Structure and Properties of Protective Composite Zr-Mo-Si-B and Hf-Mo-Si-B Coatings Deposited by Spark Plasma Sintering

CZU 621.793/.795

DOI  https://doi.org/10.52577/eom.2025.61.2.01

Coatings in the Zr-Mo-Si-B and Hf-Mo-Si-B systems were obtained by spark plasma sintering (SPS) using heterophase powders ZrSi₂-MoSi₂-ZrB₂ and HfSi₂-MoSi₂-HfB₂, manufactured by the self-propagating high-temperature synthesis method. The Zr-Mo-Si-B and Hf-Mo-Si-B coatings were characterized by a thickness of 1.3–1.4 μm, had a dense structure and contained phases in wt.%: 61 o-ZrSi₂, 15 h-ZrB₂, 15 t-MoSi₂, 8 m-ZrO₂, 1 c-ZrB and 53 o-HfSi₂, 14 h-HfB₂, 19 t-MoSi₂, 9 m-HfO₂, 5 c-HfB, respectively. The coating hardness was 15-16 GPa, the elastic modulus was 265–268 GPa, and the elastic recovery was 38–39%. The Hf-Mo-Si-B coating was characterized by the minimum values of: a) reduced wear of 4.2∙10^-5 mm³N^-1m^-1 under sliding friction conditions, b) crater volume of 5∙10³ μm³ under impact-dynamic tests, and c) oxidation rate of <2.3∙10^-3 mg/(cm²∙s) at 1200°C. SPS coatings are superior to niobium substrates in wear resistance by ~25 times and oxidation resistance by several orders of magnitude.

Keywords: spark plasma sintering, coatings, ZrSi₂-ZrB₂-MoSi₂, HfSi₂-HfB₂-MoSi₂, mechanical and tribological characteristics, oxidation resistance.