Study Onantiicingfrom Micro-nano Structuresurfaceinducedbyfemtosecondlaser

Solid surface icing is aserious problem in the field of power grid maintenance,wind power generation and aviation.Solid surface icing wouldcause huge economic losses and bring danger to personal safety,if that problem was not effectively solved.Recently,a new anti-icing method has been put forward.The micro-nano structure surface which has wetting function can effectively inhibit surface icing,and it is expected to solve the problem of surface anti-icing.Femtosecond laser scanning can directly prepare various micro and nano structures on the surface of metal,resulting in the formation of hydrophilic or hydrophobic wetting function on the surface.Therefore,based on the application requirements ofa metal materials,two kinds of typical metal materials(copper and nickel)were selected,and microsecond laser was used to prepare the micro-nano structure on the surface of the metal.The surface of the micro-nano structure was wetted and anti-icing.In the study of metal copper,the micro-nano structure was prepared directly on the copper surface by femtosecond laser.Under the condition of without any chemical modification,the spontaneous transformation from the hydrophilic to hydrophobic properties of the surface of the micro-nano structure was realized only by exposing the sample in the air,and it was found that the micro-nano dual scale surface structure was more favorable for the formation of good hydrophobicity.In the low temperature freezing delay experiment,the time forice formation on the surface of the hydrophobic micro-nano structure is obviously extended compared with the original surface,and the delay of freezing can be increased by 1 fold at the optimized condition.Moreover,the delayed effect of micro-nano structure surface freezing is related to its surface hydrophobicity at low temperature.The greater the contact angle is,the better the effect of icing delay.Further,the physical mechanism of retarding droplet freezing is analyzed by classical nucleation theory.In the aspect of metal nickel research,femtosecond laser was used to prepare micro-nano structure on pure nickel(6N)surface.The wetting property of the surface is found to be different from that of the copper micro-nano structure,and the hydrophilic property is not changed to the hydrophobic wettability in the process of air placement.The surface of the micro-nano structure was transformed into hydrophobicity by silanization,and the hydrophilic(directly processed by the femtosecond laser)and the hydrophobic function(after silanization)were systematically studied.It is found that the surface with micro-nano composite structure has a more significant delay time for ice-formation than that of the single submicron structure.The physical process of dynamic droplet icing is further studied through the dynamic characteristics of the interaction between droplet and surface.The result is shown that the surface of the hydrophobic micro-nano structure has an effective freezing delay compared with the original surface,and the surface temperature and the drop height of the liquid affect the freezing process of the surface to the droplet.