Application of operando ORP-EIS for the in-situ monitoring of acid anion incorporation during anodizing

Operando odd random phase electrochemical impedance spectroscopy (ORP-EIS) is applied to monitor the anodizing process of AA2024 in acidic media. The impedance data reveals the presence of inductive behavior during the process. We correlate this inductive behavior to the acid anion incorporation during anodizing using the surface charge approach. Moreover, the impact of anodizing parameters – including anodizing DC potential, electrolyte type and concentration – is studied on the inductive behavior, and consequently on the acid anion adsorption and incorporation. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is employed to support the operando ORP-EIS results. We conclude that operando ORP-EIS during anodizing can predict acid anion incorporation into the oxide layer.