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In this study, we investigated the effect of spray angle on the microstructure, bonding quality, and scratch resistance of cold-sprayed SS316L coatings on SS304 substrates. The coatings were deposited at spray angles of 45°, 60°, 75°, and 90° using a high-pressure cold spray system. A comprehensive analysis of the relationship between the spray angle and coating properties was conducted, with a particular focus on fracture toughness and porosity. Scratch testing, combined with real-time acoustic emission monitoring, enabled the precise identification of failure mechanisms and the assessment of coating integrity. The results indicate that microhardness and porosity are significantly influenced by the spray angle. The highest microhardness was achieved at a 45° angle, while a 90° angle resulted in the lowest porosity and superior bonding due to superior normal impact velocity. Fracture toughness was found to correlate with microstructural cohesion and particle deformation. Optimizing the incidence angle improved the coating performance by balancing strain hardening and ductility, thereby reducing the risk of premature failure. These findings are particularly relevant for industrial applications, where wear resistance and high-quality bonding are critical, such as in aerospace, automotive, and marine sectors. By adjusting the spray angles, manufacturers can enhance the longevity and reliability of the coated components, thus reducing maintenance costs and improving performance. This research highlights the importance of process parameters in achieving durable, high-quality coatings and emphasizes scratch testing as an effective, sustainable, and semi-destructive evaluation method for coating integrity. [ABSTRACT FROM AUTHOR]

Cold spray technology has become essential for industries requiring efficient material deposition, yet achieving optimal deposition efficiency (DE) presents challenges due to complex interactions among process parameters. This study developed a two-stage machine learning (ML) framework incorporating Bayesian optimization to address these challenges. In the first stage, a classification model predicted the occurrence of deposition, while the second stage used a regression model to forecast DE values given deposition presence. The approach was validated on Aluminum 6061 data, demonstrating its capability to accurately predict DE and identify optimal process parameters for target efficiencies. Model interpretability was enhanced with SHAP analysis, which identified gas temperature and gas type as primary factors affecting DE. Scenario-based inverse analysis further validated the framework by comparing model-predicted parameters to literature data, revealing high accuracy in replicating real-world conditions. Notably, substituting hydrogen as the gas carrier reduced the required gas temperature and pressure for high DE values, suggesting economic and operational benefits over helium and nitrogen. This study demonstrates the effectiveness of AI-driven solutions in optimizing cold spray processes, contributing to more efficient and practical approaches in material deposition. [ABSTRACT FROM AUTHOR]

The corrosion resistance of a Cr3C2-25(Ni20Cr) cermet coating applied to an Al7075 substrate (Cr3C2-25(Ni20Cr)/Al7075) was investigated. The coating was produced using a cold spraying (CS) method. The main aim of the research was to determine the effect of heat treatment on the properties of cermet coatings on the Al7075 substrate. The mechanical properties of the Cr3C2-25(Ni20Cr)/Al7075 composite were assessed through microhardness (HV) measurements. The surface morphology and microstructure of the specimens were examined using a scanning electron microscope (SEM). Electrochemical testing in an acidic chloride solution was employed to evaluate the corrosion behavior of the materials. The cermet coating effectively protected the Al7075 substrate from the aggressive corrosive environment. Heat treatment homogenized the structure of the cermet coating, eliminating microcracks and pores on the Cr3C2-25(Ni20Cr)/Al7075 surface. Notably, annealing at 300 °C in air significantly enhanced the corrosion resistance of the cermet coating. The corrosion rate was reduced by more than five times compared to the non-heat-treated Cr3C2-25(Ni20Cr)/Al7075 coating. [ABSTRACT FROM AUTHOR]

This research work aims to study the drilling behaviour of hybrid composite structures made of glass fibre-reinforced polymer matrix metallised with a surface aluminium layer produced via cold spray technology. The metal deposition creating the coating was optimised by applying a thermoplastic layer to the thermoset composite structure using the co-curing technique. Aiming to highlight the influence of the metallic coating on the workpiece's response during drilling, this research systematically analyses the effects of drilling parameters such as feed rate and spindle speed on delamination, burr formation and hole quality. In-process monitoring techniques, including thermocouple temperature and thrust force measurements, as well as energy consumption estimation, were utilised to evaluate drilling performance. The main findings demonstrate that selecting the composite side as the inlet surface results in the highest measured force and reduced delamination, meaning that aluminium coatings significantly impact drilling dynamics. [ABSTRACT FROM AUTHOR]

Cold spray additive manufacturing (CSAM) has gained significant attention for its rapid solid deposition capabilities. However, the presence of defects such as pores and voids limits its performance, particularly in electrochemical environments. In this study, a novel post-surface treatment, plasma electrolytic oxidation (PEO), was applied and investigated as a feasible solution to overcome these defects. Results demonstrated a successful PEO deposition on cold-sprayed 316L stainless steel (SS) due to the rapid formation and discharge of aluminate electrolytes along the surface. However, due to the severely strained and highly crystalline surface, the electric field that allows for the deposition of Al(OH)4− anions was reduced. As consequence, an uneven and rough deposition took place. Nonetheless, a successful Al2O3 film of 12.30 μm thickness was formed. Experimental tests were further conducted in simulated aqueous and biological-based solutions to test the electrochemical resistance of the deposit. Results reveal a noticeable enhancement in corrosion resistance for both solutions. This enhancement can be attributed to the "postponing" and "blocking" effect enabled by the Al2O3 film, which prevented the electrolyte solution from penetrating the CS surface. Collectively, these findings suggest that PEO is indeed a promising technique to mitigate the chemical degradation of CSAM'd 316L SS. [ABSTRACT FROM AUTHOR]

Magnesium (Mg) alloys are used more often today in the automotive and aviation industries. Owing to their many beneficial characteristics, such as higher thermal conductivity, greater strength, lower density and weight, etc., magnesium alloys tend to corrode when employed in particular moist regions, and their poor wear characteristics may reduce their lifespan. To deal with such challenges, a surface coating technique was used on the AZ31B Mg alloy with AA2024/Al2O3 coating powder through a cold spray process. The porosity, corrosion, and wear rate of the deposited Mg alloy are investigated. Box–Behnken designs (BBD) are used to plan the experimental investigation. The results were verified using the Mayfly optimization technique in MATLAB 2021, which relies on a hybrid deep belief network, and also through the BBD-response surface methodology (RSM) in Design Expert 11. The metal matrix composite coating has a minimal porosity, corrosion rate, and wear loss of 0.52%, 1.35 mm/year, and 0.52 mg, experimentally. As a result, the hybrid deep belief network-mayfly optimization estimated results are more similar to the experimental results compared to the BBD-RSM. [ABSTRACT FROM AUTHOR]

With the rapid growth of the lithium-ion battery (LIBs) market, recycling and re-using end-of-life LIBs to reclaim the critical Li, Co, Ni, and Mn has become an urgent task. Presently, high temperature, strong acid, and alkali conditions are required to extract blended critical metals (CM) from the typical battery cathode. Hence, there is a need for more effective recycling processes for recycling blended Li, Co, Ni, and their direct regeneration for re-use in LIBs. The goal of the offered paper is the development of recycling technology for degraded battery cathode-active materials based on the thermal decomposition of polyvinylidene fluoride (PVDF) using calcination and air-jet stripping of active materials. The proposed air-jet erosion method of calcined cathode material stripping from Al foil allows for the flexible industry-applicable separation process, which is damage-free for both particles and substrate. The CaO calcination air-jet separation process and equipment can significantly improve the PVDF decomposition and the separation efficiency of the cathode materials. It is demonstrated that low-temperature CaO calcination at 350–450 °C associated with air-jet separation of active material is characterized by low environmental impact, high purity of the recycled material, and low cost as compared to pyro- and hydrometallurgical methods. [ABSTRACT FROM AUTHOR]

A numerical study was performed to analyze the particle deposition of a cold spray process for the preparation of nickel electrocatalysts used in the Hydrogen Evolution Reaction (HER). The study focused on the creation of fin-shaped geometries with an optimal porosity on the electrode surface using a mask located between the nozzle exit and the substrate. Computational Fluid Dynamics (CFD) was performed on a three-dimensional high-pressure nozzle, with nickel powder used as the injection feedstock. The behavior of particles was effectively modeled through a two-way coupled Eulerian–Lagrangian approach. As per the parametric study, four masks of varying wire thicknesses and opening sizes were investigated. The masks were placed at 4 mm increments from the nozzle exit, with the substrate placed at standoff distances (SODs) of 10 mm and 20 mm. To capture the effects of the gas inlet operating conditions, two different nozzle inlet conditions were analyzed (2 MPa and 400 °C, 4 MPa and 800 °C). It was found that the nozzle inlet operating condition had the most significant impact, as it relates to the particle velocity and powder deposition. The high-pressure operating condition resulted in a deposition efficiency (DE) greater than 99.9% for all the test cases, with nearly all the impacted particles depositing on the substrate. For the medium-pressure operating condition, the DE increased linearly as the mask SOD was increased, due to the increase in the particle velocity upon impact. [ABSTRACT FROM AUTHOR]

Cold spray is a dynamic additive manufacturing process which results in a unique microstructure and mechanical properties. This work investigates cold spray deposited material under high strain-rate dynamic loading, and specifically the influence of post-build heat treatment on the material strength when subjected to incipient spallation. As-deposited and heat-treated samples were characterized and subjected to shock loading with a plate impact apparatus; the free-surface velocity was measured during the experiment, and the samples were recovered for postmortem analysis. The test results show that the as-deposited material has little to no strength under high strain-rate tensile loading and breaks into pieces. After a short heat treatment, the material recovers some of its tensile strength (compared to wrought copper) but does not exhibit the expected damage morphology and void distribution. When the heat treatment time is extended to several hours and the temperature is increased, the material exhibits ramp-like shock rise and damage formation that is widely distributed within the sample. This work contributes to a better understanding of the influence of heat treatment on the microstructure and subsequent material strength properties under high strain-rate loading, which is crucial for applications where cold spray is a technique of interest. [ABSTRACT FROM AUTHOR]

Continuous monitoring of spray velocity during the cold spray process would be desirable to support quality control, as spray velocity is the key process parameter determining the deposit quality. This study explores the feasibility of utilising Airborne Acoustic Emission (AAE) for real-time monitoring of spray velocity. Six spray tests were conducted, varying pressure and temperature to achieve different velocities. Optical means were used to measure velocity; while, the signal from the AAE was captured during deposition via a microphone. Features demonstrating a strong correlation with velocity were extracted from the acoustic signals. Both rule-based and machine learning models were employed to identify the moments where the nozzle was engaged with the substrate and diagnose the velocity. The results indicate that monitoring the spray velocity of the cold spray process using AAE is feasible. [ABSTRACT FROM AUTHOR]

This study explores the potential of cold spray technology for repairing high-strength Al7075 alloy components, particularly in the aerospace industry. The gas-atomized powder contains a dendritic cell structure with solutes segregated at the dendritic cell boundaries. Thus, direct aging of atomized powder fails to induce the formation of strengthened precipitates. Therefore, the effect of different powder pre-treatments on the deposition efficiency, microstructure, and aging behavior of the coatings was investigated. Cold spray coatings were deposited using as-received powder, solutionized, and solutionized + aged powders, revealing a significant improvement in thickness for coatings obtained using solutionized (110%) and solutionized + aged (80%) powders compared to the coating from the as-received atomized powder. Further, coatings deposited using as-received, solutionized, and solutionized + aged powders, were aged at 120 °C for various durations and the aging response of different coatings were studied. Microstructural studies revealed that gas-atomized powders exhibited dendritic structures with segregated solutes. Solutionizing eliminated the dendritic features, promoting deposition efficiency upon cold spraying. Aging of the coating from the solutionized powder led to the formation of ultrafine η' precipitates (29 ± 8 nm length, 2 ± 1 nm diameter) at peak-aged condition (after 8 h). These findings demonstrate the effectiveness of powder pre-treatment in tailoring the microstructure and deposition behavior of cold-sprayed Al7075 coatings, offering a promising approach for repair applications. [ABSTRACT FROM AUTHOR]

In this study, the influence of cold‐spray processing on the integration of 1D boron nitride nanotubes (BNNTs) into aluminum (Al) matrix composite deposits is delved into. Successful deposition of Al‐BNNT composite is achieved by pre‐spray dispersion of BNNTs in Al powder via wet mixing aided by ultrasonication. Pure Al powder deposition at 380 °C is limited by nozzle clogging, restricting the deposit thickness to 0.2 mm, while the presence of BNNTs enables longer spraying due to nozzle cleaning and damping by hard BNNTs, allowing thicker Al‐BNNT deposits of about 2 mm. Microstructural analysis reveals severely deformed Al splats decorated with a uniformly distributed network of BNNTs at the intersplat boundaries, reducing the porosity from 8% to 4% and increasing the splat flattening by 40%. Tribological testing demonstrates resistance of BNNTs to normal force, resulting in a 21% improvement in coefficient of friction and a 65% reduction in wear volume in the Al‐BNNT composite. Additionally, incorporating 3 vol.% BNNTs enhances the neutron radiation shielding by 35%. These improvements in the composites are attributed to reduced porosity and the inherent properties of BNNTs, such as high strength, the ability to produce tribofilm lubrication during dry sliding wear, and their high neutron absorption cross‐sectional area. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cold spraying methods are used to prepare Cu/Ni composite coating on Q235 substrates. The porosity, micromorphology, and microhardness and corrosion properties of the copper coating prepared by cold spraying are studied. This experiment mainly explores the microstructure and corrosion resistance of Cu/Ni composite coatings prepared by different composition powder ratios. The heat treatment process of the coating was carried out to explore the effect of the heat treatment process on the microstructure and corrosion resistance of the coating. The results indicated that the porosity of the coating increases slightly with an increase in nickel powder content. The metal nickel plays an anodic protection role in the Cu/Ni battery. However, too much nickel will lead to too much anode material, and the overall structure of the coating will be destroyed after anode corrosion. The composite coating prepared with 40 wt% nickel powder has the best corrosion resistance. After heat treatment, the corrosion resistance of copper/nickel composite coatings is reduced, and the quality of the coatings is improved. [ABSTRACT FROM AUTHOR]

This study employed a high-pressure cold spray to apply a Zn30Al alloy coating to Q235 steel substrates to provide corrosion protection for steel in marine environments. The corrosion resistance of the coatings was investigated through full immersion tests, and the corrosion mechanisms were further analyzed using electrochemical experiments. The results were compared with those of traditional flame-sprayed Zn30Al alloy coating. The findings indicate that the high-pressure cold-sprayed Zn30Al alloy coating possesses a dense microstructure with a porosity of only 0.32%, providing effective cathodic protection to the substrate during the immersion tests. The cold-sprayed Zn30Al alloy coating maintained good integrity after 720 h immersion in 3.5 wt.% NaCl solution, whereas the flame-sprayed Zn30Al alloy coating exhibited significant pitting corrosion. [ABSTRACT FROM AUTHOR]

Cold spray technology is a multifaceted, environmentally friendly, and very promising method utilised for the aim of applying coatings onto complex geometries. This research examines several challenges pertaining to cold spray coating that have the potential to restrict its practical application. The application of this methodology enhances the depth of understanding of the fundamental process, allows for precise control of coating properties, and supports the refinement of cold spray treatments. Furthermore, it exhibits the supplementary benefit of being environmentally friendly because of its eradication of hazardous emissions and utilisation of flame. Moreover, the application of gas-turbine-driven cold spray equipment provides improved accuracy in controlling the coating thickness. Additionally, it has the capability to be combined with other methods such as laser cladding and thermal spraying to enhance its overall efficiency. [ABSTRACT FROM AUTHOR]

Cold spray is a solid-state additive manufacturing technology and has significant potential in component fabrication and structural repair. However, the unfavourable strength–ductility synergy in cold spray due to the high work hardening, porosity and insufficient bonding strength makes it an obstacle for real application. In recent years, several methods have been proposed to improve the quality of the cold-sprayed deposits, and to achieve a balance between strength and ductility. According to the mechanism of how these methods work to enhance metallurgical bonding, decrease porosity and reduce dislocation densities, they can be divided into four groups: (i) thermal methods, (ii) mechanical methods, (iii) thermal–mechanical methods and (iv) optimisation of microstructure morphology. A comprehensive review of the strengthening mechanism, microstructure and mechanical properties of cold-sprayed deposits by these methods is conducted. The challenges towards strength–ductility synergy of cold-sprayed deposits are summarised. The possible research directions based on authors' research experience are also proposed. This review article aims to help researchers and engineers understand the strengths and weaknesses of existing methods and provide pointers to develop new technologies that are easily adopted to improve the strength–ductility synergy of cold-sprayed deposits for real application. [ABSTRACT FROM AUTHOR]

Superficial depositions gain interest in various industries due to the significant improvement of the properties of the base material that is subjected to superficial depositions. The deposits can be made both in the technological process of manufacturing the various components and in the reconditioning processes of the components with high levels of wear. Superficial coatings are applied with the aim of creating a protective surface layer, that is hard and resistant to both external factors and various demands. Depending on the nature of the application of the component, to be coated the mechanical, microstructural, thermal, corrosion resistance, etc. properties can be improved. The objective of this work is to demonstrate the ability of thermal deposition to improve the mechanical and microstructural properties of materials used in the construction of armour for military equipment using the Cold Spray (CS) thermal deposition method. Among all the deposition methods, this method is the only one that manages to deposit the particles below their melting point, having the lowest deposition temperatures, thus preserving the properties of the deposited material. This paper presents experimental results for armor elements that are subjected to severe exploitation regimes and contributes to the scientific progress in the field of deposits applicable to most industries such as petrochemical, military, aerospace, automotive, and medical. [ABSTRACT FROM AUTHOR]

Chromium carbide powder agglomerated with nickel/chrome was deposited using a cold spray process onto a mild steel substrate. The deposits were heat-treated at 650 °C and 950 °C in ambient conditions to reduce porosity and improve adhesion between powder particles. The corrosion behaviour of these cold-sprayed materials was studied in artificial seawater conditions using electrochemical techniques. Heat treatment at 650 °C was found to best improve corrosion resistance, while the 950 °C treatment performed better than the as-sprayed condition but lower than the 650 °C sample. Microstructural analysis revealed complex phase transformations and structural refinements with increasing heat treatment temperature. The crystallite size of both Cr3C2 and NiCr phases decreased, while microstrain and dislocation density increased due to heat treatment. The formation of and subsequent reduction in Cr23C6 content indicated a complex sequence of carbide dissolution, transformation, and precipitation processes. The 650 °C heat-treated sample demonstrated superior corrosion resistance, evidenced by the highest corrosion potential, lowest passive current, and largest charge transfer resistance. This enhanced performance was attributed to the formation of a more stable and protective passive film, optimal carbide dissolution, and a homogeneous microstructure. Meanwhile, the 950 °C treatment led to excessive carbide dissolution and formed increased interfaces between the carbide and matrix. Mechanical property changes were also observed, with carbide hardness significantly decreasing after corrosion testing. These findings highlight the critical role of controlled heat treatment in optimising the performance of cold-sprayed Cr3C2-NiCr coatings, demonstrating that achieving superior corrosion resistance requires a delicate balance between microstructural refinement, phase transformations, and preservation of coating integrity. [ABSTRACT FROM AUTHOR]

In this study, the effect of an in situ shot peening and cold spraying process for depositing niobium using nitrogen gas was studied and compared to that of traditional niobium sprayed using helium gas. The samples were evaluated using Vickers hardness indentation and defect analysis to compare the mechanical properties and microstructure of the shot-peened samples with that of the helium-sprayed samples. During this study, a mathematical model was proposed to effectively predict the amount of shot peening required to achieve a specific increase in sample hardness. A novel means of using two cold spray systems was also proposed to obtain a better level of control during the shot-peening process. It was found during this study that in situ shot peening can be used to increase the as-sprayed hardness and density of nitrogen-sprayed niobium cold spray deposits to levels comparable to niobium cold sprayed using helium gas. This offers a potential means to transition away from the use of helium gas without sacrificing material properties. [ABSTRACT FROM AUTHOR]

PEEK surface copper metallization is widely used in fields such as power, electronics, and new energy. To enhance the mechanical and electrical characteristics of copper coating on PEEK surface further, this study employed a cold spraying deposition technology of graphene-reinforced copper composite coatings. The investigation focused on the properties comparison between composite coatings and pure copper coatings, and systematically studied the influence of nozzle speed within the range of 50–200 mm/s on the structure and properties of composite coatings. Results show that the mechanical and electrical properties of composite coatings are far superior to those of pure copper coatings. And results indicate that at a nozzle speed of 100 mm/s, the composite coating exhibits the densest structure, with a porosity of 0.31% and minimal graphene aggregation, resulting in superior mechanical and electrical properties. Specifically, the friction coefficient is reduced by 46.81% compared to pure copper coating, measuring 0.4046. Additionally, the Vickers hardness of the composite coating reaches 105.96 HV, and its wear rate is 70.59% lower than that of pure copper coating, at 4.32·10−4 mm3/N·m. Furthermore, the conductivity peaks at 1.295·105 S/cm, representing a 38.77%, increase over pure copper coating. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of using cold spray for repair of Inconel 718 (IN718) components. The effect of cold spray parameters on the particle velocity, splat morphology, deposition efficiency (DE), thickness, and porosity was evaluated. Thick coatings of approximately 4 mm were deposited onto ground and polished IN718 substrates using N2 gas heated to 1000 °C with gas pressure of 5 and 7 MPa. The coatings were subjected to standard double aging (DA) and a combination of solutionizing and double aging (STDA) heat treatment. The microstructure, hardness, porosity, tensile strength, and adhesive strength of as-sprayed and heat-treated coatings were evaluated. Additionally, the tensile properties of the coating–substrate combination (sandwich samples) were also evaluated. It was observed that higher gas pressure led to increased particle velocity, decreased porosity, enhanced hardness, and improved adhesion/tensile strength. The splat size increased with higher particle velocity, indicating greater particle deformation. The DE decreased with increase in number of deposited layers and increased with increase in gas pressure. The AS coating microstructure exhibited a deformed powder microstructure having fine dendritic/cellular structure. Following the DA treatment, the dendritic features were preserved, accompanied by the precipitation of γ′, γ′′, and δ phases. After STDA treatment, a homogeneous microstructure with the presence of γ′, γ′′, and Nb and Ti carbides without any δ phase was observed. The most favorable outcomes were achieved with the 7 MPa STDA sample, yielding a minimal porosity level of 0.4 ± 0.1% and a tensile strength of 1325 ± 10 MPa with a failure strain of 6.1 ± 0.6%. The tensile strength of 7 MPa sandwich sample was found better (1049 ± 8.5 MPa) compared to stand-alone coating (965 ± 24 MPa) after DA treatment. [ABSTRACT FROM AUTHOR]

Cold spray is a material deposition technology with a high deposition rate and attractive material properties that has great interest for additive manufacturing (AM). Successfully cold spraying free-form parts that are close to their intended shape, however, requires knowing the fundamental shape of the sprayed track, so that a spray path can be planned that builds up a part from a progressively overlaid sequence of tracks. Several studies have measured track shape using ex situ or quasi-in situ approaches, but an in situ measurement approach has, to the authors' knowledge, not yet been reported. Furthermore, most studies characterize the track cross section as a symmetric Gaussian probability density function (PDF) with fixed shape parameters. The present study implements a novel in situ track shape measurement technique using a custom-built nozzle-tracking laser profilometry system. The shape of the track is recorded throughout the duration of a spray, allowing a comprehensive investigation of how the track shape evolves as the deposit is built up. A skewed track shape is observed—likely due to the side-injection design of the applicator used—and a skewed Gaussian PDF—a more generalized version of the standard Gaussian PDF—is fit to the track profile. The skewed Gaussian fit parameters are studied across two principal nozzle path parameters: nozzle traverse speed and step size. Empirical relationships between the fit parameters and the nozzle path parameters are derived, and a physics-based inverse relationship between nozzle speed and powder mass deposition rate is obtained. One of the fit parameters is shown to be an effective means of monitoring deposition efficiency during spraying. Overall, the approach presents a promising means of measuring track shape, in situ, as well as modeling it using a more general shape function. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer composites are prominent structural components in various industries such as aerospace, automotive, and wind energy. These materials are considered due to their high strength-to-weight ratio and relative ease of fabrication. However, fiber composites possess low electrical and thermal conductivities and are prone to impact-induced damage. Metallization of fiber-reinforced polymer composites has become an area of interest as a means to prevent abrasive and corrosive damage while also improving other physical properties including thermal and electrical conductivity. The possibility of using cold spray as a novel composite metallization approach has been investigated in this work. The significance of cold spray for metallization is due to relatively low process temperatures which effectively protect the underlaid substrate from potential temperature degradation. As a practical approach to further reduce the possibility of cold spray-induced damage, the present study explores the impact and failure mechanics of metal particles coated with a thin polymeric shell, hence the term polymer-coated metal particle. The thorough model-based analyses presented herein indicate that the so-called polymer-coated metal particles can be cold spray deposited without imposing significant damage to the composite substrate mainly due to the 'cushioning' effect of the thin polymer shell. The results discussed here also provide guidelines for the surface metallization of high-performance fiber-reinforced thermoplastic composites in practice. [ABSTRACT FROM AUTHOR]

The present study focused on optimizing the cold spray (CS) process parameters for depositing Fe20Cr20Mn20Ni20Co20 (Cantor alloy) coatings using mechanically alloyed (MA) powder. A two-step design of experiments approach was employed, beginning with the initial screening of input variables using the L8 Taguchi method, followed by the refinement of process parameters through the Box–Behnken design of experiments. Key performance indicators included deposition efficiency (DE), coating thickness per pass, and microstructural parameters including porosity, cracks, and interfacial defects/delamination. The study identified process gas temperature as the primary factor influencing both DE and thickness per pass. Higher gas temperature and pressure, combined with increased scanning speed, resulted in higher DE. The DE of the MA Cantor alloy powder peaked at around 14-15%, with a deposit density greater than 99% achieved at the highest process gas temperature and pressure (1000 °C and 60 bar, respectively). The average hardness of the optimal CS coating deposited using MA powder was found to be 679 ± 17 HV0.1, which is approximately 90% greater than the average hardness reported for CS coatings deposited using atomized powder. [ABSTRACT FROM AUTHOR]

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Hydroxyapatite (HA, Ca10(PO4)6(OH)2) composite coatings added in the second phase could improve the mechanical properties and bonding strength. The cold spraying technique, as a technology for the deposition of solid particles at low temperatures, is employed to deposit HA ceramic composite coatings. The nano HA material possesses characteristics that enhance properties and promote interface bonding. Due to the exceptional mechanical properties of Ti material, adding Ti particles could improve the mechanical properties of nano HA/Ti composite coatings. In order to explore the deposition deformation mechanism of composite particles under different cold spraying conditions, numerical simulation and experimental testing of deposition behaviors of dual nano HA/Ti composite particles were analyzed. As the particle velocity increased from 400 m/s to 800 m/s in the numerical simulation analysis, the more serious the deposition deformation. Meanwhile, more cracking and splashing phenomena occurred on the surface of the particle. By analyzing the stress value curve of Ti and HA units under different particle velocities, it was found that the adiabatic shear instability phenomenon occurred during the particle deposition on the substrate. In addition, the degree of particle deformation increased with the decrease in the particle size. The results of the experimental investigation were consistent with that of the numerical simulation. [ABSTRACT FROM AUTHOR]

Softening and subsequent deformation are significant challenges in additive manufacturing of thermal-curable thermosets. This study proposes an approach to address these issues, involving the preparation of thermosetting composite powders with distinct curing temperatures, the utilization of cold spray additive manufacturing (CSAM) for sample fabrication, and the implementation of stepwise curing for each component. To validate the feasibility of this approach, two single-component thermosetting powders P1 and P2 and their composite powder C were subjected to CSAM and stepwise curing. From the sample morphology observation and deposition/curing mechanism investigation based on thermomechanical analysis and differential scanning calorimetry, it is found that severe plastic deformation occurs during the CSAM process, accompanied by heat generation, leading to local melting to promote a good bond at the contact surface of the particles and form small pores. During the progressive curing, the samples printed using C demonstrate superior deformation resistance compared with those using P1 and P2, and the curing time is reduced from 16.7 h to 1.5 h, due to the sequential curing reactions of P1 and P2 components in composite C, allowing the uncured P2 and cured P1 to alternately remain solid for providing structural support and minimizing deformation. [ABSTRACT FROM AUTHOR]

The cold-spray technology has been rapidly gaining in popularity, especially over the last two decades, due to its ability for depositing coatings at relatively low temperatures in contrast to other thermal spray methods. A key challenge for this technique lies in optimization of process parameters. Particle deposition occurs by plastic deformation of the particle and the substrate, which requires a high kinetic energy of impact. This calls for a minimum threshold velocity called the critical velocity and happens to be a key factor affecting process efficiency. In this review, we focus on numerical, theoretical and experimental approaches towards measuring the critical velocity (vcr) and subsequently elucidate the factors affecting vcr. [ABSTRACT FROM AUTHOR]

The application of cold spray (CS) for 316L stainless steel (SS) has been an increasingly popular process in recent years. However, defects in the form of porosity hamper their frictional resistance. In an effort to enhance the frictional resistance of CS 316L SS, novel indirect-laser surface texturing without confinement (ILSTwC) and direct-laser surface texturing without confinement (DLSTwC) processes are introduced as viable surface texturing, densifying, and strengthening techniques. These techniques operate by taking advantage of the severe plastic deformation and heating kinetics of a pulsed laser to an externally applied mesh, thus creating a surface texture that is highly dense and work-hardened. For the ILSTwC treatment, utilizing a laser intensity of 6.13 GW cm−2 led to significant changes in surface properties. Compared to the non-textured CS surface, there was a 24.1% increase in surface roughness, a notable 262.2% increase in surface skewness, a 26.0% increase in surface hardness, and a substantial 54.4% decrease in frictional response. For the DLSTwC treatment at the same laser intensity, the surface properties exhibited contrasting behavior. There was a remarkable 80.4% reduction in surface roughness, accompanied by a 63.6% increase in surface skewness, a 26.4% increase in surface hardness, and a significant 65.1% decrease in frictional response compared to the non-textured CS surface. Between the ILSTwC and DLSTwC surfaces, the DLSTwC surface had the greatest reduction in friction due to the lessened tribological contacts from the negatively skewed surface. Based on these findings, this work indicates that laser surface texturing has an influential effect on enhancing surface hardness and density and is indeed a viable technique to control the tribological performance of harder materials such as CS 316L SS. [ABSTRACT FROM AUTHOR]

A GRCop-42 cylinder was produced by North American Manufacturing Pros using laser powder bed fusion to measure the residual stress at a bimetallic joint with NASA HR-1. Pure Ni was applied by ASB Industries as a diffusion barrier between the GRCop-42 and NASA HR-1 using cold spray. Residual stress measurements of the Ni layer in the as-cold sprayed and heat-treated conditions were collected on the top surface of the coating using x-ray diffraction with Co Kα radiation and the Sin2ψ method at multiple phi (φ) angles. Biaxial stress values and rotation angles between the original sample axes (φ = 0° direction) and the principal axes were calculated at three equally spaced locations around the perimeter of the cylindrical part. The stress measurements were plotted at their respective positions around a circle, and with the rotation angles for each, to reveal rotational symmetry in the tension and compression of the coating. [ABSTRACT FROM AUTHOR]

Cold spray additively manufactured (CSAM) aluminum 6061 components are characterized by heterogeneous compressive residual stresses induced during manufacturing. This heterogeneity is further compounded by spatial variations in microstructures and mechanical properties, leading to poor inter-particle (intersplat) bonding and significant marring of overall component performance. Thermal post-processing is a keenly researched method for recovering mechanical toughness by enhancing intersplat bonding and altering highly concentrated residual stress distributions. The current work incorporates a modified microscale–mesoscale material model into a viscoplastic self-consistent simulation framework to capture material response in the as-sprayed and post-processed states. The updated model incorporates physically informed parameters emphasizing residual stresses measured experimentally through X-ray diffraction. The model calibrated using experimental tests and published literature was able to predict the stress–strain response of CSAM parts at post-heat-treated conditions. Results of the parametric study showed the significance of intersplat boundary effects on the overall yield and strain hardening of the CSAM parts. Without any information on the processing conditions of CSAM parts, the modified plasticity model predicted the deformation response using information gathered from microstructure characterization. [ABSTRACT FROM AUTHOR]

This study employs neutron diffraction to investigate the relationship between residual stress and coating thickness in cold sprayed 304L austenitic stainless steel. Results show that shot peening predominantly impacts the residual stress profile, leading to substantial in-plane compressive force. The impact of laser heating, a widely used method to alter cold spray's microstructural properties, on the coating's residual stress is also analyzed. The findings indicate that the maximum compressive residual stress in the in-plane component is mainly independent of coating thickness, which suggests that the material properties determine the maximum residual stress. The cold sprayed deposits possessed compressive, nearly biaxial strain and stresses. After laser heating, these stresses were replaced by tensile residual stresses. Two analytical models, the Tsui and Clyne and the Boruah models, for predicting residual stresses are also evaluated, and both models provide reasonable fits to the experimental data. At this point, the deviations between the experimental results and the models are principally caused by the inability of the current models to address plastic deformation and relaxation, and the residual stresses generated by thermal gradients. [ABSTRACT FROM AUTHOR]

The grain structure evolution and nanomechanical behavior of cold-sprayed Al coating on Ti substrate with friction stir spot processing (FSSP) were studied by the electron backscatter diffraction and nanoindentation methods. The low-angle boundaries (LAGBs) fraction and the density of the geometrically necessary dislocations (GNDs) decreased from the base zone (BZ) to the stir zone (SZ). The average grain size, the LAGBs fraction and the density of the GNDs were various in different locations of the SZ, which can be attributed to the variety of local shear strain and temperature gradient during FSSP. The B/ B - component, the C component, and the A*1/ A*2 component were mainly developed in the SZ. The highest intensity of the B/ B - component appeared in the 3/8D of the SZ, indicating that the plasticized materials flowed downward experienced the highest shear strain. The materials in the heat affected zone (HAZ) underwent static recrystallization, while the continuous dynamic recrystallization (CDRX) and the geometric dynamic recrystallization (GDRX) occurred in the thermo-mechanically affected zone (TMAZ) and SZ. The nano-hardness and elastic modulus of the cold-sprayed Al coating after FSSP were comparable to those of pure Al bulk. The grain size and dislocation density were the main factors affecting the nano-hardness in the SZ. [ABSTRACT FROM AUTHOR]

This study investigated the effect of powder pre-oxidation on the microstructures and mechanical properties of cold-sprayed nickel coatings. The artificially pre-oxidized nickel powders at 200, 300 and 400 °C for 5 h show the resulting oxygen contents of 0.27, 0.36 and 0.41 wt.%, as compared to 0.21 wt.% in the feedstock powder. Microstructurally, the higher oxygen contents of the impact particles significantly increased in both the number and size of the pores in the as-sprayed coatings by using the pe-oxidized powders, as a result of the porosities of 0.7, 1.5 and 3.3% compared to 0.4% by using the as-atomized powder (natural oxidation condition). Mechanically, the increased oxygen contents of powders result in the reduced properties for the as-sprayed Ni coatings, as the microhardness of 263.2 HV0.1, 245.3 HV0.1 and 236.3 HV0.1 and the tensile strength of 94, 76 and 61 MPa by using oxidized powders compared to those of 289.2 HV0.1 and 208 MPa by using natural oxidation powder. In addition, post-spray heat treatment at 800 °C for 2 h effectively reduces the small-sized pores and nonbonded particle-particle boundaries within the coatings, which is attributed to a combination effect of annealing twins and dislocation slip during heat treatment. As a result, the microhardness significantly decreased to 135.3 HV0.1, 126.7 HV0.1, 124.5 HV0.1 and 114.7 HV0.1, while the tensile strength is increased to 210, 166, 133 and 117 MPa, respectively. [ABSTRACT FROM AUTHOR]

7-Series aluminum (Al) alloys have been widely used in aircraft and high-speed train manufacturing owing to its excellent mechanical properties and fracture toughness. However, surface problems of corrosion, wear and fatigue failure of Al alloy parts seriously affect the service life. In the present study, the noncontact laser shock peening (LSP) was applied to improve the fatigue life of the substrate before the coating deposited by cold spraying (CS). The effect of LSP on the interfacial bonding behavior between CS Al with 50 vol.% Al2O3 composite coatings and 7075 Al alloy substrate was comprehensively investigated. Results showed that after LSP treatment, the tensile strength is reduced from 47 to 34 MPa and 32 MPa when the laser shock energy was 2 and 3 J, respectively. Under the condition of shear strength, it decreases from 41.5 to 30 MPa and 26 MPa, respectively. In addition, numerical simulations were conducted on LSP and CS processes, and the results showed that with the increase of laser shock energy, the plastic deformation dissipation energy of Al particles increases gradually, while the plastic deformation dissipation energy of the matrix decreased. Therefore, the surface hardening caused by LSP treatment is the main reason for the decrease of interfacial bonding strength. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive set of characterization techniques are employed to demonstrate that the cold spray deposition process can result in a significant increase in martensite in austenitic stainless steel. The lack of consensus in the literature on the formation of strain-induced martensite in cold spray can be attributed to the diverse processing conditions and measurement techniques used in different studies. In this work, EBSD, neutron diffraction, TEM imaging, and precession electron diffraction were used in combination to examine whether strain-induced martensite is formed during cold spray deposition of 304L stainless steel powder and to give further insight into possible mechanisms controlling this phenomenon. Cold spray was performed at both 350 °C and room temperature (25 °C) to investigate the effects of spray temperature on the martensite transformation. It is shown that the strain-induced martensite formation is significantly suppressed compared to that which would be expected for comparable levels of plastic strain at quasi-static strain rates. Additionally, the spray gas temperature is shown to directly impact the microstructure formed at the prior particle interface and the formation of dynamically recrystallized regions. [ABSTRACT FROM AUTHOR]

A computational framework is proposed for modelling particle bonding in cold spray. The model is based on the commonly-held view that bonding is a consequence of jetting, namely, the large plastic strains occurring at extreme rates upon particle impact. The model incorporates a bonding criterion at contacting boundaries by introducing a novel strain-like history variable referred to as the bonding parameter conjugate to a rate-dependent evolution law. In doing so, an analogy is made with classic damage mechanics where bonding is viewed as a similar but opposite process to fracture. Two new material constants are introduced, namely, the bonding toughness and the bonding toughness rate. Furthermore, a numerical implementation of the model in the Material Point Method (MPM) is presented which, thanks to a proposed regularization technique, is free of non-physical dependence on discretization parameters. The mesh-free nature of the MPM allows avoiding the numerical issues in conventional Lagrangian and Eulerian methods such as mesh distortion and artificial dissipation. The model is calibrated numerically for aluminum-aluminum material pair using an in-house computer program. Several numerical results are presented to demonstrate that the model can accurately capture material jetting and directly relate it to bonding within the simulation. [ABSTRACT FROM AUTHOR]

Herein, the effect of heat treatment on the characteristics and properties of cold spray additive manufactured 316L stainless steel employing traditional and a new metal knitting strategy is investigated. 316L feedstock powder characteristics, the geometry of the bulk, microstructure, porosity, microhardness, mechanical isotropy, and residual stress are analyzed in both strategies in as‐sprayed and heat‐treated conditions. Results show that the traditional deposition strategy produced higher mechanical resistance, whereas metal knitting presents a better part geometry accuracy. The heat treatment significantly improves the material strength and the quality of the parts by recovery and recrystallization phenomena. The same microhardness and planar isotropy are achieved after heat treatment of samples produced by both strategies. A discussion about the mechanisms, microstructural, and residual stress evolution is presented. [ABSTRACT FROM AUTHOR]

The cold spray deposition technique has been used to produce a new class of solid lubricant coatings using powder feedstocks of the metal disulfides WS2 or MoS2, either pure or mixed with Cu and Ni metal powders. Friction and cycle lives were obtained using ball-on-flat reciprocating tribometry of coated 304 SS flats in dry nitrogen and vacuum at higher Hertzian contact stresses (Smax = 1386 MPa (201 ksi)). The measured friction and thickness of the coatings were much lower than for previous studies (COF = 0.03 ± 0.01 and ≤1 µm, respectively), which is due to their high metal disulfide:metal ratios. Cu-containing metal sulfide coatings exhibited somewhat higher cycle lifetimes than the pure metal sulfide coatings, even though the Cu content was only ~1 wt%. Profiling of wear tracks for coatings tested to 3000 cycles (i.e., pre-failure) yielded specific wear rates in the range 3–7 × 10−6 mm3N−1m−1, similar to other solid lubricant coatings. When compared to other coating techniques, the cold spray method represents a niche that has heretofore been vacant. In particular, it will be useful in many precision ball-bearing applications that require higher throughput and lower costs than sputter-deposited MoS2-based coatings. [ABSTRACT FROM AUTHOR]

The cold spray (CS) process is an advanced material deposition method that has emerged as a versatile method to create high-performance coatings and functional components. This process offers unique advantages in achieving exceptional material adhesion and properties without needing high-temperature melting or heating. The CS process enables the deposition of cermets, allowing it to combine the favorable properties of their constituent phases. This review article explores the bonding mechanism specific to the CS deposition of cermets, highlighting its contrast with that of pure metals. It subsequently investigates the pivotal role played by ceramic particles in the overall efficiency of the CS deposition process, emphasizing the need for a comprehensive understanding of particle properties to achieve quality coatings for specific applications. The paper explores the challenges and limitations imposed by the CS process of cermets in optimizing the crucial parameters. It dissects the influence of interfacial bond strength and porosities on the tribological and corrosion properties of CS-deposited coatings. The discussion extends to the significant role played by substrate in shaping the coating's characteristics. The potential for enhancing coating properties through post-processing treatments is also thoroughly examined. The review article also discusses current advancements in the field and contemplates potential future directions, offering a comprehensive exploration of CS deposition of cermets and its multifaceted considerations. [ABSTRACT FROM AUTHOR]

The effect of niobium ion implantation on the surface and scratch properties of a WC-5wt.%Ni cold sprayed coating was investigated with accelerating energies of 60 and 170 keV and fluences of 5 × 1016 and 8 × 1016 ions cm−2, respectively. High-resolution Rutherford backscattering spectroscopy spectra revealed that Ni-Nb and WC-Nb amorphous layers had likely formed. Using ion implantation parameters of 60 keV with a fluence of 8 × 1016 ions cm-2 (coating 608-NB), higher Nb peak intensities were found. Oxide formation in the form of NbO, NbO2, and Nb2O5 was detected with high-resolution x-ray photoelectron spectroscopy spectra analyses on the 608-NB coating, in conjunction with the intermetallic, thereby having the best coating properties: higher hardness, low roughness, and scratch properties compared to the other ion-doped samples. The failure mechanisms of all the coatings were found to be similar, showing angular cracks, cone cracking, and primary delamination. [ABSTRACT FROM AUTHOR]

Thermal management is key to enabling increasingly powerful chips and heterogeneous integrated 2.5D/3-D systems. Composite materials with high thermal conductivities that can be placed at different levels of proximity to the die provide new solutions for heat dissipation. Here we report the fabrication of thick copper-diamond composite !lms using cold spray, which is a high-throughput, low-thermal-budget deposition technology. In cold spray, feedstock micro powder is accelerated in a specially designed nozzle by a heated pressurized gas and adheres to the substrate upon high-speed impingement. This process achieves higher deposition rates than other methods used in semiconductor manufacturing (such as electroplating). It also produces films that are denser and much less porous than ones produced by conventional thermal spray techniques. In this work, we first use process and thermal simulations to determine the requirements of the micro diamond powder feedstock, including the diamond core size, metal-clad thickness, core-clad interfacial resistance, and volume fraction to enable the cold spray of copper-diamond composites with thermal conductivities that are higher than copper. Subsequently, we perform a systematic characterization of the diamond powders from several suppliers, including the purity, metal oxygen content, particle morphology, and metal-clad adhesion. This characterization reveals the challenges of meeting all the specs using currently available diamond powders. Finally, we cold spray copper-diamond composite films on a variety of substrates with tunable thicknesses between 100 mm and 2 mm, achieving a thermal conductivity that is approximately 10% higher than cold-sprayed pure copper. Further improvement of the thermal properties relies on continued innovation in powder surface modification and powder storage/shipping methods. [ABSTRACT FROM AUTHOR]

The effect of coating thickness (CT) on the microstructures, hardness, and wear of cold sprayed Ti-6Al-4V (CS-Ti64) coatings was systematically investigated since the prolonged high pressure CS deposition could change their microstructures and porosity levels. In addition, the CT was relatively important for their durability, performance, and service life. Therefore, the CS-Ti64 coatings with different CT of 100-3000 μm were prepared on commercially available Ti64 (CA-Ti64) substrates via high pressure CS processes. The CS-Ti64 coatings had low porosity levels wherewith severely deformed Ti64 particles with a crescent-shape could be seen in their crosssectional microstructures. The hardness of the CS-Ti64 coatings increased with increased CT probably due to their lowered bulk porosity levels associated with longer high pressure CS deposition. As a result, the increased CT from 100 to 3000 μm resulted in a 9.8% decrease in the wear of the CS-Ti64 coatings. The wear of the CS-Ti64 coating with 3000 μm was 16.8% lower than that of the CA-Ti64 as all the CS-Ti64 coatings had lower wear than the CA-Ti64. It could be concluded that the prolonged high pressure CS deposition for the thick CS-Ti64 coatings had an influence on their porosity, hardness, and wear. [ABSTRACT FROM AUTHOR]

Cold spray technology, as an emerging surface engineering technique, effectively prepares hard coatings by high-speed projection of powder materials onto substrates at relatively low temperatures. The principal advantage of this technology lies in its ability to rapidly deposit coatings without significantly altering the properties of the substrate or powder materials. Carbon-based materials, especially carbides and diamond, etc., are renowned for their exceptional hardness and thermal stability, which make them indispensable in industrial applications requiring materials with high wear resistance and durability at elevated temperatures. This review elucidates the fundamental principles of cold spray technology, the key components of the equipment, and the properties and applications of hard coatings. The equipment involved primarily includes spray guns, powder feeders, and gas heaters, while the properties of the coatings, such as mechanical strength, corrosion resistance, and tribological performance, are discussed in detail. Moreover, the application of this technology in preparing metal matrix composite (MMC) materials with carbon-based reinforcements, including tungsten carbide, boron carbide, titanium carbide, and diamond, are particularly emphasized, showcasing its potential to enhance the performance of tools and components. Finally, this article outlines the challenges and prospects faced by cold spray technology, highlighting the importance of material innovation and process optimization. This review provides researchers in the fields of materials science and engineering with a comprehensive perspective on the application of cold spray technology in MMC materials with carbon-based reinforcements to drive significant improvements in coating performance and broaden the scope of its industrial applications. [ABSTRACT FROM AUTHOR]

This paper presents the results of an extensive investigation into the durability of cold spray repairs to corrosion damage in AA7075-T7351 aluminium alloy specimens where, prior to powder deposition, the surface preparation involved grit blasting. In this context, it is shown that the growth of small naturally occurring cracks in cold spray repairs to simulated corrosion damage can be accurately computed using the Hartman–Schijve crack growth equation in a fashion that is consistent with the requirements delineated in USAF Structures Bulletin EZ-SB-19-01, MIL-STD-1530D, and the US Joint Services Structural Guidelines JSSG2006. The relatively large variation in the da/dN versus ΔK curves associated with low values of da/dN highlights the fact that, before any durability assessment of a cold spray repair to an operational airframe is attempted, it is first necessary to perform a sufficient number of tests so that the worst-case small crack growth curve needed to perform the mandated airworthiness certification analysis can be determined. [ABSTRACT FROM AUTHOR]

This study focuses on the successful fabrication of three distinct types of CoCrFeNi high entropy alloy (HEA) coatings through cold spray (CS) technology, with an emphasis on analyzing the impact of varying crucial CS parameters (spraying temperature and the range of powder particle size), on the coating's microstructure and tribological properties. Contrasted with conventional thermal spraying techniques, lower operational temperature in CS safeguards the materials from undergoing oxidation or phase transitions that are typically induced by high-temperature conditions. Additionally, the high-velocity impact of particles onto the substrate within CS process triggers plastic deformation, resulting in the creation of coatings that are characterized by heightened hardness, and greater density. Such coatings exhibit significantly enhanced performance and durability. The cocktail effect observed in CoCrFeNi HEA is reflected in a suite of exceptional properties that markedly surpass those exhibited by traditional alloys. Chiefly, this phenomenon is manifested through the alloy's exceptionally high hardness and dense structure, positioning CoCrFeNi HEA as a promising candidate for applications in high-wear scenarios. Experimental outcomes indicate that when smaller powder particles and higher spraying temperatures are employed, the porosity of CSed CoCrFeNi HEA coatings was observed to decrease by nearly an order of magnitude, concomitant with a 22.46% enhancement in microhardness. This improvement in microhardness translates into a significant reduction of over 72% in the wear rate, underscoring the positive correlation between enhanced microstructural integrity and wear resistance properties. By meticulously tuning spraying temperature and powder particle size, the resulting microstructure can be rendered increasingly dense and refined. [ABSTRACT FROM AUTHOR]

With the widespread use of nuclear energy, the storage of surplus spent fuel has emerged as a critical issue that needs to be solved, especially for the efficient absorption of neutron radiation and secondary γ-rays generated by spent fuel produced when 10B absorbs neutrons. In this work, B4C/Al and W/B4C/Al coating were prepared on 316 L stainless steel by cold spraying. The microstructure and tensile properties of the coatings were investigated. The performance of the thermal neutron and secondary γ-rays absorption of the two coatings were simulated using the Monte Carlo approach. The results indicated that, compared to the B4C/Al coating, the W/B4C/Al coating exhibited better mechanical properties due to the tamping effect of the W particles. In addition, the secondary γ-rays absorption property was improved due to the addition of W. [ABSTRACT FROM AUTHOR]