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(TiZrNbTa)Nx films were fabricated at various nitrogen flow ratios (RN2) through reactive direct current magnetron co-sputtering. The structural, mechanical, and anticorrosive properties of the (TiZrNbTa)Nx films were explored. The metallic TiZrNbTa film formed a body-centered cubic phase, and the film (N05) deposited at RN2 = 5% exhibited a nanocrystalline structure consisting of close-packed hexagonal and face-centered cubic (FCC) phases. In contrast, the films prepared at RN2 > 10% demonstrated an FCC phase. The N05 film has hardness and elastic modulus of 23.5 and 220 GPa, respectively, the highest hardness and relatively lower elastic modules among the studied nitride films. Moreover, the N05 film has the highest polarization resistance of 198 kΩ·cm2 measured by the potentiodynamic polarization method. The chemical states of the (TiZrNbTa)Nx films were examined by X-ray photoelectron spectroscopy.

In this study (NbTaMoW)Nx films were fabricated through reactive co-sputtering using four pure-element targets at various nitrogen flow ratios (RN2). It was also explored the phase structures, mechanical properties, and corrosion resistance properties of these films. The results indicated that the stoichiometric ratio x of the (NbTaMoW)Nx films increased with increasing RN2, accompanied by body-centered cubic metal phases transformation to face-centered cubic covalent nitride phases. These face-centered cubic phases were classified into phases with M2N-dominant and phases with MN-dominant structures. The results also indicated that the (NbTaMoW)Nx films prepared at RN2 values of 0.2–0.4 exhibited high hardness and Young's modulus values of 29.3–31.7 and 333–396 GPa, respectively. Using potentiodynamic polarization and electrochemical impedance spectroscopy, it was determined that the corrosion resistance of the SUS420 substrate was effectively improved with the deposition of one nitrogen-free NbTaMoW film and four nitrogen-containing (NbTaMoW)Nx films. It was also observed the highest corrosion resistance in the (Nb0.16Ta0.29Mo0.32W0.23)N0.07 film because of its dense microstructure.

In this study, NbTaMoW medium-entropy alloy films were prepared using a cosputtering apparatus with four sputter guns. Pure-element targets were used for sputtering. The rotational speeds of the substrate holder (RS) were 1–30 rpm. Lower RS values resulted in the formed films exhibiting a multilayer stacked structure with a cyclical gradient concentration. The crystalline phases, mechanical properties, and oxidation behavior of the prepared NbTaMoW films were investigated. The uniformity of the prepared multilayered alloy films increased with the RS value. The monolithic NbTaMoW alloy films prepared at 30 rpm exhibited a single body-centered cubic (BCC) phase, hardness of 12.9 GPa, and Young's modulus of 278 GPa. The BCC phase evolved into a combination of multiple BCC phases when RS was

In this study, the feasibility of using ZrO2 coatings, fabricated through the atmospheric pressure plasma jet technique, as top coats in thermal barrier systems was explored. Inconel 617 was used as the substrate material, and sputtered laminated RuAl/RuAlZr/Ru was used as the bond coat. >20-μm-thick ZrO2 coatings were deposited through several iterations of deposition at 500 °C and annealing at 600 °C; here, ZrO2 existed in the tetragonal phase. The tetragonal ZrO2 was stable after annealing at up to 700 °C but transformed into a mixture of tetragonal and monoclinic ZrO2 phases when annealed at >800 °C. The thermal stability of the ZrO2/RuAl/RuAlZr/Ru/Inconel 617 assembly was evaluated at 800–900 °C in air. The variations in volumetric fractions of the tetragonal and monoclinic ZrO2 phases were recorded; 44% of the tetragonal phase remained after 100 h of annealing at 800 °C, whereas 80% of the tetragonal phase had transformed into the monoclinic phase after 4 h of annealing at 900 °C. Observation of BC after annealing at 800 °C indicated that a dense thermally grown oxide scale, comprising O and Al, formed between the ZrO2 and RuAl layers, which impeded the inward diffusion of O. The inhibition of O diffusion declined with the crystallization of the thermally grown oxide scale into the δ-Al2O3 phase when the annealing time was extended.