Tribological Properties Study of Solid Lubrication with TiO(2) Powder Particles

Titanium dioxide (TiO(2)), by its tribological behavior, is known as a solid lubricant. TiO(2) as a solid lubricant, together with tungsten disulfide (WS(2)) and molybdenum disulfide (MoS(2)) decreases friction and excessive wear. By compacting TiO(2) powder, pellets are formed. Studies and research on the solid lubricant coatings were conducted with success on a tribometer with the possibility of making two simultaneous contacts, pellet/disk, and slider pad/disk. On the disk of a tribometer, we studied the lubrication characteristics of the TiO(2) powder particles as the third body by intentionally transferring. Results show that the TiO(2) pellet behaved like an effective oil-free lubricant by self-repairing and self-replenishing. In experiments, a TiO(2) pellet is intentionally sheared against the surface of the disk, while the slider pad slips loaded on the lubricated surface until the deposited powder film is exhausted. A theoretical model control volume fractional coverage (CVFC) was used to estimate both the wear rate for the lubricated pellet/disk sliding contact and the friction coefficient at the pad/disk separation surface. According to materials properties, disk velocity, pellet and slider pad load, the pellet wear rate, and slider pad friction coefficient, using the CVFC model, can establish the pellet wear rate, and slider pad friction coefficient. The fractional coverage represents a parameter of the CVFC model that varies with time, and it is useful for estimating the film amount from the third body that covers the disk asperities. Model results well enough describe the tribological behavior of the sliding contacts in experiments, both qualitatively and quantitatively. In addition, the theoretical results obtained by modeling and the experimental those obtained in the process of friction, are compared.