Abstract
This study focuses on surface modification of aluminum alloys (Al–Si) with high silicon content using plasma electrolytic oxidation (PEO). The influence of Al2O3 and SiO2 particles, introduced both separately and in combination, into a sodium aluminate-based electrolyte during high-frequency treatment (2000 Hz). Examination of surface and cross-sections using a scanning electron microscope SEM showed an increase in the compactness of the coating when Al2O3 particles were introduced. The addition of SiO2 particles tended to promote a smoother surface and a slight reduction in the porosity and defect density. However, when these particles are added together, especially at high concentrations, an increase in structural defects and crack formation is observed. X-ray diffraction analysis revealed that the γ-Al2O3 phase was present in all coatings. In the samples with Al2O3 addition, the α-Al2O3 diffraction signal became stronger compared with the other coatings. Tribological tests revealed that the addition of Al2O3 particles significantly improved wear resistance, while the introduction of SiO2 particles contributed to the stabilization of the friction coefficient. Thus, Al2O3 particles were the most effective in enhancing the mechanical properties of the coating.