The comparison of structure and properties in DC magnetron sputtered and HiPIMS W-C:H coatings with different hydrogen content

The comparison of the structure, composition, hardness and friction behavior of DCMS and HiPIMS W-C:H coatings made by hybrid reactive deposition in the presence of C2H2 and H2 in Ar atmosphere revealed a transition from textured to columnar-like structures with the increased addition of acetylene in DCMS coatings whereas only amorphous-like structures were produced by HiPIMS. The hybrid sputtering involves acetylene and hydrogen dissociation and recombination reactions in the plasma resulting in the generation of carbon as well as –CH3 and =CH2 radicals which are chemisorbed at the growing coating surface. The concentration of hydrogen in carbon matrix seems to be controlled by –CH3 and =CH2 radicals and not by the amount of molecular hydrogen. The main advantage of HiPIMS compared to DCMS technology includes coefficients of dry friction below 0.1 attributed to the formation of lubricious transfer layer at moderate level of hardness (around 20 GPa) over the studied acetylene additions range. Hybrid HiPIMS technology seems to offer possibilities for substantial COF decrease without hardness degradation which results in widening of the potential of W-C:H coatings for practical engineering applications.