Carbon surface modifications during sliding test and friction behavior of carbon thin films against XC 48 steel

Abstract

The anisotropic properties of carbon due to sp 2, sp 3, and π bonds can lead to different carbon surfaces with different chemical, mechanical and tribological properties. This paper reports on fundamental friction and wear mechanisms of graphite, diamond and carbon coatings: diamond-like carbon (DLC) with nanophase diamond structure, amorphous carbon (a-C) corresponding to graphite and diamond structure, amorphous hydrogenated carbon films (a-C:H) with more graphite, and amorphous diamond film (a-D) obtained by ablation laser of the diamond structure. The friction coefficients μ of carbon and carbon coatings can be varied by a factor of 50 ( μ=0.02–1) and the wear rate by factor of 10 2–10 4 according to the nature of the carbon film, the tribocontact environment, and the temperature. A compilation of the last 10 years' published studies on the mechanical and tribological behavior of different carbon coatings will be presented and discussed in order to specify the tribological film behavior according to its nature and mechanical properties. The transition phenomenon from mild wear to severe wear is investigated for each rubbing surface. Many surface structural modifications occur during friction. Scanning electron microscopy, X-ray analysis and diffraction electron microscopy analyses of the sliding surface will be presented and discussed.