Tribological behavior of nano TiO2 as an additive in base oil

The effects of titanium dioxide additives on the lubricated friction and wear behavior of self-mated E52100 bearing steel were investigated using a reciprocating pin-on-disk apparatus. The additives were (a) nano-sized titanium dioxide (TiO2), in the form of anatase, and (b) commercially available TiO2 (P25) which contains a mixture of rutile and anatase phase. These were added to a re-refined base oil (mineral oil). Nano TiO2 powder was synthesized by ethylene glycol mediated co-precipitation technique and characterized by X-Ray Diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Nanoparticles (20-25 nm in size) were also characterized by TEM and scanning electron microscopy (SEM). The friction and wear characteristics were examined at a constant applied load and rate of reciprocation. All concentrations of P25 increased the coefficient of friction, but the addition of TiO2 nanoparticles reduced the variability and stabilized the frictional behavior. (C) 2013 Elsevier B.V. All rights reserved.