Zinc Particles Research Articles

A novel one-pot method to synthesize hierarchical mesoporous carbon foams with ZnO coating

The ever more diverse applications of carbon materials require new fabrication methods to satisfy the demand of functionalization. This work seeks extending functionality of carbon foams known to be determined by their porous properties, which in turn are mainly produced during synthesis. In this work, we report a simple and versatile method to produce hierarchical mesoporous carbon with bottom-up grown crystalline ZnO coating obtained in one pot. The synthesis is based on foaming xylene-epoxy-zinc suspensions, which are further subjected to carbonizing treatments. Two carbon foams carbonized at high (1000 °C) and low (500 °C) temperatures are compared. During carbonization, zinc particles were found to diffuse towards the foam's surface and evaporate in case of the high temperature process, whereas reaction to form the crystalline ZnO coating was found in the low temperature process. The surface area and pore volume of the carbon foams depend on the carbonizing temperature due to the direct relation with the diffusion rate of particles in the material. This also explains the formation of the oxide layer at the foam external surface observed in the low temperature treatment. This work highlights the possibilities of improving the functionality of porous carbon materials by adding ceramic coatings.

Remediation of Heavy Metals Using Selected Agricultural Waste: Sunflower Husk and Durian Leaves

This study revealed the behaviour of sunflower husk (SFH) and durian leaves (DL) as an adsorbent that could treat the aqueous solution to be free of heavy metal ions. The batch method was utilized. The influence of pH, contact time and initial metal concentration were described. The impact of pH on the uptake levels of the metal particles by both selected adsorbents were delineated between pH 4 to pH11. It was observed that the best value of pH for copper and zinc removal was 8 in case of SFH and it was 9 for DL. The process tends to be rapid the initial 10 minutes for SFH and 5 minutes for DL and an equilibrium time of two hours was needed for the copper and zinc particles adsorption onto SFH and an equilibrium time of one hour was needed for the copper and zinc adsorption onto DL. The Freundlich and Langmuir isotherm models are used to decide the adsorption parameters. The Freundlich isotherm model tends to fit the equilibrium data better than Langmuir isotherm model. The outcomes demonstrated that SFH and DL hold great potential to be utilized as low cost dry biomass adsorbent in the order SFH < DL.

Deposition of Zinc Species in 3D Structured Zinc Anodes in Nonstirred Alkaline Systems Observed by X‐Ray Micro Tomography

This work focuses on the deposition mechanism of zinc within nonstirred alkaline cells. A zinc anode based on zinc particles and a 3D copper foam is examined with X‐ray micro tomography to visualize its structural changes after discharging and recharging. To this end, zinc and zinc oxide components of the anode are distinguished in the tomography images, and a 3D model is reconstructed to investigate zinc deposition. The results contribute to the general understanding of structural changes during cycling to develop new concepts to stabilize the zinc anode and enhance the performance of zinc–air batteries.

Strategies for Hydraulic Recharge of Zinc-Air Flow Batteries

The increased use of fluctuating renewable energy calls for efficient, safe and environmentally friendly energy storage solutions. To meet the variable power-, capacity- and profitability requests of mobile and stationary applications, it is necessary to identify promising materials. Zinc-air batteries with specific energy density higher than lithium-ion and low cost, highly available, eco-friendly active materials are suitable to fulfill these requirements. The use of a flow battery type with zinc-particles suspended in alkaline solution (zinc-slurry) in addition with high performance oxygen-reduction electrodes enables the development of high-power zinc-air batteries. This setup also allows the independent scaling of capacity and power. The recharging of this system can be performed due to classical electrical charging or due to a hydraulic recharge by changing the used zinc-slurry with a fresh one. The cooperative project, ZnMobil, funded by the Federal Ministry of Economic Affairs and Energy in Germany combines the experience of industrial and academic partners (Covestro Deutschland AG; Grillo-Werke AG; VARTA Microbattery GmbH; Accurec Recycling GmbH; Technical University Freiberg, Gottfried Wilhelm Leibniz University Hannover; University of Duisburg-Essen; the fuel cell research center ZBT GmbH) to develop a zinc-air flow battery with high performance and economic efficiency. Here we present strategies for the hydraulic recharging of zinc-air flow batteries. The battery system consists of a 100 cm² copper plate as current collector for the zinc-suspension electrode and an oxygen reduction electrode with a gas-diffusion layer (supplied by Covestro Deutschland AG). The zinc-slurry contains zinc particles (supplied by Grillo-Werke AG) suspended in alkaline solution (30 wt.-% KOH) and stabilized with polyacrylic acid. Depth-of-discharge and battery resistance were measured for zinc-slurries in a flow system under regulated conditions. The influence of the depth-of-discharge and several additives on the rheology of the zinc-slurries was evaluated. Depending on the current density and additive selection, it is possible to achieve energies of up to 300 Wh during discharge.

Electrochemically Produced Zinc Oxide Electrode in Rechargeable Alkaline Batteries

The zinc electrode is a commonly used negative electrode in a host of commercially important battery systems such as Zinc- Manganese dioxide (Zn-MnO2) and Silver – Zinc (Ag2O-Zn) batteries. Out of these the Zn-MnO2 battery is a commercially successful non-rechargeable battery because of its inherent safety, low cost and relatively high energy density. Recent experimental work has shown that a rechargeable Zn-MnO2 battery is capable of giving 3000 cycles when cycled at 10% of the MnO2 theoretical 1 e- capacity and 1.5% Zn 2e- capacity. However, at higher zinc utilization the battery is short-lived. Dendrite shorting, shape change and MnO2 poisoning are some of the main mechanisms of zinc electrode failure. These failure mechanisms are closely related to the high electrochemical solubility and the unrestrained movement of zincate ions, formed at the anode on discharge. Therefore, it is imperative to immobilize zincate ion either via complexation or intercalation. Hydrotalcite-like layered materials are recently reported as anode active materials for Nickel -Zinc batteries and have been suggested to capture zinc ions into their structure. We report the cycling performance of Zinc Aluminum Bismuth hydrotalcite for 900 cycles at 10% zinc utilization in 6 M potassium hydroxide solution saturated with zinc oxide against Nickel oxyhydroxide cathode. X-ray diffraction results show the presence of zinc oxide on discharge and do not support the presence of a layered hydrotalcite after cycling, as has been reported in literature. This is attributed to the instability of the hydrotalcite crystal structure in concentrated alkaline electrolytes. The results of this study show improved performance because of zinc oxide saturated electrolyte. To inherently reduce the tendency of the zinc electrode for dendrite shorting and shape change we investigate a fundamental question of the difference between the cycling of a zinc electrode versus the cycling of an electrochemically formed zinc oxide electrode. A novel, first of its kind, battery cycling protocol is reported where manganese dioxide cathode is cycled against a zinc oxide anode formed in-situ. This is made possible by first deeply discharging the manganese dioxide against a metallic zinc electrode resulting in complete conversion of metallic zinc to zinc oxide. Subsequent cycling of the electrochemically formed zinc oxide anode and cathode is carried out at a shallow depth of discharge. Adopting this strategy has resulted in improved cycle life at 12% utilization of the zinc electrode. We dissect the cells at different cycles to see an evolution of the active material in the cell with metallic zinc and the cell with electrochemically formed zinc oxide. Bulk electrolyte analysis for zincate ion shows that the zinc oxide cell is under-saturated while the metallic zinc cell is saturated with zincate ions. Optical Microscopy images of the zinc oxide anode show the presence of finer zinc particles embedded inside a zinc oxide matrix. Preliminary analysis results show that cycling of electrochemically produced zinc oxide rather than metallic zinc anode reduces shape change and dendrites because of reduction of zincate ions in the bulk electrolyte.

PEGylated zinc oxide nanoparticles induce apoptosis in pancreatic cancer cells through reactive oxygen species

In this study, the authors have successfully prepared the polyethylene glycol (PEG)-coated zinc oxide nanoparticles (ZNPs) and studied its effect in pancreatic cancer cells. The authors have observed a nanosized particle with spherical shape. In this study, the authors have demonstrated the cytotoxic effect of ZNP and PZNP in PANC1 cells. To be specific, PZNP was more cytotoxic compared to that of ZNP in PANC1 cancer cells. The authors have further showed that apoptosis is the main mode of cytotoxic activity. It is worth noting that PEGylation of ZNP did not decrease the cell killing activity of zinc particles, whereas it further increases its anticancer effect in the pancreatic cancer cells. The authors have observed a significant upregulation of proapoptotic BAX while expression of antiapoptotic Bcl-2 was significantly downregulated indicating the potent anticancer effect of zinc nanoparticles. Overall, PEGylation of ZNP could be an effective strategy to improve the stability, while at the same time, its anticancer activity could be enhanced for better therapeutic response.

Development of a sustainable coating and repair material to prevent bio-corrosion in concrete sewer and waste-water pipes

Concrete biogenic corrosion (bio-corrosion) in wastewater pipes occurs mainly because of the diffusion of aggressive solutions and in situ production of sulfuric acid by sulfur-oxidizing microorganisms. The prevention of concrete bio-corrosion usually requires modification of the concrete mix or the application of a corrosion-resistant, chemical/antimicrobial-coating layer on the inner surface of the pipe to inhibit biological activity and provide a protective layer between the concrete surface and corrosive solution. However, the short bio-resistant lifetime due to undesired leaching of biocides to the surrounding environment coupled with the coating's poor acid-resistant properties have increased the requisite for safe, more efficient, environmentally friendly and long-lasting alternatives.In this paper, three broad families of coating materials were investigated. These comprised Portland cement-based, geopolymer-based and geopolymer magnesium phosphate-based coatings. These three coatings carried in separate formulations, intermixed Zinc particle and Zinc-doped clay particles. These were in turn compared with ordinary cement-based coatings without Zinc or Zinc-doped clay. For the Zinc-doped clay particles, sodium-bentonite were impregnated with zinc ions to create a biocide-loaded carrier. The coatings’ chemical stability and resistance to biogenic corrosion were investigated by testing samples in an accelerated bio-corrosion chamber designed and developed by the authors. Variations in flexural strength were studied to evaluate the properties and performance of the coated samples after corrosion. Results show that the developed coating materials have significantly superior resistance to biogenic corrosion compared to ordinary cement-based coatings.

A Brief Communication on the Improved Mechanism of Graphene on Zinc-Rich Coatings

Gallic acid-based epoxy resin monomer was synthesized by the natural extract of gallnut for the efficient dispersion of graphene in epoxy resin. The graphene zinc-rich anticorrosion coatings were further prepared on the basis of the graphene / gallic acid-based epoxy resin monomer dispersion system. Electrochemical experiments and spectral characterization were carried out to study the effect of graphene on zinc-rich coatings and its mechanism. Experiments showed that graphene enhanced the cathodic protection currents of the zinc-rich coatings and prolonged the cathodic protection time. Simultaneously, graphene slowed down the penetration of corrosive media into the coatings. The conductivity of graphene improved electrical contact between zinc particles as well as zinc and iron, and transformed un-activated zinc particles into activated zinc particles. The dispersed and layered structure of the graphene extended the permeation path of the corrosive medium, which resulted in reduced permeation rate and decreased water content of the coatings. It was demonstrated by the tracking of zinc corrosion products by micro-area Raman spectroscopy.

Effects of Ultrafine Nano‐zinc Particles on Cardiac Structure and Function in Myocardial Infarction Mice

ObjectiveWe aimed to illustrate the association between ultrafine nano zinc particles inhalation and cardiac structure and function in myocardial infarction (MI) mice.Method6‐week‐old ICR mice were divided into three groups randomly: sham group, MI group and MI exposure group, 12 mice in each group. We preformed LAD ligation operation in MI group and MI exposure group. After postoperative two weeks MI exposure mice were put into ventilation chamber which filled with 500ug/m3 ultrafine nano zinc particles for 6 hours per day, while MI group mice and sham group mice were cultivated in normal environment. After exposure 8 weeks, we use Vevo 2100 machine to acquire heart function measurements. Then we collected blood sample and killed mice and obtain heart samples that were used for immunohistochemistry. The apoptosis myocardium were measured by immunofluorescence. Elisa method was used to detect the catecholamine expression in plasma. The changes of collagen were measured by Masson trichrome staining.ResultsCompared with the sham group, the EF in MI exposure group and the MI group decreased significantly (p&lt;0.05), and the decrease in MI exposure group was more obvious. The results of immunofluorescence showed that the number of apoptotic cells in MI exposure group increased significantly (p&lt;0.05) and the myocardial cells exaggerated significantly. In addition, the norepinephrine in the peripheral blood of MI exposure group was increased significantly (p&lt;0.05), in the same time the Marsson trichrome staining results showed that the collagen content of MI exposure group's myocytes increased significantly (p&lt;0.05).ConclusionNano‐zinc particles inhalation can aggravated ventricular remodeling and heart dysfunction and increased myocardial cell apoptosis after myocardial infarction in mice.Support or Funding InformationShenzhen Science and Technology Innovation Institution (China) Grant JCYJ20160427170536358 (Y Huo)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Optimization of the Electrolyte Parameters and Components in Zinc Particle Fuel Cells

Zinc (Zn)-air fuel cells (ZAFC) are a widely-acknowledged type of metal air fuel cells, but optimization of several operational parameters and components will facilitate enhanced power performance. This research study has been focused on the investigation of ZAFC Zn particle fuel with flowing potassium hydroxide (KOH) electrolyte. Parameters like optimum electrolyte concentration, temperature, and flow velocity were optimized. Moreover, ZAFC components like anode current collector and cathode conductor material were varied and the appropriate materials were designated. Power performance was analyzed in terms of open circuit voltage (OCV), power, and current density production and were used to justify the results of the study. The flow rate of the electrolyte was determined as 150 mL/min in the self-designed configuration. KOH electrolyte of 40 wt% concentration, at a temperature of 55 to 65 ℃, and with a flow velocity of 0.12 m/s was considered to be beneficial for the ZAFCs operated in this study. Nickel mesh with a surface area of 400 cm2 was chosen as anode current collector and copper plate was considered as cathode conductor material in the fuel cells designed and operated in this study. The power production of this study was better compared to some previously published works. Thus, effective enhancement and upgrading process of the ZAFCs will definitely provide great opportunities for their applications in the future.

Improved Discharge Capacity of Zinc Particles by Applying Bismuth-Doped Silica Coating for Zinc-Based Batteries

Corrosion and discharge behavior of battery-grade zinc particles coated with a silica layer doped with bismuth was investigated and compared with untreated zinc powder. Electrochemical investigations were carried out in half-cell configuration. The electrolyte was 6 M KOH in excess. Coated zinc particles provided a discharge capacity of 737 mAh g−1 (89.9% DoD) versus 633 mAh g−1 (77.2% DoD) of untreated zinc particles after a dwell time of 1 h in KOH. The silica coating reduced the direct contact of the zinc surface with the electrolyte and thus minimized the hydrogen evolution reaction, which led to an increased discharge capacity. Additionally, bismuth doping enhanced conductivity within the silica coating and increased zinc utilization. Those coated zinc particles inhibited corrosion, i.e., corrosion efficiency reached 87.9% compared to uncoated zinc. Additionally, the coating achieved a capacity retention of 90.9% (670 mAh g−1) after 48 h dwell time in 6 M KOH. The coatings were prepared by sol-gel technology and characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface determination.

Using KDF material to improve the performance of multi-layers filters in the reduction of chemical and biological pollutants in surface water treatment

Multi-layers filters are usually used in conventional water treatment plants to purify water, reduce turbidity, and remove plankton and undesired odours. Multi-layers filter consists of basic layers represented in graded sand and supporting gravel layers. This research aims to study the efficiency of such filters after the addition of new layers made of copper and zinc particles by 50% per each with high purity, which are traditionally called KDF (Kinetic Degradation Fluxion). The purpose of adding such layers is to increase the efficiency of filters in the removal of diverse chemical contaminants of heavy elements (Lead, Nickel, iron, etc.), and chlorine to use them in traditional or advanced filter stations, such reverse osmosis plants or ion exchange water filters. A glass tube was filled with KDF, sand and gravel layers and used as a multi-layer's filter, and tests were carried out on a water sample that has been prepared in the lab with concentration of 2 mg/l for heavy elements and 5 mg/l for chlorine. Flow rates of the tested water sample were 20, 40, 60, 80 and 100 l/hr. The results show a very high efficiency of such filters to remove of chlorine from the treated water by 90% and more, while the efficiency of the modified filter to remove lead, nickel and iron was 92%, 88%, and 67% respectively; however, there was no significant records in removing the biological contaminants.

Designing reduced graphene oxide/zinc rich epoxy composite coatings for improving the anticorrosion performance of carbon steel substrate

Graphene nanosheets are impermeable to chemical molecules and electrical conductivity. Thus, they are attractive candidates to enhance an epoxy zinc rich coating with a significant anticorrosion performance. Several studies focus on investigating the role of graphene in reinforcing the corrosion resistance of the coatings. However, there is a paucity of study that analyzing the anticorrosion relationship between the feature of graphene and epoxy zinc rich coating. The present study reported on epoxy zinc rich coatings with enhanced anticorrosion performance via embedding reduced graphene oxide/graphene oxide (rGO/GO) nanosheets. Thus, rGO and GO were prepared from natural graphite powder via the modified Hummers method. The results of Raman, XPS, FT-IR, SPM, and TEM analyses revealed the quintessential structure and morphology of rGO and GO. In addition, results from electrochemical measurements and the scanning vibrating electrode technique indicated that rGO effectively enhanced the cathodic protection duration of epoxy zinc rich coatings. rGO nanosheets exhibited dual functions that were identified in two aspects. First, the impermeable barrier role was exerted by including prepared rGO nanosheets into the polymer matrix. Second, superior electrical conductivity was utilized since the rGO nanosheets improved the efficiency of the electrical connection between the zinc particles and steel substrate.

Microstructure and improved tribological performance of graphite/copper‑zinc composite coatings fabricated by low pressure cold spraying

It is a challenge to obtain metal-solid lubricant composite coatings with good tribological performance by cold spraying due to the poor interfacial bonding between solid lubricants and metal matrix along with uncompacted microstructure of the resulted composite coatings. Here, we report the preparation of graphite reinforced copper based composite coatings with improved self-lubricating and anti-wear performance by low pressure cold spraying via the rational feedstock design in combination with metallic pretreatment of graphite. Zinc particles are blended with the copper particles and used as the feedstock to produce a fully dense copper‑zinc matrix and ZnO during sliding process, which produces the durable binding of lubricating graphite ingredients to the contact surfaces. The graphite lubricants are pretreated with electroless copper coatings to improve their compatibility with copper‑zinc matrix and their content in the cold-sprayed composite coatings. It is found that graphite/copper‑zinc composite coatings with low COF, good wear resistance and high load capability can be obtained by tuning the content of copper-coated graphite in the feedstock. The mechanism on reduction of friction and wear for graphite/copper‑zinc composite coatings is also discussed.

The surface-modified effects of Zn anode with CuO in Zn-air batteries

Copper oxide nanoparticles (CuO-NPs) can be used to prevent dendrite formation and increase the reversibility of Zn anode. The zinc surface was modified with CuO and the Cu source used was copper nitrate. It also contained 0.1 wt%, 0.5 wt%, 1.0 wt%, and 3.0 wt% CuO by weight of zinc. The morphologies of the Zn surfaces modified by CuO-NPs were observed by scanning electron microscopy (SEM). The structures of the surface-modified and bare zinc powders showed that the modification did not affect the crystal structure, but Cu 2p details from XPS were detected in the form of a satellite peak of CuO. SEM images of CuO modified on the zinc particles revealed homogeneous modification on the Zn surface. The use of an appropriate CuO particle can prevent direct contact with Zn and KOH electrolyte, and minimize side reactions within the batteries. In a DC-cycling test, the 0.1 wt% CuO-modified Zn anode powder provided the best cycle performance up to 24 h. A surface-modified zinc electrode can increase reversibility and reduce self-discharge with electrochemical stability. The results suggest that surface modification is effective for improving the comprehensive properties of Zn anode materials for Zn-air batteries.

The structure and properties of the coating based on particles of copper and zinc deposited by gas-dynamic spraying

The results of the study of the structure and properties of the coating based on a particulate mixture of Cu and Zn deposited by the method of cold gas-dynamic spraying are presented. The presence of diffusion during the deposition of a coating with the formation of a solid solution of copper in zinc is shown. The process of predominant diffusion of copper into zinc with a slight exposure time in the furnace with the formation of intermetallic compounds Cu5 Zn8 and CuZn, the mass fraction of which reaches 44% and 28%, respectively, is revealed. The diffusion coefficient of copper to zinc is not less than 1.56×10−13 m2·s−1. An increase in the exposure time leads to a decrease in the content of beta (β ′ ) and gamma (γ) phases to ≈ 15% and the formation of a solid solution of zinc in copper (α phase, 58%) with a different ratio of initial components. The formation of electronic compounds reduces the cohesive strength of the coating metal by almost two times, and an increase in the proportion of the phase leads to an increase in the cohesion above the initial value.

Effects of conductive polymers (type and concentration) in coatings with zinc particles of different shapes

The objective of this work was to compare the anticorrosion effects of organic coatings containing zinc metal consisting of either lamellar particles or isometric particles and to reduce the zinc metal content of the coatings while preserving their high anticorrosion efficiency. The optimization and Zn metal content reduction can be achieved using zinc with a lamellar particle shape and application of conductive polymers. Conductive polymers are expected to enhance the electrochemical effect of zinc metal in paints. Organic coatings with lamellar zinc particles also exhibit better mechanical properties. Optimization of the amount of zinc lamellar particles could promote a wider use of this material in anticorrosion paints. The conductive polymers used in this work included polyaniline phosphate, polyaniline benzoate, and carbonized polyaniline. A solvent-based epoxy–ester resin served as the binder. Model paints consisting of this resin and containing different concentrations of polyaniline phosphate, polyaniline benzoate, and carbonized polyaniline were prepared. The paints were tested at the critical pigment volume concentration (CPVC) of Zn dust and at lower Zn dust concentrations, specifically 2% below the CPVC. The paints containing combinations of zinc and a conductive polymer contained the sum of the pigments just below the CPVC of the zinc dust species used. This implies a level of 39% of (PVCZn-lam) for the systems with lamellar zinc and a level of 61% of (PVCZn–sf) for the systems with spherical zinc. The pigment volume concentration (PVC) of the conductive polymers in the zinc-containing paints was (based on results obtained previously) 1%, 5%, and 10% in the systems with lamellar zinc and 1%, 5%, 10%, and 15% in the systems with spherical zinc. The organic coatings were subjected to accelerated cyclic corrosion tests and electrochemical measurements. The sample containing polyaniline carbonate (PVC = 1%) and spherical zinc exhibited a significantly lower corrosion rate as compared to that of uncoated steel.

Vector Flow Imaging of a Highly Laden Suspension in a Zinc-Air Flow Battery Model.

Flow batteries using suspension electrodes, e.g., zinc-air flow batteries (ZABs), have recently gained renewed interest as potential candidates for grid energy storage or mobile applications. The performance of ZABs depends on the local flow conditions of the suspension in the electrochemical cell, which acts as an electrode. Hence, it is crucial to measure and understand the complex flow characteristics of such solid-liquid suspensions. The investigated suspension electrode is an opaque slurry that consists of microscopic zinc particles and an aqueous potassium hydroxide electrolyte. Commonly, ultrasound Doppler velocimetry is used for flow imaging in opaque fluids. However, due to the high particle concentration in the suspension electrode, strong scattering and wavefront distortions of the ultrasound are introduced. In this paper, we show that this results in an increased measurement uncertainty for Doppler-based velocity estimation. Instead, ultrasound image velocimetry is applied to measure the 2-D and two-component flow field in the zinc-electrolyte suspension. This is possible by adapting the measurement system to the suspension with a calibration setup. The total measurement uncertainties of 4.1% and 2.5% for the axial and lateral flow components are derived from the calibration measurements. For the first time, the flow field of such a suspension could be measured in a scaled fluidic model of a ZAB. The comparison of the estimated flow rates from the velocity profiles showed good agreement to a gravimetric reference. A significant difference in the flow characteristics of a macroscopically homogeneous electrolyte and the same electrolyte loaded with 8 vol.-% zinc particles, i.e., the suspension electrode, was found. Along with the demonstration of the measurement technique for opaque, concentrated suspensions, the measurement data will be used to calibrate and validate numerical models for comparable multiphase fluids.

Features of the formation process of brass coating by gas-dynamic deposition of copper and zinc particles

Coatings deposited on the surface of samples of steel 40X by the method of gas-dynamic deposition using the finished mechanical mixture of particles of copper, zinc and aluminum oxide. X-ray structural phase analysis reveals significant differences in the structure and phase composition of the coating applied when the nozzle is displaced by 2 mm and 3 mm. During gas-dynamic deposition of the coating using a mechanical mixture of copper, zinc and aluminum oxide (corundum) particles, in the deposited metal layer, copper, zinc, solid solution of copper in zinc (η-phase) and intermetallic (electronic) compounds are exposed based on CuZn3 (ε-phase) and Cu5Zn8 (γ-phase). Primary diffusion of copper to zinc is recorded; the diffusion coefficient has a high value of 0.75-2.25 x 10-8 cm2/s. The deformation of particles is accompanied by the formation of stresses, then their relaxation will take place due to the cooperative displacement of atoms, which will significantly increase the rate of diffusion of copper into zinc. In this case, a high value of the diffusion coefficient for gas-dynamic deposition of a coating based on copper and zinc particles should be attributed to a significant increase in point defects (vacancies) in zinc, as well as the onset and relaxation of deformation – stresses in copper particles. Analysis of the technological factors of deposition shows the effect of deformation on the diffusion of copper into zinc.

Development of Gradient Concentrated Single-Phase Fine Mg-Zn Particles and Effect on Structure and Mechanical Properties

In this study, we used powder metallurgy process to develop gradient concentrated single-phase fine magnesium–zinc alloy particles. Fine magnesium particles were initially dry coated with nanometer size zinc particles in homogeneous manner and cold compacted to cylindrical billet. Zinc atoms were diffused in to the magnesium particles during high-temperature sintering process and produced the single-phase gradient solid solution. The gradient concentration of zinc induced gradual grain refinement in the magnesium particles. The powder metallurgy processed gradient concentrated alloy particles showed an excellent level of hardness, strength, ductility, and fracture toughness in their bulk form, which was even much higher when compared with unalloyed magnesium. Despite having gradient solid solution structure, the developed alloy particles showed homogeneous properties in their bulk form.