Preparation And Reseaches Of Superhydrophobic Surfaces On The Iron Substrate

Wettability is one of the very important property to determine the qualitiy of solid surfaces. Because of the large application of superhydrophobic surface, the research has attracted great attentions. Steel is a common kind of material that is extensively used in many areas owing to its particular properties such as good mechanical properties, perfect electrical conductivity and so on. Practically, the only factor which limits the lifetime of steel is corrosion which disables its excellent properties. To solve these problems, we herein fabricated Fe-Zn-ZnO and Fe-Sn superhydrophobic surfaces by electrochemical machinining and followed by subsequent thermal annealing withoout introducing any low surface energy organics. And the formation mechanism, the principle and application of superhydrophobic surfaces were also analysed.(1) We firstly fabricated micro/nano Fe-Zn-ZnO superhydrophobic surfaces by electrochemical machinining and followed by subsequent thermal annealing. These surfaces display water contact angles(WCA) larger than 150° and sliding angles(SA) less than 10°. The instruments and equipments used in this method were in common, the preparations were of low cost, the experimental procedures were quick and effective, which broke the traditional preparation methods for superhydrophobic surfaces. And by annealing in the drying oven, we did not introduce any organic matters. Through analyzing superhydrophobic surfaces, the surface chemical compositions and formation mechanism were studied. A series of influencing factors should be considered to prepare optimized superhydrophobic surfaces. These include annealing conditions, the concentration of zinc ion(CZI), electrochemical deposition time and etching time. The annealing treatment leads to the most critical factor. After electrochemical depositionon, the surfaces showed superhydrophilic state, however after annealing, they presented superhydrophobic state,The presence or not of filter papers in the process of annealing has crucial influence, and only add filter papers can ensure the formation of superhydrophobic surface. Based on the XPS, XRD and SEM results, it can be concluded that after annealing, the grown Zn micro/nano-particles were well crystallized, the remaining 95.3 % served as the contactarea of the water droplet and air,which can reduce the surface energy and improve the superhydrophobicity. Then the principle and the growth mechanism of Fe-Zn-ZnO micro-nano superhydrophobic were studied. The durability of the SHSs and the freezing properties of water droplets on sample surfaces were also done to show the superhydrophobic surfaces have good environmental stability in the atmosphere. Through the corrosion test, they showed good corrosion resistance.(2) We firstly fabricated micro-nano Fe-Sn superhydrophobic surfaces by electrochemical machinining and followed by subsequent thermal annealing. We analyzed the wettability, the morphology and the chemical composition of superhydrophobic surfaces.Through the single factor experiments, the Fe-Sn superhydrophobic surfaces were the result of comprehensive effects of etching time, electrochemical deposition, electrolyte concentration, annealing temperature and annealing time. The best conditions for its preparation were considered. The experiment proved that the superhydrophobic surfaces in the atmosphere had good environmental stability and soil corrosion resistance. Annealing has played a very key role in the process of building superhydrophobic surfaces on the metal substrates, which provides a train of thought for large applications of superhydrophobic surfaces in industry and agriculture.