Deposition of chromium nitride coatings using vacuum arc plasma in increased negative substrate bias voltage

• CrN coatings deposited on front and reverse side of substrates.
• Number of macroparticles on the front side is three times higher than on the reverse.
• The macroparticles embedded on the reverse side are statistically larger.
• Increase in substrate bias voltage reduces the roughness surface of the coatings.

The deposition methods of thin films which allow to obtain good quality coatings are still being developed. The paper presents a particular influence of the substrate bias voltage on the results of the deposition of chromium nitride coatings on HS6-5-2 steel substrates on the front and reverse side of the substrates with respect to the cathode by cathodic arc evaporation. The deposition was carried out at a fixed nitrogen pressure amounted to 3.0 Pa and the negative substrate bias voltages: 70, 150, 300 V. The difference in the deposition rate, phase and chemical composition, amount and dimensional distribution of macroparticles and surface roughness were studied and analyzed. It was found that the coatings obtained on the reverse side of the substrate were characterized by a nearly 3-times smaller amount of surface defects, more than twice the lower surface roughness and similar chemical composition as the coatings deposited on the front side of the substrate. The measurements have also shown that the hardness of the coatings obtained on both sides of the substrate is comparable, and decreases with increasing the negative substrate bias voltage.