Wear reduction mechanisms within highly wear-resistant graphene- and other carbon-filled PTFE nanocomposites

Abstract

In recent years, a few select carbonaceous fillers with nanometer-size dimensions, such as graphene platelets, activated carbon nanoparticles and carbon nanotubes, have been shown to reduce the wear rates of PTFE to levels approaching 10−7 mm3/Nm and below. X-ray diffraction (XRD) and attenuated total reflectance (ATR) mode IR spectroscopy are used to show that these highly effective fillers provide wear resistance to PTFE through shared mechanisms. These mechanisms are also shown to operate in highly wear-resistant composites of PTFE with nanometer-sized particles of α-phase alumina. Addition of these highly effective fillers to PTFE results in a greater resemblance of the crystalline structure of PTFE at room temperature with a tougher and higher temperature phase. When slid against steel countersurfaces under ambient conditions, these fillers embedded within the PTFE matrix also enable the formation of robust transfer films through the formation of metal chelates.