Mechanical and tribological properties of ATP-modified GF/UHMWPE water-lubricated bearing composites

Filling ultra-high molecular weight polyethylene (UHMWPE) with glass fiber (GF) alone can significantly enhance its wear resistance but does not effectively reduce the friction coefficient. To improve the tribological properties of GF/UHMWPE composite, modified attapulgite (mATP), treated with gamma-methacryloxypropyl trimethoxysilane (KH570), was used as the filler. The influence of mATP mass fraction on composite properties was investigated, and the performance of the mATP/modified-GF (mGF)/UHMWPE composites was further examined. The composites were characterized for their melting and crystallization behavior, thermal expansion, surface wettability, hardness, and mechanical properties. Their tribological performance was evaluated through pin-on-disk tests under both dry friction and water lubrication conditions, as well as disk-on-disk water lubrication tests, with 304 stainless steel as the material for the sliding counterface. The worn surface morphology and wear mechanisms of the composites were analyzed. The results indicate that KH570 effectively modifies ATP and GF. Compared to GF/UHMWPE composites, mATP/GF/UHMWPE composites exhibit enhanced mechanical properties. An optimal ATP content decreases the friction coefficient under both dry friction and water- lubrication conditions, enhancing wear resistance. Composites with 4 wt% mATP show optimal performance. Further modification of GF enhances the overall performance of the composite material.