The Self-clean Aluminum Surface With Excellent Durability And Corrosion Resistance

There are many instances of superhydrophobic surfaces in nature, such as the legs ofwater spiders, lotus leaf, wings of butterflies and so on. Inspired by nature, scientistsattempt to make artificial superhydrophobic materials. As a new kind of functional surfaces,superhydrophobic materials can be applied into a wide range of fields including thefabrication of self-clean windows, anti-freezing materials and anti-corrosive coats,transporting fuels, microfluidics and the automobile industry.However, low durability, fragility and complex technics limit the industrial producingof superhydrophobic surfaces. So our research focus on developing facile and low cost wayof preparing superhydrophobic surface. Moreover, we discuss its properties of application.At first, we achieve alumina with hierarchical structures which consist of micro stairsand nanopore arrays by way of treating the aluminum plate in the sulfate solution at lowvoltage for long time and anodizing in oxalic acid at high voltage. Then we use fluorinatingagent to modify the rough alumina surface which we have treated before to gain superhydr-ophobic surface. What is more, the contact angle of superhydrophobic surface is170.9°and the sliding angle is1°respectively.Then we take a series of experiments to examine our superhydrophobic sample, theresults show that it has many outstanding properties.(1) The sand which covers thesuperhydrophobic alumina surface can be collected by water droplets and then will slide offwith them, therefore the sample has self-clean performance.(2) After impacted by sand for20minutes and rubbed by rough polypropylene fabric whose length is400cm, the samplestill maintain good performances because of that the alumina’s surface on aluminumsubstrate could increase the sample’s mechanical stability apparently.(3) The result ofthree-electrode system test shows that the superhydrophobic alumina surface has the bestanti-corrosive function because of that the air cushion which store in the pores of the rough alumina surface decrease the reaction between the work electrode and electrolyte solution.(4) With the increasing of the pressure by way of changing the sizes of different droplets onthe surface of superhydrophobic alumina film, the drops can keep stable Cassie condition,so our sample is able to resist compression.(5) In the examination of freeze, the superhy-drophobic alumina surface also shows excellent anti-freezing property even though thetemperature of outdoor is low to-20℃. We discover that there is no ice on the surface ofsuperhydrophobic alumina, and this is opposite to the aluminum plate and superhydro-philic surface. What is more, the snow and ice will agglomerate into a whole droplet aftermelting and slide off the sample’s surface quickly.At last, we prepare a type of material through pouring one kind of perfluorinated fluid(a type of particular lubricant oil) into the nanopores of superhydrophobic alumina’s roughsurface. A wide types of liquids can’t wet the lubricant-infused hydrophobic surface, suchas vegetable oil, glycerol, alcohol and so on. The self-healing function is worth mentioning,it can repossess hydrophobicity and oleophobicity with the help of capillary action evenafter that we destroy the micro structure of its surface.