Dynamic mechanical response and fade-recovery performance of friction composites: effect of flyash and resin combination

Flyash-filled and glass fibre-reinforced phenolic composites have been fabricated by compression molding. The composites were characterized for their mechanical, thermo-mechanical, tribological and morphological attributes. Temperature dependence of mechanical properties has been investigated using dynamic mechanical analyzer. Tribological properties of the composites were evaluated by chase friction tester conforming to SAE J661a standard. An inverse relation between the storage modulus and wear has emerged, indicating wear to be mainly controlled by the fibre/filler matrix interfacial characteristics. Tribo-analysis reveals improvement in the friction fluctuations, whereas wear resistance deteriorates with increase in the ratio of flyash to resin content. Temperature-dependent reduction and revival of friction coefficient revealed the improvement in the average friction-recovery performance although the friction-fade response was found to be mostly unaffected due to compositional variation. SEM analysis is carried out to study the topography of the contact patches/friction film and associated wear mechanism of the phenolic-based composites, which has further revealed more of the secondary plateaus for composites containing more of the phenolic content. Disc rubbing intensity, as obvious from the energy-dispersive X-ray analysis (Fe content), becomes less prominent with increase in the ratio of flyash to resin content.