,degreasing treatment is used to remove the slag and oil stain on the groove array structure surfaces.Finally,the micro-nano structures were prepared on the groove array structure surfaces by using the characteristics that electrochemical deposition can process surfaces with different shapes and prepare micro-nano structures.The main research contents of this paper are as follows:(1)Combine the theoretical basis of surface wetting and the research status of anisotropic wetting and superhydrophobicity,analyze the construction of existing anisotropic wetting and superhydrophobic surfaces and according to the existing theoretical basis of wettability surface strategy,the design strategy of anisotropic wetting superhydrophobic is proposed,and finally a combined process of laser ablation and electrochemical deposition is proposed to prepare anisotropic wetting superhydrophobic metal surfaces.(2)According to the design strategy of anisotropic wetting surface,the anisotropic groove structure surfaces were prepared by picosecond laser ablation.Firstly,the orthogonal experiment was designed to preliminarily determine the influence weight of laser parameters on the morphology of groove structure.Then,the influence of picosecond laser parameters(scanning speed,scanning times and scanning interval)on anisotropic groove structure(periodic interval and depth)was studied by single factor variable test.The results show that when the laser power is 4.8 W and the scanning speed is 350 mm/s,the ordered groove array structure can be prepared,and the periodic interval and depth of the groove array structures can be controlled by controlling the scanning times and scanning speed.(3)By measuring the sliding angle and contact angle perpendicular and parallel to the groove direction,the wettability of anisotropic groove structures with different periodic intervals and depths was analyzed,and the influence of groove structures on anisotropic wettability was studied.According to the established droplet contact model,it is found that the larger the periodic interval of groove array is,the greater the anisotropy of contact angle is.And then the greater the difference of adhesion in two directions,and the greater the sliding anisotropy.(4)According to the design strategy of superhydrophobic surface,the controllable superhydrophobic surfaces were prepared by electrochemical deposition.Firstly,the influence of electrochemical deposition parameters(current density,deposition time and molar concentration of ethylenediamine hydrochloride)on micro-nano structures and wettability was studied by single factor variable method.Then the durability and corrosion resistance of micro-nano structures prepared by electrodeposition were studied.The results show that when the current density is 2.0 A/dm~2,the molar concentration of ethylenediamine hydrochloride is 0.3 mol/L and the electrodeposition time is 180 s,the densely distributed micro-nano papillary structure can be prepared,and the contact angle reaches the maximum value of 157.12°,and the prepared surface shows good durability and corrosion resistance.(5)According to the design strategy of anisotropic wetting superhydrophobic surface,the anisotropic wetting superhydrophobic surfaces were prepared by the combination process of picosecond laser ablation and electrochemical deposition,and its anisotropic wetting performance was studied.Based on the established droplet contact model,according to the anisotropy of contact angle and sliding angle,the effect of adhesion on sliding angle anisotropy can be neglected,and the groove array structure has a more obvious blocking effect on water droplets.In this paper,a new design strategy of anisotropic wetting superhydrophobic surface is proposed,and the groove array surfaces with micro-nano papillary structure were prepared by combined process.Finally,the influence of combined process on the surface morphology and anisotropic wetting performance was discussed.Its characteristics of both anisotropic wetting and superhydrophobic function provide a new idea and method for its application in the fields of microfluidic system,tissue engineering and surface water collection.