A Strategy to Construct Long-Range Fullerene-Like Nanostructure in Amorphous Carbon Film with Improved Toughness and Carrying Capacity

This study demonstrates a novel strategy to construct long-range fullerene-like nanostructures in amorphous carbon films, which we called the 'external-field-induced growth effect', i.e. using the target poisoning phenomenon in the magnetron sputtering process and adjusting the target as Ni catalytic material. A fullerene onion precursor can be first produced at an external sputtering target surface through the synergistic catalytic effects of both the Ni catalyst and plasma, and then the fullerene precursor was further sputtered to form fullerene-like nanostructured carbon film with optimized sputtering current, which consists of cross-linked open-loop fullerene sheets with huge amounts and long range sizes. Such a special structure endows the film great toughness and carrying capacity without sacrificing high hardness, so that it has no cracks at high contact stress (maximum Hertz contact stress: 21 GPa), and can work well at high contact stress (maximum Hertz contact stress: 3.2 GPa) with still long wear lifetime similar to that observed at low contact stress, which means it can be reliably applied in high-load conditions, and provides a new way to resolve the brittleness problem of amorphous carbon films by adjusting intrinsic carbon nanostructure.