Synergetic effect of oleophilic textured surfaces and MoS2 on the tribological properties of Ti-6Al-4V alloy under dry and lubricated sliding conditions

In the present work, surface modification of Ti-6Al-4V alloy was carried out using Laser surface texturing (LST). The investigation aims to explore the synergetic impact of LST and molybdenum disulfide (MoS2), as a solid lubricant, on the tribological properties of Ti-6Al-4V alloy. Three types of LST textures (Circular, triangular, and square textures) were created on the Ti6Al4V alloy. Subsequently, tribological tests were conducted on a universal tribometer (ball-on-disc), at a load of 20 N with a frequency of 15 Hz. The worn surface was analyzed using various methods, including optical microscopy, 3D-profilometer, FESEM, EDAX analysis, and Raman spectroscopy. The study compared the coefficient of friction (COF) and wear behavior of un-textured surfaces (U-TS) with those of textured surfaces (T-S) under both dry sliding conditions (D-SC) and lubricated sliding conditions (L-SC). The results demonstrated a significant reduction in the COF and wear coefficients on the T-S. Specifically, the circular texture exhibited significant results with a 10.30%, 10.42%, and 28.80% decrease in COF and a remarkable reduction of 39.22%, 47.51%, and 77.90% in wear coefficients compared to the U-TS tested under D-SC and L-SC (using PAO-4 and PAO-4 + 1% wt MoS2). Severe abrasion, adhesion, and delamination as the primary wear mechanisms were observed on the U-TS and T-S under D-SC, while the L-SC was characterized by mild adhesive and delamination wear on the U-TS and T-S. The carbon layer formation and concentration of Mo and S particles resulted in lower friction and wear coefficients for the U-TS, and T-S under L-SC (PAO-4 + 1% wt MoS2). The analysis indicated that the use of LST and solid lubricant nanoparticles on a Ti-6Al-4V alloy would result in improved service life and better endurance in cutting tools and tribo-mating parts.