Mechanical properties and Raman spectra of a-C:H and a-C:H:N coatings

Disordered a-C:H and a-C:H:N layers with dispersed Ti atoms were prepared by d.c, unbalanced planar magnetron sputtering onto HSS substrates covered by titanium buffer. Chemical composition of films was determined by Rutherford backscattering analysis, structural aspects were studied by Raman spectroscopy. According to this, films prepared at temperatures higher than 400 degrees C may be classified as glassy carbon. The films exhibit very good overall adhesion and other mechanical properties, though results of mechanical experiments are rather peculiar and difficult to interpret: microhardness measurement gives unrealistic results because of pronounced cracking in the direction of indenter's diagonals and adhesion is influenced by coatings which are composed from titanium buffer and carbon film, i.e. they are bi- layered.