| Poor corrosion resistance has become the Achilles heel of magnesium alloy,this curse of magnesium seriously restricts the wide spread application.Therefore,it is of great significance to study novel and effective method to improve the corrosion resistance of magnesium alloy.The superhydrophobic surface has excellent water repellence due to its special wettability.The construction of a superhydrophobic layer on the surface of the substrate can greatly enhance the corrosion resistance of the substrate.In this paper,a novel nontoxic one step hydrothermal method,one step electrodeposition method and electrochemical preparation of superhydrophobic powder method are used to fabricate superhydrophobic layer on the surface of magnesium alloy,to improve the corrosion resistance of magnesium alloys and to promote the application of magnesium alloys.The wettability,composition,morphology and electrochemical corrosion resistance of the prepared coatings were characterized using contact angle tester,scanning electron microscope,Fourier transform infrared spectrometer,X-ray photoelectron spectrometer and electrochemical workstation.A one-step hydrothermal method was used to construct a hydrophobic coating on the surface of magnesium alloy,which simplifies the traditional two-step construction method.Pure water,ethanol and stearic acid were used as reactants in the experiment,and the fluorosilanes commonly used in traditional methods were discarded.Three groups of different hydrothermal reaction durations were designed to explore the effect of time on the hydrophobic layer.The three hydrophobic coating samples had similar surface topography.The contact angles were 145.6°,147.9°,and 146.8°,respectively,which were close to the superhydrophobic state.Compared with the original AZ31 magnesium alloy substrate,the corrosion resistance of the three coating samples has been greatly improved.With the extension of one-step hydrothermal treatment time,the thickness of the hydrophobic coating increases,and the corrosion resistance of the coating increases.Hydrophobic coatings exhibit superior performance compared to conventional coatings of the same thickness.A one-step electrodeposition method was used to construct a superhydrophobic coating on the surface of magnesium alloy.Using magnesium nitrate and ethanol solution of stearic acid as electrolyte,four groups of electrolytes with different ratios of stearic acid and magnesium nitrate were designed to explore the influence of electrolyte to the process.The contact angles of the four coating samples were 136.4?,152.7?,156.2?and 155.1?.The addition of magnesium nitrate in the solution increased the hydrogen evolution reaction in the electrodeposition process,which was not conducive to electrodeposition process.During the deposition process,the sample prepared in a molar ratio of stearic acid to magnesium nitrate of 10:1 had the best corrosion resistance,and its corrosion circuit density was 3.74?10-8 A/cm2,far lower than the corrosion current density of the magnesium alloy substrate.Inspired by the worst-performance electrolyte group in the one-step electrodeposition experiment,the same experimental device was used to prepare the superhydrophobic powder using this group of electrolyte,and the conductivity was increased by using a copper mesh to increase the efficiency of the preparation.The use of commercial binders to assist the application of powder samples to the surface of magnesium alloys has successfully improved the corrosion resistance of magnesium alloy substrates. |
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