Influence of fillers on the low amplitude oscillating wear behaviour of polyamide 11

The oscillating wear failure of the materials is frequently observed in various tribo-applications such as bearings, gears, bushes, palliatives, bolted and riveted joints and seals, etc. where oscillations of small amplitude or vibrations are inevitable. In general, the oscillating wear performance of the materials depends on the amplitude of oscillation, its frequency and duration, load, contact geometry, environment, etc. A vast literature is available reporting on the influence of fillers and fibres on the adhesive (unidirectional) and abrasive wear behaviour of polyamides (PAs) but not much on their oscillating wear behaviour. For the present study, PA 11 and its three composites containing short glass fibres (GF) and metallic powdery fillers such as bronze and copper were selected for the investigations. Experiments were carried out on the SRV Optimol instrument in pin on disc configuration, under various loads at room temperature. It was observed that the GF reinforcement greatly improved the friction and wear performance of PA 11. Incorporation of bronze and copper powders in GF reinforced composite further improved the friction and wear behaviour of PA 11. Copper proved to be beneficial filler than the bronze in this context. Worn surface studies were also done to investigate the wear mechanisms. The SEM and EDAX studies on the copper-containing composite indicated that the film transfer on the disc was very thin, uniform and coherent. It showed evidence of Cu transfer on the disc, which was thought responsible for strong adherence of the film to the mild steel disc resulting in the best friction and wear behaviour of the composite.