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High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at liquid nitrogen temperature, bulk Cu/Ag (5% vol. Ag) alloys serve as precursors for room-temperature wire drawing. The Cu/Ag-alloyed bulk CS deposit presents a high yield strength of about 510 MPa with a corresponding electrical resistivity of 1.92 µΩ·cm (at 293 K). The Cu/Ag-alloyed wires show a very high ultimate tensile strength (1660 MPa at 77 K or 1370 MPa at 293 K) and low electrical resistivity (1.05 µΩ·cm at 77 K or 2.56 µΩ·cm at 293 K). Microstructural studies via STEM allow us to understand this very high level of mechanical strength. The results evidence that materials developed by CS exhibit very high mechanical properties compared to materials prepared by other routes, due to the high velocity of the deposited particles, which leads to high initial deformation rates and specific microstructural features. [ABSTRACT FROM AUTHOR]

For high-level radioactive waste, the French National Radioactive Waste Management Agency is currently developing a 500 m deep geological disposal facility called Cigéo. Carbon steel containers will be used to contain the wastes in the specific conditions of the disposal. The use of a sacrificial coating was studied as an additional protection for the containers against corrosion. A previous work had shown the possibility to use Zn-Al coatings in this specific medium. To optimize the coatings' performance, the cold-spraying process was considered instead of the previously used wire arc spraying because it can increase the cohesion between the particles in the coating. Moreover, three aluminum contents, i.e., 5, 15 and 25 wt.%, were considered. The characterization of the obtained coatings revealed a strongly heterogeneous composition for the lower Al content (5 wt.%), with local Al contents from 1.3 wt.% Al to 44.5 wt.% Al. The corrosion study was carried out in a specific solution mimicking the pore solution of the surrounding cementitious material designed for disposal at a temperature of 50 °C. First, the polarization curves acquired with coated steel electrodes revealed the pseudo-passive behavior of the 25 wt.% Al coating, while for the other compositions, the coating remained active. Moreover, the higher aluminum content (25 wt.%) induced an important decrease in potential, with a possible risk of hydrogen embrittlement for the protected steel. Secondly, the sacrificial properties were investigated through 6 months of experiments using coated electrodes with cross-like defects and coated electrodes coupled with bare steel electrodes. Whatever the composition of the coating, the protection was maintained, with the 15 wt.% Al coating giving the best performance. [ABSTRACT FROM AUTHOR]

Cold gas dynamic spraying is a solid-state processing technique that is particularly attractive for surface coatings, 3D near-net shape additive manufacturing, and component repairs with an advantage of high-deposition efficiency. This technique has the sustainable potential to change the future industrial and manufacturing environment, especially in the fabrication process of complex flight-critical components that are made of aluminum. This paper investigates the microstructure of aluminum coatings generated onto a commercial Al plate called FORTAL (Al 7075-T6) via cold spraying using helium as the propellant gas. Three Al coatings (pure Al, AlSi10Mg, and Scalmalloy) are compared under a similar deposition condition. The top view of the coating revealed the highest deformation (high flattening) in the case of pure Al powders, whereas both the AlSi10Mg and Scalmalloy powders exhibit less flattening. The cross sections show fine equiaxed grains within the pure Al coating and extremely fine grains for both the AlSi10Mg coating and the Scalmalloy coating, with more extremely refined grains within the Scalmalloy coating. These results suggested an onset of recrystallization within the Al coating that is attributed to the heat generated by the strong plastic deformation. Less thermally activated recrystallization occurred within both AlSi10Mg coating and Scalmalloy coating due to their stronger mechanical properties. The structure rather resulted from the dynamic due to the high strain rate collision. The extremely fine structure is mostly at the powder/powder interface within the Scalmalloy coating and is developed towards the powder region which is also within the AlSi10Mg coating. Better plastic deformation occurred within the AlSi10Mg powder compared to the Scalmalloy powder that have a higher mechanical resistance. Together, these results evidence a limited thermally activated recrystallization within the Al alloys despite the highest deposition condition being used. The pure Al powders can also achieve a state of equiaxed fine grain due to the better plastic deformation. [ABSTRACT FROM AUTHOR]

In this study, simulation and experimental methods were used to investigate the influence of cold spray conditions on AISI 316L stainless steel coatings. The effect of both helium and nitrogen gases used was investigated. The temperature, particle sizes of spraying powder, and distance from the nozzle throat to the impinging point were estimated by using the Kinetics Spray Solutions GmbH software. The 316L stainless steel (SS) coatings were examined by X-ray diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray Microanalysis. The tribological behavior was evaluated under different loads (2 N and 5 N) in dry conditions. It was found that the nitrogen and helium propellant gas with high speed and fine particles led to produce good coatings with dense microstructures. From the nanoindentation experiments, the Young's modulus and hardness of the SS 316L samples were enhanced of about 8% with helium due to the high particle velocity. It was shown that the wear resistance of SS 316L produced with helium was higher than that of the standard SS 316L coatings. The coatings produced with helium revealed lower friction coefficient (0.65) and wear rate (6.9 × 10–4 mm3/Nm) under 2 N applied load than that obtained nitrogen. It was also found that the SS 316L cold sprayed by helium with dense structure presents high hardness and good tribological performance that can be suggested for several applications. [ABSTRACT FROM AUTHOR]

Low-pressure cold spray (LPCS) has broadened the application field of cold spray owing to its portability and low cost. For additive manufacturing (AM) based on LPCS (LPCSAM), it is important to investigate the effects of parameters such as temperature and pressure of the gas, stand-off distance, gun traverse speed, and the number of scanning passes of the gun on the deposition and properties. This study aims to determine the optimal kinematic spray parameters for spraying Cu+Al 2 O 3 powder onto an aluminum substrate through LPCS, so as to prepare for the next AM work. The deposition mass, deposition rate, microhardness, and roughness under different spraying conditions were studied. The best spraying effect, with a high deposition rate and without nozzle clogging, was obtained at a nitrogen pressure of 0.9 MPa and a temperature of 400°C., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the study reported in this article., (Copyright 2023, Mary Ann Liebert, Inc., publishers.)