Tribological performance study of carbon fibre-carbon nanotube multiscale reinforced polytetrafluoroethylene composites

To avoid the fibre damage and serious pollution caused by the traditional chemical methods, this study synthesized the carbon fibre (CF)-carbon nanotube (CNT) micro-nano multiscale reinforcer by rare-earth LaCl₃ surface treatment method, and then prepared CF-CNT multiscale reinforced polytetrafluoroethylene (PTFE) composites via sintering process. The morphology and surface microcrystalline structure of the reinforcer, and the hardness, crystal structure and wettability of the composite were characterized, and the influence mechanism of the CF-CNT multiscale reinforcer on the crystallinity and surface energy of the PTFE composite was revealed. The coefficient of friction and wear rate of the composites were tested under different reciprocating tribological test parameters, every stage of the friction process was thoroughly discussed with the proposition of corresponding friction and wear mechanism. These results demonstrate that: the avoidance of fibre damage and toxic raw materials distinguishes the proposed CF-CNT reinforcer synthesis method from the traditional methods. The lower surface energy of CF-CNT reinforced composite decreases its initial friction coefficient. The wear rate of the CF-CNT reinforced composite is reduced by 75.3%, which is superior to the counterpart in similar studies. The multiscale structure and La(III) on CF-CNT improve the interface bonding performance of the CF-CNT reinforced composites, prevent the generation of large and hard wear debris during the surface yielding process as well as promoting the formation of high strength and stable transfer film. The tribological behaviors of the CF-CNT reinforced composites is sensitive to the reciprocating frequency and load, the higher frequency and lower load favour the lower wear rate. This study synthesized CF-CNT multiscale reinforcer via rare-earth LaCl₃ surface treatment method to enhance the tribological properties of PTFE composite, the obtained research conclusions are instructive for the design of high-performance polymer composite.