Аңдатпа
The study aims to strengthen cylindrical liners by plasma electrolytic oxidation (PEO) and to determine the optimal processing parameters for forming wear-resistant coatings. The results of laboratory experiments were transferred to practical application for liner strengthening, followed by testing coatings formed directly on real components. PEO was applied to cylindrical sleeves made of eutectic aluminum–silicon alloy EN AC-48000 to form mechanically strong and wear-resistant oxide coatings. The coating had a two-layer structure: a dense inner barrier layer and a porous outer layer. The effect of SiO2 (~20 nm) and Al2O3 (~30 nm) nanoparticles in the electrolyte on the morphology, phase composition, microhardness and tribological characteristics of the coatings was evaluated. The optimal PEO parameters were determined as 325 V, duty cycle 25%, processing time 12 min, average current density 1.4 A·dm−2, and concentration of Al2O3 + SiO2 (5 + 5 g L−1). Under these conditions, the coating achieved a maximum microhardness of 259 HV, a low coefficient of friction of ~0.50 and a wear rate of 0.81 × 10−4 mm3·N−1·m−1. X-ray diffraction analysis confirmed the formation of γ-Al2O3 without changing the silicon phase. The results provide quantitative data on the effects of nanoparticles and PEO parameters on coating properties, which is important for the development of long-life part surfaces. The increased microhardness and wear resistance are attributed to the formation of the ceramic γ-Al2O3 phase and the densification of the porous structure due to the incorporation of Al2O3 and SiO2 nanoparticles, which reduce defect density and limit the adhesive–abrasive wear mechanism.