Polymers are widely used in bearing applications. In the case of water-lubricated stern tube bearings, thermoplastic polyurethane (TPU)-based composites are used due to their excellent wear resistance, corrosion resistance, and tunable mechanical properties. Their tribological performance, however, depends on operating conditions. In this work, TPU was blended with carbon fiber, graphene platelet, and ultra-high molecular weight polyethylene (UHMWPE). Friction tests of TPU based-composites against copper countersurface were carried out in water to mimic the actual operating conditions of the bearing. Most of the resulting contacts were in the boundary lubrication regime, in which friction was attributed to both contact mechanics of asperities as well as water lubrication. Our results show that the viscoelasticity of TPU has a considerable impact on its tribological performance. Water lubrication at 50 °C promotes the softening of polymer surface material during sliding, resulting in higher fluctuation in the coefficient of friction and wear loss. This is attributed to the reduced thermomechanical properties. In addition, Schallamach waviness is observed on worn surface. The tribological properties of TPU are significantly improved by the inclusion of carbon fiber, graphene platelet, and UHMWPE. The formation of graphene transfer-layers and UHMWPE transfer film reduces friction and wear loss, while the inclusion of carbon fiber enhances wear resistance due to improved mechanical properties and load bearing capacity.

聚合物广泛用于轴承应用。在水润滑艉轴管轴承中，采用热塑性聚氨酯（TPU）基复合材料，因为它们具有优异的耐磨性、耐腐蚀性和可调的机械性能。然而，它们的摩擦学性能取决于操作条件。在这项工作中，TPU 与碳纤维、石墨烯片和超高分子量聚乙烯 (UHMWPE) 共混。 TPU 基复合材料与铜配合面的摩擦测试在水中进行，以模拟轴承的实际工作条件。大多数产生的接触都处于边界润滑状态，其中摩擦归因于粗糙体的接触力学以及水润滑。我们的结果表明，TPU 的粘弹性对其摩擦学性能有相当大的影响。 50℃的水润滑会促进滑动过程中聚合物表面材料的软化，导致摩擦系数和磨损损失更大的波动。这是由于热机械性能降低所致。此外，在磨损表面观察到沙拉马赫波纹。通过添加碳纤维、石墨烯片和 UHMWPE，TPU 的摩擦学性能得到显着改善。石墨烯转移层和UHMWPE转移膜的形成减少了摩擦和磨损，而碳纤维的加入则由于改善了机械性能和承载能力而增强了耐磨性。