| Magnesium alloys are produced in large quantities and have many excellent properties,such as light weight,low density,high specific strength and excellent biocompatibility.At present,it is widely used in all walks of life.However,the active and easily corroded properties of the alloy greatly limit its application and development in production and life.Therefore,surface treatment technology can enhance the corrosion resistance.In this paper,dual-component silane coatings,silane/GO composite coatings and textured silane/GO composite coatings were successively prepared on the surface of AZ31B magnesium alloy.The surface morphology,composition and wettability of the as-prepared samples were observed by a scanning electron microscopy,energy-dispersive spectrometry,Three-dimensional profiler,X-ray photoelectron spectroscopy,fourier transform infrared spectrometer,Raman spectroscopy and optical contact angle measuring instrument.The electrochemical propertie was tested by an electrochemical workstation.The research results are as follows:(1)Dual-component silane films composed of trimethoxy and bis[3-(triethoxysilicon)propyl]-tetrasulfide(BTESPT)were prepared on the surface of Mg alloy by self-assembly method.The influence of alkyl chain length of films was investigated by selecting trimethoxysilane with different alkyl chain length.The corrosion resistance of different samples was analyzed and a dual-component silane film with the best corrosion resistance was proposed.The results presented that when the molar ratio of BTESPT to octadecyltrimethoxy silane(OTMS)was 1:2,the corrosion resistance of dual-component silane was the best,which was better than that of single silane component silane film and other dual-component silanes.This was because OTMS silanes with the largest chain length had high density CH2,and BTESPT silanes have-S-S-S-S-chains,which greatly improved the hydrophobicity.Meanwhile,there were also a large number of siloxane networks in the silane films.Therefore,BTESPT/OTMS dual-component silane film could protected Mg alloy.(2)On the basis of the previous research,combined with self-assembly technology and spin coating method,APS-GO/BTESPT/OTMS composite coating was prepared on the surface of Mg alloy,BTESPT and OTMS hybrid GO to further improve the corrosion resistance of the coating.The prepared composite coating Mg-APS-GO/BTESPT/OTMS showed the best hydrophobicity and corrosion resistance.The Ecorr of the composite coating was-0.739 V,713 m V more than that of the Mg alloy substrate.icorr was 6.682×10-7 A·cm-2,which was reduced by nearly 3 orders of magnitude compared with the mg alloy matrix,and the corrosion rate Pi was 0.01526837.The-S-S-S-S-chain in the outer layer of BTESPT/OTMS dual-component silane and the high density CH2 improved the hydrophobicity of the coating,thus avoiding a large amount of water adsorption on the surface of the coating.The surface hydrophobicity,silane and GO barrier effect delayed the penetration of corrosive media,and enhanced the corrosion resistance of Mg alloy.(3)On the basis of the previous research,combined with laser etching method,the texture silane/GO composite coating was successfully prepared on the surface of Mg alloy.The surface texture of the Mg alloy improved the surface roughness of the substrate,molded the woven structure,and enhanced the adhesion to the composite coating.When the laser-etched groove spacing was 0.05mm and the substrate surface texture was meshed,the textured silane/GO composite coating prepared had the best hydrophobicity and corrosion resistance.The water contact Angle was 140°,the self-corrosion potential was-0.41V,and the self-corrosion current density was 9.189×10-8A·cm-2. |
PDF Full Text Request