STRUCTURAL AND MECHANICAL-PROPERTIES OF NIOBIUM-CONTAINING AMORPHOUS HYDROGENATED CARBON-FILMS (NB-C-H)

The mechanical and microstructural properties of Nb-containing amorphous hydrogenated carbon films were determined with complementary techniques. For the characterization of the mechanical behaviour the residual stress, the abrasive wear, the film hardness and Young's modulus (using a nanometer indenter), and the fracture strain were measured. One of the most striking results is a substantial minimum in the abrasive wear of the Nb-C:H films for 10-20 at.% metal concentration. X-ray diffraction techniques (wide angle as well as small angle diffraction) and X-ray photoelectron spectroscopy revealed a granular structure of the Nb-C:H films with precipitated clusters (2-4 nm diameter) of cubic NbC surrounded by a metal-free a-C:H matrix.