The role of carbon fibers and silica nanoparticles on friction and wear reduction of an advanced polymer matrix composite

MD Sliding Simulations of Amorphous Tribofilms Consisting of either SiO2 or Carbon

“…In our previous experimental work, the beneficial role of silica nanoparticles in a hybrid polymer matrix composite was attributed to the formation of a silica-based tribofilm [12,13]. The low friction observed if such a film had formed was attributed to the mixing of the silica with a soft constituent such as graphite or epoxy particles [13].…”

“…Actually, smooth sliding and a rather low coefficient of friction (COF) of 0.2 were predicted if the silica nanoparticles constituting the tribofilm were mixed with either 10% graphite or 20% epoxy (volume fractions). The very low COF of 0.06 observed under the most severe stressing conditions, i.e., if the product of pressure and sliding velocity was equal to 24 MPa¨m/s, could not be explained by MCA modeling [13]. Since both amorphous carbon and the silica-based film were observed in the wear scar, their sliding behavior was the focus of interest.…”

“…Our own interest in amorphous tribofilms originates from experiences made with hybrid polymer-based nanocomposites which were developed for anti-friction and anti-wear applications [12,13]. It has been shown that only if the composites contain both micron-sized carbon fibers and a certain amount of silica nanoparticles, the desired low friction and wear properties are preserved during severe stressing conditions.…”

“…Österle et al [13] explained the anti-friction behavior of the silica-based tribofilm with a nanoscopic model based on movable cellular automata (MCA). Actually, smooth sliding and a rather low coefficient of friction (COF) of 0.2 were predicted if the silica nanoparticles constituting the tribofilm were mixed with either 10% graphite or 20% epoxy (volume fractions).…”

Molecular dynamics study of sliding mechanisms of carbon in the amorphous-like state

“…Although the beneficial effects on friction and wear reduction are beyond dispute, the reasons are not so obvious. It was shown in [3,4] that effective tribofilms formed during automotive braking consist of structural features on the nanometer scale. Furthermore, we could simulate the sliding behavior of such films by nanoscale modeling.…”