The evidence of cathodic micro-discharges during plasma electrolytic oxidation of light metallic alloys and micro-discharge intensity depending on pH of the electrolyte

Protons, at a relatively low intensity of electric field, may acquire high kinetic energy; because of their smallest radius, protons have a greater mean free path than other cations. They may therefore acquire high kinetic energy, even at relatively low intensity electric field, and hence implement an intensive bombardment of the vapor phase molecules and the metal substrate at the bottom of the coating pores. Electrons injected from molecules and metal substrate during the bombardment are likely to be the founders of electron avalanche.