Tribochemical Transformation of Nano iO₂ to Ilmenite on the Surface of Wearing Steel Parts: Antiwear Action of Nano TiO₂ as an Additive in Engine Oil

TiO₂ nanoparticles of average size about 20-30 nm were hydrothermally synthesized from TiCl₄ under mild acidic conditions. The nanoparticles were mixed with dispersant and base oil to give partially transparent concentrate having 1.5Wt% of Ti content. The concentrate was dispersed in hexane and base oil to characterize, respectively by electron microscopy (TEM) and DLS (Dynamic light scattering). The concentrate was diluted with base oil to have ppm level of Ti containing dispersion blends which were evaluated for wear and friction control performance. Nano TiO₂ containing fully formulated oil blend has shown excellent load bearing capability in SRV test. Four ball test result shows WSD (wear scar diameter) considerably reduced to 0.30 mm for TiO₂ added blend compared to neat base oil (0.60mm). The performance of TiO₂ added blend was comparable to secondary ZDDP (zinc dialkyl dithiophospate) added blend under identical condition. Raman spectrum of the worn surface on the tested ball revealed the presence of ilmenite (FeTiO₃) and no deposits of pure TiO₂.