Structure, Mechanical Properties, and Oxidation Resistance of ZrB2, ZrSiB, and ZrSiB/SiBC Coatings

Abstract

ZrB₂, ZrSiB single-layer coatings, and ZrSiB/SiBC multilayer coatings have been fabricated by magnetron sputtering. The coating structure is studied by X-ray powder diffraction analysis, scanning electron microscopy, and glow-discharge optical emission spectroscopy. The mechanical properties of the coatings are identified by nanoindentation. The oxidation resistance and thermal stability of the coatings are studied in the temperature range of 600–1200°C. Doping the ZrB₂ single-layer coatings with silicon reduces the grain size of the hexagonal ZrB₂ phase from 8 to 2 nm. Application of silicon-containing layers results in complete amorphization of the structure of ZrSiB/SiBC multilayer coatings. The ZrB₂ coatings are found to possess the best mechanical properties: hardness of 37 GPa, Young’s modulus of 400 GPa, and elastic recovery of 73%. The ZrSiB coatings are characterized by the highest oxidation resistance: they resist oxidation at temperatures up to 1500°C due to the formation of a protective SiO₂-based film on their surface.