Synergistic Coupling Effects of Temperature and Load on Dry Sliding Friction and Wear Properties of (TiBw + Ti5Si3) / TC4 Composites

This work aims to investigate temperature-load coupling effects on high-temperature tribological behaviors of (TiBw+Ti5Si3)/TC4 composites. It intends to overcome the insufficient high-temperature wear resistance of titanium alloys and supplement research deficiencies of TMC wear mechanisms under complex service conditions. Dry sliding tests were performed on a pin-on-disc tribometer at 100–600 ℃ and 300–600 N (600℃). The results show that the composite has a critical temperature of 300 ℃ and a critical load of 500 N. Below these thresholds, the tribo-layer is loose and discontinuous, dominated by abrasive and adhesive wear with severe plastic deformation and stress concentration in the subsurface. Above the thresholds, a compact tribo-layer consisting of TiO2, FeO, Fe2O3 and reinforcements forms, leading to a transition to mild oxidative wear. Compared with TC4 alloy, the TMCs showed a 78% reduction in wear rate under the same tested conditions. The minimum specific wear rate reaches -1.55×10-7 mm3/(N·mm) at 600 ℃/500 N. TiBw improves wear resistance via load transfer and grain pinning and acts as a skeleton to stabilize the tribo-layer, which provides physical isolation and lubrication for friction reduction. In the high-wear state, the subsurface deformation zone is characterized by extensive plastic deformation and stress concentration. In the low-wear state, the stress distribution becomes uniform and the deformation zone shrinks. The wear mechanism transitions from mechanically dominated wear to oxidative wear. The composite exhibits optimal performance at ≥300 ℃ and about 40 MPa contact stress, providing theoretical support for hot-end components in aerospace engines.