Oxidation and Improvement of the Wear Behavior of Ti-6Al-4V Alloys by Surface Treatments

Titanium and titanium alloys, especially Ti-6Al-4V, are used in the aerospace, automotive, marine, medical, and chemical industries due to their high strength, low density, high corrosion resistance, and excellent mechanical properties. Since water vapor is present in many atmospheres where titanium alloys are used at high temperatures, the effect of water vapor on the growth of the oxide scale and the formation of the oxygen diffusion zone was investigated. Additionally, oxidation for a controlled time can be used as a surface treatment for Ti alloy because the poor wear resistance of untreated Ti-6Al-4V hinders its wider applications. In this study, the influence of different surface modifications on the tribological behavior of Ti-6Al-4V was compared. The surface modifications were categorized as: 1) single-step process (oxidation), 2) two-step process (oxidation+reduction), 3) three-step process (oxidation+reduction+reoxidation), 4) oxidation at reduced oxygen partial pressure, and 5) Zr slurry diffusion coating followed by subsequent oxidation. The wear tests were performed using a Si3N4 counterpart with a pin-on-disc configuration.