The effects of treatment by methane plasma source ion implantation (high voltage pulses of –20 kV, gas pressure around 1 Pa) on a carbide forming metal, tungsten, and a typical non carbide former, gold, were investigated. The influence of process time (0.5, 1 and 2 h) and repetition rates (1, 2 and 4 kHz) on composition, structure, hardness and tribological properties was studied. A gradient compositional layer in the implanted surface layer was confirmed by XPS and SIMS depth profile measurements for all treated samples. The amount and the depth of implanted carbon increased with the process time and repetition rate for each substrate. Additionally, the lateral homogeneity of the carbon implantation on the gold samples was checked by EPMA, since polycrystalline materials with a high sputter yield tend to exhibit lateral inhomogeneities.

The formation of metal-carbon chemical bonds was shown by the chemical shifts of the implanted carbon atoms and the W substrate atoms in the XPS measurements, as well as by GXRD results, with the amount of WC depending on the process conditions. Measurements of hardness and tribological surface properties of implanted and untreated samples were also performed.

Ruriko Hatada, TU Darmstadt, Materials Science, Germany
Stefan Flege, TU Darmstadt, Materials Science, Germany
Koumei Baba, Industrial Technology Center of Nagasaki, Japan
Wolfgang Ensinger*, TU Darmstadt, Materials Science, Germany

*presenting author