碳纤维和氟化钙协同提高PTFE摩擦学性能研究  

Synergetic Role of Carbon Fibers and Calcium Fluoride Particles on Enhancing Tribological Performance of PTFE

作　　者：王壮 喻萍 刘根 车清论 张嘎[2] 郑少梅 WANG Zhuang;YU Ping;LIU Gen;CHE Qinglun;ZHANG Ga;ZHENG Shaomei(School of Mechanical and Automotive Engineering,Qingdao University of Technology,Shandong Qingdao 266033,China;State Key Laboratory of Solid Lubrication,Lanzhou Institute of Chemical Physics,Chinese Academy of Sciences,Gansu Lanzhou 730000,China)

机构地区：[1]青岛理工大学机械与汽车工程学院,山东青岛266033 [2]中国科学院兰州化学物理研究所固体润滑国家重点实验室,甘肃兰州730000

出　　处：《摩擦学学报》2023年第6期657-665,共9页Tribology

基　　金：山东省自然科学基金(ZR2020ME135)资助。

摘　　要：聚合物复合材料由于其自润滑特性和化学稳定性高等优势,在汽车和装备领域运动机构的摩擦学设计中发挥着越来越重要的作用.本研究系统考察了氟化钙(CaF_(2))颗粒的加入对聚四氟乙烯(PTFE)和碳纤维(CF)增强PTFE材料摩擦学性能的影响规律.研究发现,在PTFE中添加CaF_(2)颗粒可明显改善基体材料的抗磨性能.尤其,与分别填充有CaF_(2)陶瓷颗粒或CF的PTFE材料相比,同时填充CaF_(2)和CF的PTFE多元复合材料的耐磨性能分别提高了11.1和2.47倍.CF与CaF_(2)表现出显著的协同抗磨作用,同时该多元复合材料表现出极低的特征磨损率[8.9×10^(-7)mm^(3)/(N·m)]和优异的自润滑性能.通过多种表征手段深入分析了金属对偶表面生长转移膜的微观结构以及界面的物理化学反应和产物.结果表明,PTFE发生摩擦化学反应并生成的羧酸基团,随后与CF研磨产生的石墨碳、破碎的CaF_(2)以及其摩擦化学反应产物碳酸钙(CaCO_(3)与CaO)在闪温和机械力作用下发生摩擦烧结,促使易剪切、高承载特性转移膜在金属对偶表面生长,大幅降低了PTFE复合材料的磨损.研究结果为设计超低磨损的新型聚合物自润滑复合材料奠定了基础.By reason of the self-lubrication characteristic and high chemical resistance of polymer composites,they are more and more utilized for designing motion systems in the fields of automotive and equipment.In this work,calcium fluoride(CaF_(2))particles were compounded into polytetrafluoroethylene(PTFE)and conventional PTFE composite reinforced with carbon fibers(CF).It was demonstrated that the addition of CaF_(2)improves wear resistance of PTFE.More interestingly,a synergetic role of CF and CaF_(2)on enhancing wear resistance of PTFE was identified.The composites filled with combined CF and CaF_(2)exhibits a very low specific wear rate,i.e.8.9×10^(−7)mm^(3)/(N·m).In comparison to the PTFE composites filled with CaF_(2)ceramic particles or CF,the wear resistance of the composite filled with multiple CF and CaF_(2)was improved by 11.1 and 2.47 times,respectively.Multiple characterization methods were used to comprehensively analyze microstructures and the transfer film and to shed light on complex tribophysicochemical reactions and products occurring at the friction interface.Our results demonstrated that carboxylic acid groups were generated due to tribo-chemical reactions of PTFE molecules.Afterwards,tribological products of PTFE,graphitic carbon ceramic deriving most probably from pulverized CF,CaF_(2)particles,and tribological products of CaF_(2)(CaCO_(3)and CaO)were mixed at the interface and finally tribo-sintered into a compact transfer film.It was surmised that the high tribological performance of the CF/CaF_(2)-filled PTFE was associated with growth of the hybrid transfer film probably having an easy-shearing characteristic and high load-bearing capability.Outcome of the present work pave a route for formulating novel extremely wear-resistant polymer composites.

关 键 词：PTFE基复合材料 氟化钙 干摩擦 转移膜 摩擦化学 

分 类 号：TH117.1[机械工程—机械设计及理论]