Structural, mechanical and tribological properties of ZrC thin films deposited by magnetron sputtering

In the present study, thin coatings of ZrC were deposited by reactive pulsed magnetron sputtering of a zirconium target in an Ar + C2H2 atmosphere on HS6-5-2 steel substrates, and their phase composition, microstructure, coating chemistry, mechanical and tribological properties were studied. The phase composition and microstructure were studied using standard techniques such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The surface chemistry of the coatings was analysed by using a surface sensitive X-ray photo-electron spectroscopy (XPS). The experimental results were also compared with the results of the ZrC coatings produced using a reactive atmosphere of Ar + CH4 obtained by other authors. In particular, a correlation between the phase composition, microstructure, mechanical and tribological properties of the ZrC coatings is developed and discussed here. Carbon appears in these coatings as an amorphous structure with a high fraction of sp(2) bonds and the share of this phase in the coating grows with an increase of the total carbon concentration. Results reveal rather narrow range of carbon concentrations near 50 at. %, in which the coatings are characterized by the maximum values of hardness and Young's modulus.