A New Understanding of the Dielectric Breakdown Theory from the Study of Plasma Electrolytic Oxidation of Carbon Steel

Schematic illustration of the PEO of the carbon steel in 8 g·L^-1 NaAlO2+2 g·L^-1 NaH 2PO4:(a)the sample before the application of anodic current,(b)the moment after the application of anodic current,(c)the deposition of an aluminum phosphates or AAP layer on the steel surface,(d)the initiation of plasma discharges through the breakdown of the dielectric layer,(e)stable discharges at later stage of PEO.