Corrosion inhibition of Ti6Al4V alloy by a protective plasma electrolytic oxidation coating modified with boron carbide nanoparticles

Plasma electrolytic oxidation (PEO) is a cost-effective and versatile technique to achieve protective oxide coatings in light metals. Composite coatings containing B4C nanoparticles were produced by the PEO technique on a Ti6Al4V alloy. The influence of nanoparticles on the microstructure and corrosion resistance of the prepared ceramic composite coatings, as well as its incorporation mechanism into the PEO layer, were investigated. B4C nanoparticles were added to aluminate-based electrolytes and a pulse power supply was used as a constant voltage regime to obtain PEO composite coatings. Improvement in corrosion protection was also assessed by electrochemical impedance spectroscopy (EIS) and polarization tests, illustrating that a reduction in the corrosion resistance ratio was 8 for the composite coating compared to 16 for the sample without nanoparticles, after three weeks of immersion. The effect of nanoparticles on the phase composition was examined by X-ray diffraction (XRD) tests. Moreover, scanning electron microscopy (SEM) images illustrated the capability of B4C nanoparticles in filling the inherent pores of PEO coatings. •Fabrication of plasma electrolytic oxidation coatings modified with B4C nanoparticles on Ti6Al4V alloy•The significant role of electrophoretic force and trapping in the melted oxide layer on particle absorption.•Sealing the inherent pores of the PEO coating by the B4C nanoparticles.•Employing the voltage of 400V protects the PEO composite coatings upon three weeks in 3.5% NaCl.