Cold Spray Method Research Articles

Fabrication and characterization of aluminum-based powders multi-reinforced with nano- and microparticles

Multi-reinforced powders were obtained by high-energy ball milling in a planetary mill. The process of obtaining heterogeneous powders consisted of two stages. At the first stage, a nanocomposite powder of AlMg6 + 0.3 wt.% C60 was obtained. In the second stage, 10, 30, 50, and 70 wt.% Al2O3 were added to the obtained nanocomposite powder and processing continued. Methods such as scanning electron microscopy, X-ray diffraction, and particle size analysis were used to characterize the obtained powders. It is shown that after the first stage of processing, the particles of the composite powder are characterized by an irregular shape. C60 reinforcing particles in the form of nanosized agglomerates were fixed on the surface of aluminum powder particles. After the second stage of processing, the particle size of the powder mixture decreased from 17.8 to 12.3 μm, while the proportion of Al2O3 particles increased from 10% to 70% by weight. It is shown that the synthesized heterogeneous powders were a mechanical mixture consisting of complex composition agglomerates and micro-sized ceramic particles. Complex composition agglomerates were formed from nanocrystalline matrix material particles and C60, and also with Al2O3 microparticles embedded in them, as well as located on the surface. The concentration of Al2O3 particles on the surface and inside the agglomerates increased with increasing weight fraction of ceramic particles in the mixture. It has been found that the introduction of 10-70 wt. % Al2O3 into the powder mixture increases the microhardness of the powder particles by approximately 16-23%. The resulting multi-reinforced powder mixtures can be utilized for coating deposition using the cold gas dynamic spraying method.

WE43 Magnezyum Alaşımının Soğuk Sprey Kaplama Yöntemi ile Al/Zn/Al2O3 ve Zn/Al2O3 Kaplanması ve Aşınma Davranışlarının İncelenmesi

Mg alaşımları otomotiv, uçak, uzay ve haberleşme sektörlerinde düşük özgül ağırlıkları ve yüksek mukavemetli olması nedenleriyle tercih edilmektedir. WE serisi, Mg, Y, Nd, nadir toprak elementlerini içeren Mg alaşımları serisidir. Bu alaşım serisi için sürünme dayanımı iyi olsa da aşınma dayanımı gelişmeye açıktır. Bu çalışmada amaç, özgül ağırlıkları nedeni ile kullanım potansiyeli yüksek olan WE43 Mg alaşımlarının aşınma dayanımını arttırabilecek kaplamaların, endüstride de kolaylıkla uygulanabilecek bir yöntem kullanarak geliştirilmesidir. Bu amaçla soğuk sprey kaplama yöntemi kullanılarak aynı zamanda yüzeyleri fazlasıyla aktif olan magnezyum alaşımlarının oksitlenmeden kaplanması sağlanmış ve aşınma dayanımı geliştirilmiştir. Yüzeyleri ince kumlama işlemiyle pürüzlendiren WE43 Mg alaşımları soğuk sprey yöntemi kullanılarak Al/Zn/Al2O3 ve Zn/Al2O3 içerikli ve ticari isimleri sırasıyla DYMET K-20-11 ve DYMET K-00-11 olan tozlar kullanılarak 500ºC sıcaklıkta N2 koruyucu gaz atmosferi altında süpersonik hızlardaki tozlar için 6 g/dak. toz besleme hızıyla altlıklar üzerine püskürtülmüştür. Farklı içerikli tozlarla kaplanmış ve kaplanmamış numunelerin morfolojik analizleri SEM ve XRD yöntemleri ile incelenmiş, kaplama kalınlıkları kesitten alınan SEM görüntülerinden ölçülmüş, EDS analizleri ile elementlerin yüzde oranları tespit edilmiştir. Ayrıca aşınma performansının incelenmesi için ball-on disk aşınma testlerinden hacim kayıpları değerlendirilmiştir. Sonuç olarak, soğuk sprey kaplamalarla, kaplamasız duruma göre WE43 alaşımlarının aşınma kaybı yaklaşık %40 oranında azalmıştır.

Structure and Properties of Composite Coatings Cold Sprayed from Powder Mixtures of Aluminum and Boron Carbide

In the present work, an experimental study of the effect of aluminum and boron carbide powder mixture composition on the microstructure and basic properties of the cold sprayed coatings was carried out for the first time. A series of coatings deposited on stainless steel substrates was obtained. The microstructure of the deposited coatings was analyzed by scanning electron microscopy and X-ray diffraction analysis. The microhardness and bonding strength of the coatings were measured. It was shown that an increase from 0 to 72 vol.% in the boron carbide content in the powder mixture leads to an increase in its content from 0 to 15-17 vol.% in the coating, its microhardness – from 46.3 to 72.4 HV0.3, and bonding strength – from 17.4 to 61.4 MPa. The obtained results open up broad prospects for the application of the cold spray method to deposition of functional coatings, which are highly demanded in the nuclear industry.

60% IACS Conductive Metal Coating on a Polymer Surface: Achievement of a Highly Efficient Additive Processing by Cold Spraying

This paper investigates a current challenge that enables the hybridization of different materials using a solid-state additive principle. We investigate the suitability of such a principle to easily and efficiently grow a metallic electrically conductive coating on a polymer substrate. The additive principle is obtained using the high-pressure cold spraying (CS) method whose literature does not include an achievement as suggested in this paper, that is, to obtain a good conductive copper coating onto polymer with a very high deposition efficiency by tuning the effect of the stand-off distance, transverse speed of the nozzle, and temperature of the carrier gas on the deposition efficiency (DE) in order to overcome delamination and erosion, and thus to improve the DE. A good coating formation up to 400 µm can be obtained, which implies that a standoff distance higher than 100 mm is needed, since both a high gas temperature (400–500 °C) and high gas pressure (30 bars) are required. A nozzle scanning velocity in the range of 200–300 mm/s gives the highest DE. The results reveal that the Cu coating on PEEK reaches a DE up to 91%, leading to an electrical conductivity up to 60% IACS (International Annealed Copper Standard). Thus, parametric analysis, along with the deposition optimization, promises to be feasible for the future in terms of DE improvement along with a good electrical conductivity in CS.

Effect of Standoff Distance on Corrosion Resistance of Cold Sprayed Titanium Coatings

A titanium protective layer was deposited onto Al7075 substrate (Al7075/Ti) by a cold spray method (CS) with different standoff distances (SoD) of the nozzle from the specimen surface. The aim of this research was to study the influence on the mechanical properties and corrosion resistance of the Ti coating on Al7075 substrate. The surface and microstructure of Al7075/Ti was observed by a scanning electron microscope (SEM). The corrosion test of the materials was carried out by using the electrochemical method. The SoD had a significant effect on the microstructure of the coatings and their adhesion onto Al7075 substrate. The highest level of microhardness (248 HV0.3) value was achieved for deposits obtained with the SoD of 70 mm. The corrosion tests showed that the mechanism of electrochemical corrosion of titanium coatings is a multi-stage process, and the main product of the corrosion process was (TiO2)ads. However, the polarization resistance (Rp = 49 kΩ cm2) of the Al7075/Ti coatings was the highest, while the corrosion rate (υcorr = 13.90 mm y−1) was the lowest, for SoD of 70 mm.

New possibilities of using cold kinetic deposition

This work deals with the properties of the protective layer applied to the base material using the cold spray method. Aluminum plate, on which a thin layer of copper was applied, served as the basic material. The samples prepared in this way were subjected to accelerated corrosion tests. Sensors for measuring the acoustic emission signal were attached to the samples. The recording was an acute emission and was taken during the entire period of corrosion. The properties of the deposited layer were also verified using metallography.

Multiscale Simulation of Shot-Peening-Assisted Low-Pressure Cold Spraying Based on Al-Zn-Al2O3 Coatings

Low-pressure cold spraying has gained much significance for its good economy in recent years. However, compared with high-pressure cold spraying, the unsatisfactory performance of coatings prepared by this method is a key problem restricting its further development. To improve the properties of the coating without incorporating severe conditions, the paper proposed an original shot-peening-assisted low-pressure cold-spraying method (i.e., SP-LPCS). By proceeding with cold spraying and shot peening alternately, SP-LPCS was proved to enhance the mechanical property of the coating effectively. Mixed particles of Zn, Al, and Al2O3 were adopted as the coating powder. Effects of shot-peening pressure, flow rate, and shot size on the micromorphology and the microhardness variance were studied. Results shows that the thickness of the plastic deformation layer stabilizes as the impact time increases to 6. The microscopic simulation of the deformation shows that according to the different metal characteristics of the powder, brittle grains fracture while plastic grains go through deformation and refinement. Meanwhile, the porosity decreases greatly after the impacts, resulting in a higher denseness of the coating. Several factors mutually contribute to the performance improvement of the coating. The microhardness of the material was increased after SP-LPCS, and obvious strengthening belts were observed, with the highest microhardness being 90.93Hv.

Structural analysis and mechanical properties of some coatings obtained by cold spray method. A review

In this paper a documentation was made to highlight the characteristics obtained on surface modifications by means of the Cold Spray, using different powders based on tungsten carbide (WC) and agglomerated with nickel, sprayed on different materials, as well as the possibility of using 52100 steel, which is often used in the manufacture of rolling bearings and which has acquired high performances both in terms of wear and fatigue and in terms of high resistance due to the alloying with chromium and the high percentage of carbon. Studies on the use of WIP-C1 powders, powders attributed exclusively to the cold spraying process, and the prior use of WIP-BC1 powders, intended to establish a stronger bond between the substrate and the base layer, have shown that good wear and impact resistance is obtained and the risk of delamination and interfacial porosity has been minimised. Studies with different coating compositions using several methods to improve surface quality by surface spraying, namely HVOF (high velocity oxygen fuel), CGDS (cold gas dynamic sterilization) and CS (cold spray), led to an improvement in performance, with the cold spray process showing improved scratch resistance, good adhesion between the substrate and the sprayed layer and higher hardness. Surface spraying is an efficient process to obtain additional characteristics, improving mechanical, tribological, corrosion and erosion properties, and of all the other techniques, Cold Spray becomes competitive because it is the only technology that deposits particles below the melting point.

A preliminary study into the effect of oxide chemistry on the bonding mechanism of cold-sprayed titanium dioxide coatings on SUS316 stainless steel substrate

Current attention has focused on the preparation of thick ceramic coating of nano­structured materials as feedstock material using the thermal spray process. The cold spray method has appeared as a promising process to form ceramic nanostructured coating without significantly changing the microstructure of the initial feedstock materials due to its low processing temperature. However, deposition of ceramic powders by cold spray is not easy due to the brittle characteristics of the material. In this study, TiO2 coatings were deposited on unannealed stainless steel substrates and substrates that were annealed from room temperature to 700 °C prior to spraying. The adhesion strength was evaluated to investigate the bonding mechanism. The influence of the remaining surface oxide layer of chromium oxide, Cr2O3, which is thermodynamically preferred for stainless steel, on the bonding mechanism involved was investigated. The results showed that by increasing the annealing substrate temperature of stainless steel, the adhesion strength of the coatings (thicker oxide) is also increased. As a result, the bonding between the cold-sprayed TiO2 particle and the steel substrate is given by the chemical bonding of an inter-oxide reaction.

Surface modification of magnesium alloys using thermal and solid-state cold spray processes: Challenges and latest progresses

• Diverse surface modification techniques for Mg and its alloys are introduced. • Mechanical, tribological and corrosion behavior of thermal sprayed coatings are presented. • Benefits and restrictions of the cold spray (CS) process are introduced. • The latest development of cold spray (CS) process for industrial applications is presented. • Bonding mechanism at the Mg alloy/cold sprayed layer interface is introduced. Potential engineering applications of magnesium (Mg) and Mg-based alloys, as the lightest structural metal, have made them a popular subject of study. However, the inferior corrosion and wear characteristics significantly limit their application range. It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate's surface characteristics. Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance. Among these, thermal spray (TS) technology provides several methods for deposition of various functional metallic, ceramic, cermet, or other coatings tailored to particular conditions. Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications. In this context, the cold spray (CS) method, as a comparatively new TS coating technique, can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies, like the high-velocity oxy-fuel (HVOF) spray method. Moreover, the CS process, as a revolutionary method, is able to repair and refurbish with a faster turnaround time; it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes, such as welding or other TS processes using a high-temperature flame. In this review paper, the recently designed coatings that are specifically applied to Mg alloys (primarily for industrial applications) employing various coating processes are reviewed. Because of the increased utilization of CS technology for both 3D printed (additively manufactured) coatings and repair of structurally critical components, the most recent CS methods for the surface treatment, repair, and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail. Lastly, the prospects of this field of study are briefly discussed, along with a summary of the presented work.

Fabrication of Ta-Ag composite deposits via cold spray: Investigation of bonding mechanism and deposition behavior

Cold spray is a solid-state deposition technology that can achieve deposition of pure metal, alloys, and composites with high efficiency. By taking the advantage of cold spray method, in this work, Ta and Ag were successfully used to fabricate Ta-Ag composite deposits for the first time, despite their significantly different properties. It was found that mechanical bonding was the major deposition mechanism between Ta and Ag. The Ag volume in the mechanically mixed powder influence the deposition between Ag and Ta particles. Deposition of Ta-Ag powder was same as pure Ta powder when Ag volume was low, and the small volume of deposited Ag inhibit the deposition of Ta particles. Higher Ag volume in powder promoted the deposition of Ta particles via mechanical interlocking due to the formation of large Ag agglomerates.

The Effect of Cu Additions on the Antibacterial Properties of Metallic Glassy Ni50TM50 (TM; Ti, Zr) Binary Systems

Antibacterial agents derived from classic organic compounds have been frequently employed for a number of years as a protective layer for biofilms. On the other hand, these agents often comprise dangerous components that, due to their interaction with toxic compounds, may be damaging to human beings. This hazard may be caused by the agents’ proximity to the toxic substances. Over the course of the past three decades, a variety of approaches, such as the utilization of a broad spectrum of metallic and oxide materials, have been the subject of research in order to develop a diverse selection of antibacterial coating layers that are acceptable. One of these approaches is the use of silver nanoparticles. It has been established that the cold spray technique, a solid-state method compatible with nanopowders, has shown higher performance and is the most effective strategy for coating materials. This has been proven via testing. It is possible to produce one-of-a-kind material coatings in ways that are not even remotely imaginable with any other thermal coating method, which is the primary reason for its prominence in contemporary production. The capacity to do so is what provides it with an advantage over its rivals in the market. This current study was conducted, in part, to investigate the effects of Cu-alloying elements on the antibacterial behavior of metallic glassy alloys on Ni50TM50 (TM; Ti, Zr) and Cu50TM40Ni10 (TM; Ti, Zr) systems prepared by the mechanical disordering technique, in conjunction with the cold spray method. These alloys were created by combining the mechanical disordering technique with the cold spray method. The arc melting process was employed to generate master alloys consisting of Ni50Ti50, Ni50Zr50, Cu50Ti40Ni10, and Cu50Zr40Ni10 for the purpose of this investigation. The master alloys were then used as feedstock materials for the creation of metallic glassy powders. Following the pulverization of the alloys of each system into a powdered form, the mixtures were charged through a high-energy ball milling operation for a duration of 50 h. Using the cold spray technique, the as-milled powders, which were metallic glasses, were applied singly in order to coat SUS304 sheets. The method was employed for this purpose. After the addition of Cu to the two binary Ni50TM50 (TM; Ti, Zr) alloys, the antibacterial properties of their corresponding metallic glassy phases were found to be significantly enhanced. This was shown by the fact that they were successful in preventing the development of biofilm by E. coli in contrast to the other systems that were evaluated.

Synthesis of Al-Al2O3-CNF Composite by Cold Spray Method: Powder Preparation and Synthesized Objects Characterization.

This paper is devoted to studying the composite material of the aluminum–alumina–carbon nanofiber (CNF) system. The paper considers in detail the process of preparation of the specified composite by ball milling, as well as the process of synthesis of a solid object (coating) by the cold spray method. The synthesized objects were studied using optical and electron microscopy, and the hardness of objects of various compositions was measured. The processes of interaction of composite particles are discussed in detail. The influence of CNF on the distribution of particles in a solid object and on the hardness of objects has been considered and discussed.

Cold-spray manufacturing of Zn/ZnO nanocomposite targets for ZnO sputtering

ABSTRACT The quality of sputtered thin films depends largely on the employed target’s chemical, electrical, and microstructural characteristics. This paper explores the application of cold spraying (CS) in manufacturing dense, uniform, and high-performance sputtering targets for ZnO thin films. Zn/ZnO nanocomposite powders with 25, 50, and 75 wt-% ZnO were cold sprayed on Cu substrate. The samples were characterized with respect to their prime properties as well as their performance when used as targets to produce ZnO thin films. By increasing the amount of the nanoparticles in the target, the electrical resistivity and densification of the targets increased at the price of decreased deposition efficiency. Furthermore, the maximum sputtering rate and the most uniform thin film were obtained from the target containing 50 wt-% ZnO. The results confirm the viability of the CS method for manufacturing high-quality Zn/ZnO sputtering targets that can be directly deposited on backplates without additional adhesion treatments.

Microstructure, mechanical and tribological properties of cold sprayed Cu[sbnd]W coatings

This paper presents the results of the investigation of the microstructure and properties of copper‑tungsten coatings with different compositions on aluminum alloy substrates. Coatings were obtained by cold spray method using powder mixtures as feedstock. The effect of the powder mixture composition on the deposition efficiency and the tungsten content in the coating have been studied. X-ray diffraction analysis was used to investigate the phase composition and to reveal the peculiarities of changes in the crystalline structure of copper and tungsten particles after cold spraying in relation to the coating composition. Using the method of instrumental indentation on cross-sections of the coatings mechanical properties were measured. It was shown that increasing of tungsten content in the coatings contributes to increasing the microhardness and Young's modulus of the coatings. The mapping images showed that all coatings were characterized by non-uniformity of mechanical properties over the cross-section. The bonding strength of coatings significantly increases with increasing tungsten content in the feedstock. CuW coatings are characterized by lower specific wear rate values and higher coefficients of friction under dry sliding wear conditions in a ball-on-flat mode compared to pure copper coating.

Experimental studies and numerical simulation of cold spray technique to investigate the effect of operating parameters on the thickness of Fe/TiO2 self-cleaning film

A self-cleaning solution based on sol-gel and hydrothermal processes was applied to prepare the self-cleaning Fe/TiO2 surfaces on a ceramic substrate using the cold spray method. Moreover, a numerical method was employed to investigate the effect of spraying operation conditions, including carrier gas pressure, the standoff distance, and traverse speed on the coated layer thickness. Seven samples were prepared under different spray operating conditions. The results indicated that as the pressure increases from 2 to 4 bar, the average film thickness increases from 1.7 to 5.5 μm. In addition, when traverse speed rises to 1.8 cm/s, the surface coating substantially becomes thinner to <2 μm. Besides, it was observed that the coating thickness has the maximum value at a certain standoff distance between the spray gun and the substrate surface. Finally, the results were compared with those of the numerical simulation, properly consistent with a maximum relative error of <5%. Besides, the photocatalytic decomposition rate of formic acid by the coated surface at the spray pressure of 4 bar, the traverse speed of 1.2 cm/s, and the standoff distance of 10 cm was >94%. Additionally, the antibacterial tests showed a high potent surface activity against S. aureus and E. coli. Bacteria. Consequently, the proposed optimum condition was proved to be appropriate for preparing self-cleaning coatings.

Wearable multifunctional soft sensor and contactless 3D scanner using supersonically sprayed silver nanowires, carbon nanotubes, zinc oxide, and PEDOT:PSS

The multifunctional soft sensor developed here is capable of simultaneously sensing six stimuli, including pressure, bending strain, temperature, proximity, UV light, and humidity, with high accuracy and without interference among the respective built-in components. The sensor is fabricated via a facile, scalable, and cost-effective supersonic cold-spraying method using silver nanowires (AgNWs), carbon nanotubes (CNTs), zinc oxide (ZnO), and conducting polymer poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). A mask and laser cutter are used in conjunction with the supersonic cold-spraying method to produce miniaturized multifunctional sensors that can be readily installed on various substrates; for example, the production of gloves capable of multifunctional sensing. In particular, the proximity sensor of the multifunctional glove sensor can produce a three-dimensional (3D) image of a scanned object, showing high potential for use in military, medical, and industrial applications.

Properties of coatings obtained from a mechanically treated boron-containing mixture of powders by cold spray method

For composite coatings obtained by cold spraying from powder mixtures of compositions Al + 50 wt.% B and Al + 50 wt.% B4C prepared in a V-shaped mixer and by mechanical processing in a planetary mill, a comparison of effect of these methods for preparing mixtures on the boron (boron carbide) content in the coating was carried out. It is shown that, regardless of the method of preparation, the boron and/or boron carbide contents in the coating have close values, which is confirmed by the results of X-ray phase analysis and visual processing of images of the coating structure. Keywords: cold spray, composite material, high-energy planetary mill, aluminum, boron carbide, X-ray phase analysis.

Mechanism of heterogeneous flow—solid substrate interaction on the formation of coatings of different thicknesses using different types of spray accelerators

Physical processes of the inleakage of a supersonic heterogeneous flow of air-powder mixture to a solid substrate, tested on the experimental setup designed for applying protective coatings by a cold spray method, are considered. The interaction of a particle with a flat plane and cylindrical solid substrates, the multilayer coatings and the application of coatings using spray accelerators of different configurations are considered. A mathematical model is demonstrated based on the equation of energy balance in the impact area intended to estimate the interaction between a particle and a solid substrate during impact, as well as examples of results calculated using this model. Methods for calculation of the thickness of the coating applied to flat plane and cylindrical substrates are described. The features of one-step and multi-step coating applications with and without additional exposures are described. As an example, the results of testing the coating for porosity are given. A list of factors and additional exposures affecting the strength of the coating is given.

Mechanism of the powder material particle in different phase states—solid substrate interaction

The paper discusses impact of solid and molten particles of a powder material in heterogeneous flow acting on solid surface and its effect on characteristics of coating applied by a gas-dynamic (cold spray) method. An equation of energy balance in impact zone of the particle on the substrate is given. Obtained equation accounts the particle size, mass average temperatures in heated portions of the particle and the substrate, before impact temperatures of the particle and the substrate, fraction of the heated mass of the particle and the substrate during impact, specific heat capacities of the particle and the substrate material, the Brinell characteristic, and deformation of a solid particle. Results of the bibliographic study of the molten metal droplet formation, their kicks in the substrate depending on its velocity, substrate temperature and surrounding gas pressure are presented. The differences in the impact mechanism of solid and molten particles on the substrate and their influence on the coating formation and its properties are determined. Recommendations for operating parameters of high-quality coating are given.