Evolution of tribologically induced chemical and structural degradation in hydrogenated a-C coatings

The coatings with gradually varying chemical composition and structure were obtained by PECVD method from methane precursor and various admixtures of Ar. The composition of emitted gases and triboemission behaviour were studied for these coatings and correlated with the coating properties and deposition conditions. A new analytical approach was developed that allowed identification of the emitted gas species with much higher accuracy than conventional techniques. For the first time, triboemission of alkanes higher than propane was observed. By the application of kinetic model to the analysis of triboemission time series, chemical and structural degradation in carbon coatings could be traced in course of tribological tests.