Thickness-dependent structure and properties in zirconium carbide ceramic via orientated deposition

Abstract

The fine-tuning of controlled structure and property evolution of zirconium carbide (ZrC) ceramic is essential for its functional applications, especially with insufficient understanding of the size effect mechanisms. In this investigation, the physically vapor-deposited ZrC (PVD-ZrC) ceramic was fabricated through magnetron sputtering, with a specific focus on its thickness-dependent growth and evolution of composition, microstructure, growth texture and mechanical properties. As prepared PVD-ZrC presents a hybrid structure characterized by amorphous carbon and nanocrystalline ZrC, with diversity in crystallinity, crystallite size, and growth pattern determined by target power, gas-flow pressure and substrate temperature. Moreover, the PVD-ZrC ceramic deposited by directional deposition, exhibits a structure transition from equiaxed crystals to dense columnar fiber crystals and an isotropy-toward texture. As the thickness increases, the stress gradually shifts towards tensile stress with a weaker fracture toughness. Through the First-principle calculation, it is illustrated that the mechanical properties of bulk polycrystalline ZrC are evidently different from low-dimensional polycrystalline ZrC film. This mechanism of thickness-dependent structure and properties is dominant by the surface effect, size effect, grain boundary effect, and stress effects.