Effect of sodium pentaborate (B5H10NaO13) nanoparticle addition to oxide coatings grown on AZ31 magnesium alloy by micro arc oxidation method on mechanical, corrosion and adhesion properties of coatings

AZ31 magnesium alloy is one of the lightweight metallic engineering materials that are widely used in many industrial areas such as aviation, space, automobile and electronics industries, biomedical applications, where structural weight reduction is at the forefront of design principles. This study focuses on the growth of MgO and MgO:B₅H₁₀NaO₁₃ doped oxide coatings on the surface of AZ31 magnesium alloy by micro arc oxidation (MAO) method in order to improve its usage areas and lifetime in industrial applications, and to investigate the structural, morphological, adhesion and corrosion properties of the grown coatings. In the study, MgO coatings were grown by MAO method and MgO:B₅H₁₀NaO₁₃ doped composite oxide coatings were grown by adding sodium pentaborate (B₅H₁₀NaO₁₃) nanoparticles into the electrolytic solution in MAO method. The phase structure of the grown coatings was determined by X-ray Diffraction (XRD), microstructure by Scanning Electron Microscopy (SEM) and chemical composition by Energy Dispersive X-ray Spectroscopy (EDS). The hardness of MgO and MgO:B₅H₁₀NaO₁₃ doped composite oxide coatings were determined by microhardness tester, the adhesion resistance with the base material was determined by Scratch Tester and the corrosion resistance was determined by potentiodynamic polarization tester. As a result, it was observed that dense and homogeneous coatings were grown on the surfaces of particle-added (MgO:B₅H₁₀NaO₁₃) coatings, that porosity and pore sizes on the surfaces of the coatings were reduced, that microcracks were reduced, and that coatings with high bond strength with the base material were grown. It was also determined that the corrosion resistance of the coatings with particle addition (MgO:B₅H₁₀NaO₁₃) was higher than the corrosion resistance of the coatings without particle addition (MgO).