石墨烯/高密度聚乙烯在水润滑条件下的摩擦学性能研究

目的 探究石墨烯/高密度聚乙烯高分子材料在水润滑条件下的摩擦学性能,提高高密度聚乙烯的自润滑和耐磨损性能.方法 采用石墨烯纳米片填充高密度聚乙烯材料,利用RTEC摩擦磨损试验机,开展新型复合材料在水润滑条件下的摩擦学性能研究.通过分析新型复合材料的典型机械性能、摩擦系数、磨损形貌以及摩擦副接触表面的元素成分及分布情况,揭示石墨烯/高密度聚乙烯在水润滑条件下的摩擦磨损机理.结果 新型复合材料的拉伸强度、撕裂强度和肖氏硬度均随着石墨烯纳米片含量的增加而先增高后降低,1.5％石墨烯纳米片改性高密度聚乙烯表现出最高的强度,分别为19.81 MPa、31.34 MPa和92.6HSA.新型复合材料的平均摩擦系数和体积行程磨损率总体随着石墨烯含量的增加而减小,1.5％石墨烯纳米片改性的高密度聚乙烯平均摩擦系数和体积行程磨损率比纯高密度聚乙烯分别降低了53.6％和73.9％.Si3N4陶瓷球与1.5％、0.6％石墨烯纳米片改性高密度聚乙烯进行3600 s对磨试验,其磨损区域的碳元素质量分数分别约为3.5％和0.3％,表明含量较高的石墨烯纳米片有利于在微观界面形成石墨烯润滑层,从而降低摩擦系数.结论 石墨烯纳米片显著影响高密度聚乙烯的自润滑性能和耐磨损性能,适量的石墨烯纳米片促进了高密度聚乙烯磨损界面石墨烯润滑层的形成,降低摩擦系数和磨损量.该研究可为设计低摩擦、耐磨损的水润滑轴承复合材料提供参考.

Study on Tribological Properties of Graphene/High-density Polyethylene under the Water-lubricated Conditions

This paper is to study the tribological properties of graphene/high-density polyethylene composites under the water-lubricated condition and improve the self-lubricating and wear resistance of high-density polyethylene (HDPE). Graphene nano-sheets (GNS) were used to modify high-density polyethylene material. The RTEC wear test apparatus was used to test the tribological performances of modified composites under water-lubricated conditions. The friction and wear mechanism of graphene/HDPE under water lubrication condition was revealed by analyzing the typical mechanical properties, coefficient of friction (COF), wear morphology, and element composition and distribution of the contact surface of the friction pairs. The results showed that the tensile strength, tear strength and Shore hardness of the modified composites increased first and then decreased with the increasing of GNS mass content, and HDPE modified by 1.5% GNS exhibited the highest values of 19.81 MPa, 31.34 MPa, and 92.6HSA, respectively. The average COF and volume stroke wear rate of the modified composites decreased with the increasing of GNS mass content, and the average COF and wear rate of HDPE modified with 1.5% GNS were reduced by 53.6% and 73.9% respectively compared with pure HDPE. The carbon element mass fraction in the wear area of the Si3N4 ceramic ball sliding against with HDPE modified by 1.5% and 0.6% GNS for 3600 s wear test were approximately 3.5% and 0.3% respectively, which indicated the higher mass content of GNS was beneficial to the formation of the GNS lubricating layer on the micro-interface, and resulted in reducing the COF. In a summary, GNS significantly affected the self-lubricating performance and wear resistance of HDPE. Appropriate mass content of GNS promoted the formation of a GNS lubricating layer at the wear interface of HDPE, and reduced the COFs and wear volumes. The results in this study contribute to design the water-lubricated stern tube bearing polymers with low friction and high wear resistance.