Tribological Behavior and Wear Mechanisms of Powder Metallurgy Copper-Titanium Dioxide Composites under Dry Sliding Conditions

This research analyzes the tribological properties and wear mechanisms of copper-titanium dioxide (Cu-TiO₂) metal matrix composites developed using powder metallurgy subjected to dry sliding conditions. Cu-TiO₂ composites having TiO₂ nanoparticles of 0, 2, 4, 6, and 8 wt% were developed via mechanical mixing, cold compaction (300 MPa), and sintering (900°C in hydrogen) and tested tribologically comparing against hardened steel (EN31) counterface using a pin-on-disk tribometer at loads of 10, 20, 30N while sliding at velocities of 0.5, 1.0, 1.5m/s. Wear mechanisms were  examined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and surface profilometry. Results indicated that wear resistance was enhanced with TiO₂ additions, with the most favorable performance at 6 wt% TiO₂ loading. The wear rate decreased from 2.45 × 10⁻⁴ mm³/Nm for pure copper, to 0.68 × 10⁻⁴ mm³/Nm for Cu- 6wt%TiO₂ (72% improvement). The coefficient of friction decreased from 0.52 to 0.38 with increasing addition of TiO₂. Observations according to wear mechanisms determined that the severe adhesive and abrasive wear conditions  experienced in the pure copper material evolved into mild oxidative wear when subjected to the TiO₂-reinforced composites. From the tests it was noted that a tribolayer formed which included TiO₂ particles and copper oxidizing compounds which had attributed positively to the tribological properties of the material. These results emphasize the potential of Cu-TiO₂ composites for improving wear resistance in sliding bearing and electrical contact applications.