Manufacturing and Tribological Behavior of Self-Lubricating Duplex Composites: Graphite-Reinforced Polymer Composites and Polymer-Infiltrated Metal Networks

Self-lubricating duplex composites comprising a top layer of polymer-based composites, i.e. bismaleimide (BMI) filled with a wide range of graphite (Gr) content (0-55 wt.%), and a bottom layer of infiltrated metal networks were manufactured by a hot compression-molded method. Melting points and polymerization temperatures of as-received BMI powder and BMI + Gr blends were investigated to determine infiltration process. The polymerization peaks move to higher temperatures with increase in graphite content. For cured polymer composites, the hardness measured by nanoindentation keeps increasing with graphite content without degradation up to 55 wt.%. Tribological performance of the top and bottom composites was examined individually, with focus placed on the development and stability of lubricating transfer film and tribofilm. For the top polymer composites, 25 wt.% Gr (or equivalently 17 vol.%) is sufficient to form lubricating transfer film and reduces the friction to the lowest similar to 0.15. For the bottom infiltrated metal networks, the BMI + 55% Gr-infiltrated network is adequate to develop fully covered transfer films and achieve low friction throughout the test. Those results shed lights on design and manufacturing of self-lubricating polymer matrix composites on metallic components that undergo severe running conditions.

Automated summary

Self-lubricating duplex composites consisting of a top layer of polymer composites and a bottom layer of infiltrated metal networks were produced with varying graphite content, showing that the graphite content affects the performance of the graphite composites and providing insights into the design principles for manufacturing self-lubricating polymer matrix composites.