Effects of Dopants on Scratch Responses of Diamond-Like Carbon Films by Rockwell C Diamond Indenter

Micro-scratch responses of diamond-like carbon (DLC) films deposited with different dopants (i.e., Si, Cr, and H) were investigated by Rockwell C diamond indenter under progressive normal load linearly increasing from 5 mN to 15 N. Three critical loads can be identified from residual scratch morphology according to different periodic and symmetrical damage patterns. The results under small loads show: The addition of H can enhance normal contact and residual hardness of DLC films. Fracture toughness of both film and film/substrate system can be quantified by scratch-based linear elastic fracture mechanics. H-DLC film exhibits the smallest fracture toughness, and Si-DLC and Cr-DLC films have larger fracture toughness and critical loads than pure DLC film.