Cailiao Baohu (Aug 2022)
Effect of Chemical Conversion Treatment by Adding Rare Earth Oxide in Ultrasonic Environment on the Corrosion Resistance of AZ31 Magnesium Alloy
Abstract
In order to improve the corrosion resistance of AZ31 magnesium alloy, a chemical conversion coating was prepared on the surface of AZ31 magnesium alloy by adding an appropriate amount of rare earth oxide (ie, cerium oxide and lanthanum oxide respectively) in an ultrasonic environment. Through the hydrogen evolution experiment, it was found that the AZ31 magnesium alloy chemical conversion coating sample added with cerium oxide had the lowest hydrogen evolution, indicating that its corrosion resistance was optimal. Through the corrosion morphology observation by SEM, it was found that the surface of the chemical conversion coating sample added with cerium oxide was relatively smooth and flat after immersion, indicating that this coating could protect the magnesium alloy substrate well. From the results of polarization curve experiment, it was found that the corrosion potential of the conversion coating sample added with cerium oxide moved positively in comparison with the original magnesium alloy, and its corrosion current density was lower than that of the original alloy. Therefore, the corrosion resistance of AZ31 magnesium alloy could be improved by the chemical conversion coating formed by adding cerium oxide under ultrasonic environment.
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