Mechanical and Tribological Properties of Rice Husk Biochar‐Reinforced Glass Fiber/Ultra‐High Molecular Weight Polyethylene Composites for Water‐Lubricated Bearings

ABSTRACT Adding glass fiber (GF) to ultra‐high molecular weight polyethylene (UHMWPE) significantly improves wear resistance with minimal effect on the friction coefficient. To improve tribological performance, rice husk biochar (RHB) carbonized at 500°C was added as a synergistic filler. The effect of 0–4 wt.% RHB content on the mechanical, tribological, and wettability properties of the composites was investigated, and the microscopic morphology and composition of RHB were analyzed. Tribological behavior was evaluated by pin‐on‐disk tests under dry and water‐lubricated conditions, followed by worn surface and wear mechanism analyses. Incorporating RHB and GF significantly enhances the mechanical and tribological performance of the composites compared to pure UHMWPE. The optimum RHB content is 3 wt.%, at which the average friction coefficients under dry and water‐lubricated conditions are reduced from 0.17 and 0.13 to 0.14 and 0.04, respectively. Additionally, the hardness, tensile strength, and modulus increased by 12.2%, 33.5%, and 37.61%, respectively. The performance enhancement is mainly attributed to the unique microporous structure and porous characteristics of RHB, which form good embedding with the matrix, enhance rigidity, and improve wettability. Carbon and SiO ₂ in RHB provide stable support and lubrication, reducing friction and wear.