Exfoliation corrosion of Al-Li alloy 2090-T6 in EXCO solution: A study of electrochemical noise and electrochemical impedance spectroscopy

摘要

The initiation and propagation characteristics of the exfoliation corrosion (EC) of 2090-T6 Al-Li alloy in EXCO solution has been studied using electrochemistry impedance spectroscopy (EIS), electrochemical noise (EN), and optical microscope techniques. A four-stage evolution of localized corrosion from pitting to EC has been found on the surface of the alloy during immersion, and two equivalent circuit models were developed to fit the EIS data of the initiation and propagation stages of EC according to their corresponding physicochemical properties respectively. The results also show that the wavelet transform based on EN analysis can be used as a more efficient method than other traditional electrochemical techniques to evaluate EC property of this aluminum alloy and to identify different localized corrosion stages.