The improved mechanical and tribological properties of amorphous carbon film by doping boron carbide

Recently, we have reported that graphite-like tribolayers formed on the sliding interface is essential to low friction in nitrogen for amorphous carbon-based (a-C) films with low hydrogen content. Therefore, for hydrogen free a-C film, it is necessary to promote the formation of graphite-like tribolayers for friction reduction. Borides has been proved an effective graphitization catalyst that accelerates the graphitization process of different carbon materials, yet has not been tried for a-C film under friction. Here, we fabricated the a-C and B4C doped a-C (B4C/a-C) films on 304 stainless steel substrates by unbalanced magnetron sputtering equipment. Compared to a-C film, B4C/a-C film exhibited better mechanical properties, as well as superior lubrication performance. Therein, the improved mechanical properties of B4C/a-C film are favorable for the excellent wear resistance. Besides, the friction reduction of B4C/a-C film is attributed to catalytic graphitization of tribolayers formed on the sliding interfaces triggered by B4C. This work indicates that B4C/a-C film will become an alternative solid lubricant material for a wide range of applications in the mechanical engineering fields.