Enhanced corrosion and tribocorrosion behavior of Ti6Al4V alloy by auto–sealed micro-arc oxidation layers

Abstract

Surface modification of titanium alloys are being considered to justify their use as articulating surfaces. This study examined the corrosion and tribocorrosion behavior of Ti6Al4V specimens whose surfaces were modified using micro-arc oxidation (MAO) at −3 o C and + 20 °C. After MAO, the porous oxide layers containing Ca and P that are incorporated from the electrolyte, were fabricated on the surface. Many of the pores were sealed by the deposition of erupted materials on the surface of −3 °C MAO layers, resulted in a reduced surface fraction of open-porosities. Corrosion studies revealed nearly 80 mV positive shifting of corrosion potential and more than 50% decrease in the passive current density of auto-sealed layers. In contrast to the sudden potential drop of the untreated Ti6Al4V alloy, the MAO layers showed no significant decrease during the tribocorrosion. The presence of a relatively smooth surface with some parallel scratches were the main characteristics of mild abrasive wear as the dominant wear mechanism of the −3 °C MAO layers.