Structure and Properties of Hard, Wear-Resistant Cr-Al-Si-B-(N) Coatings Obtained by Magnetron Sputtering of Ceramic Composite Targets

Hard Cr-Al-Si-B-(N) coatings were deposited in Ar and Ar–15%N2 medium by d.c. magnetron sputtering of composite targets manufactured using self-propagating high-temperature synthesis. The structure of the coatings was studied by X-ray diffraction, scanning and transmission electron microscopy, energy dispersion spectroscopy, and glow discharge optical emission spectroscopy. The coating properties were determined by nanoindentation, scratch testing, and tribological pin-on-disc testing at room and elevated temperatures. The oxidation resistance and diffusion barrier properties of the coatings were also evaluated. The results obtained showed that non-reactive coatings had a coarse crystalline structure and contained Cr5Si3, CrBx, and Cr2Al phases. The introduction of nitrogen into the coating composition promoted crystallite refinement and structural amorphization. Non-reactive CrAl4Si11B21 coatings had a maximum hardness up to 29 GPa and an elastic modulus up to 365 GPa. The introduction of nitrogen into the coating composition resulted in a 16–32% reduction in mechanical properties. The CrAl6Si12B5N25 coating, which exhibited maximal plasticity index H/E = 0.100 and resistance to plastic deformation H3/E2 = 0.247 GPa, was characterized by a minimum wear rate Vw = 5.7 × 10−6 mm3N−1m−1 and a friction coefficient of 0.47. While the CrAl18Si11B5N26 coating demonstrated a record level of oxidation resistance and successfully resisted oxidation up to a temperature of 1300 °C.