AC-electrochemical cleaning versus AC-anodising of aluminium

AC-electrochemical cleaning and AC-anodising of rolled AA1050 in phosphoric acid have been investigated under constant AC-current conditions. Inductively coupled plasma optical emission spectrometry (ICP-OES) and potential response measurements demonstrate the transition from AC-anodising to AC-cleaning for different electrolyte concentrations and current densities. The mechanisms of the anodic and cathodic reactions reveal themselves in the respective potential responses. With TEM a thin non-porous oxide film of less than 10 nm is observed on the AC-cleaned substrate. AES depth profiling reveals the presence of remnant phosphorus from the electrolyte in the thin surface oxide layer.