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

Abstract

Plasma electrolytic oxidation (PEO) is a cost-effective and versatile technique to achieve protective oxide coatings in light metals. Composite coatings containing B 4 C 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. B 4 C 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 B 4 C nanoparticles in filling the inherent pores of PEO coatings. • Fabrication of plasma electrolytic oxidation coatings modified with B 4 C 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 B 4 C nanoparticles. • Employing the voltage of 400V protects the PEO composite coatings upon three weeks in 3.5% NaCl.