Effects of different nanoparticles additions on composition and properties of oxide layers formed by plasma electrolytic oxidation on cast Al-Si alloy

Abstract

The effect of additions to the electrolyte of SiO2, Si3N4, Y2O3, WC and TiC nanoparticles (NPs) with a similar particle size on the structure, composition and properties of oxide layers formed by plasma electrolytic oxidation (PEO) on a cast Al-Si alloy 357.0 (7.5 wt % Si) was investigated. The oxide layers were studied by scanning electron and confocal laser microscopy (SEM and CLSM), energy dispersive X-ray microanalysis (EDXMA), X-ray diffraction analysis (XRD), and instrumental indentation. The thickness, roughness, microhardness and wear resistance of the oxide layers were determined. A complex positive effect of all types of particles added to the electrolyte on the hardness and wear resistance of the oxide layers has been established. The greatest positive effect was exerted by the addition of tungsten carbide NPs to the electrolyte – an increase in the average microhardness from 882 MPa in the base version to 1354 MPa and a decrease in the average reduced wear from 592 ng/(N*m) to 65 ng/(N*m), respectively.