Tribological Behavior of SAE 4140 Steel Coated with Titanium Dioxide Film

The aim of this work is to evaluate mechanical and specifically tribological properties of TiO2 (titanium dioxide) coatings on SAE 4140 steel. The substrates were quenched, tempered and plasma nitrided prior to the deposition of the thin films. The TiO2 films were deposited in two different routes: namely reactive and metallic deposition. The samples were characterized by X-ray diffraction (XRD), Vickers microhardness (HV), instrumented indentation, measurement of film thicknesses through scanning electron microscopy (SEM) and film adhesion via Rockwell C indentation (VDI 3198 standard). The tribological behavior was evaluated using pin-on-disc wear tests (ASTM G99-17 standard). Consequently, the tribological performance of samples with and without a TiO2 film was examined, the results indicate that the films increased surface hardness and had good adhesion to the substrate, however, statistically no significant changes were noted in the wear resistance.