The Influence of Nitrogen Flow Rate on the Structure and Properties of Mo-Hf-Y-Si-B-N Coatings

Abstract

This work is devoted to the production of Mo-Hf-Y-Si-B-N coatings using magnetron sputtering with varying N2 flow rate; the analysis of magnetron discharge plasma; and the investigation of the structure, and optical, mechanical, and tribological characteristics, as well as crack resistance and oxidation resistance, of the coatings. The results show that Mo-Hf-Y-Si-B-N coatings were characterized by a dense, homogeneous structure. The non-reactive coatings had a maximum growth rate of 270 nm/min. An increase in the flow rate of N2 from 0 to 37.5 sccm led to a decrease in the growth rate by 5.4 times. Mo-Hf-Y-Si-B-N coatings were X-ray amorphous. In non-reactive coatings, the presence of Mo-Si and Mo-B bonds was revealed. The introduction of nitrogen contributed to the formation of an additional Si-N bond, an increase in the proportion of which led to an increase in transmittance. The Mo-Hf-Y-Si-B coating was characterized by a hardness value of 14 GPa. The maximum hardness of 16 GPa was observed in coatings obtained at nitrogen flow rates of 12.5 and 25.0 sccm. A further increase in the consumption of N2 to 37.5 sccm led to a decrease in hardness by 38%. The coating obtained at a flow rate of 25 sccm N2 was characterized by maximum elastic recovery of 57%, elastic strain to failure of 0.098, and resistance to plastic deformation of 0.157 GPa. An increase in nitrogen flow rate from 0 to 12.5 sccm contributed to a decrease in the wear rate of coatings under sliding friction conditions by 40%. The non-reactive Mo-Hf-Y-Si-B coating had the best oxidation resistance at 1000 °C.

Keywords

• MoSi₂-based coatings
• magnetron sputtering
• structure and phase composition
• mechanical properties
• oxidation resistance