Role of phase composition of PEO coatings on AA2024 for in-situ LDH growth

Abstract

Plasma electrolytic oxidation (PEO) is an environmentally friendly anodizing technique leading to the formation of a ceramic-like coatings under high-voltage discharges. Layered double hydroxides (LDHs) were grown directly on γ, αand amorphous Al 2 O 3 powders, respectively, in order to investigate the phase responsible for in-situ LDH growth on PEO coating. Furthermore, it is shown that LDH growth is limited by the high tortuosity of the PEO layer and the accessibility of Al(OH) 4- anions from the substrate covered with thin amorphous aluminum oxide, through the pores.