Study On The Preparation And Anti-icing Properties Of Micro/Nano Structured Superhydrophobic Coatings On Cu Substrates

Wettability of solid surfaces is one of the most important properties and have been generatedby either coating low surface energy on surface or creating a rough topography on solid surfaces.Superhydrophobic surface with contact angles(CA) greater than150°，inspired by lotus effect,have attracted great interest in fundamental research over the past two decades. In this dissertation,here we report the simple chemical deposition approach to fabricate superhydrophobic thin filmswith hierarchical structure on Cu substrates. In addition, detailed micro/nano structurecharacterization and the related properties tests were also carried out. The main contents andresults are listed as following:Firstly, hierarchical superhydrophobic surfaces were prepared using a simple “two foil”method, which employed an interfacical reaction between an aluminum foil and a copper foil inthe ammonia solution. Such bayerite surfaces can be further modifed with stearic acid, leading tothe superhydrophobicity with a contact angle of165.14°and very low sliding angle.The influenceof the reaction time and ammonia concentration on the wettability has been investigated, indicatethat the system in3ml25%ammonia for a short duration of3h was sufficient to achieve thesuperhydrophobicity.Secondly, the Al2O3film can be prepared by the annealling process of Al(OH)3film at400℃for2h.The results from the scanning electron microscopy(SEM) observations indicatedthat the biomimic surfaces composed of Al2O3nanorods and hierarchical structures similar to thatof the lotus leaf. Both the X-ray diffraction(XRD) and Fourier transform IR(FT-IR) resultsdemonstrate that the surface microstrucutres aggregate with a chemical composition of Al2O3. Thewater contact angles of as-prepared film was158.47°. Further investigatigations have indicatedthat both the surface hierarchical morphology and the chemieal composition play an important rolein the superhydrophobicity.Thirdly, we report reliable chemical bath deposition method to fabricate ZnO thin film on theCu substrate. The ZnO thin film with nanorods structure could be prepared by adding NO3NH4. Inaddition, the six prism-like shaped grown on the surface were fabricated by addingC6H5Na3O7.2H2O. We find that different additivies is crucial for the formation of micro/nanostructures, which suggests the role of cooperative processes involving nucleation and particlegrowth for the formation of these structures. The water contact angles of the nanorods structureand six prism-like ZnO film were155.31°and151.87°, respectively. The self-cleaning property of the as-prepared ZnO was investigated.Fourthly, delay in freezing of static water pools on the as-prepared superhydrophobicsurfaces was investigated. We experimentally demonstrate that drop can be significant delayed infreezing, when depositing water on cold superhydrophobic surfaces.In general, the present study opens up simpel and economical wet chemical spproach for thefabrication of superhydrophobic surfaces with the micro/nano structures on engineering metallicmaterials.