Tribological performance of metal doped diamond-like carbon films deposited by cathodic arc evaporation

Abstract

Abstract Diamond-like carbon (DLC) films were synthesized using a cathodic arc evaporation (CAE) process. Energetic Cr plasma with intensive ion energy activates the decomposition of C 2 H 2 and deposits an amorphous carbon film containing a mixture of sp 2 and sp 3 carbon bonded structures which result in a DLC film of 3824 Hv(25 g) microhardness. The Cr metal inclusion and ion bombardment aid in stress release and increase of film density. Both Raman and electron energy loss spectroscopy (EELS) identified the formation of DLC films. The Raman G peak shifts from the 1580 cm −1 of pure graphite to 1550 cm −1 for DLC. EELS depicts the characteristic carbon-K edge, bearing an amorphous DLC signature feature. A residual peak at 282 eV demonstrates the inclusion of sp 2 graphite-like carbon bonds in the DLC matrix. The CAE synthesized DLC film possesses an apparent adhesion strength of 55 N. Premature chipping occurs at a very early stage in the scratch test. However, the damaged DLC film continuously provides lubrication with low friction resistance. We speculate on a DLC–graphite transformation, which supplies graphite as a solid lubricant to reduce the friction resistance. The pin-on-disk wear test demonstrates an excellent wear performance of 3000 m of wear endurance tested under 10 N at 0.3 m/s.