Oxidation-Resistant Coatings Based on High-Entropy Alloy (MoTaNbZrHf)SiB with Increased Silicon Content, Deposited by Magnetron Sputtering

In this work, the following coatings were obtained by magnetron sputtering of (MoTaNbZrHf)SiB and SiBC targets: single-layer (MoTaNbZrHf)SiB, double- and multilayer (MoTaNbZrHf)SiB/SiBC, and nanocomposite (MoTaNbZrHf)-Si-BC coatings. Particular attention was paid to studying the effect of increased silicon content on the structure and oxidation resistance of developed coatings. Results showed that single-layer and nanocomposite coatings have a homogeneous structure with a uniform distribution of elements across the thickness. Double- and multilayer coatings contained (MoTaNbZrHf)-Si-B/Si-B-C layers with a thickness of 9.1/3.9 and 1.7/0.6 μm, respectively. Introduction of additional silicon-containing phases into the composition of (MoTaNbZrHf)-Si-B coatings led to a decrease in the specific mass change from –3.1 to 0.15–0.20 mg/cm² at a temperature of 1000°C. Annealing at a temperature of 1500°C showed that the double-layer (MoTaNbZrHf)-Si-B/Si-B-C coatings have a minimum oxide layer thickness of 9.2 μm and a specific mass loss of 0.95 mg/cm², which is 1.5 and 1.8 times lower than the values obtained for the single-layer (MoTaNbZrHf)-Si-B coating. At 1600°C, the single-layer (MoTaNbZrHf)-Si-B coating was completely oxidized, while the double- and multilayer (MoTaNbZrHf)-Si-B/Si-B-C coatings were partially preserved, which is due to the high silicon content in their composition.