Optimizing process parameters in cold spray additive manufacturing: A data-driven, simulation-based multi-objective approach

In-flight temperature of solid micrometric powders during cold spray additive manufacturing

Achieving simultaneously improved tensile strength and ductility of a nano-TiB2/AlSi10Mg composite produced by cold spray additive manufacturing

In this work, the influence of thermal pre-processing upon the microstructure and hardness of Al 6061 feedstock powder is considered through the lens of cold spray processing and additive manufacturing. Since solid-state cold spray processes refine and retain microstructural constituents following impact-driven and high-strain rate severe plastic deformation and bonding, thermal pre-processing enables application-driven tuning of the resultant consolidation achieved via microstructural and, therefore, mechanical manipulation of the feedstock prior to use. Microstructural analysis was achieved via X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, energy dispersive spectroscopy, and differential thermal calorimetry. On the other hand, nanoindentation testing and analysis were relied upon to quantify pre-processing effects and microstructural evolution influences on the resultant hardness as a function of time at 540 °C. In the case of the as-atomized powder, β-Mg2Si-, Al-Fe-, and Mg-Si-type phases were observed along polycrystalline grain boundaries. Furthermore, after a 60 min hold time at 540 °C, Al-Fe-Si-Cr-Mn- and Mg-Si-type intermetallic phases were also observed along grain boundaries. Furthermore, the as-atomized hardness at 250 nm of indentation depth was 1.26 GPa and continuously decreased as a function of hold time until reaching 0.88 GPa after 240 min at 540 °C. Finally, contextualization of the observations with tuning cold spray additive manufacturing part performance via powder pre-processing is presented for through-process and application-minded design.

Widespread adoption of additive manufacturing (AM) is hindered by challenges in achieving part quality using metrics such as geometry accuracy and porosity. These metrics are affected by the microstructure and mechanical properties of fabricated parts which can be controlled by the AM’s process parameters. Fine-tuning these parameters can enable control over the part quality. In this study, an optimization-based approach for selecting the AM process parameters is proposed for achieving part quality. The proposed approach integrates design of experiments, AM process simulation, surrogate modeling, and multi-objective optimization. While the proposed approach is general and applicable to any AM process, the applicability of the proposed approach is demonstrated through a laser powder bed fusion (LPBF) process. Three LPBF process parameters, namely layer thickness, laser power, and scanning speed are considered for obtaining optimized part quality considering geometric accuracy and porosity. A cylinder and a heat exchanger example are used to demonstrate the effectiveness of the proposed approach with the LPBF process. For these examples, it is shown that with the optimized process parameters, the part has about 17% better geometric accuracy when compared to the unoptimized part while satisfying a porosity requirement. The results also reveal that laser power is the most influential process parameter affecting both the geometric accuracy and porosity.

ConspectusMost metal additive manufacturing (AM) methods involve the melting or sintering of feedstock powder or wire using an energy source (laser, electron beam, or electric arc). Solid-state AM, sometimes also known as non-beam-based AM, is a process in which the deposited material does not melt and is built up layer-by-layer, typically through severe plastic deformation. Initially considered to be a coating technique, by virtue of its high deposition rate, cold spray additive manufacturing (CSAM) is attractive as a solid-state AM technology. In the CSAM process, metal powder particles are impacted onto a substrate at a supersonic velocity and relatively low temperature. The CSAM process reduces or eliminates many problems associated with melting or beam-based AM methods, making the CSAM technically attractive for a wide range of applications, such as in the aerospace, automobile, marine, biomedical, machinery, and energy sectors.In this Account, the author briefly reviews the setup of a cold spray system and discusses the strengths and drawbacks of CSAM compared with thermal sprays and beam-based AM processes, as well as applications in relevant industries. The author summarizes the bonding mechanisms proposed for the cold spray process. The focus of this Account is to review the microstructure evolution of several typical model metals (copper, nickel, aluminum, and titanium) during the cold spray process. The author shows a large variety of microstructure characteristics (recrystallized grains, annealing twins, shear bands, submicron-sized grains, deformation twins, and nanometer-sized grains) in cold-sprayed copper, dynamic recrystallization of cold-sprayed nickel, and the formation of refined grains even below 10 nm in size in cold-sprayed aluminum. The magnitude of the stacking fault energy of as-sprayed materials considerably influences the microstructure after cold spray and postprocessing. Due to the relatively low thermal conductivity and ductility of titanium, cold spraying of titanium shows both a high deposition efficiency and relatively high porosity of as-sprayed parts, as well as a heterogeneous microstructure. Moreover, the Account introduces the postprocessing heat treatment and nanoindentation characterization of cold-sprayed materials. A fundamental understanding of microstructure evolution during and after the cold spray process is essential for optimal mechanical properties. Lastly, the author provides a perspective on applying old lessons and taking advantage of new techniques and materials, including powder characterization, hybrid additive manufacturing, machine learning for searching process windows, nanomechanical testing, and emerging alloys (high-entropy alloys, nanocrystalline alloys, and quasicrystals), to advance the research and applications of CSAM.

Cold spray additive manufacturing (CSAM) is a cutting-edge high-speed additive manufacturing process enabling the production of high-strength components without relying on traditional high-temperature methods. Unlike other techniques, CSAM produces oxide-free deposits and preserves the feedstock's original characteristics without adversely affecting the substrate. This makes it ideal for industries requiring materials that maintain structural integrity. This paper explores strategies for improving material quality, focusing on nozzle design, particle size distribution, and fine-tuning of process parameters such as gas pressure, temperature, and spray distance. These factors are key to achieving efficient deposition and optimal bonding, which enhance the mechanical properties of the final products. Challenges in CSAM, including porosity control and achieving uniform coating thickness, are discussed, with solutions offered through the advancements in machine learning (ML). ML algorithms analyze extensive data to predict optimal process parameters, allowing for more precise control, reduced trial-and-error, and improved material usage. Advances in material strength, such as enhanced tensile strength and corrosion resistance, are also highlighted, making CSAM applicable to sectors like aerospace, defense, and automotive. The ability to produce high-performance, durable components positions CSAM as a promising additive-manufacturing technology. By addressing these innovations, this study offers insights into optimizing CSAM processes, guiding future research and industrial applications toward more efficient and high-performing manufacturing systems.

Cold spray additive manufacturing (CSAM), a solid-state supersonic deposition technique combining cold spray and additive manufacturing, is gaining attention for its potential in large-scale manufacturing, construction, and repair of engineering components. CSAM enables the fabrication of three-dimensional parts and promises significant benefits to the production sector. This review explores recent advancements and key challenges in implementing CSAM for applications in maintenance, refurbishment, and sustainable fabrication. The study highlights CSAM's practical advantages, including reduced environmental impact and improved product design and customisation. Despite current challenges, findings suggest that strategic planning and optimised production techniques can overcome existing barriers. Additionally, the review identifies future research directions aimed at establishing CSAM as a robust and widely accepted additive manufacturing technology. With further development, CSAM holds the potential to transform modern manufacturing through enhanced efficiency, sustainability, and functionality in producing complex technical components.

3D volume construction methodology for cold spray additive manufacturing

Cold Spray Additive Manufacturing (CSAM) produces freeform parts by accelerating powder particles at supersonic speed which, impacting against a substrate material, trigger a process to consolidate the CSAM part by bonding mechanisms. The literature has presented scholars’ efforts to improve CSAM materials’ quality, properties, and possibilities of use. This work is a review of the CSAM advances in the last decade, considering new materials, process parameters optimization, post-treatments, and hybrid processing. The literature considered includes articles, books, standards, and patents, which were selected by their relevance to the CSAM theme. In addition, this work contributes to compiling important information from the literature and presents how CSAM has advanced quickly in diverse sectors and applications. Another approach presented is the academic contributions by a bibliometric review, showing the most relevant contributors, authors, institutions, and countries during the last decade for CSAM research. Finally, this work presents a trend for the future of CSAM, its challenges, and barriers to be overcome.

Cold spray process (CSP) is a thermal spray technology in which coating (10–40 µm) is formed in the solid state by the impingement of power particles with supersonic velocity (200–1,200 m/s 2 ) on coupon employing compressed gas jet, below the melting point of coating powder. It is commonly referred as cold gas dynamic spray, high velocity powder deposition, kinetic spray and kinetic energy metallisation process. Using CSP, various engineering materials (metals, polymers and ceramics) and its composites can be deposited. It is unique and promising approach for obtaining surface coating and offers various technological benefits over thermal spray as kinetic energy is employed for deposition rather than thermal energy. This offers great benefits in additive manufacturing (AM) to develop a component denser, low oxide coating free of tensile residual stresses, and undesired chemical reactions compared to conventional AM and coating techniques. Cold spray additive manufacturing (CSAM) is the powerful and emerging technique in the field of AM to develop engineering components with improved performance covering broad range of functionalities of surface, subsurface and interfaces. There are few flaws in this technique; however, extensive research work is going in CSAM and repairing of components to meet the real-time applications. The main objective of this review article is to summarise the history, effect of process parameters on surface coating, research and development in CSP along with its implementation in AM, component repairing and biomedical, antimicrobial and electrical applications. A discussion on future trends in CSAM is also provided at the end part of this article.

Experimental and numerical study of deposition mechanisms for cold spray additive manufacturing process

A comprehensive review on sustainable cold spray additive manufacturing: State of the art, challenges and future challenges

A new additive manufacturing (AM) process, high pressure cold spray, has shown to provide structural integrity along with improved machining characteristics compared to existing thermal spray processes. The U.S. Army overhauls the UH-60 Black Hawk helicopter components including the transmission and gearboxes. When performing the overhaul of the transmission assembly, corrosion has been found on the transmission housings. The cold spray AM process was used to repair corrosion to an existing sump housing. Using inspection, stress analysis, and testing, the cold spray AM was qualified from an airworthiness perspective as a replacement to thermal (flame) spray processes. Re-establishing blueprint tolerances on an existing operational sump housing required employing techniques not used at initial manufacture and gave improvements on the setup and final surface finish. The cold spray repair was found to be cost effective. This repair can be employed on other similar magnesium alloy housings and aluminum alloy housings.

To have a further study on the dynamic response characteristics of process parameters in cold metal transfer wire plus arc additive manufacturing(CMT-WAAM), the paper selects aluminium alloy 2319 as experimental material. On the basis of previous experiments, step response experiments were carried out for the forming parameters, welding speed(WS), wire feeding speed(WFS), arc length correction and pulse correction included. After WEDM, the width and height of the single layer single pass(SLSP) were captured respectively, and then the image processing algorithm was used in Halcon12.0 software for edge extraction and static extraction of sample contour’s morphology features. In this paper, different feature extraction algorithms were proposed for the layer height and the pass width, and the characteristics of process parameters were given.

Environmental impact of cold sprayed 3D-Printed aluminium metal parts