A series of the multicomponent thin films (binary: Ti-C; Ti-Ag and ternary: Ti-C-Ag; Ti-C-Al) were fabricated by Thermionic Vacuum Arc (TVA) technology in order to study the wear resistance and the anticorrosion properties. The effects of Ti amount on the microstructure, tribological and morphological properties were subsequently investigated. TVA is an original deposition method using a combination of anodic arc and electron gun systems for the growth of films. The samples were characterized using scanning electron microscope (SEM) and a transmission electron microscope (TEM) accompanied by selected area electron diffraction (SAED). Tribological properties were studied by a ball-on-disc tribometer in the dry regime and the wettability was assessed by measuring the contact angle with the See System apparatus. Wear Rate results indicate an improved sliding wear behavior for Ti-C-Ag: 1.31 × 10−7 mm3/N m (F = 2 N) compared to Ti-C-Al coating wear rate: 4.24 × 10−7 mm3/N m. On the other hand, by increasing the normal load to 3 N an increase to the wear rate was observed for Ti-C-Ag: 2.58 × 10−5 mm3 compared to 2.33 × 10−6 mm3 for Ti-C-Al coating.
Autonomous smart natural ventilation systems (SVS) attached to the glass façade of living quarters and office buildings can help reducing the carbon footprint of city buildings in the future, especially during warm seasons and can represent an alternative to the conventional mechanical ventilation systems. The work performed in this manuscript focuses on the investigation of bacteria trapping and killing efficiency of stainless steel grids coated with a mixed layer of Cu-Ag. These grids are to be employed as decontamination filters for a smart natural ventilation prototype that we are currently building in our laboratory. The tested grids were coated with a mixed Cu-Ag layer using thermionic vacuum arc plasma processing technology. The fixed deposition geometry allowed the variation of Cu and Ag atomic concentration in coated layers as a function of substrate position in relation to plasma sources. The test conducted with air contaminated with a pathogen strain of staphylococcus aureus indicated that the filtering efficiency is influenced by two parameters: the pore size dimension and the coating layer composition. The results show that the highest filtering efficiency of 100% was obtained for fine pore (0.5 × 0.5 mm) grids coated with a mixed metallic layer composed of 65 at% Cu and 35 at% Ag. The second test performed only on reference grids and Cu-Ag (65–35 at%) under working conditions, confirm a similar filtering efficiency for the relevant microbiological markers. This particular sample was investigated from morphological, structural, and compositional point of view. The results show that the layer has a high surface roughness with good wear resistance and adhesion to the substrate. The depth profiles presented a uniform composition of Cu and Ag in the layer with small variations caused by changes in deposition rates during the coating process. Identification of the two metallic phases of the Cu and Ag in the layers evidences their crystalline nature. The calculated grain size of the nanocrystalline was in the range 14–21 nm.
Beryllium-deuterium co-deposited layers were obtained using DC magnetron sputtering technique by varying the Ar/D2 gas mixture composition (10/1; 5/1; 2/1 and 1:1) at a constant deposition rate of 0.06 nm/s, 343 K substrate temperature and 2 Pa gas pressure. The surface morphology of the layers was analyzed using Scanning Electron Microscopy and the layer crystalline structure was analyzed by X-ray diffraction. Rutherford backscattering spectrometry was employed to determine the chemical composition of the layers. D trapping states and inventory quantification were performed using thermal desorption spectroscopy. The morphology of the layers is not influenced by the Ar/D2 gas mixture composition but by the substrate type and roughness. The increase of the D2 content during the deposition leads to the deposition of Be-D amorphous layers and also reduces the layer thickness by decreasing the sputtering yield due to the poisoning of the Be target. The D retention in the layers is dominated by the D trapping in low activation binding states and the increase of D2 flow during deposition leads to a significant build-up of deuterium in these states. Increase of deuterium flow during deposition consequently leads to an increase of D retention in the beryllium layers up to 300%. The resulted Be-D layers release the majority of their D (above 99.99%) at temperatures lower than 700 K.
Reduced activation ferritic and martensitic steel like EUROFER (9Cr-1W) are considered as potential structural materials for the first wall of the future next-generation DEMOnstration Power Station (DEMO) fusion reactor and as a reference material for the International Thermonuclear Experimental Reactor (ITER) test blanket module. The primary motivation of this work is to study the re-deposition of the main constituent materials of EUROFER, namely tungsten (W), iron (Fe), and chromium (Cr), in a DEMO type reactor by producing and analyzing complex WxCryFe1−x−y layers. The composite layers were produced in laboratory using the thermionic vacuum arc (TVA) method, and the morphology, crystalline structure, elemental composition, and mechanical properties were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), micro-X-ray fluorescence (micro-XRF), and glow discharge optical emission spectrometry (GDOES), as well as nanoindentation and tribology measurements. The results show that the layer morphology is textured and is highly dependent on sample positioning during the deposition process. The formation of polycrystalline WxCryFe1−x−y was observed for all samples with the exception of the sample positioned closer to Fe anode during deposition. The crystalline grain size dimension varied between 10 and 20 nm. The composition and thickness of the layers were strongly influenced by the in-situ coating position, and the elemental depth profiles show a non-uniform distribution of Fe and Cr in the layers. The highest hardness was measured for the sample positioned near the Cr anode, 6.84 GPa, and the lowest was 4.84 GPa, measured for the sample positioned near the W anode. The tribology measurements showed an abrasive sliding wear behavior for most of the samples with a reduction of the friction coefficient with the increase of the normal load.
Formation of Be-W mixed layers in thermonuclear fusion reactors can potentially alter the retention of hydrogen isotopes and affect the retention and release properties of these isotopes. This paper reports on the retention and release characteristics of D from reference Be, W layers as well as three Be-W mixed layers with well-defined atomic concentrations (2:1, 1:1, 1:2). The layers resulted from the sputtering of Be and W materials in Ar:D (1:1) mixture at 2 Pa using DC magnetron sputtering. The mixed layers’ deposition parameters were varied to adjust accordingly the deposition rate for each material in order to obtain the desired concentrations. Scanning electron microscope images showed that morphology is independent of composition for samples deposited on silicon substrates. In contrast, layers deposited on tungsten revealed a textured surface and morphological changes with W concentration variation. X-ray diffraction patterns of mixed layers evidenced the presence of a polycrystalline tungsten phase. Additionally, the degree of crystallinity is highly influenced by the plasma parameters and enhanced amorphization is evidenced by a decrease of crystalline size by a factor of 10 for mixed layers compared to the W reference layer. The release behavior of D from the layers is affected by the trapping contribution of both Be and W. Compared with implanted layers, presented in literature studies, the co-deposited layers show a high D occupancy of low energy trapping states, the majority of the D retained in the samples being released at temperatures below 623 K. High energy trapping becomes more pronounced for layers with a high Be concentration. The oxygen contamination observed for Be layers points to a mitigation of D retention in low energy trapping states and shifts the desorption chart towards a higher temperature due to enhanced retention in BeO associated traps. The D retention presents a linear decrease of W concentration in the sample.
In the nuclear industry, coated cladding is a topical problem and it is chosen as the near-term and most promising ATF (Accident-Tolerant Fuel) cladding concept. The main objective of this concept is to enhance the accident tolerance of nuclear power plants and accordingly, the performance of cladding is expected to be improved. This work assesses the corrosion performance of a Zircalloy-4 alloy coated with a thin chromium coating by MS (magnetron sputtering), tested under a CANDU (CANada Deuterium Uranium) reactor primary circuit simulated condition (LiOH solution, 10 MPa, 310 °C, pH = 10.5). The anticorrosive performance is evaluated by a gravimetric analysis, a metallographic analysis, X-ray diffraction, electronic microscopy, and electrochemical methods. A four times less gain mass was noticed compared to uncoated Zircaloy-4, indicating a smaller corrosion rate. The SEM micrographs illustrate that the coatings are still adherent, and they are keeping the initial morphological characteristics during the autoclaving process. A SEM cross-section analysis shows values of the thickness of the coatings between 0.8 and 1.46 µm. By XRD, the presence of Cr2O3 oxide is identified. Electrochemical testing confirms good stability and good corrosion performance of Cr coating over time under autoclave conditions.