A novel strategy for improving tribological properties of a-C films in vacuum by Au doping and self-migration

This study reports a special interaction between Au nanoparticles and carbon dangling bonds in Au/amorphous carbon (a-C) composite films. Enlightened by this special interaction, a self-migration intelligent lubrication strategy is developed to overcome the lubrication failure of carbon films in vacuum. The special interaction enables Au atoms to be dispersed stably in the amorphous carbon network, but Au atoms to separate from the a-C phase and continuously self-migrate to the counterface under friction, eventually forming the as-reported Au-C friction pair that has excellent lubricating properties in vacuum. Moreover, the self-migrating and lubricating mechanisms are investigated through molecular dynamics simulations. The results will provide new ideas and approaches for designing intelligent lubrication materials and controlling the dangling bonds of carbon materials.