Dynamics of microdischarges evolution during plasma electrolytic oxidation in alkaline and silicate-alkaline electrolytes

The dynamics of microdischarges evolution during plasma electrolytic oxidation (PEO) of AMg6 aluminum alloy at anode-cathode mode in alkaline and silicate-alkaline electrolytes was investigated. Experimental studies were carried out using high-speed photography of surface being treated of the alloy synchronized with the registration of the electric current and voltage in the «alloy being treated ‒ electrolyte ‒ counter electrode» system. As a result, the ranges of electrical voltages at which surface being treated is affected by sporadic weak and plural weak, medium, as well as powerful anode microdischarges were identified. The conditions of sporadic cathode microdischarges displaying were determined. Differences in the dynamics of microdischarges evolution during PEO processes in alkaline and silicate-alkaline electrolytes were shown and determined their influence on the thickness, through porosity and microhardness of the formed coatings.