Enhanced Tribological Behavior of Titanium Grade 2 through Gas Nitriding: Process, Characterization and Performance Evaluation

The wear of metallic components often leads to damage and loss of functionality due to dimensional degradation. Gas nitriding of titanium grade 2 is a promising technique to improve its low wear resistance, offering a simple and cost-effective methodology. Samples were encapsulated in quartz tubes to create a nitrogen-rich atmosphere, with heat treatment conducted for 9 hours at 850 °C. The nitrided layer, comprising TiN and Ti₂N phases (5.22 µm) and a diffusion zone (4.55 µm), formed during the process. The analyses confirmed the formation of these nitrides. The initial hardness of 168 HV increased to 811 HV after nitriding. Reciprocal friction wear tests showed that the coefficient of friction (COF) of the nitrided sample was 0.22, compared to 0.33 for the as-received material, resulting in a 33% reduction. The positive tribological effect of nitriding can be attributed to the increase in hardness after gas nitriding leading to a reduction in the COF value. Scratch tests revealed cohesive failures (parallel and angular cracks) and adhesive failures (circular cracks) without substrate exposure, indicating satisfactory adhesion properties of the nitrided layer. This study demonstrates a promising approach to nitriding of titanium, considering the formation of desired nitrides and enhanced wear performance.