Preparation And Properties Of TiO₂ Superhydrophobic Coating On Mg Alloy Surface

Biomimetic superhydrophobic surface originates from the biomimetic principle of lotus leaf.Because of its unique self-cleaning method and anti-corrosion effect,it has broad prospects for development.It has become one of the hotspots of the research.Magnesium alloys is a kind of popular materials in many fields,such as mechanical manufacturing,biomedicine and aerospace,because of its excellent mechanical properties and low density.However,magnesium alloy is too active and easy to be corroded,which limits its further application.Substration the superhydrophobic film on the magnesium alloy can effectively isolate the corrosion medium and the base to solve this problem.In this paper,superhydrophobic surfaces of titanium dioxide were prepared by hydrothermal method,electrostatic self-assembly method and impregnation method on magnesium alloy substrates.The surface morphology and chemical composition of the samples were analyzed by means of scanning electron microscopy?SEM?,X-ray diffraction?XRD?and Fourier transform infrared spectroscopy?FT-IR?.The wettability,stability and corrosion resistance of the samples were analyzed by contact angle test,friction and wear test and electrochemical test.A superhydrophobic film containing titanium dioxide was prepared on AZ31magnesium alloy by a two-step method.The first layer of hydroxide film is formed by anodizing the pretreated magnesium alloy blank sample.Then the titanium dioxide is grown on the anodized layer by hydrothermal method.The micro-nanostructure of the surface is successfully constructed,and the contact angle reaches 159.6 degrees after modification and the sliding angle reaches 4.7 degrees.Anodic oxide film is more conducive to the growth of titanium dioxide.Compared with the blank magnesium alloy,the corrosion current of superhydrophobic surface is reduced by four orders of magnitude.The impedance values of superhydrophobic samples have also been greatly improved.The superhydrophobic film of titanium dioxide/PDDA was fabricated by electrostatic self-assembly method.The contact angle of friction reaches 156.6 degrees and the sliding angle reaches 4.5 degrees.The adhesion of the film reaches grade 3 of national standard.It has good self-cleaning and anti-icing properties and effectively protect the substrate.No corrosion occurrs after immersed in 3.5 wt%NaCl solution for 7 days.The superhydrophobic film can effectively improve the corrosion resistance of the magnesium alloy.The layered TiO₂ was prepared on the AZ31 Mg alloy by hydrothermal method and loaded wrinkled silicon dioxide?KCC-1?on the layer by dipping method.After modificated by stearic acid,the surface shows superhydrophobic.The anticorrosive effect of the superhydrophobic surface is studied by detecting the electrochemical impedance spectroscopy and polarization curves in 3.5 wt%NaCl solution for a week.Superhydrophobic surfaces also exhibited chemical stability,physical stability and UV tolerance.In addition,the TiO2 containing in the film have a certain photocatalytic decomposition performance of organic contaminants on the surface,combining the self-cleaning property,the surface shows excellent adaptability to the outdoor environment.