The Influence of Cu Nanoparticles on the Tribological Properties of Polydopamine/PTFE plus Cu Films

Polydopamine (PDA) is effective in increasing the adhesion between polytetrafluoroethylene (PTFE) and a stainless steel substrate, as a result reducing the wear in PTFE films by up to 500 times. By incorporating Cu nanoparticles in PTFE films, the wear resistance can be further enhanced. The present study examined the influence of Cu nanoparticles on the tribological properties of PDA/PTFE films. Tribological tests were carried out using a linear-reciprocating, ball-on-flat configuration. The surface morphology and film wear were characterized using atomic force microscopy, scanning electron microscopy, optical microscopy, and contact profilometry. The results show that at a particularly low concentration of 0.01 wt%, Cu nanoparticles doubled the wear life of PDA/PTFE films. The increased wear resistance resulting from the incorporation of Cu nanoparticles is explained by four factors: increased spreading of the film resulting from a lower melting point, the formation of micro-cracks on the film surface reducing debris size, the formation of a transfer film on the counterface, and enhanced adhesion between the PTFE + Cu composite and PDA, as well as enhanced cohesion in the composite film.