Influence of electrical parameters on particle uptake during plasma electrolytic oxidation processing of AM50 Mg alloy

The influence of electrical parameters on microstructure and composition of coatings by plasma electrolytic oxidation (PEO) with particle addition was investigated. PEO coatings were produced on AM50 magnesium alloy from an alkaline phosphate based electrolyte (1 g/l KOH + 20 g/l Na3PO4) with 5 g/l SiO2 particle (1-5 μm) addition. Besides the most common electrical parameters (voltage and current density), frequency and duty ratio have effect on the uptake of particles during PEO processing. Higher duty ratio and lower frequency allow to incorporate more particles into the PEO coating. The area of the melting pools, as indicated by the size and area of the open pores on the coating surface, can be considered as one important factor to determine the particle uptake during PEO processing.