Effect of nitrogen concentration in a gas mixture on the structure and properties of Zr–B–(N) coatings obtained by the HIPIMS method

Abstract

In this work, Zr–B–N coatings were obtained by the method of high-power impulse magnetron sputtering (HIPIMS) in Ar, Ar + 15%N2, and N2 gaseous media using a ZrB2 SHS target. Sputtering was carried out at the following parameters: medium power of 1 kW, peak power of 70 kW, peak current of 130 A, frequency of 100 Hz, pulse duration of 200 μs. The working pressure in the vacuum chamber was 0.1–0.2 Pa, the distance between the substrate and the target was 80 mm, and the coating deposition time was 40 minutes. Glass, silicon, and high-speed steel were used as substrates. For comparison with the HIPIMS method, the coatings were also applied by direct current magnetron sputtering (DCMS) at an average power of 1 kW. The composition and structure of the coatings were studied by scanning electron microscopy (SEM), glow discharge optical emission spectroscopy (GDOES), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The mechanical, tribological and optical properties of Zr–B–N coatings, as well as resistance to impact dynamic loading, were studied. All coatings were characterized by a dense structure and the absence of columnar grains. With the help of spectroscopic structural studies of coatings, it was revealed that during deposition in a reaction medium, the BN phase is formed, which has a significant effect on the microstructure and characteristics of the coatings. An increase in the nitrogen concentration in the gas mixture during the deposition of Zr–B–N coatings led to an increase in the optical transmittance of the coatings up to 97 %, resistance to cyclic impact dynamic loads by 40 %, and a decrease starting value of friction coefficient by 60 %. The non-reactive coating had a maximum hardness of 19 GPa and an elastic modulus of 221 GPa.