Structural and mechanical properties of niobium-containing amorphous hydrogenated carbon films (Nb-C:H)

Metal containing amorphous carbon films show excellent tribological properties with improved adhesion on metal substrates. By varying the kind of metal and the metal content in the films physical properties like optical absorption, electrical conductivity and mechanical properties can be changed. In order to get insight into the factors influencing the abrasive wear behavior, structural and mechanical investigations were performed on Nb-C:H. Films with metal contents between 0 and 50 at % Nb were prepared in a combined plasma- CVD/RF-sputtering process using different hydrocarbon gases and various total pressures. Atomic concentrations were properties of the NbC precipitation. The microstructure of the films revealed a granular structure of nanocrystalline NbC particles embedded in a matrix of highly crosslinked CHsubx-units. Mechanical properties were investigated by nanometer indentation, flexural strength, residual stress, friction coefficient and abrasive wear measurements. The res ults of the investigations are discussed in terms of the relations between fundamental mechanical properties, tribological behaviour and the film microstructure.