Fabrication Of Bionic Superhydrophobic Surface And Its Anti-icing Performance

Ice coating on the surface is a common phenomenon in nature,but the problem of which has brought a lot of inconvenience and even loss to industrial development and people's lives,especially machinery and equipment,power transmission equipment,and aerospace equipment,which need to work under extreme conditions.There are several limitations to traditional de-icing methods that have been proved to inhibit their applications over the past few years.It has become a good way to prevent ice frozen on the surface by covering the surfaces with ice-phobic materials.For this reason,the development of efficient anti-icing coatings has become a hot research topic.Inspired by the unique characteristics of the natural creatures,many ice-phobic materials have been developed that can remove ice from the surface by means of external forces such as wind,gravity and vibration.The super-hydrophobic coatings with the self-cleaning property have been proved to be able to effectively prevent the accumulation of snow,frost or ice on the surface,on which the ice adhesion strength is extremely low,helpful for ice-melting or de-icing.However,there are still some problems that need to be solved for the practical applications of super-hydrophobic anti-icing surfaces.For example,the anti-icing mechanism under low temperature conditions is not perfect,the surface mechanical strength and stability are insufficient,and the anti-icing performance is not stable enough under complex environmental conditions.Based on domestic and foreign researches,this paper explores the anti-icing mechanism of super-hydrophobic surfaces with the self-cleaning property under low-temperature conditions,as well as designs and develops new types of anti-icing surfaces.The main research results of this article include:(1)Based on the current research and development status of anti-icing performance detection equipment,the measurement indexes of anti-icing equipment are systematically summarized,and an integrated ice adhesion detection equipment is designed and constructed,which simplifies the test operation steps and improves the authenticity and accuracy of the data results,and has wide application prospects,suitable for promotion and use.(2)Inspired by the typical plants with super-hydrophobic characteristics,such as lotus leaves,a structured super-hydrophobic surface was prepared,the anti-icing performance of which was tested and analyzed.7075 aluminum alloy is used as the test substrate which is widely used in aircraft and ships.In this study,a superhydrophobic self-cleaning surface was successfully prepared after laser processing and stearic acid modification at room temperature for 1 hour.Surface morphology,chemical composition and wettability were characterized by SEM,XPS,Fourier transform infrared spectroscopy(FTIR)and contact angle measurement.The morphology of the structured sample includes round humps,square protrusions and mountain-like structures.The structured surface shows excellent superhydrophobicity,with a WCA of 166 ± 2 °.In addition,the self-established detection device was used to test the anti-icing performance of the as-prepared surface,and the freezing process of the cooling water was recorded.Moreover,a heat transfer model for the heat transfer process between the droplet and the structured surface was constructed,and the heat transfer behavior on the interface was analyzed.This study provides new ideas for analyzing the heat transfer process of superhydrophobic surfaces.(3)A bionic superhydrophobic surface with a micro-nano layered structure was successfully prepared on 7075 aluminum alloy with a contact angle of 164 ° and a sliding angle of 2 ° by a simple anodic oxidation method.By simulating the natural environment conditions,the anti-/de-icing performance of the as-prepared surfaces was tested,on which the dynamic process of supercooled water droplets with different pH values was analyzed.Based on the theory of energy loss between interfaces,the relationship between spreading diameter and the rebounding height of the droplet is constructed,which is of significance for the design and preparation of new super-wetting surfaces.(4)A non-fluorinated super-hydrophobic anti-/de-icing surface with a water contact angle of 155 ° and a sliding angle of 5 ° was prepared by laser processing and wet etching.The ice adhesion strength and ice shear strength of superhydrophobic surfaces and untreated aluminum alloy surfaces were tested by the self-developed surface ice adhesion detection equipment.Through the analysis of the ice adhesion strength of the superhydrophobic surface,it is found that the ice adhesion strength is positively related to the effective specific surface area of the ice-solid interface,while the ice shear strength depends on the contact form of the ice-solid interface.In addition,by constructing the thermodynamic relationship between the icing delay time and the frozen temperature,the heat loss efficiency of the surface with different wetting characteristics was calculated,and the reason for the icing delay performance of the superhydrophobic surface was quantitatively proved.Under low-temperature conditions,the air cushion on the super-hydrophobic surface can prevent secondary freezing of melted-water and potential surface contamination.(5)Through the combination of subtractive manufacturing and additive manufacturing,a new method of preparing staggered penetration surfaces is proposed.It was observed that during the collision and shrinkage of water droplets,the water droplets were split into multiple parts,which can significantly reduce the contact time before the water droplets freeze.By testing the anti-/de-icing performance of staggered wetted surfaces,it was found that the freezing delay time is positively related to the diameter of the super-hydrophilic regions and negatively related to the distance of adjacent hydrophilic regions.Moreover,the stress concentration at the edges between the super-hydrophilic regions results in a significant reduction in ice shear strength.In addition,particle ice,different from glaze ice and frost ice,was found on staggered wet surfaces in the actual environmental testing,because the smaller contact area with the substrate makes it easier to be removed.Through cyclic icing/melting and friction-wear tests,mechanical performance and durability of the as-prepared surface were tested.Therefore,this novel staggered wetting surface exhibits excellent anti-/de-icing performance and has potential application prospects.