Corrosion resistance improvement of magnesium alloy using nitrogen plasma ion implantation

Magnesium and its alloys are receiving more attention due to their low mass density as construction materials. However, their poor corrosion resistance has hampered their wide application in industries. In this work, we conduct plasma ion implantation on magnesium alloys. This technique possesses the capability of treating objects with irregular shape, and it is also a clean process. During plasma ion implantation, nitrogen plasmas were employed. After treatment, Rutherford backscattering spectrometry (RBS) was used to evaluate the elemental depth profiles, and N1s spectra along the depth were acquired by X-ray photoelectron spectroscopy (XPS). The film structural identification of phases was performed by X-ray diffractometry (XRD). The corrosion behavior of the samples was evaluated using immersion test and potentiodynamical polarization test. We have found that the processes can effectively improve corrosion resistance of magnesium alloys. However, the implantation parameters have to be chosen closely and the improvement of corrosion resistance is mostly dependent on implantation voltage and incident dose. The results have demonstrated that the corrosion potential can be improved by 200 mV and the corroded area of the samples properly treated is substantially reduced compared to that of untreated ones after immersion tests.