Effect of bias voltage on microstructure and mechanical properties of nanocomposite ZrCN films deposited by filtered cathodic vacuum arc

Nanocomposite ZrCN films consisting of nanocrystalline ZrCN grains embedded in nitrogen-doped amorphous carbon film are deposited by filtered cathodic vacuum arc technology under different bias voltages ranging from 50 to 400 V. The influence of bias voltage on the characterization and the mechanical properties of the ZrCN films are investigated by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and nano-indentation. The bias voltage has a subtle effect on the ZrCN grain size, which is around 9.5 nm and keeps almost constant. A slight increase of the bias voltage induces a relatively high sp 3 fraction about 40% in N-doped amorphous C films but leads to the graphitization of the films under a higher voltage. The best mechanical property of the ZrCN film with the hardness of 41 GPa is obtained under the bias voltage of 200 V, indicating the positive effect of slight increase of ion bombardment on the hardness of the films.