The influence of substrate bias voltage on the morphology and properties of ZrN coatings deposited by magnetron sputtering

The substrate bias voltage (U B ) plays an important role in the coating formation processes using the Physical Vapor Deposition method and affects the morphology of the coatings as well as their physical properties, microhardness, elastic modulus, stresses, as well as the structure and phase composition, microstructure or density. To characterize ZrN coatings formed by magnetron sputtering at substrate bias voltages from –10 V to –100 V, X-ray diffraction (phase composition), scanning electron- and atomic force microscopy (for surface morphology and distribution of macroparticles on the coating surface, tribological properties), and nanoindentation (for microhardness and elastic modulus) were used in the study. With the increase in the negative substrate bias voltage, an increase in the intensity of the ZrN (200), (220) and (222) diffraction lines was observed relative to the ZrN (111) line. The roughness of the coatings decreased with the increase in the negative substrate bias voltage. The highest microhardness, 30.6 GPa, was measured for coatings formed at U B = –50 V. The coating deposited at –100 V showed low wear resistance (due to the low H/E coefficient, showing low elastic behavior of the coating under load). Multi-cycle tribotests were additionally performed on the coating that were deposited at –10 V and showed high wear resistance , with changes in speed (1.99–8.00 μm/s), number of cycles (from 10 to 50) and load (from 8 to 27 μN). The obtained results can be used in developing wear-resistant coatings for friction units of various devices in mechanical engineering and instrument making, power engineering, and transport.