Insights into plasma electrolytic oxidation treatment with particle addition

• The coating microstructure and composition can be controlled by particle addition.
• SiO2 nanoparticle can be used as sintering additive for PEO coating.
• The nature of the particle determines its uptake and incorporation mode.

Plasma electrolytic oxidation (PEO) processing has received considerable attention for improving the corrosion or wear resistance of magnesium and its alloys. However, it cannot provide high-barrier long-term protection due to its high porosity. A novel approach is to introduce reactive particles to PEO coatings, aiming to seal the porosity and to provide wider range of coating compositions. Experiments with nano- and micro-sized SiO2 particles and different concentrations of KOH in the electrolyte provide new insights into possible up-take and incorporation mechanisms of particles during PEO processing.