Surface modification of magnesium alloy AZ31 for the enhanced corrosion behavior

초록

Magnesium alloys, which has the low density and high mechanical strength, is attractive for a wide variety of practical applications, especially in the electronic devices. Despites these advantages of the magnesium, low anti-corrosion prevents it from commercialization. Magnesium and its alloys tend to be oxidized easily in the air and aqueous atmosphere. To solve the corrosion of magnesium, the formation of thick and stable passive films are important factors [1, 2, 3]. In this study, AZ31 samples were treated by electro-degreasing, immersing and aging method to remove organic compounds on surface of alloys and to make passivation films, which has effect on corrosion resistance of AZ31. To measure corrosion resistance of treated samples, salt spray test (SST) was employed under blowing of 5wt% NaCl solution. The surface morphology of AZ31 samples was examined by the scanning electron microscopy (SEM). X-ray photoelectron spectroscopy was utilized to characterize the composition of films formed by different treatments. From XPS data, it was confirmed that the films consist of magnesium oxide (MgO), hydroxide (Mg(OH)2), and MgCO3. As a result, aging treatment was very effective, showing the highest best corrosion resistance due to formation of stable passive films.