Analysis of Tribo-corrosion Properties of MAO/DLC Coatings Using a Duplex Process on Ti6Al4V Alloys

In recent years, various technologies have been increasingly investigated for the surface modification of Ti and Ti alloys. Microarc oxidation (MAO) is one of the effective techniques to improve surface properties. However, it has some disadvantages for sliding wear applications and/or aggressive environments. In this study, the combined MAO and closed field unbalanced magnetron sputtering process was used to deposit duplex MAO/diamond-like carbon (DLC) coatings on Ti6Al4V alloy. Analysis of the microstructures, morphology, and crystallographic structure were performed by using a SEM, Raman, and XRD. The wear, corrosion, and tribo-corrosion properties of the coatings were investigated using the pin-on-disk wear test, potentiodynamic polarization test, and combining tribo-corrosion test unit, respectively. The results of this study have shown that duplex MAO/DLC coatings exhibit better wear, corrosion, and tribo-corrosion properties than the DLC or MAO monolayer on Ti6Al4V alloy substrate. MAO/DLC coatings exhibited dense structure, lower coefficient of friction and corrosion current density, and higher tribo-corrosion resistance. The results have also shown that MAO/DLC duplex coatings on Ti6Al4V substrates increased the tribo-corrosion resistance by acting as a barrier layer.