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Superhydrophobic Coating Prepared And Study On Corrosion Resistance Of AZ31Magnesium Alloy

Posted on:2014-05-09Degree:MasterType:Thesis
Country:ChinaCandidate:J SunFull Text:PDF
GTID:2251330422950814Subject:Physical chemistry
Abstract/Summary:PDF Full Text Request
In the past few decades, magnesium alloy is widely used in different fields,especially in automotive and aerospace industry. The application of magnesium alloycan help save fuel and increase carrying capacity. However, the application has beenseverely restricted by the low corrosion resistance of magnesium alloy. By comparingthe domestic and international research status, this paper is about the preparation ofsuper hydrophobic coating on AZ31magnesium alloy by anodic oxidation method andchemical composite plating method so as to improve the corrosion resistance ofmagnesium alloy. In the process of the anodic oxidation, with NaBr as electrolyte, thesurface of AZ31magnesium alloy oxidizes to a rough structure which is to bechemically modified by organics with low surface energy. The successful preparation ofsuper hydrophobic coating on AZ31magnesium alloy improves the corrosion resistanceof magnesium alloy. In the process of chemical composite plating, NanoTiO2isdeposited on the surface of chemical plating Ni+P alloy. After chemical modification,the preparation of the super hydrophobic coating on AZ31magnesium alloy iscompletely successful, which also improves the corrosion resistance of AZ31magnesium alloy.By X-ray diffraction (XRD), scanning electron microscopy (SEM), Fouriertransform infrared spectrometry (FTIR), energy spectrum (EDS), electrochemicalworkstation (CHI), optical contact angle tester and other testing means, the structure,morphology, composition, corrosion resistance, contact angle and other functions of thesample surface can be tested and analyzed.Research shows that: when NaBr is used as the electrolyte, the optimalconcentration of0.2mol/L, the current density of250mA/cm2, distance between thepoles of20mm, fixed in t=12min, the mass fraction of ethanol solution of FAS of1wt%,the heating time of15min, the heating temperature is120℃, the maximum contactangle of the prepared super-hydrophobic coating is155.5°, and the rolling angle is lessthan10°.The optimum system in the process of chemical composite plating is asfollowed: nickel sulfate concentration of18g/L, sodium hypophosphite of24g/L, mixedwith Nano TiO2optimal concentration of4g/L and the optimum concentration of TiO2incorporation into4g/L. The best contact angle of the prepared super-hydrophobiccoating is160.8°, and the rolling angle is less than5°.In order to further increase the super hydrophobic property and corrosionresistance performance on the surface of the magnesium alloy, this experiment studiesthe effect on the contact angle and the corrosion resistance by doping NanoTiO2.The results show that: NanoTiO2concentration has a great effect on the properties of thecoating.TiO2can change the microstructure of the chemical plating Ni+P alloy, andmake the composite coating modified by low surface energy material process superhydrophobic performance.
Keywords/Search Tags:AZ31magnesium alloy, superhydrophobic coating, anodic oxidationmethod, chemical composite coating, NanoTiO2
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