Structural and mechanical properties study of CNx/MoS2 multilayer coatings obtained by sputtering

Abstract

This work documents the study of samples of CNx/MoS2 multilayer coatings, deposited by magnetron sputtering technique, using 10% and 16% of N2 concentration in the Ar/N2 gas mixture to obtain two sample sets with different nitrogen concentrations in the CNx layers. The samples were grown on Si (100) and AISI 304 steel substrates to carry out different characterizations. The microstructure of the samples was investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM) and x-ray diffraction (XRD). The chemical structure and vibrational modes present in the multilayer coatings were evaluated using x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy, respectively. The analysis revealed that the CNx layers are amorphous, while the MoS2 layers show a polycrystalline structure with basal planes perpendicular to the substrate surface. Finally, the mechanical properties were evaluated by nanoindentation and pin on disk tests, respectively. The results revealed that the concentration of N in the CNx layer is fundamental in determining the mechanical properties. In the test carried out in a humid environment, the samples with the lowest concentration of N in the CNx layers present lower values in the coefficient of friction.