Effect of substrate bias on the properties of DLC films created using a combined vacuum arc

The results of the research on the formation of amorphous diamond-like carbon (DLC) thin films from unfiltered plasma flow generated in the combined vacuum-arc are presented in the article. The films were deposited on silicon (Si 100) and high-speed steel substrates at the negative substrate bias potential over 0 to –500 V range. The dependence of the physical and mechanical properties of thin DLC films on the substrate bias voltage were investigated using profilometry, scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy, nanoindentation testing and scratch tests. The SEM studies have shown that the negative substrate potential significantly affects the thickness and roughness of the synthesized DLC films, regardless of the substrate material. The obtained results on the structure and mechanical properties of the films show that amorphous carbon coatings synthesized at negative substrate potential values of –100 and –125 V have the smallest ID/IG ratio and the highest internal stress values, and also have the best mechanical properties—hardness of 57 GPa and elastic modulus of 580 GPa.