Tribological properties of platinum/ruthenium/nitrogen doped diamond-like carbon thin films deposited with different negative substrate biases

The platinum/ruthenium/nitrogen doped diamond-like carbon (PtRuN-DLC) thin films were deposited on Si substrates via DC magnetron sputtering by varying negative substrate bias. The tribological performance of the PtRuN-DLC films was systematically investigated using ball-on-disc microtribological test. The Raman results showed that the increased negative substrate bias significantly increased the number of sp³ bonds in the PtRuN-DLC films as a result of the increased kinetic energies of impinging ions. The adhesion strength of the PtRuN-DLC films apparently decreased with increased negative substrate bias due to the promoted residual stress in the films. The tribological results clearly revealed that the increased negative substrate bias decreased the friction and wear of the PtRuN-DLC films by improving the sp³ bonded cross-linking structures of the films. It can be concluded that the PtRuN-DLC films could effectively prevent their underlying Si substrates from wear as the negative substrate bias had a significant influence on the tribological properties of the PtRuN-DLC films.