Effect of carbon nanotubes additive on tribocorrosion performance of micro-arc oxidized coatings on Ti6Al4V alloy

Ti6Al4V alloy subjected to the combined effects of wear and corrosion (tribocorrosion) in corrosive media shows severe deterioration. This study aimed to investigate the tribocorrosion behavior of oxide films produced by micro-arc oxidation (MAO) in a 3.5% NaCl solution. MAO ceramic coatings were obtained on Ti6Al4V alloy using the MAO process in alkaline electrolytes with different carbon nanotubes (CNTs) concentrations. The morphology and composition of MAO coatings were investigated using SEM, XRD, and Raman spectroscopy. Their friction reduction and wear resistance performance was evaluated under dry sliding conditions. Potentiodynamic polarization was used to assess the corrosion resistance of the MAO-coated Ti6Al4V specimens. Tribocorrosion behavior was evaluated by the evolution of open circuit potential (OCP) and coefficient of friction (COF) before, during, and after reciprocating sliding. The results showed that CNTs were incorporated in MAO coatings obtained in electrolytes containing CNTs and enhanced MAO coatings' corrosion and tribocorrosion resistance. The MAO coatings obtained in electrolytes containing 0.15 g/L CNTs possessed the best corrosion and tribocorrosion resistance.