In Situ Synthesis of TiO ₂ Decorated g‐ C ₃ N ₄ Hybrids as Efficient Additives for Enhanced Tribological Properties of Ultra‐High Molecular Weight Polyethylene Composites

ABSTRACT In this work, a hybrid filler g‐C ₃ N ₄ @TiO ₂ consisting of g‐C ₃ N ₄ and TiO ₂ was prepared by an in situ surface growth strategy. The hybrid was then incorporated into ultra‐high molecular weight polyethylene (UHMWPE) by melt compounding to improve wear resistance. The morphology observation revealed that 3 wt% g‐C ₃ N ₄ @TiO ₂ could uniformly disperse in the UHMWPE matrix without visible aggregates. The UHMWPE composites containing g‐C ₃ N ₄ @TiO ₂ exhibited enhanced thermal stability, crystallinity as well as storage modulus. The tribological tests demonstrated that the UHMWPE composite containing 3 wt% g‐C ₃ N ₄ @TiO ₂ achieved the lowest coefficient of friction (0.162) and a significantly reduced wear rate (3.27 × 10 ⁻⁶ mm ³ /N·m). These values represented reductions of 28.0% and 47.9%, respectively, compared to pure UHMWPE. The surface analysis confirmed that the presence of g‐C ₃ N ₄ and TiO ₂ had good synergistic effects on the formation of a continuous, compact tribofilm, which effectively reduced direct contact and abrasive wear. The improved tribological behavior is ascribed to the layered g‐C ₃ N ₄ contributed lubrication through interlayer shearing, while TiO ₂ nanoparticles enhanced the mechanical strength and wear resistance of the tribofilm, ensuring its durability under sliding conditions. This work offers a feasible way to develop hybrid additives for UHMWPE composites with low coefficient of friction and good wear resistance.