Integrated manufacturing of REciclable multi-material COmposites for the TRANSport sector

By van der Waals (vdW) composite (graphene/MoS2 etc.) nanopowder?to?heterojunction conversion under graphene edge?oxygen incorporation, a coexistent structure of nanoscale homojunctions and heterojunctions is formed on the grinding balls. Tunable, wide?temperature (?200 to 300 °C) and macroscale superlubricity (0.005) is achieved on diamond?like carbon surfaces by nanoscale vdW heterojunction?to?homojunction transformation unlike traditional incommensurability?to?commensurability theory.Achieving macroscale superlubricity of van der Waals (vdW) nanopowders is particularly challenging, due to the difficulty in forming ordered junctions before friction and the friction?induced complex contact restructuration among multiple nanometer?sized junctions. Here, a facile way is reported to achieve vdW nanopowder?to?heterojunction conversion by graphene edge?oxygen (GEO) incorporation. The GEO effectively weakens the out?of?plane edge–edge and in?plane plane–edge states of the vdW nanopowder, leading to a coexistent structure of nanoscale homojunctions and heterojunctions on the grinding balls. When sliding on diamond?like carbon surfaces, the ball?supported structure governs macroscale superlubricity by heterojunction?to?homojunction transformation among the countless nanoscale junctions. Furthermore, the transformation guides the tunable design of superlubricity, achieving superlubricity (µ ? 0.005) at wide ranges of load, velocity, and temperature (?200 to 300 °C). Atomistic simulations reveal the GEO?enhanced conversion of vdW nanopowder to heterojunctions and demonstrate the heterojunction?to?homojunction transformation superlubricity mechanism. The findings are of significance for the macroscopic scale?up and engineering application of structural superlubricity.

» Publication Date: 06/08/2023

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