An investigation of the coating/substrate interface of plasma electrolytic oxidation coated aluminum

Plasma electrolytic oxidation (PEO) coatings were fabricated on AA1060 commercial pure aluminum and detached from the substrate by an electrochemical method. The front view and fracture cross-section morphologies of the coating/substrate (C/S) interface were observed by scanning electron microscopy (SEM). The results show that the C/S interface layer consists of inter-connected tiny globular particles. During the PEO process, the thickness of the C/S interface layer and the diameter of the inter-connected tiny globular particles maintain approximately constant values of ~ 1 μm and ~ 0.7 μm, respectively. Based on the results, a C/S interface discharge mechanism is proposed and discussed.