Ultra-low-wear polyethylene (ULWPE) is a new metallocene catalyzed high density polyethylene (HDPE)material. Previous studies have demonstrated that it has excellent biocompatibility and wear resistance, whereupon indicating great potential in the applications to artificial joints. However, as a newly developed material, its tribological behavior and wear resistance mechanism has not been well understood. In the current study, we experimentally evaluated the tribological behavior of ULWPE, and investigated its high wear resistance mechanism in terms of microstructure, crystallization properties, mechanical, physical, and chemical properties. ULWPE manifested the best tribological performance on pin-on-disc (POD) wear tests compared with the most widely used artificial joints materials, with a wear volume of 0.720 ± 0.032 mm³/million cycles (Mc) and 0.600 ± 0.027 mm³/Mc against cobalt-chromium (CoCr) alloy disc and zirconia toughened alumina (ZTA) ceramic disc, respectively. The results of the wear morphology analysis showed that the surface of ULWPE was the slightest, with no obvious surface damage, debris shedding and wear pits. We reveal that three major factors mainly contributed to its high wear resistance. First, ULWPE demonstrated a high crystallinity and a compact crystalline morphology comprised of long linear molecular chains, which contributed to its good mechanical performance. As confirmed by the mechanical test, ULWPE had a very high density, hardness, and tensile elongation at break. The high hardness and strength laid a solid foundation to a low wear volume, and its high ductility and hardness helped to endure abrasive and adhesive wear, resulting in excellent wear resistance. Second, the results of wettability analysis showed that the contact angle formed on the surface of ULWPE was the lowest and the surface energy was the highest. The hydrophilicity of ULWPE provided good lubrication conditions in body fluid. Third, it also had a lower oxidation index. The high hardness, high strength, high ductility and good wetting of ULWPE materials reduced the damage of the material to adhesion and abrasive wear, resulting in excellent wear resistance.

超低磨损聚乙烯（ULWPE）是一种新型的茂金属催化的高密度聚乙烯（HDPE）材料。先前的研究表明，它具有出色的生物相容性和耐磨性，因此表明在人造关节中的巨大应用潜力。然而，作为一种新开发的材料，其摩擦学行为和耐磨机理尚未得到很好的了解。在当前的研究中，我们通过实验评估了ULWPE的摩擦学行为，并从微观结构，结晶特性，机械，物理和化学特性方面研究了其高耐磨性机理。与最广泛使用的人工接头材料相比，ULWPE在针盘式（POD）磨损测试中表现出最佳的摩擦学性能，磨损量为0.720±0.032 mm³ /百万循环（Mc）和0.600±0.027 mm ³/ Mc分别抵抗钴铬（CoCr）合金盘和氧化锆增韧氧化铝（ZTA）陶瓷盘。磨损形态分析的结果表明，ULWPE的表面最细，没有明显的表面损伤，碎屑脱落和磨损坑。我们发现，三个主要因素是造成其高耐磨性的主要原因。首先，ULWPE表现出高结晶度和由长线性分子链组成的致密晶体形态，这有助于其良好的机械性能。如机械测试所证实，ULWPE具有非常高的密度，硬度和断裂拉伸伸长率。高硬度和强度为低磨损量奠定了坚实的基础，其高延展性和硬度有助于承受磨料和粘合剂的磨损，从而具有出色的耐磨性。第二，润湿性分析结果表明，在ULWPE表面形成的接触角最低，表面能最高。ULWPE的亲水性为体液提供了良好的润滑条件。第三，它的氧化指数也较低。ULWPE材料的高硬度，高强度，高延展性和良好的润湿性减少了材料对附着力和磨料磨损的损害，从而获得了极好的耐磨性。