As an emerging additive manufacturing method, cold spray additive manufacturing (CSAM) has attracted more and more researchers’ attention due to its unique advantages. However, only a few researchers have studied the fabrication of complex structural components. Therefore, it is important to develop a general CSAM framework that is suitable for the fabrication of different shapes of workpieces. In particular, the choice for the optimal kinematic spraying parameters, the prediction of deposit evolution and the planning of spraying trajectory are the most basic and crucial. Different sub-modules are integrated in the proposed framework to solve these problems. In detail, the modeling methodology is used to obtain the optimal kinematic spraying parameters and to predict the deposit evolution in the simulation. Based on the feasible parameters, the trajectory planification methodology is used to generate the spraying trajectory for the workpiece being manufactured, especially the workpiece with complex structure. Finally, the simulation and experimental results of a fabrication for a workpiece with complex structure provide the developed system is reliable and effective. The framework developed in this paper can considered as a general tool for additive manufacturing of with complex structural workpieces in the CSAM.

The objective of this work is to assemble an aluminum alloy to a steel to reduce the final mass of this assembly. Doing that, cold spray is considered as an efficient solution. Surfaces are previously prepared with a texturing laser to improve the adhesion of the coating on the substrate. Deposits are slightly rough (Ra < 10 μm), porosity is less than 1% and adhesion is higher than 80 MPa for textured surfaces. These high values are also due to the high filling rates in holes (100% for steel and 65% for aluminum alloy). Shear values obtained through the combination of laser texturing and cold spray for multi-material assembly are of 90 MPa (a heat treatment of 3h at 300°C applied on the joining point improves mechanical strength and increases it by three). By analogy with linear joining methods such as Laser Welding (190 MPa), the values obtained in uniaxial tension by this assembly method are significantly lower (around 50 MPa). It can be explained by the nature of the joining bead, which is made of aluminum alloy.

Cold Spraying is an emerging additive manufacturing method that uses a high-speed collision of micrometre sized powders capable of producing a solid-state bonding. Such a principle has led to the recent development of a coating for various surface functionalization and additive manufacturing applications. This paper is the result of an experimental study on the evolution of the deposit properties (ultimate strength, and porosity) generated by the additive growth during cold spraying. The deposit characterization shows the existence of ultimate strength gradient. For samples taken from the bottom to the top of the deposit, the ultimate strength decreases but there is no significant change in porosity value. The porosity evolutions do not allow to establish a generalized law of variation. The numerical analysis of the additive growth shows that the thermomechanical response of the stacking powder during the additive growth can decrease the bonding capacity, the thermomechanical heating (due to the plastic work) and the gradient of thermal kinetics.

One of the main problems that slows down the implementation of the green hydrogen (H 2 ) economy is the cost of water electrolysis. While part of this cost is associated to the price of electricity, a significant part relies on the parts of the electrolyzers. Despite their advantages, Proton Exchange Membrane Water Electrolyzers (PEMWE) still have to overcome some drawbacks to reduce its H 2 production cost, while maintaining high efficiencies. For decades, thermal spraying has been used for the production of coatings all over the world because of its versatility in industry for machinery and tools preservation, surfaces protection and corrosion prevention. This study demonstrates the possibilities of Cold Gas Spray (CGS) for the cost-reductive production of a component of PEMWEs, the Bipolar Plates (BPPs), by metal 3D printing. In this process, the incorporation of a mask between the nozzle exit and the substrate can drastically transform the BPP production to a very fast and automatic bottom-up process where material is deposited layer by- layer for building up the three-dimensional flow field patterns from a flat surface. Microstructure and topography of 3D printed BPPs were inspected by microscopy techniques. For evaluating the fulfilment of BPPs requirements (interfacial contact resistance and corrosion resistance) the new BPPs were characterized following the Davies’ method and with potentiodynamic test in O 2 -saturated H 2 SO 4 solutions, respectively.

Developing a cost-effective fabrication method for devices containing metal channels with surface features on the submillimeter scale is essential for the development of novel, high efficiency micro-reactors and heat sinks. Traditional methods are limited by their high cost, low geometric accuracy, high energy consumption, and long processing times. This study presents a low-cost additive manufacturing method using twin wire arc spray to make surface features at the sub-millimeter scale. Water-soluble polyvinyl alcohol (PVA) paste is first placed onto a mold containing a negative of the desired surface features and allowed to cure. The cured PVA is removed from the negative and metal sprayed onto its surface. The deposited metal film was backed by epoxy for added rigidity. The PVA paste was then dissolved in a water bath, resulting in a metal surface with the surface features of the mold. Surface features with length scales as small as 200 μm were reproduced. Coating delamination was prevented by minimizing the temperature of the substrate during spraying by increasing the standoff distance and scanning speed of the spray torch.

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing for a wide variety of industrial and medical applications due to their excellent mechanical properties. However, these applications are often limited by relatively low thermal stability and conductivity compared to metals. Many methods developed to metallize polymers, including vapor deposition and thermal spray processes, can lead to poor quality control, low deposition rate, and high cost. Thus, cold spray is a promising potential alternative to rapidly and inexpensively produce polymer-metal composites. In this study, we investigated the deposition characteristics of metalpolymer composite feedstock, composed of PEEK powder with varying volume fractions of copper (Cu) flake added, onto a PEEK substrate. We prepared the Cu-PEEK composite powder in varying compositions by two methods: hand-mixing the powders and cryogenically milling the powders. Scanning electron microscopy (SEM) of the feed mixtures shows that cryogenically milling the polymer and metal powders together created uniformly distributed micron-scale domains of Cu on PEEK particle surfaces, and vice versa, as well as consolidating much of the porous Cu flake. In lowpressure cold spray, the relatively large volume fractions of PEEK in the composite mixtures allowed for lower operating temperatures than those commonly used in PEEK metallization (300-500 °C). While the deposition efficiencies of each mixture were relatively similar in single-layer experiments, deposits formed after multiple passes showed significant changes in deposition efficiency and composition in PEEK-rich feedstock mixtures. SEM of deposit surfaces and cross-sections revealed multiple co-dominant mechanisms of deposition, which affect both the porosity and final composition of the deposit. Though present in all samples analyzed, the effects of cryogenic milling were more prevalent at lower Cu concentrations.

Cold spraying (CS) has proved as an attractive and rapidly developing solid-state material deposition process that allows for fast formation of high quality, large 3D volume objects. Low risks of undesirable heat effects lead to increased interest in CS-based rapidly additive manufacturing (AM). However, by continuous powder spraying and high-pressure gas operation, cold spray additive manufacturing (CSAM) in terms of shape building is rather sensitive to operating parameters and imposes high requirements on the control of process conditions and locally needed kinematics. Every step of the manufacturing process therefore needs to be well conceived and planned, especially with regard to the toolpath planning and implementation. This is not only essential to meet basic performance requirements, but also needed to realize the desired accuracy. In order to tackle above needs, the present study presents a new toolpath planning method for 3D volume build-up to improve manufacturing accuracy and flexibility by cold spray additive manufacturing. Applied benchmarking tests prove acceptable shape accuracy and demonstrate that the current method can enhance the capabilities of CSAM for nearnet shape construction. This implies that careful planning and manufacturing strategies should enable to overcome the challenges associated with CSAM.