Bionic Design And Anti-icing Mechanism Of Superhydrophobic Surface On Aluminum Alloy Substrate

In the low temperature environment,the freezing of the solid surface has brought many losses and potential dangers to industrial production and social life,especially mechanical equipment and electronic devices working in extreme environments.Traditional de-icing methods such as mechanical de-icing,electrothermal de-icing,and chemical methods have low efficiency and high cost,and new de-icing technologies need to be developed.In recent years,researchers have proposed surface anti-icing coatings for surface anti-icing.It has the characteristics of simple preparation and easy promotion.In this study,inspired by the unique wettability of natural organisms,a macrostructured superhydrophobic and efficient anti-icing coating was proposed and constructed.The macroscopic structure can further reduce the solid-liquid contact area,so that the droplets on the solid surface delay icing to achieve anti-icing performance,and then combined with photothermal reaction to achieve de-icing performance.Aiming at the poor water impact resistance of superhydrophobic coatings,a preparation scheme of superhydrophobic coatings to solve this problem is further proposed.The surface morphology,wettability,self-cleaning,mechanical durability,chemical stability and anti-icing properties of the prepared superhydrophobic coatings were measured,and the related mechanisms between performance,structure and composition were revealed.The macrostructure of 7075 aluminum alloy was prepared by laser processing,and the superhydrophobic coating was sprayed on the laser processed and non-laser processed aluminum alloy to realize the macrostructure superhydrophobic coating.With epoxy resin as binder,polydimethylsiloxane as low surface energy material,multi-walled carbon nanotubes and nano-silica as fillers,anhydrous ethanol as diluent,a superhydrophobic coating with multi-walled carbon nanotubes wrapped by silica as mastoid structure was formed.The contact angle of the aluminum alloy superhydrophobic coating is 156.9°,and the contact angle of the superhydrophobic coating with macroscopic structure is 159.0°.Aluminum alloy superhydrophobic coating and macrostructure superhydrophobic coating have excellent properties in mechanical durability of sandpaper wear and quartz sand impact,and chemical stability of strong acid and alkali immersion.When simulated illumination is given at room temperature,the equilibrium temperature of the macrostructure superhydrophobic coating is 5 °C higher than that of the non-macrostructure superhydrophobic coating.At-15 °C,the anti-icing time of the macrostructure superhydrophobic coating is 574 s,which is about 4 times that of the aluminum alloy superhydrophobic coating.At-20 °C,the photothermal de-icing time of the macrostructure superhydrophobic coating is 122 s,which is about half of the photothermal de-icing time of the aluminum alloy superhydrophobic coating.It can be seen that the macrostructure superhydrophobic coating has better performance in delaying icing and photothermal deicing than the non-macrostructure superhydrophobic coating.The water impact resistance of superhydrophobic coating is a key problem restricting its development.A superhydrophobic coating with water impact resistance was constructed.A superhydrophobic coating with micro-nano hierarchical structure and low surface energy was prepared by spraying method.The coating has excellent self-cleaning,mechanical durability and chemical stability.Under the impact of low-speed water droplets,the droplets can rebound as a whole and leave the surface.When the high-speed water droplets impact,the droplets will break into small droplets.The coating can withstand 7.8 m/s water impact and has little effect on wettability.The delayed icing time of the superhydrophobic coating in the simulated environment at-15 °C is 132 s,which is significantly longer than that of the bare aluminum alloy substrate.In terms of ice adhesion,the shear strength of the superhydrophobic coating is lower than that of the aluminum alloy surface,which provides a research idea for mechanical de-icing in a specific environment.The prepared superhydrophobic coating has considerable potential for application in rainy areas.