Yuan Yang, Zhang Youqiang, Li Weijie, Geng Liuyuan, Fan Pengwei, Luo Shuli
Collage of Mechanical and Electrical Engineering, Tarim University, Alar, 843300, Xinjiang, China.
Modern Agricultural Engineering Key Laboratory at Universities of Education Department of Xinjiang Uygur Autonomous Region, Alar, 843300, Xinjiang, China.
Sci Rep. 2025 Jun 2;15(1):19245. doi: 10.1038/s41598-025-03909-5.
Due to its excellent friction and wear properties, polyethylene is often used in bearings, seals and driveline systems together with metal-coated components. Therefore, how to study the contact friction behavior and wear mechanisms of polyethylene molecular chains with metal surfaces on a microscopic scale is a current scientific problem to be solved. In this study, molecular dynamics simulations were used to investigate the changes in contact interface morphology, plastic deformation, friction temperature, and friction properties of amorphous polyethylene and chromium under different conditions. The results show that during the friction process, the movement of amorphous polyethylene chains is mainly affected by the roughness peaks on the surface of the chromium plate and the inter-chain entanglements, forming a "migration-detachment-migration" process, which leads to the generation of a plastic flow layer. The height of the roughness peak on the contact surface is critical for the regulation of frictional properties. At a normal load of 1 GPa, the number of contact atoms on the surface increased by 20% as the height of the rough peak increased to 6 Å compared to a smooth surface. During friction, the plastic flow layer thickness increased from 10 Å to 16 Å as the normal load increased from 1 GPa to 5 GPa, which is about 60% increase in the plastic flow layer thickness. And as the sliding velocity increases to 3 Å/ps, the thickness of the plastic flow layer increases by 70%, which in turn leads to higher atomic mobility and atomic wear. In addition, the modulation of chain entanglement by normal load and sliding velocity is revealed by analyzing the distribution of C-C-C bond angles, with normal load being more sensitive to the angular change of amorphous polyethylene chains. As the normal load increases, some of the C-C-C bond angles begin to shift from 110° to 115°, which in turn increases atomic wear. This study has certain theoretical guiding significance for studying the tribological behavior of amorphous polyethylene and metal.
由于其优异的摩擦磨损性能，聚乙烯常与金属涂层部件一起用于轴承、密封件和传动系统中。因此，如何在微观尺度上研究聚乙烯分子链与金属表面的接触摩擦行为及磨损机制是当前亟待解决的科学问题。本研究采用分子动力学模拟方法，研究了非晶态聚乙烯与铬在不同条件下接触界面形态、塑性变形、摩擦温度及摩擦性能的变化。结果表明，在摩擦过程中，非晶态聚乙烯链的运动主要受铬板表面粗糙度峰和链间缠结的影响，形成“迁移-脱离-迁移”过程，导致塑性流动层的产生。接触表面粗糙度峰的高度对摩擦性能的调节至关重要。在1 GPa的法向载荷下，与光滑表面相比，当粗糙峰高度增加到6 Å时，表面接触原子数增加了20%。在摩擦过程中，随着法向载荷从1 GPa增加到5 GPa，塑性流动层厚度从10 Å增加到16 Å，塑性流动层厚度增加了约60%。当滑动速度增加到3 Å/ps时，塑性流动层厚度增加70%，进而导致更高的原子迁移率和原子磨损。此外，通过分析C-C-C键角分布揭示了法向载荷和滑动速度对链缠结的调制作用，其中法向载荷对非晶态聚乙烯链的角度变化更为敏感。随着法向载荷的增加，一些C-C-C键角开始从(110^{\circ}) 转变为(115^{\circ}) ，进而增加了原子磨损。本研究对研究非晶态聚乙烯与金属的摩擦学行为具有一定的理论指导意义。
