Einsatz des Rastertunnelmikroskops und des Rasterkraftmikroskops zur Untersuchung von amorphen Metall-Kohlenstoff-Nanocompositschichten. Abschlußbericht zum Projekt der Volkswagenstiftung

Metal containing amorphous hydro-carbon films are protective coating materials with very low friction, high hardness and wear resistance, combined with an adjustable electrical conductivity. The structure of these films, consisting of nanometer size metallic particles in a hydro-carbon matrix, was investigated by means of scanning tunneling microscopy /atomic force microscopy (AFM/STM), transmission electron microscopy (TEM), small angle x-ray scattering (SAXS), x-ray diffraction (XRD), electron probe microanalysis (EPMA), secondary ion mass spectroscopy (SIMS) and tribological tests (friction, wear). Structur analytical methods (STM, TEM, SAXS, XRD) were used to investigate size- and distance distributions of the metallic particles of Au-, Pt-, W- and Fe containing films, with the point of main effort on the scanning probe techniques. Sample surfaces were cleaned by plasma etching methods and special procedures were developed to compensate for tip convolution effects in size and dista nce determination by STM. Barrier hight images (dI/dz) were used to distinguish the metallic particles and the amorphous hydro-carbon matrix. Friction force microscopy (FFM) was used to get high resolution frictional images of the surfaces. Friction coefficients were determined as a function of metal content in the film on submicron areas and were compared with macroscopic frictional tests showing resonable agreement. Micro-wear tests were performed with a diamond tip (AFM) and the dependence of wear on load and numer of revolutions was compared with theoretical wearmodels. Material fatigue could be found as one important wear mechanism dependeing on the metal content and kind of metal in the film