Friction and wear in sliding contact of cast iron against phenolic resin composites reinforced with carbonaceous fibers from plantain fiber bundles

The tribological behavior of novolac phenolic resin matrix composites reinforced with carbonaceous fibers was studied. The carbonaceous fibers were obtained from Colombian plantain crops residues by slow pyrolysis, through a process that allows retaining many morphological aspects of the natural fibers. The aim of this study is to determine the effect of this kind of carbonaceous fibers as a potential reinforcement or lubricant filler for tribological applications. Novolac phenolic resin with HMTA as curing agent and carbonaceous fibers obtained by slow pyrolysis of leaf sheaths plantain fibers from Urabá-Colombia, were used to obtain a composite material by compression molding process. Composite samples with different fiber volume fractions were tested in sliding contact against cast iron in a pin-on-disc wear testing machine equipped with a load cell for on-line measurement of friction force. At the end of the tests, the worn surfaces and the debris were analyzed in SEM. A decrease in friction coefficient and wear of composites was observed with the increase in fiber volume fraction, which was associated to a beneficial effect of the detachment of carbonaceous material from the worn surface. Under the tested conditions, this material remains at the interface between the composite and the cast iron, and acts as a solid lubricant. On the other hand, surface fatigue was identified as the dominant wear mechanism of the phenolic matrix.