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Many strategies have been developed to prevent procedural pain in pediatric emergency units, where nurses play a vital role in ensuring patient comfort. Easy-to-use and inexpensive nonpharmacologic analgesic methods are important in emergency units. This study was conducted to determine the effect of cold spray and ice applied during venipuncture on the level of fear and pain in children aged 7 to 15 years. This was a randomized controlled experimental study of 96 children between the ages of 7 and 15 years (cold spray group, ice group, and control group) who were scheduled to have venous access in the pediatric emergency clinic and met the sampling criteria. Evaluations of the children, parents, and observers in the groups found a statistically significant difference between the pain and fear scores after the intervention compared with the preintervention (P <.001). The pain and fear scores of the children in the control group were higher than the scores of those in the spray and ice groups (P <.001); the pain and fear scores of the children in the spray group were lower than the scores of the children in the ice group and statistically significant (P <.001). In conclusion, cold spray applied during intravenous access in children aged 7 to 15 effectively reduces pain and fear and should be used in the emergency unit. [ABSTRACT FROM AUTHOR]

Cold spraying is currently developing as a high potential technique for the repair of metallic components, particularly for the deposition of heat-and oxidation-sensitive materials. However, for the appropriate application, it is essential to prepare the component surface suitably to ensure optimum prerequisites for the subsequent material deposition by cold spray. Thus, this work proposes a concept for robot-guided pre-machining for repair by cold spray that includes removal of the damaged volume while considering the requirements for subsequent material deposition. In this concept, digital component and damage data define the dimensions and boundary conditions for material removal. This involves designing a parametric pre-machining target geometry for the damaged component by computer-aided design software that can handle variable surface types. The pre-machining target geometry is adapted to the damage characteristics by considering length, width, depth and orientation. To produce the pre-machining target geometry by machining tools, the adjusted component is exported to computer-aided manufacturing software. The applicability of this concept has been successfully demonstrated on digital use cases with exemplary components and damages as well as by practical application with a milling robot in a laboratory environment. The results demonstrate the capability of this concept for preparing damaged components and promise a high potential to ensure the required prerequisites for high-quality component repair by cold spray. [ABSTRACT FROM AUTHOR]

A honeycomb-like porous self-supporting Ni-Al(G) electrode was successfully prepared by low-pressure cold spraying combined with heat treatment. The main components of the electrode were Ni and NiAl. Graphene was uniformly dispersed throughout the electrode, exhibiting a 3-D distribution, which increased the active site of electrode and improved the electron exchange rate. The electrochemical properties of the Ni-Al(G) electrode were characterized using 6 M KOH. As a result, the Ni-Al(G) electrode requires only an overpotential of 130 mV to achieve a current density of 100 mA cm−2, and a Tafel slope of 35.5 mV dec−1. In addition, the electrode exhibited excellent stability. The addition of graphene and the honeycomb-like porous structure of the Ni-Al(G) electrode resulted in an excellent hydrogen evolution activity. This study provides a simple and rapid technique for building high-performance, low-cost, and industrially available electrodes for the efficient alkaline HER. [ABSTRACT FROM AUTHOR]

In this study, a detailed investigation is conducted on cold sprayed copper coatings in their as-deposited state as well as after annealing at 350 °C for 1 h. The local variations of microstructure and hardness are revealed through a combination of electron backscattered diffraction and high-speed nanoindentation mapping techniques. While a highly heterogeneous microstructure is present in the as-deposited material, annealing results in a more uniform grain size, an increase in the fractions of twin and twin-related boundaries and a decrease in the density of geometrically necessary dislocations and low angle grain boundaries. The relative contributions of grain boundary hardening and work hardening are evaluated via hardness line profile analyses. The identification of oxide films along splat-splat interfaces suggests a potential additional factor contributing to local hardness. • Cold sprayed Cu materials for used nuclear fuel containers were studied using EBSD and nanoindentation. • Both microstructural and mechanical heterogeneity decreased after annealing. • The relative contributions of grain boundary hardening and work hardening were evaluated. • Oxide films along the interfaces of adjacent splats were identified. [ABSTRACT FROM AUTHOR]

• Seamless gradient structure of SiC/CuCrZr and AlN/CuCrZr layer is fabricated by CS. • The gradient coating addresses the challenge of strength and conductivity. • Hardness and thermal conductivity of the gradient coating fit ROM. • Gradient structure achieves comprehensive wear resistance and thermal property. To address the inherent challenge of optimizing both strength and conductivity of the CuCrZr alloy, cold spraying is employed to enhance its surface with a comprehensive range of performance attributes. A novel gradient structure, featuring a SiC/CuCrZr layer at the top and an AlN/CuCrZr layer at the bottom, successfully fulfills the comprehensive requirements for wear resistance and thermal conductivity. Results show that the composite coating is composed of extensively deformed CuCrZr particles and undeformed ceramic particles and its microhardness and thermal conductivity closely adhere to the rule of mixtures. Additionally, the gradient coating shows the equivalent wear resistance to the SiC-CuCrZr coating. This study demonstrates the remarkable versatility of cold spraying in fabricating seamless gradient coating, while achieving predictable and controllable variations in microhardness and thermal conductivity across the coating's thickness. [ABSTRACT FROM AUTHOR]

This study integrates graphene-based nanostructures as reinforcement in a Ti matrix to produce coatings using the Cold Gas Spray (CGS) technique, aiming to enhance mechanical and tribological properties while overcoming some of the limitations of conventional thermal spray methods. The hypothesis holds that incorporating Carbon Nanofibers (GFs) into Ti matrices significantly reinforces these properties compared to pure Ti coatings. The study employed ball milling for the powders obtaining, CGS deposition, and various analytical tests to evaluate the performance of Ti-GFs and pure Ti coatings. Results revealed that Ti-GFs coatings significantly improved in mechanical properties, achieving ultimate tensile strength up to 456 MPa and a strain increase to 2.27%. These improvements are attributed to effective load transfer across the Ti-GFs interfaces, facilitated by strong chemisorption interactions. Additionally, heat treatments at 1000 °C relieved residual stresses and promoted microstructural changes via atomic diffusion, further contributing to the coatings' strength and ductility. Tribological assessments revealed a 21% reduction in the coefficient of friction for Ti-GFs coatings compared to as-sprayed Ti, though was 2% higher than that of Ti-Bulk. This suggests the potential of graphene as a nanoscale lubricant, though further optimization of GFs dispersion and interface interactions may result in even lower coefficient. These findings highlight the potential of GFs reinforced metal matrix composites applied by CGS for critical applications in sectors such as aerospace and biomedical, which demand materials with high strength and reduced mechanical wear. The study also identifies key areas for future research, including the optimization of graphene dispersion and interface bonding, to fully exploit the benefits of GFs in CGS coatings. [Display omitted] • Carbon nanofibers in Ti matrices via Cold Gas Spray significantly boost corrosion resistance, showcasing protective capabilities. • Tensile and wear test improvements confirm carbon nanofibers effectiveness as a reinforcing material for Ti coatings. • Cold Gas Spray boosts tribological properties of Graphene-reinforced Ti coatings by reducing friction coefficient. [ABSTRACT FROM AUTHOR]

This study presents a numerical analysis of commercially pure Ti and Ti–6Al–4V powders under cold spray conditions. The primary objectives are to investigate the deformation mechanisms, splat formation during the cold spray process, and the impact of the oxide layer. Initially, structural data obtained from transmission electron microscopy (TEM) are used to model the oxide structure through molecular dynamics simulations. Subsequently, molecular dynamics are employed to evaluate the mechanical properties of the oxide layer. Finally, finite element-based models are utilized to analyze and visualize the deformation process and the thermal effects when single Ti/Ti–6Al–4V particles impact substrates of the same material. These results offer an understanding of splat evolution and oxide residuals that affect particle attachment to substrates of the same material. The implications of these findings for designing and developing robust cold-sprayed Ti alloys are briefly discussed, emphasizing the potential for optimizing cold-spray process parameters and enhancing coating quality. [Display omitted] • Amorphous TiO 2 on CP-Ti and Ti–6Al–4V lowers properties, affecting deposition. • CP-Ti bonds better than Ti–6Al–4V due to higher deformability and adhesion. • Deposition efficiency rises up to 800 m/s, but plateaus beyond 1000–1200 m/s. • Nanoscale oxides raise critical velocity and weaken interfacial strength in coating. [ABSTRACT FROM AUTHOR]

[Display omitted] • 60 samples were manufactured, and the porosity was measured via image analysis. • Comparison of data preparation methods such as filter-based feature selection and principal component analysis. • Training of machine learning algorithms with prepared datasets. • A prediction accuracy of less than 0.7% porosity was achieved. The desired porosity level of cold-sprayed titanium parts varies depending on the application and therefore requires precise control. To achieve the desired porosity the selection of the correct spray parameters is essential. This study investigates how the cold spraying process affects porosity levels through the application of machine learning techniques. 14 parameters are recorded during the cold spraying process of titanium parts, with the porosity level of each process being manually measured through the analysis of microscope images. Due to the high cost associated with generating data, the dataset size was limited for this study. To alleviate this problem such that machine learning models can be properly trained, this paper carefully enhances a firsthand dataset by using feature engineering, feature selection, and dimension reduction techniques. The study implemented random forest, gradient boosting, and neural network algorithms, with the neural network model demonstrating the best performance. This model achieved an RMSE of 0.7 % on unseen data. For the spray parameter ranges of the available dataset, based on the Shapley value analysis, the spray angle has been identified as the most influential feature of the model for predicting porosity. [ABSTRACT FROM AUTHOR]

Amorphous alloy coatings, known for the exceptional wear resistance, have emerged as a key solution for enhancing the wear performance of magnesium alloys under harsh environments. In this study, Fe-based amorphous alloy coatings were deposited on magnesium alloy by cold spraying technology, and the influence of microstructural evolution on the wear performance of coatings under dry sliding wear conditions was discussed. The results showed that a dense adherent oxide layer with a thickness of ∼700 nm comprising nanograins of less than 8 nm was formed at the outmost surface, which played a role of self-lubricating. Underneath, a 1 μm thick nanocrystalline-amorphous layer with nanograins of ∼20 nm dispersed in the amorphous alloy matrix was formed through in-situ crystallization induced by flash temperature. This composite structure prevented the formation of shear bands in amorphous alloys and enhanced the durability. Therefore, the transition from abrasive wear to adhesive wear was a consequence of the microstructural evolution from a dual-phase composite layer to a self-lubricating oxide layer. • The in-situ formation of nanocrystalline-amorphous dual-phase layer was discovered. • The outmost adherent oxide layer with ultra-fine nanostructures provides lubrication effect. • The relation between microstructural evolution and COF of running-in stage was elucidated. [ABSTRACT FROM AUTHOR]

• Laser post-treatment successfully eliminated defects in Al-coated PEEK. • Laser improved the adhesive strength and electrical conductivity of deposits. • Degradation of PEEK during the process facilitated its bonding with Al coating. To improve the bonding strength and electrical conductivity(σ) of cold-sprayed Al coatings on polyetheretherketone(PEEK) substrates, laser post-treatment was employed as an effective strengthening method without decomposition of the polymer substrates. Optical and electron microscopy observations were used to examine the microstructures and tensile fracture surfaces of the Al coatings fabricated with various laser powers. X-ray diffraction and electron backscatter diffraction were employed to investigate the phase composition and grain information of each coating. Hardness, pull-out adhesion, and electrical conductivity tests were performed to investigate the effect of laser power on the mechanical and physical properties of cold-sprayed Al coatings. The results revealed that despite the formation of several hundred micrometer-sized pores on the PEEK side, the porosity of the laser post-treated Al coatings significantly decreased, and the particle–particle interfaces were greatly healed with increasing laser power. The heat input induced large-scale recrystallization and significantly reduced the dislocation density in the samples. The XRD pattern revealed that no oxidation phase appeared following the laser treatment under the protection of Ar. The electrical conductivity and bonding strength of the Al coatings increased by up to 40 % and 167.4 %, respectively, after the laser post-treatment. [ABSTRACT FROM AUTHOR]

The solid-state additive manufacturing (AM) process Cold Spray (CS) has recently gained importance in science and industry. It offers advantageous properties like high deposition rates and low oxide build-ups. During the process, powder particles are accelerated to supersonic speeds by a carrier gas. The resulting particle velocity is crucial for the deposition quality and must comply with the processed powder material. Analyzing the CS process the powder gas flow rate, a so far slightly investigated parameter, seems to be of major importance. This paper investigates the influence of the powder gas flow rate on the quality of cold sprayed CW106C. [ABSTRACT FROM AUTHOR]

It was aimed to evaluate the efficacy of Buzzy and cold spray in reducing pain, anxiety, and fear of children during venipuncture in the emergency department (ED). This study is an experimental, parallel-group (intervention-control), randomized controlled, single-blind design. The study was conducted with 161 children aged 5–12 years in pediatric ED. Data were collected by the 'Personal Information Form', 'Wong Baker-Facial Expression Rating Scale', 'Child Anxiety Statement Scale', and 'Child Fear Inventory'. Data were analyzed with descriptive statistics, Mann Whitney U test, Kruskal Wallis H test, and Intraclass Correlation. Descriptive features of the children were homogeneous. 'Wong Baker-Facial Expression Rating Scale', 'Child Anxiety Statement Scale', and 'Child Fear Scale' score averages of the children in the control group were higher than the children in the Buzzy group and the cold spray group (p < 0.001). The pain scores of the Buzzy group were higher than those in the cold spray group (p < 0.001). The anxiety and fear mean scores of the children in the Buzzy and cold spray groups were similar (p > 0.05). It was determined that Buzzy and cold spray were more effective than standard care in reducing the level of pain, anxiety, and fear in children ages 5–12 years during venipuncture in the pediatric emergency. The cold spray was more effective in reducing pain than Buzzy. Nurses can use Buzzy and cold sprays to manage the fear, anxiety, and pain associated with venipuncture. • The use of non-pharmacological methods is very important in the management of pain, anxiety, and fear in children. • Buzzy and cold spray were effective in reducing pain, anxiety, and fear in 5-12 children during venipuncture. • The cold spray was more effective in reducing pain than Buzzy [ABSTRACT FROM AUTHOR]

[Display omitted] • First use of cold spray for composite coatings in anti-laser applications. • ZrC-Cu reflective coatings successfully deposited via cold spray process. • No ZrC decarburization or copper oxidation observed in coatings. • Cu-30 %ZrC achieved 85 % bulk copper reflectivity at 1080 nm wavelength. • All coatings, except Cu-85 %ZrC, resisted physical damage under laser tests. Lasers are very powerful and can produce high temperatures, capable of melting materials when projected with an appropriate power, exposure time, distance, and beam width. High energy lasers are used for attacking enemy aircraft and missiles; however, the same threat is inevitable to the allied aircraft and missiles. Surface coatings have proven to be a viable solution to reduce damage from such laser attacks. In the present work, ZrC-Cu-based highly reflective coatings were deposited on Al-6061 alloy using the cold spray to develop laser damage resistance. Microstructural characterization, XRD, micro-hardness, reflectivity measurements, and laser ablation tests were conducted on the developed materials. The results showed improved ceramic retention and mechanical properties along with minimal porosity in the coating with increasing ZrC content in the feedstock. Additionally, the XRD analysis revealed that Cu-ZrC composite coatings could be produced by cold spray, without decarburisation of ZrC or oxidation of Cu. Owing to the exceptional purity in coatings, highly reflective coatings were obtained. At the target wavelength of 1080 nm, Cu-30 %ZrC composition achieved a remarkable reflectivity of 75 % (85 % of bulk copper). The coatings with compositions of Cu-30 %ZrC, Cu-50 %ZrC and Cu-70 %ZrC remained undamaged under laser irradiation, whereas Cu-85 %ZrC exhibited a laser ablation pit. These findings provide valuable insights into developing optimized ZrC-Cu coatings against laser irradiation. [ABSTRACT FROM AUTHOR]

• New maximum curvature method to capture quench temperature for bottom reflood test. • Performance evaluation of Cr-coated ZIRLO cladding under simulated LOCA condition. • Modification of existing quench temperature correlation for thin wall cladding. • Multiple quench tests to investigate the mechanical integrity of Cr-coated cladding. Chromium (Cr) coated cladding is the most promising candidate for near-term accident-tolerant fuel (ATF) for current light water reactors (LWRs) because of its excellent oxidation resistance at high temperatures. For deployment of the Cr-coated cladding as ATF, the performance should be evaluated under various conditions, including the loss-of-coolant accident (LOCA). In this research, a single-rod reflood facility was constructed to investigate the quenching behavior and performance of Cr-coated cladding under bottom reflooding at high temperature conditions up to 1200 °C. Quench tests were performed using an uncoated, cold spray Cr-coated, and PVD Cr-coated Zr-alloy at various initial temperature ranges from 600 °C to 1200 °C with 20 K of water subcooling and 4.5 cm/s of reflood velocity. The quench temperatures were obtained at four different axial locations based on the maximum curvature method developed in this study. The bottom reflood quench test results indicate that the quench temperature increases with increasing initial cladding temperature and decreasing axial distance from the bottom. The quench temperature was not notably different for uncoated Zr-alloy and Cr-coated Zr-alloy, regardless of the coating deposition method. However, above 1000 °C, the Cr-coated Zr-alloy showed a consistent and predictable quench temperature in contrast with the uncoated Zr-alloy for which the quench temperature data were severely scattered. The underestimation by the existing quench temperature model was observed with the current test using typical cladding thickness (0.57 mm). The thin cladding thickness was suggested as the reason for the underestimation. The modified Kim and Lee's correlation is proposed for better prediction of the thin-walled Zr-alloy cladding. The Cr-coating appears to mitigate the degradation of the mechanical integrity of the underlying Zr-alloy tube under severe oxidation and repeated thermal cycling, by virtue of superior oxidation resistance. It indicates that the coated cladding provides better integrity and performance in power transient conditions such as load-following operation. Post-test characterization showed the Cr-coating oxide layer thickness to be an order of magnitude lower than that of the uncoated cladding. The change in wettability was minimal in all test cases despite the trend of increasing roughness with the increasing initial temperature. [ABSTRACT FROM AUTHOR]

Eutectic high entropy alloys (EHEAs) are reported to exhibit excellent mechanical properties which are useful for coating applications. In this study, we have produced AlCoCrFeNi 2.1 EHEA coatings using the cold spray, high velocity oxygen-fuel (HVOF), and plasma spray techniques and compared their bonding characteristics, microstructure and hardness. We observe body-centered cubic (bcc) to face-centered cubic (fcc) phase transformations in all the types of coatings. The high processing temperatures in HVOF and plasma sprays lead to the segregation and depletion of Al from Ni-and Al-rich bcc/B2 regions and form Al 2 O 3. In the cold sprayed coatings, we observe that a fraction of lamellar microstructure is preserved after cold spraying. Regarding the hardness, the cold sprayed coatings exhibit hardness in the range of 440–498 HV due to high work hardening and low oxygen content below 4 at.%; the HVOF coatings show the hardness in the range of 380–556 HV due to the effects of oxide dispersion strengthening with 13–28 at.% oxygen; The plasma sprayed coatings exhibit the hardness in the range 208–258 HV and 6.1–13.4 at.% oxygen. This study demonstrates the feasibility to produce thick and dense EHEA coatings using the above spray techniques, and the cold sprayed coatings exhibit relatively high hardness and low oxygen levels. • This study produced AlCoCrFeNi 2.1 HEA coatings through cold spray, HOVF, and plasma spray methods. • Cold spray produces AlCoCrFeNi 2.1 coatings with high hardness and low oxidation levels. • Formation of Al 2 O 3 segregates Al from NiAl-rich bcc/B2 regions, leading to phase transformation. [ABSTRACT FROM AUTHOR]

Copper coatings on steel, manufactured by a novel combination of two different manufacturing technologies, electrodeposition and cold spraying, are employed as a corrosion barrier in the current design of used fuel containers (UFCs) for the long-term storage of Canada's used nuclear fuel. This study examines such copper coatings on a prototype container section, with a particular focus on the interface region where copper materials fabricated by the two processes converge. Distinct microstructures for the electrodeposited and cold sprayed copper layers were observed. An unexpected recrystallized layer on top of electrodeposited copper was identified for the first time. Local annealing at 350 °C and 600 °C for one hour resulted in more homogeneous microstructures and Vickers hardness profiles among the copper layers, which is favorable for this application by reducing processing related heterogeneity in the interface region. More homogenized structures with high fractions of special grain boundaries in this region are expected to provide enhanced mechanical and corrosion properties. • Microstructural analysis was performed on Cu coatings for used fuel containers. • A recrystallized layer between electrodeposited and cold sprayed Cu was identified. • Annealing reduces microstructural and mechanical heterogeneity. • Nanotwinned electrodeposited Cu experiences texture evolution during annealing. [ABSTRACT FROM AUTHOR]

The development of thick cold sprayed deposits of hard amorphous/nanocrystalline Aluminum High Entropy Alloys (Al HEA) is limited by their poor plastic deformability. To address this, Al HEA powder (Al 90.05 Ni 4.3 Y 4.4 Co 0.9 Sc 0.35 (at. %)) is blended with soft Al 6061 in a 1:1 wt% ratio and cold sprayed. The microstructure of the composite deposits reveals that while Al HEA splats undergo limited deformation, Al 6061 splats deform extensively. Extreme deformation of Al 6061 captures the hard Al HEA particles, resulting in a composite deposit of 5 mm thickness, compared to 0.2 mm for pure Al HEA. Within the composite, Al HEA particles deform through shear band propagation and viscous flow, whereas Al 6061 splats deform via dislocation slip motion. These deformation mechanisms induce interface nanocrystallization, leading to a 123 % increase in lattice strain, a 67 % reduction in crystallite size, and an 800 % increase in dislocation density compared to the initial feedstock. This microstructural evolution, combined with the presence of hard Al HEA regions, results in a mean hardness of 2.56 GPa and an elastic modulus of 76 GPa. These values represent a 47 % and 6 % improvement over conventional polycrystalline cold-sprayed aluminum deposits. Thus, this study provides insights into the microstructural and interface evolution and its effect on indentation characteristics for making high-strength Al HEA deposits. • High strength hybrid amorphous aluminum high entropy (Al HEA) and Al 6061 deposit by cold spray • Soft Al 6061 enhances deposition efficiency, increasing thickness by 6x, effectively capturing hard Al HEA powders. • Interface microstructural evolution: nanocrystallization in Al HEA and dynamic recrystallization in Al 6061. • The hybrid deposit demonstrates 47 % increase in hardness and 6 % higher elastic modulus compared to conventional Al alloy [ABSTRACT FROM AUTHOR]

Tribaloys, renowned for their effectiveness in high-temperature anti-wear applications, derive their exceptional wear resistance from hard intermetallic Laves phases, such as Co 3 Mo 2 Si and CoMoSi, within a eutectic Co-solid solution. In this study, Tribaloy 800 (T800) particles were blended with NiCr particles, and the combined feedstocks were deposited using the cold spray (CS) technique over Nimonic 80A substrate. The aim was to enhance wear resistance at high temperatures (700 °C). Microstructural analyses were conducted on both the feedstock particles and the deposited material to discern the evolving phases, microstructures, morphologies, and to investigate localized bonding at the interface. Subsequently, dry sliding wear tests were performed on both the substrate and the deposited material at both ambient and elevated temperatures (700 °C) using an alumina ball as counter material. The specific wear rate obtained for the NiCr-T800 coating specimen and the substrate at room temperature was found to be 63 × 10−5 mm3/Nm and 12 × 10−5 mm3/Nm, whereas at 700 °C, it was found to be 10 × 10−5 mm3/Nm and 5 × 10−5 mm3/Nm, respectively. The coating comprising NiCr-T800 demonstrated significantly enhanced wear resistance at both temperatures. This improvement was attributed to several factors: the deformation of NiCr splats, the development of compressive residual strains due to high velocity impact of particles, the uniform dispersion of T800 particles, the evolution of hard Co 3 Mo 2 Si Laves phases, and the development of NiO, Cr 2 O 3 and NiCr 2 O 4 Glaze oxide layer at 700 °C. This Glaze layer acted as a barrier, impeding direct contact between the CS coating and the alumina ball. • Dense and adherent deposit of NiCr-T800 coating (2.1 mm thickness) was obtained. • The evolution of Co 3 Mo 2 Si Laves phase was obtained from the T800 particles. • The CoF of the deposit was multiple times lower than the substrate at RT and 700 °C. • The wear mechanism observed at RT are adhesive, delamination and oxidative wear which changed to oxidative wear at 700 °C. [ABSTRACT FROM AUTHOR]

In this study, the Al x CoCrFeNi high entropy alloy coatings are firstly prepared on the surface of the substrate by cold spraying technology, followed by nitriding treatment. This study investigates the effects of nitriding on the microstructure, mechanical properties and wear mechanisms of Al x CoCrFeNi high entropy alloy coatings at different temperatures. The results reveal that increasing Al content causes the phase structure transition from FCC phase to BCC phase, correlating with enhanced mechanical properties and tribological performances. Nitriding further promotes these properties by introducing FCC phases and various nitrides. Among the tests, the Al 0.7 CoCrFeNi high entropy alloy coating exhibits the highest microhardness and best wear resistance after nitriding. The wear mechanisms of Al x CoCrFeNi high entropy alloy coatings vary with different temperatures, the detail as follows: at 25 °C and 100 °C, the coatings mainly experience fatigue, spalling, and oxidation wear. As the temperature increases to 300 °C the wear mechanisms transition to abrasive wear and adhesive wear, and at 500 °C, it mainly the plastic deformation. In contrast, the nitriding Al x CoCrFeNi high entropy alloy coatings exhibit abrasive wear at 25 °C, which shifts to fatigue and oxidation wear as the temperature increases. • Prepared the AlCoCrFeNi high entropy alloy coatings with different Al content by cold spraying. • The Al x CoCrFeNi high entropy alloy coatings are strengthened using the post-treatment technique (nitriding). • The wear mechanisms of Al x CoCrFeNi high entropy alloy coatings at various temperatures was studied. [ABSTRACT FROM AUTHOR]

This study examined the characteristics of mechanically alloyed (MA) Cantor alloy powder and the coatings produced from it using various deposition techniques, including cold spray (CS), high-velocity oxy-fuel, high-velocity air-fuel, and laser cladding (LC). Microstructure analysis of the MA powder revealed an irregular morphology and incomplete elemental mixing. The microstructure of the CS coating displayed an FCC crystal structure, with some XRD peaks corresponding to BCC phases due to the presence of unmixed elements. In contrast, all other coatings also exhibited oxides alongside FCC and BCC phases, with the LC coating containing a higher concentration of oxides. These coatings demonstrated high density and diverse microstructures, with CS coatings demonstrating effective transfer of powder microstructure. The CS coating had the highest hardness (679 ± 17 HV 0.1) due to the retention of deformed microstructure from the powder, whilst the LC coating had the lowest hardness (215 ± 10 HV 0.1). CALPHAD calculations using Thermo-Calc suggest that the presence of oxides in the coatings could be thermodynamically feasible, depending on the conditions. Deposition efficiency varied significantly among the methods, with LC achieving the highest efficiency (63 ± 6 %) and CS the lowest (14 ± 1 %). [Display omitted] • MA powder displayed irregular morphology and incomplete elemental mixing • CS coating had an FCC structure with some BCC phases from unmixed elements • LC coating showed more oxides and had the lowest hardness among coatings • CS coating retained deformed microstructure, resulting in highest hardness • LC achieved the highest deposition efficiency, whilst CS had the lowest [ABSTRACT FROM AUTHOR]

This study investigates the high temperature wear behaviour of a WE43 Mg alloy after covering it with single and dual layer coatings. For this purpose, cold spray and micro-arc oxidation processes were employed individually and sequentially. Single-layer coatings fabricated by cold spray and micro-arc oxidation processes were Al/Al 2 O 3 composite and MgO-based ceramic, respectively. Sequential application of cold spray and micro arc oxidation processes induced dual layer coating upon synthesizing an external Al 2 O 3 –based layer over the Al/Al 2 O 3 composite layer. Results of the wear tests conducted under the load of 2 N revealed the superior resistance of the dual layer coated sample against the rubbing action of the counterface compared to single layer coatings. Thus, the presence of a relatively hard and tough external Al 2 O 3 -based layer over the Al/Al 2 O 3 composite layer sustained protection up to the temperature of 320 °C, where the dominant wear mechanism was fatigue wear. However, the increase in the test temperature to 350 °C caused detachment of the external Al 2 O 3 -based layer. Reduction of the wear test load from 2 to 1 N resulted in the remaining of external Al 2 O 3 -based layer intact with the underlying Al/Al 2 O 3 composite layer even at a test temperature of 350 °C. It is therefore concluded that the combination of cold spray and micro-arc oxidation processes is promising to broaden the reliable use of WE43 and other Mg alloys in wear related applications at high service temperatures. [Display omitted] • Sequential application of CS and MAO processes formed dual layer coating on WE43. • Dual layer coating provided superior protection against wear up to 320 °C under 2 N. • Protectivity of dual layer coating is sustained at 350 °C under 1 N. • Dual layer coating is promising for high temperature wear related applications. [ABSTRACT FROM AUTHOR]

• Incorporating µB 4 C particles reduced Al powder size by 14%. • SEM analysis confirmed uniform particle distribution in coatings. • Reinforcing particles decreased surface roughness by 47%. • Enhanced wear resistance was observed, reducing wear volume loss by 36%. • Coatings with nano-additives showed shallower wear tracks, lowering wear depth profile values by 28%. A compositionally graded, dual-reinforced aluminum metal matrix composite was applied onto the AA7075 substrate through cold spray. The coatings consisted of layers with varying compositions of 10, 15, and 20 vol% μB 4 C, designed to enhance wear resistance. Compositional grading of the coating extended to the top layer, which features a dual-reinforced layer comprising 2 vol% boron nitride nanotube (BNNT) and 2 vol% nB 4 C. [ABSTRACT FROM AUTHOR]

Fatigue crack growth and fracture of a thick 6061 aluminum cold spray coating on 6061-T6 aluminum substrate were studied through in-situ observation of fatigue crack growth through the coating to the interface in notched four-point bend samples. Mode I cracking was observed through the coating before delamination at the substrate. Crack tip strain fields during the delamination event were plotted with DIC. Interfacial steady-state strain energy release rates were measured using the bimaterial four-point bend solutions by Charalambides. The interfacial crack primarily spread cleanly along the coating/substrate interface, with a post-fracture surface morphology containing a wavy structure with an amplitude on the same order of magnitude as the cold spray particle diameters. The in-situ video of crack propagation and coating-substrate delamination provides lessons for improving the coating-substrate interfacial toughness and thus expands use cases for structural cold spray applications • Fatigue crack propagated along interface of 6061 cold sprayed deposit and like substrate. • Mode I fatigue crack produced a mix of intra and inter-particular failure in the cold spray deposit. • Crack tip strain field interactions may be responsible for delamination of cold spray deposit from interface before crack contacted interface. [ABSTRACT FROM AUTHOR]

Triboelectric nanogenerators (TENGs) have gained remarkable attention in energy harvesting and smart sensing, allowing for converting mechanical energy into electrical energy. Despite great potential and progress made in this field, there remains a high demand for high-performance electrodes that are produced with sustainable, low-cost, lightweight, and durable materials such as polymers. Here, by combining the material extrusion 3D printing and the cold spray particle deposition methods, we employ a complete additive manufacturing (AM) approach to fabricate functionalized electrodes on 3D-printed parts for TENG technology. First, polylactic acid (PLA) parts were produced by material extrusion printing. Next, the cold spray process (CS) was utilized as just a one-step fabrication method of the conductive electrodes on the printed parts, eliminating the need for surface activation, over-plating, curing, and/or post-processing. Additionally, the process-structure-property relationships of the CS process were uncovered to fabricate high-performance electrodes for TENGs. The resulting electrodes demonstrate promising electrical conductivity (9.8 × 104 S.m−1), adhesive strength, stability, and micro-roughness (R a = 6.32 µm). The TENG with the fabricated electrode generates an open-circuit voltage of 174 V, which is nearly 1.85–2.9-fold higher than that of the control TENGs. It achieves the short-circuit density of ≈ 55 mA/m2, and the power density of 1676 mW/m². Besides, to address the low-spatial resolution of the cold spray metallization, a manufacturing pathway is proposed, aiming to achieve higher line resolution (1 mm linewidth) electrodes for polymer electronics. This work provides a manufacturing strategy that can advance the field of TENG and polymer electronics by addressing the limitations of conventional electrode manufacturing techniques. [Display omitted] • A complete additive manufacturing method was developed for functionalized electrodes. • Direct writing of functional electrodes on 3D-printed parts was achieved for TENGs. • The electrodes exhibit promising conductivity (9.8 × 104 S.m−1), stability, adhesive strength, and micro-roughness R a = 6.32 μm). • TENG with fabricated electrode demonstrated ≈ 2.9-fold higher energy harvesting performance compared to control TENG. [ABSTRACT FROM AUTHOR]

The tribo components often fail to perform in a desired way due to absence of adequate lubrication in severe conditions and may cause loss of material. Even under room temperature (RT), it is desirable to maintain the proper lubrication for efficient functioning. In recent years, many efforts have been made to develop a coating material which can facilitate low friction and wear properties in diverse working conditions. The proper use of the solid lubricants can deliver utmost lubricity and, therefore, minimize the loss of materials. Solid lubricating coatings have found various industrial applications in harsh environmental conditions, such as in internal combustion engine, gas turbine and aircraft. As far as development of coating is concerned, cold spray (CS) technology has been observed to develop the coatings at relatively low temperature (avoids decomposition) as compared to conventional thermal spray technologies (plasma spray & high velocity oxy fuel). In the current investigation, synergistic response of the participating solid lubricants viz. silver (Ag), molybdenum disulfide (MoS 2) and hexagonal boron nitride (h-BN) on the tribological properties of the developed coatings were studied in various working regime of loads. The tribological characteristics of different composite coatings, such as NiAl-MoS 2 -Ag (NB0), NiAl-MoS 2 -Ag-5 wt. % hBN (NB5), NiAl-MoS 2 -Ag-7.5 wt % hBN (NB7.5) and NiAl-MoS 2 -Ag-10 wt % hBN (NB10) against alumina ball were explored at various loads (6, 11, 16 and 21 N) and at a fixed speed of 0.3 m/s under room temperature (RT). The fixed concentration of Ag and MoS 2 with varying weight percentage of h-BN (0, 5, 7.5 and 10 wt %) were introduced as solid lubricants for evaluating the lubricating potential of h-BN. During the tests, coefficient of friction (COF) and wear rate were observed to lessen as the load increased from 6 to 16 N. However, increased COF and wear rate were noticed for all the participating coatings at higher load (21 N). The ideal content of hBN in the deposited coatings was ascertained in order to get the utmost favourable lubricating conditions. It was observed that NB7.5 coating exhibited the enhanced tribological characteristics under the aforesaid operating conditions. Coating NB7.5 shows the best friction and wear characteristics during each testing load and reached a COF (0.19) and wear rate (2.1 × 10−5 mm3/Nm) at 16 N load. The observed wear mechanisms were analysed on the basis of the synergy shown by Ag, MoS 2 , and hBN as well as the optimal hBN level in the coating (NB7.5) which helped in attaining the improved tribological properties. • Ni-based coatings containing Ag, MoS 2 , and h-BN were deposited via cold spray route. • Tribological performance of the coatings has been evaluated by carrying out tests at room temperature in a working regime of loads i.e. 6, 11, 16 and 21 N. • Coating NB7.5 showed consistently low friction coefficient and wear with a COF ∼0.19 at 16 N load. • Optimum wt. % of h-BN and synergetic action of h-BN with Ag and MoS 2 in the coating NB7.5 resulted in improvement in tribological performance of coating. [ABSTRACT FROM AUTHOR]

Graded composite fillers exhibit unique advantages in alleviating residual stress in ceramic/metal brazed joints. However, traditional methods for preparing graded composite fillers are often complex and may deplete their strengthening phases. In this study, cold spray additive manufacturing was employed to fabricate yttria-stabilized zirconia (YSZ)-Ti 25 Zr 25 Ni 25 Cu 25 -Ag graded composite coatings on Cu substrates to serve as fillers. The graded composite coatings and the resultant Ti 3 SiC 2 /Cu brazed joints were systematically characterized to elucidate the deposition mechanism of the coatings and its residual stress-relaxed mechanism. The bondings between particles in the coatings, based on their plastic deformation ability, were classified into noncrystalline weak bonds and homogeneous strong bonds. Both bondings facilitated the elemental interdiffusion between filler and Cu substrate during the heating process, which contributed to the formation of Ag-Cu eutectic. This significantly reduced the required brazing temperature and its induced residual stress. Furthermore, the solid phase transformation of graded-distributed YSZ within the brazing seam from tetragonal to monoclinic achieved a smooth thermal transition and releasing residual stress at the same time. Consequently, the shear strength of the brazed joint reached to the highest value of 110.23 ± 3.45 MPa, which was Much higher than the previously reported values. This study introduces a novel method for residual stress relaxation assisted with cold spray technology and broadens its application in the brazing field. [Display omitted] • The cold spray additive manufacturing achieved the fabrication of graded composite coatings filler successfully. • The bonding mechanism between the particles during the cold spray process depended on their plasticity. • The interdiffusion between graded composite coatings filler and substrate led to much lower brazing temperature. • The graded-distributed yttria stabilized zirconia caused the smooth transition of coefficients of thermal expansion. [ABSTRACT FROM AUTHOR]

[Display omitted] Conventional testing procedures often encounter challenges to characterize the mechanical properties of deposits of limited thickness such as coatings. To overcome this limitation, the literature has explored various miniature-testing methods, and, among these, the small punch test has emerged as a promising solution offering the main advantage of requiring a minimal volume of material. This study focuses on cold sprayed deposits in as-sprayed and thermally treated conditions and presents the results of an experimental campaign of mechanical characterization of 316L steel and copper deposits. In parallel, small punch tests are simulated numerically with inverse analysis to estimate comprehensively the stress-strain curves. Results suggest an extremely brittle behavior of the as-sprayed specimens and a good agreement between the experimental and numerical estimations of the mechanical properties of the ductile thermally treated specimens. Ultimately, the findings highlighted the sensibility of the small punch test to the microstructure and its gradients of cold sprayed deposits. [ABSTRACT FROM AUTHOR]

Experimental and theoretical investigations of nozzle clogging in WC-Co cold spray nozzles using nickel powder were conducted. Computational fluid dynamics (CFD) was used to show that the highest particle impact kinetic energy density occurs just downstream of the nozzle throat, where clogging is common. CFD also showed particles impact the nozzle wall at angles between 0.3°–5°, with smaller particles having higher velocities and temperatures. An experimental setup was used to investigate the effects of substrate temperature, surface roughness, and incidence angles on material deposition. Scanning electron microscopy revealed nickel particles smeared on the substrate surface, with more deposition on smoother surfaces. Energy dispersive X-ray spectroscopy (EDS) showed more nickel deposited at higher substrate temperatures and lower impact angles. Finite element simulations indicated nickel powder reaches temperatures above its melting point while sliding along the WC-Co substrate and predicted localized melting. Particle smearing is identified as the cause of nozzle clogging based on experimental and simulation results. • Oblique particle impacts cause clogging in cold spray nozzles. • Impacts 40–100 mm after the nozzle throat, at 0.3°–5° deposit on the surface. • Deposition increases at higher substrate temperatures and shallower impact angles. • Nickel powder interface melts while sliding along the substrate due to friction. • Stacked nickel layers, each 10–30 nm thick, are observed on the substrate. [ABSTRACT FROM AUTHOR]

Strengthening in metal matrix composites (MMCs) is primarily due to the load transfer from the compliant matrix to the stiff reinforcement. While internal load transfer has been studied for conventionally manufactured MMCs, the extent to which it may be affected by the preexisting defects in additively manufactured MMCs remain elusive. In this study, we performed uniaxial compression loading on cold sprayed Ni–CrC particulate-reinforced MMC. We observe significantly enhanced strength and ductility compared to the brittle behavior previously reported in tension for the same MMC. In contrast to the absence of load transfer in tension, the presence of initial defects did not preclude the internal load transfer in the composites under compressive loading. In-situ high-energy X-ray diffraction analysis revealed a relatively constant load partitioning in the elastic regime, which aligned well with predictions by the Eshelby's inclusion model. Furthermore, an internal load transfer was observed from the Ni matrix to the CrC reinforcement upon plastic deformation of the Ni matrix. Finite element modeling further confirmed this and demonstrated that localized tensile stress at the interface in the transverse direction resulted in the interfacial debonding and partial relaxation of the matrix. We also report reinforcing particle fracture upon further compression which in turn triggered the eventual failure of the MMC. • We additively manufactured Ni–CrC metal matrix composites with cold spray. • Load partitioning between Ni and CrC remains unchanged in the elastic regime. • Internal load transfer from Ni to CrC begins with the plastic deformation of Ni. • Transverse tensile stresses at the interface results in interfacial debonding and strain relaxation in Ni. • Fracture of CrC triggers the eventual failure of the composite. [ABSTRACT FROM AUTHOR]

Using cold spray technology to prepare amorphous alloy coatings can effectively prevent crystallization, thereby preserving the excellent properties of amorphous alloys. However, interfacial bonding significantly affects performance, such as weak bonding impacting the durability and stability of the coating. Therefore, in-depth study of the interfacial bonding mechanism is crucial for a comprehensive understanding of coating properties. This paper uses cold spray technology to prepare Fe-based amorphous alloy coating on 6061 aluminum alloy substrates. The bonding mechanisms at the particle/substrate, particle/particle, and coating/substrate interfaces are studied, and the fracture behavior in the tensile bond strength test is analyzed. The results show that the heat accumulation and the increase in strain rate generated by the particles impacting the substrate cause the viscosity of the amorphous alloy to suddenly decrease from 1.2 × 103 g·cm−1 s−1 to 8.4 × 10−1 g·cm−1 s−1. Increased fluidity and micro-friction accelerate the mixing of elements and form a metallurgical bond at the particle/substrate interface. Meanwhile, the oxides at the particle/particle interface are extruded, and the exposed fresh metal is subjected to a huge shear rate to promote atomic fusion. Tamping of the subsequent particles leads to further deformation of the deposited particles, forming a stronger metallurgical bond and mechanical anchoring at the particle/particle interface. In addition, the continuous impact of particles triggers dynamic recrystallization of the substrate, and the average grain size decreases from 14.28 μm to 1.39 μm. This fine-grained structure strengthens the mechanical anchoring of the coating/substrate interface. Furthermore, the bonding strength measured by the tensile test is determined to be 18.51 MPa. The main reasons for the final fracture occurring in the coating are the coating pores, cracks formed by shear bands accumulated in free volume, and the low adhesion oxide layer at the particle interface. • The metallurgical bonding is related to viscous flow and micro friction. • Oxides play an important role in the bonding of particle/particle interface. • The fine-grain strengthening of the substrate enhances the mechanical anchoring. • The causes of tensile fracture are pores, weak interface bonding, and cracks. [ABSTRACT FROM AUTHOR]

For a deeper understanding of the cold-sprayed aluminum alloy as well as coating/substrate bonding and splat/splat adhesion mechanisms, X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were employed to systematically investigate the phase composition, microstructure and interfacial characteristics of cold sprayed (CS) 2024Al coating on 2024Al-T3 substrate. Within the internal structure of the layer, recrystallization processes induced by intense stress were seen, resulting in the formation of nanograins with sizes ranging from 30 to 100 nm, as well as ultrafine grains with sizes ranging from 100 to 300 nm. The bonding modes of the splat/splat and coating/substrate interface include mechanical bonding and metallurgical bonding; mechanical interlocking was seen as a special mechanical bonding method to enhance the adhesion strength between coating and substrate. Overall, mechanical bonding was the predominant bonding method, with metallurgical bonding as a supplementary bonding method within the coating and at the coating/substrate interface. There were no apparent pores and gaps between the particles in the mechanical bonding area and between the coating and the substrate. In regions of metallurgical bonding, adiabatic shear instability promoted the occurrence of dynamic recrystallization (DRX) on the one hand, leading to viscous flow of local materials, which damaged the original splat/substrate bonding surface and generating new bonding surfaces, on the other hand, promoted atomic diffusion between the coating and the substrate, allowing a close lattice match formed at the splat/substrate interface. Furthermore, the numerical simulation results of a single particle reflect, on the one hand, the plastic deformation occurred between the particles and the substrate during the deposition process, and on the other hand, the temperature at the metal jet increases in a short period of time, which made it possible for dynamic recrystallization to occur in this area. Therefore, the CS 2024Al coating exhibited excellent comprehensive properties with a porosity level of 0.31 ± 0.09%, a hardness of 157.3 ± 13.7 HV 0.025 , and an adhesion/cohesion strength exceeding 55.5 MPa. These properties were derived from the strong bonding among splats and between the splats and the substrate. [Display omitted] • CS 2024Al layer exhibited dense microstructure and high bonding strength to the substrate. • DRX formed grains, and the dislocation structure of the CS 2024Al layer was analyzed. • Both mechanical and metallurgical bonding existed at the splat/substrate interface • Mechanical and a small amount of metallurgical bonding existed at the splat boundary. • The large grains prevalent in the CS 2024Al layer are inherited from its powder. [ABSTRACT FROM AUTHOR]

[Display omitted] • ML models effectively predict particle velocities in cold spray of titanium. • Novel binning strategy significantly improves the prediction performance. • ML models effectively predict DE with and RMSEs of 3.2 % (SVR) and 5.5 % (NN). This study demonstrates the efficacy of machine learning (ML) techniques, specifically Support Vector Regression (SVR) and Neural Network (NN) models, in predicting the spray plume characteristic particle velocity distribution during cold spraying of Titanium. Considering the complexity of particle velocity distribution, models with the single particle velocity, average particle velocity and particle count in the spray plume have been explored associated with a novel data binning mechanism. The models achieved a root mean square error (RMSE) of approximately 41 m/s when tested for predicting the average particle velocity depending on the lateral position within the spray plume. The models for single particle velocity exhibited inferior performance, ascribed to the stochastic nature of single particles in the spray plume. In addition to predicting particle behaviour, the ML-based models were combined with a semi-empirical method to forecast deposition efficiency (DE) in cold spray operations. The developed DE prediction models showcased promising results, achieving an RMSE of 3.2% DE and 5.5 % DE using SVR and NN, respectively. These findings emphasize the potential of ML approaches in enhancing predictions of the particle velocity distribution and DE in cold spraying titanium which can be leveraged to optimize spray parameters and save raw material and cost. [ABSTRACT FROM AUTHOR]

Nickel-Aluminum-Bronze powder was heat-treated to reduce martensite and segregated into three sizes for Cold Spray deposition. Heat treatment (HT) significantly increased deposition efficiency (DE) from 20 % to nearly 100 %. Mechanical properties (hardness, scratch) and electrochemical corrosion tests were conducted to evaluate inter-splat bonding. Performance tests revealed that as-received (AR) powder deposit exhibited superior properties, albeit with a low DE. Among HT powders, the coarser size exhibited better inter-splat bonding due to particle size and surface oxide of the powder. The AR powder's enhanced performance is linked to a novel densification mechanism. [Display omitted] • New densification mechanism for hard-to-deposit materials like NAB • Dynamic phase change diminished martensite during cold spraying of NAB • Heat treatment and particle size strategy explored for first time in cold spray NAB • Corrosion behavior of cold-sprayed NAB studied for the first time • Corrosion products formed are different in weak vs best inter-splat bonded deposits [ABSTRACT FROM AUTHOR]

Cold spray is a form of cryotherapy used in acute injuries at sports medicine. In the current study, we aimed to investigate the acute effect of cold spray application as a treatment strategy for acute sports injuries on the mechanical properties of the rectus femoris muscle in athletes. The study included 23 volunteer active male athletes between the ages of 18–23 with a subepidermal fold thickness of the rectus femoris muscle between 5 mm and 15 mm. Skin temperature (thermal camera) and mechanical property evaluations of the muscle (Myoton Pro) were measured before, immediately after, and in 2 min, 5 min, 10 min and 15 min intervals following cold spray application. The skin temperature value of the athletes were significantly lower even in the 15-min interval following application (p < 0.001). Muscle tone increased significantly after the application and in the second minute compared to the pre-application (p < 0.001). Muscle stiffness increased significantly only after the second and fifth minutes compared to the pre-application (p < 0.001). Muscle decrement showed an increase in all time-points compared to the pre-application (p < 0.05). In athletes, the rectus femoris muscle has been observed to become harder and less elastic following cooling with cold spray. These changes did not improve completely following the 5 min. The muscle regained its mechanical properties at the earliest approximately 10 min after the cold spray application. [ABSTRACT FROM AUTHOR]