Effect of Adding TiO_2 Nanoparticles to a Lubricant Containing MoDTC on the Tribological Behavior of Steel/Steel Contacts Under Boundary Lubrication Conditions

摘要

The tribological performance of lubricants containing TiO_2 nanoparticles and Molybdenum DiThioCarbamate (MoDTC) was investigated using a reciprocating ball-on-flat tribometer in steel-steel contacts. Lubricants containing only MoDTC were used for comparison. The influences of the additive concentration (0.1 wt% and 0.5 wt%) and of the roughness of the counterparts (R_a from 10 to 200 nm) on the performance of the lubricant were studied. Improved friction modification and anti-wear properties were found when TiO_2 nanoparticles were blended with MoDTC compared to MoDTC alone, even at low concentration and with rough surfaces. XPS characterizations and FIB-TEM analyses of tribofilms were performed and suggested that the formation of MoS_2 from MoDTC is favored in the presence of TiO_2 nanoparticles. The results are discussed, taking into account the tribocatalytic properties of TiO_2 nanoparticles.