Effect of the nitrogen inducing agents on the corrosion behavior of the oxide coatings prepared by electrolytic plasma processing on the Al2021 alloy

Abstract

The AlON–Al 2O 3 oxide coatings were prepared on the Al2021 alloy by the electrolytic plasma processing (EPP) method at room temperature in 15 min under a hybrid voltage with various nitrogen inducing agents. The nitrogen inducing effects were studied by X-ray diffractometer (XRD), scanning electron microscopy (SEM). The corrosion behavior was evaluated by electrochemical tests in a 3.5 wt% NaCl solution under static conditions by open circuit potential and potentiodynamic polarization. The results show that NaNO 2 is a suitable steady nitrogen inducing agent to prepare a uniform and dense AlON–Al 2O 3 coating on the Al2021 alloy to protect the substrate corrosion.