Influence of SiO2 nanoparticles incorporating into ceramic coatings generated by PEO on Aluminium alloy: Morphology, adhesion, corrosion, and wear resistance

In this investigation, plasma electrolytic oxidation method was employed to incorporate SiO2 nanoparticles at concentrations of 5, 10, and 15 g/l in Al2O3 ceramic coatings on al7075. Phases, morphology and chemical composition and corrosion behavior of all specimens were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), EIS and polarization tests, respectively. A pin-on-disc test with an applied force of 10 N against 52100 steel pin was employed to evaluate the wear quality. The results showed incorporating 10 g/L of SiO2 nanoparticles modified the microstructure of coating better than other concentrations of nanoparticles and with the most closed cavities, had an adhesion strength of 47 MPa and a corrosion rate of 5.2 × 10-9 A.cm−2 which was 24 times less than that of the substrate (12.65 × 10-8 A.cm−2). In addition, 10 g/l of SiO2 nanoparticles formed a dense coating and played a role as a solid lubricant in abrasion so that it had the lowest friction coefficient and abrasion depth.