Christophe Verdy

Purpose: The purpose of this paper is to develop a toolpath-driven parametric design methodology for additively manufactured continuous carbon fibre-reinforced lattice structures to overcome design difficulties from fibre deposition constraints, enable reinforcement of cellular architectures, and incorporate manufacturing limitations and fibre-orientation control. Design/methodology/approach: An integrated workflow combines evolutionary computation and parametric mapping to optimise four key variables – unit cell size, infill size, deposition direction and material ratio. The workflow also guides reinforcement using a shortest-path algorithm that directly generates continuous, printer-ready toolpaths bypassing conventional slicing steps. The framework was implemented using in-house computational tools and validated by fabricating hexagonal lattice specimens printed with continuous carbon fibre; results were compared to parts produced using commercial slicers for mechanical performance and surface finish. Findings: The toolpath-driven approach preserves fibre continuity and enables explicit orientation control while embedding manufacturing constraints into the design loop. Fabricated hexagonal lattice specimens printed with the proposed method exhibited improved stiffness and better surface finish than equivalent parts produced with conventional slicers. The framework streamlines the digital chain by outputting ready-to-print toolpaths, reducing process-induced fibre interruptions and enabling property customisation via geometric and material parameters. Originality/value: This work progresses beyond conventional reinforcement of solids or beam geometries by coupling cellular-architecture design with process-aware toolpath generation. Eliminating the slicing stage and embedding manufacturing constraints in the workflow provides a unified design-to-process pipeline for composite lattice printing.

New copper–tungsten (W–Cu) composite wires are developed for the winding of non-destructive pulsed magnets. A micrometric Cu powder coated with a nanometric layer of W (1.8 vol%) was used as the starting material. W is chosen for its very high shear modulus, and its introduction at the nanometric scale aims to avoid co-deformation incompatibilities during wire drawing. Composite cylinders were fabricated by cold spraying and then deformed by wire drawing at room temperature, allowing the fabrication of wires.

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.

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.

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.

Cold spray process was chosen as a good candidate for dimensional restoration and protection of components. Commercially pure aluminum, aluminum-alloy or titanium were recommended for different applications. This paper investigates laser surface texturing association to enhance durability of sprayed coatings. Laser is easy automated, localized and reliable process. It was applied for prior-surface treatment. Textured surfaces were produced and compared to conventional treatments, such as grit-blasting, in terms of deposition efficiency and adhesion bond strength. Patterns promoted direct particle embedment. Particle-substrate interface exhibited significant temperature rate and strain in cavities. Intimate contacts and particle compressive states were assumed responsible for improvement. The particle deformation and bonding behaviors were evaluated and discussed for the different configurations. Thus, window of deposition was increased with laser surface texturing. Anchoring mechanisms increased two fold the adhesion strength compared to conventional pre-treatments. In one case, the interface was stronger than the coating cohesive strength.

This study focuses on the effects of a surface mechanical attrition treatment on the structural and mechanical behavior of arc-sprayed Ni–Cr coatings deposited on steel substrates. The surface of the as-sprayed and SMATed coatings was characterized by X-ray diffraction, Scanning Electron Microscopy, and non-contact profilometry. The coating porosity was evaluated by using image analysis software. The residual stresses were determined using X-ray diffraction with the sin²ψ. Indentation tests were carried out on the cross sections of the different coatings to evaluate their hardness. The wear properties of the coatings were assessed using a pin-on-disk tester at ambient temperature without lubrication. The results showed that surface mechanical attrition treatment (SMAT) induced a grain refinement on the coating surface due to severe plastic deformation, which was associated with a significant improvement of the mechanical properties.