Study on surface modification and corrosion resistance of magnesium alloy for automobile
Four modified coatings(excluding organic modified silicate coatings and organic modified silicate coatings)were prepared on the surface of magnesium alloy for automotive using spin coating method.The microstructure of the modified coatings and their corrosion resistance after immersion in 3.5%NaCl solution for different times were compared and analyzed.The results showed that the corro-sion potential of the coating A sample before immersion and the coating sample soaked for 1-9 days both shifted in a positive direction compared to the magnesium alloy matrix,resulting in a significant decrease in corrosion current density.The corrosion resistance of coating A was significantly better than that of the magnesium alloy matrix;The corrosion potential of the four modified coatings shows a positive shift compared to the magnesium alloy substrate,and the corrosion potential of organic modi-fied silicate coatings(coating B,coating C,and coating D)is corrected compared to coating A.The corrosion current density is smaller than that of coating A.The order of corrosion current density from low to high is:coating C<coating D<coating B<coating A<substrate.As the soaking time prolongs,the corrosion current density of the four modified coatings increases.However,under the same soaking time,the corrosion tendency of coating B and coating C is smaller than that of coating A,and the corro-sion rate is slower than that of coating A.Moreover,coating C(KH-570/BTMSE=3/2)has the best corrosion resistance.
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