No abstract

No abstract

Abstract:The dry friction and sliding wear behavior of sintered PTFE containing various amounts of functionalized graphene (GR) were studied in this work. GR was incorporated in 0, 0.25, 0.75, 1, 2 and 4 vol%, respectively. Sliding wear tests were performed in ring(metal)-on-plate(PTFE) (ROP) test rig under ambient temperature setting 1 m/s sliding speed and 1 MPa contact pressure. The dynamic coefficient of friction (COF) and specific wear rate (ws) data were determined. Very low COFs (0.12-0.14) were measured for PTFE containing 2 or 4 vol% GR which was attributed to the formation of a tribofilm on the countersurface. ws went through a maximum (peaked at doubling that of the unmodified PTFE at about 0.75 vol% GR) as a function of GR content. Ultralow ws data in the range of 10 -6 mm 3 /(N.m) were measured for the PTFE nanocomposites with 2 and 4 vol% GR. This was reasoned by the formation of a robust tribofilm, the development of which was followed by scanning electron microscopy (SEM) by inspecting the worn surface of PTFE nanocomposites and that of the steel ring of the ROP test rig. Fourier transform infrared spectroscopic results confirmed the formation of carboxyl groups in the tribofilm. They were 2 supposed to react with the functional groups of GR and to create complexes with the metal countersurface ensuring the tribofilm with high adhesion and cohesion strengths.