Tribological characterization of nanoparticle filled PTFE: Wear-induced crystallinity increase and filler accumulation
L. F. Toth, G. Szebenyi, J. Sukumaran, P. De Baets
Vol. 15., No.10., Pages 972-986, 2021
DOI: 10.3144/expresspolymlett.2021.78
DOI: 10.3144/expresspolymlett.2021.78
Corresponding author: G. Szebenyi 
GRAPHICAL ABSTRACT
ABSTRACT
The present research aims to clarify the friction and wear behavior, the transfer layer formation, and the wear mechanism of mono-filled polytetrafluoroethylene (PTFE). A well-known limitation of PTFE is the low wear resistance, which can be surpassed with the use of micro- or nanoparticles. The applied fillers were graphene, alumina (Al2O3), boehmite alumina (BA80), and hydrotalcite (MG70). The samples were produced by room temperature pressing – free sintering method. All specimens were tested with a pin-on-disc tribo-tester in dry contact condition against 42CrMo4 steel disc counterface with 3 MPa contact pressure and 0.1 mm/s sliding speed. PTFE filled with 4 wt% Al2O3 achieved the highest wear resistance; the increase was more than two orders of magnitude compared to the neat PTFE. This improvement comes from the protective transfer layer formation due to the Al2O3 and the iron-oxide accumulation on the polymer contact surface. Significant wear-induced crystallinity was also registered, which originated from the mechanical chain scission of the PTFE molecular chains during the wear process.
