The oxidation resistance under LOCA conditions of bilayer Cr/Mo coating deposited on Zr-1Nb zirconium alloy was investigated in this paper. The bilayer Cr (8 μm)/Mo (3 μm) coatings were deposited by magnetron sputtering. Then, oxidation resistance under high-temperature oxidation at 1200–1400 °C in a water steam was studied. The use of a Mo sublayer resulted in limiting Cr-Zr interdiffusion under high-temperature oxidation. It was shown that the Mo barrier sublayer (~3 μm) can provide the protective behavior of the Cr/Mo-coated Zr at 1330 °C in a water steam for at least 720 s. The weight gain of the bilayer Cr/Mo samples was comparable with the monolayer Cr samples after oxidation at 1400 °C. In addition, the analysis of the Cr/Mo-coated Zr alloy oxidation behavior at 1400 °C was carried out.

This article describes the oxidation resistance of laser beam welds made from E110 zirconium alloy with a chromium coating obtained using multi-cathode magnetron sputtering. Oxidation tests of the welded Zr alloy without and with Cr coating were performed in an air atmosphere at 1100 °C for 2–90 min. Then, analysis of their cross-section microstructure in different regions (weld, heat-affected, and bulk zones) was done using optical microscopy. Hardness measurements and three-point bending tests demonstrated the hardening of the Cr-coated welded Zr alloy after the oxidation that is discussed in the article. Brittle fracture behavior was observed for uncoated Zr weld even after a short period of high-temperature oxidation.

New metal–ceramic laminated composites Ta/Ti₃Al(Si)C₂–TiC were obtained by spark plasma sintering. The samples were synthesized at a temperature of 1250°C and a pressure of 50 MPa for 5 min. For formation of the composites, preceramic paper with a powder filler based on the MAX phase of Ti₃Al(Si)C₂, as well as metal foils made of tantalum, were used. The phase composition, microstructure, and elemental composition were analyzed by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy, respectively. It was found that as a result of sintering, dense multilayer composites were formed, consisting of tantalum metal layers, ceramic layers containing Ti₃Al(Si)C₂, TiC, and Al₂O₃ phases, as well as reaction layers ~13 μm thick at the metal–ceramic interface enriched with Ta, Al, and Si. Based on the mechanical test data, the ultimate bending strength of the obtained composites was determined (σ_bs = ~430 MPa). Metal–ceramic laminated composites with a refractory tantalum layer were shown to exhibit a ductile fracture mechanism accompanied by a more than fourfold increase in absolute deformation compared to a Ti₃Al(Si)C₂-based ceramic composite. This is achieved due to deflection, branching of cracks at the metal–ceramic interface, and plastic deformation of tantalum layers.

New metal–ceramic laminated composites Ta/Ti3Al(Si)C2–TiC were obtained by spark plasma sintering. The samples were synthesized at a temperature of 1250°C and a pressure of 50 MPa for 5 min. For the formation of composites, preceramic paper with a powder filler based on the MAX phase Ti3Al(Si)C2, as well as and metal foils made of tantalum, were used. The phase composition, microstructure and elemental composition were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. It was found that as a result of sintering, dense multilayer composites were formed, consisting of tantalum metal layers, ceramic layers containing Ti3Al(Si)C2, TiC and Al2O3 phases, as well as reaction layers ~13 μm thick at the metal–ceramic interface, enriched with Ta, Al and Si. Based on mechanical test data, the ultimate bending strength of the obtained composites was determined (σbs = ~430 MPa). Metal–ceramic laminated composites with a refractory tantalum layer were shown to exhibit a ductile fracture mechanism, accompanied by a more than fourfold increase in absolute deformation compared to a Ti3Al(Si)C2-based ceramic composite. This is achieved due to deflection, branching of cracks at the metal–ceramic interface and plastic deformation of tantalum layers.

The effect of the crystal structure of the Mo sublayer on the resistance of the zirconium alloy Zr–1Nb with a Cr/Mo coating to high-temperature oxidation in air is studied. Three types of coatings are deposited by magnetron sputtering: single-layer Cr coating with a thickness of 8 µm and two-layer coatings with a sublayer of Mo (3 µm) of various textures and an outer protective layer of Cr (8 µm). Different textures of molybdenum films are formed by changing the configuration of the magnetron-sputtering system. Coated samples are oxidized in an atmospheric oven at 1100°C for 15, 30, 45, and 60 min. The results of X-ray-diffraction- and scanning-electron microscopy show that the use of a Mo sublayer limits the mutual diffusion of the Cr–Zr system. The diffusion of Mo leads to the formation of interdiffusion layers of Cr–Mo and Mo–Zr. Faster diffusion is observed at the Cr–Mo interface. The thickness of the residual Cr layer in two-layer coatings is greater than that in a single-layer coating under similar oxidation conditions.