A Comparative Study of Different Poly (Lactic Acid) Bio-Composites Produced by Mechanical Alloying and Casting for Tribological Applications

The aim of this study was to fabricate different self-lubricating poly (lactic acid)-based bio-composites reinforced with mono- and multi-fillers of carbon fibers, graphene nanoparticles, and a soft Sn-based brazing alloy (Sn89-Zn8-Bi3) using a two-step process consisting of mechanical alloying followed by casting. The results showed that the incorporation of the different fillers on the PLA surface by mechanical alloying was quite homogenous. The volume ratio between the PLA and the fillers was 1:0.02, respectively. The PLA sample reinforced with short carbon fibers and graphene nanoparticles presented the highest hardness (84.5 Shore D, corresponding to a 10% increase compared to PLA) and the lowest specific wear rate (1.5 × 10(−4) mm(3)/N·m, one order of magnitude lower than PLA). With regard to the coefficient of friction, the lowest value was obtained for the sample reinforced with graphene (0.43, corresponding to a decrease of 12% compared to PLA).