Fabrication Of Bionic Lotus Leaf Surfaces And Study On Its Anti-icing Performance

The problem of icing on surfaces is one of the severe challenges in the fields of power,communication and transportation.Traditional deicing methods can not solve the problem of icing on surfaces fundamentally and effectively.In recent years,the solution of the problem has gradually changed from ‘deicing' to ‘anti-icing'.There has important scientific significance and practical application value to develop a surface that can reduce or even eliminate surface icing.Although some important progress has been made in the research of anti-icing surfaces at home and abroad,the effect of surface on ice formation and its mechanism are still unclear.On the basis of previous research,this paper starts from the idea of anti-icing on superhydrophobic surfaces,uses improved molding method to simulate the Lotus leaf's surface structure and its hydrophobic properties.The surfaces with different microstructure scales are prepared,and the freezing process of static droplets on the surfaces,behavior of droplets impacting on cryogenic surfaces and surface condensation and frosting process are studied,which clarify the effect of different microstructures on anti-icing and provide a basis for optimizing anti-icing surfaces.The results of this study mainly include the following aspects:(1)Biomimetic superhydrophobic surface(hierarchical structure)of lotus leaf was obtained on epoxy resin substrates by improved template method and zinc oxide hydrothermal growth method,it's contact angle and sliding angle were 151.5 degrees and 7.4 degrees respectively.This method can quickly and economically reproduce the surface microstructures of plant and animals.Meanwhile,the smooth surface,nanostructured surface and lotus leaf-like microstructure surface were obtained by the same method,which laid a material foundation for the follow-up study of the mechanism of surface icing.(2)For the anti-icing surface,the surface should have a stable hydrophobic property,which can make droplets roll off the surface in time at low temperature.During the cooling process of static droplet freezing experiment,it is proved that the surface with dense nanostructure can prevent droplets from entering the surface microstructure.Dense nanostructure is conducive to maintaining the hydrophobic property of the surface at low temperature.(3)The delay freezing time of droplets on the surface is not affected by the hydrophobicity of the surface,but by the surface roughness and surface chemical energy,which also determine the hydrophobicity of the surface.The hydrophobicity of the surface is not directly related to the delay freezing time of droplets on the surface.From the point of delayed freezing,if the surface chemical energy is the same,surfaces with the smooth structure or nanostructure are better for delayed freezing.In the design of anti-icing surface,the roughness of the surface should be reduced to increase the effect of delayed icing.(4)On the surface of superhydrophobic hierarchical structure,droplets are bounced up after impact.Until the surface temperature decreases to-30 ?,the surface starts occurrence with ice.The superhydrophobic surface with low adhesion force can effectively make the impact droplets bounce up and be discharged from the surface in time.(5)By observing the process of surface freezing and condensation,it is found that dense nanostructures can make condensation droplets coalesce and bounce off the surface,thus reducing icing.For the development of anti-icing surface,dense nanostructure surface can reduce the adhesion of condensate droplets on the surface,thus reducing icing.