Tribological performance of a novel wide-temperature applicable a-C/(WC/a-C) film against M50 steel

To improve the wide-temperature applicability of amorphous carbon-based films, a novel a-C/(WC/a-C) film compositing of a-C nano-layers and super-latticed WC/a-C nano-multilayers was proposed and successfully fabricated on M50NiL substrate by an unbalanced magnetron sputtering system. For comparison, a monolayer a-C film and a super-latticed WC/a-C film were also prepared on the same substrates. The microstructures, mechanical properties and thermal stability of the as-deposited films were investigated. Particularly, the tribological behaviors of films against M50 counterpart were evaluated at the temperatures ranging from 25 °C to 350 °C. The results showed that because of the excellent thermal stability of super-latticed WC/a-C sublayers, the a-C/(WC/a-C) film has effectively overcome the poor tribological performance of a-C film at high temperatures (≥200 °C). While benefiting from the good toughness of a-C sublayers, the a-C/(WC/a-C) film showed significant better wear resistance than the WC/a-C film at the temperatures of 25–200 °C. The best wide-temperature applicability of the novel a-C/(WC/a-C) film should be attributed to the favorable mechanical properties, together with the formations of carbon-rich transfer film at 25–150 °C and WO₃-rich transfer film at 200–350 °C.