Improvement of corrosion resistance in AZ31 magnesium alloys by immersion in NaOH solution saturated with CO2 gas

초록

Magnesium alloys have been regarded as promising materials among the commercially available metals due to its low density as well as excellent mechanical properties in the areas of automotive, mobile, and aerospace. However, there is a critical limitation in the use of magnesium alloy because of low corrosion resistance. An improvement of corrosion resistance is, therefore, essential by surface modification such as anodizing, conversion coating, electrochemical plating, electrolytic plasma oxidation, and etc. Especially, conversion coatings have been widely applied to magnesium alloys owing to low cost and simplicity in operation. In this study, immersing solution for the conversion coating on the surface of AZ31 was prepared by using 0.5 M NaOH solution saturated with CO2 gas. Immersing treatments were conducted with respect to immersion times at room temperature. Corrosion test was carried out to evaluate the enhancement of corrosion resistance using 5 wt. % NaCl solution and physical characterization was examined by scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS).