Single Dense Layer of PEO Coating on Aluminum Fabricated by “Chain-like” Discharges

Reducing the loose-layer-to-dense-layer ratio in PEO coatings on aluminum and its alloys is the key to improving their corrosion resistance and expanding their applications in the aerospace industry and other fields. In this paper, we describe the discharge evolution during the PEO process in exhaustive detail and report the appearance of a novel "chain-like" discharge for the first time. We investigated the microstructure and composition of PEO coatings using a scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The results reflected that the coating composition changed from amorphous Al