Tribological Behavior of Polytetrafluoroethylene-Silica Composites

The effect of finely dispersed silica on the structure and mechanical and tribological characteristics of polytetrafluoroethylene-silica composites is studied. It is shown that the introduction of a small amount of filler (0.5%) results in qualitative and quantitative changes in the supermolecular structure of the polymer matrix, which entail variations in the friction coefficient and wear rate of the composites.(1) During friction, dispersion of the filler and its accumulation in the composite's surface occur. Within a narrow range of the filling degree, this causes a considerable rise of the abrasiveness of the composite accompanied with high wear resistance, which may be attributed to an increase in the adhesion of transfer films. The maximal wear resistance of polytetrafluoroethylene-silica composites is found when the filler is present in a small quantity, providing for a combination of high strength characteristics, low friction coefficient, and moderate abrasiveness.