| As an important material surface treatment technology,thermal spraying has the advantages of prominent economic benefits,flexible processing.Thermal spraying Zn-Al-Mg alloy coating method is a newly developed anticorrosive technology in the field of long life anti-corrosion for large steel constructions.Therefore,it is very important to study the preparation and corrosion resistance of Zn-Al-Mg coatings to create high performance coatings.Zn-Al-Mg,Zn-Al and Zn coating were prepared on 20 steel substance by supersonic arc spraying.SEM was used in analyzed the surface morphologies of the Zn-Al-Mg coatings,X-Ray diffraction were employed in examining the structure and phases of the coatings.Gray method was used to determine the porosity of the coating.Tensile test was carried out by universal tensile testing machine.Electrochemical experiments were employed to compare the corrosion resistance behaviors of the Zn-Al-Mg coating with the pure Zn coating and Zn-Al coating in 3.5wt% NaCl solution and simulated acid soil solution.On the basis of the electrochemical experiments,the paper had carried out immersion test to verify the corrosion resistance of Zn coatings,Zn-Al coatings and Zn-Al-Mg coatings.The results show that The Zn-Al-Mg coating is compact and well bonded with the substrate.The porosity of Zn-Al-Mg coatings is 3.8%,the bonding strength of the coating is 3.7Mpa,the thickness of the coating is 300?m.The spinel oxides in the the coating are useful for improving the corrosion resistance.The current density of Zn-Al-Mg coating is lower than Zn-Al coating and Zn coating.The electrochemical resistivity of Zn-Al-Mg coating is 2 times of the Zn coating.The spinel oxides exist in the coating.During corrosion,the corrosion block the pores on the surface of the coating and prevent the coating from corroding effectively.The self-sealing characteristic is beneficial to Zn-AL-Mg coating.The Zn-Al-Mg coating had higher corrosion resistance than the pure Zn coating and Zn-Al coating. |
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