Zn Particles Research Articles

Microstructures and mechanical properties of Al/Zn composites prepared by accumulative roll bonding and heat treatment

Al/Zn composites were fabricated using 1060-Al plates and Zn particles by accumulative roll bonding and heat treatment. X-ray diffraction analysis reveals that most of the Zn phase in the final Al/Zn composite disappeared in the Al matrix. Scanning electron microscopy and energy-dispersive X-ray spectroscopy analyses revealed excellent solid solution regions distribution in the final Al/Zn composite. The final Al/Zn composite showed higher hardness values of the solid solution regions than the Al matrix. Compared with ARBed monolithic 1060-Al, the Al/Zn composites had higher strength without sacrificing ductility.

Cyclic Voltammetry of Zn/Zn(II) Couple in Dycyanamide Anion and Bis-(trifluoromethylsulfonyl)Imide Anion Based Ionic Liquids

The electrochemistry of a Zn/Zn(II) couple was studied and compared in four kinds of room temperature ionic liquids (RTILs) (1-butyl-1-methylpyrrolidinium dicyanamide (BMP-DCA), 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI), 1-butyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (BMP-TFSI) and 1-methyl-1-pentylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPP-TFSI)), with the aim of screening desirable RTILs as replacements for traditional aqueous electrolytes for Zn rechargeable batteries. Cyclic voltammetry was used to study the reversibility and cyclability of Zn redox in each RTIL. The morphology of Zn deposits prepared from each RTIL was characterized by scanning electron microscopy. The results show that Zn redox has the best cyclability in the DCA-based RTIL, with the Zn deposit morphology characterized by finely dispersed rods composed of granular Zn particles (~50-100 nm in size). In TFSI-based ionic liquids, the Zn/Zn(II) couple reaction had a higher current density than that in the DCA-based ionic liquid, implying different electron transfer processes. BMP-DCA and EMI-TFSI are promising RTILs worthy of further investigation.

Influence of Intermittent Air Introduction on Formation of Zn Films by Mechanical Coating Technique

The influence of intermittent air introduction on the formation of Zn films during mechanical coating process was investigated. A series of contrast experiments were carried out. The XRD and EDS results showed that Zn particles were slightly oxidized. The SEM images indicated that disk-like zinc oxide (ZnO) nanocrystals were formed. The formation of disk-like ZnO made the morphology of Zn films more uneven and irregular. On the other hand, it increased the adhesion strength of Zn films to Al2O3 balls and hence the exfoliation of Zn films was not found.

Dissolved and particulate zinc and nickel in the Yangtze River (China): Distribution, sources and fluxes

Dissolved and particulate Zn and Ni concentrations were determined at 76 locations along the Yangtze River basin from the headwaters to the estuary during flood and dry seasons. Spatial and temporal variations of Zn and Ni were investigated and six major source zones were identified. The Three Gorges Dam (TGD) blocked most of the suspended loads and extremely low concentration of Zn and Ni were observed downstream of the dam. Dissolved (ranging from 0.062 to 8.0μgL−1) and particulate (ranging from 12 to 110mgkg−1) Ni showed similar levels of concentrations during flood and dry seasons, whereas dissolved (ranging from 0.43 to 49μgL−1) and particulate (ranging from 54 to 1100mgkg−1) Zn were slightly and much lower in the flood season than dry season, respectively. This was attributed to the increased water discharge during the flood season causing a dilution effect and sediment resuspension. In the flood season, average concentrations of Zn and Ni were higher in the main channel than in tributaries, due to soil erosion and mining activities providing the dominant inputs. The situation was opposite in the dry season, attributed to the contribution of municipal sewage, industrial activities, and waste disposal. During the flood season, dissolved Zn and Ni concentrations were negatively correlated with pH. Water and suspended particulate matter (SPM) from the upper reaches, middle reaches, and lower reaches of the Yangtze River were characterized by their Zn and Ni concentrations. The Panzhihua, Nanling and Tongling mining areas were considered as the most important source zones of particulate Zn and Ni. The Chongqing region, Wuhan region and the Yangtze River Delta provided most of the dissolved Zn and Ni inputs into the river. Annual net flux of Zn (10–72×105kga−1) and Ni (5.0–19×105kga−1) in each source zone were estimated according to their respective influent and effluent fluxes. Contributions of the source zones to Zn and Ni transport decreased from the upper reaches to the lower reaches.

On the Effect of the Presence of Solid Diluents during Zn Oxidation by CO2

We consider the solar thermochemical production of H2 and CO (syngas) from H2O and CO2 via a two-step ZnO/Zn redox cycle. The first step, driven by concentrated solar radiation, is the endothermic thermolysis of ZnO producing a gaseous mixture of O2 and Zn-vapor, which upon quenching precipitates a solid residue comprising Zn and ZnO in variable ratios. The second, nonsolar step is the exothermic oxidation of Zn by H2O and/or CO2 to form fuel (H2 and/or CO) and the solid product ZnO which is recycled to the solar reactor. It has been recognized that the presence of inert ZnO during the second step affects both the oxidation kinetics and the final asymptotic conversion of Zn. However, while the fraction of ZnO in a mixture with Zn leaving the thermolysis step generally varies with a solar reactor/quencher design and experimental conditions, all previously reported analyses have studied the oxidation kinetics of either pure Zn or of Zn particles blended with ZnO in a specific, preset mass ratio. This work examines the effect of dilution with inert particles on the Zn oxidation by CO2. Blends of commercially available Zn with ZnO or Al2O3 particles have been tested by thermogravimetry. The setup was carefully designed to ensure the absence of heat and mass-transfer intrusion on the oxidation kinetics while using a 15% CO2–Ar mixture or pure CO2 at 350 °C < T < 400 °C and ambient pressure. The effects of inert particle type, mass fraction, and blending method are reported and used to propose a simplified multipath reaction mechanism. The results are compared to the performance of a Zn/ZnO powder produced in a solar reactor.

Effects of Airborne Metals on Lung Function in Inner Mongolian Schoolchildren

To evaluate the effects of particles and their components on lung function. A panel study was conducted on 107 primary schoolchildren. The peak expiratory flow rate (PEFR) for each subject was measured three times a day for 40 days continuously. Particulate air concentrations were measured every day. The concentrations of Pb, Ni, Fe, Mn, Cr, As, Cd, and Zn in particles were measured. Linear mixed-effect models were used to estimate the associations between particles, metal elements, and PEFR. We found that the increase in particles in air was associated with a significant reduction in PEFR. Its effects lasted 2 to 5 days. Pb, Ni, Fe, Mn, and Cr in particles also reduced PEFR. As and Cd increased PEFR. Zn showed inconstant effects on PEFR. This study suggested that most metal components in particles have negative effects on children's lung function.

Water Assisted Conversion of ZnO from Metallic Zinc Particles

Zinc oxide (ZnO) was synthesized by solid-liquid reaction of raw Zn particles in water. The synthesized ZnO were characterized with X-ray diffraction (XRD), scanning electronic microscopy (SEM) and photoluminescence (PL) spectrophotometer. The XRD pattern confirmed that the formation of ZnO with wurtzite structure and ZnOOH crystals. The SEM study clearly exhibited a honeycomb-shaped structure of the Zn/ZnO/ZnOOH composites. Room-temperature PL spectra have been observed a very weak UV emission at 376 nm and a very strong yellow-green emission at 538 nm. Furthermore, a possible mechanism of the water-assisted conversion of ZnO from metallic Zn particles was discussed.

A novel low-cost sodium–zinc chloride battery

The sodium–metal halide (ZEBRA) batteries have been considered as one of the most attractive energy storage systems for stationary and transportation applications. Even though the battery technologies have been widely investigated for a few decades, there is still a need to further improve the battery performance, cost and safety for practical applications. In the present work, a novel low-cost Na–ZnCl2 battery with a planar β′′-Al2O3 solid electrolyte (BASE) was proposed, and its electrochemical reactions and battery performance were investigated. Compared to Na–NiCl2 chemistry, the ZnCl2-based chemistry was more complicated, in which multiple electrochemical reactions including liquid-phase formation occurred at temperatures above 253 °C. During the first stage of charge, NaCl reacted with Zn to form Na in the anode and Na2ZnCl4 in the cathode. Once all the NaCl was consumed, further charge with the reaction between Na2ZnCl4 and Zn led to the formation of a NaCl–ZnCl2 liquid phase. During the end of charge, the liquid phase reacted with Zn to produce solid ZnCl2. To identify the effect of liquid-phase formation on electrochemical performance, button cells were assembled and tested at 280 and 240 °C. At 280 °C, with the liquid phase formed during cycling, cells revealed quite stable cyclability. On the other hand, more rapid increase in polarization was observed at 240 °C where only solid-state electrochemical reactions occurred. SEM analysis indicated that the stable performance at 280 °C was due to the suppressed growth of Zn and NaCl particles, which were generated from the liquid phase during the discharge of each cycle.

Behavior and trends for Zn in Saronikos Gulf

The study of Zn in the water column of Saronikos Gulf in Greece during a two year period between 2008 and 2010 added data to the available time series of metal data for this marine area since 1985. The Saronikos Gulf, is directly influenced by the Athens metropolitan area. The operation of the Wastewater Treatment Plant of Athens situated on the small island of Psitalia, in 1995, was considered to be the turning point in the efforts of de-pollution of the gulf. Major sources of pollution for the gulf include also the port of Piraeus, with intensive navigation and shipping activities and the significant industrial activity occurring along the coast of Attica. This study of dissolved and particulate Zn gave results consistent with previous studies of the area such as the prevalence of the dissolved form of Zn and the most affected areas being the smaller most enclosed Gulf of Elefsina and Psitalia Island near the wastewater outfall. However, the concentrations of Zn were below toxic levels for marine aquatic organisms. Furthermore, a clear decrease in the Eastern part of the gulf was exhibited as well as a more subtle decrease in the gulf of Elefsina. The levels of Zn in Saronikos Gulf were found comparable to those of other Greek coastal areas.

Ultrasonication Induced Synthesis of Zn/ZnO Core-Shell Structures

Metal-semiconductor Zn/ZnO core-shell structures are fabricated by a simple ultrasonic process of raw Zn particles in water. The crystal structure, morphologies and fluorescence of the Zn/ZnO core-shell particles are characterized with X-ray diffraction (XRD), scanning electronic microscopy (SEM) and fluorescence spectrophotometer. The XRD pattern confirms that the shells of the Zn/ZnO core-shell particles are composed of Wurtzite ZnO crystals. The SEM study clearly exhibits the formation of ZnO on the surface of Zn spheres. The room-temperature fluorescence spectra have been observed a strong ultraviolet (UV)-visible emission at 381 nm and a yellow-green deep-level emission at about 534 nm. It is noted that the very broad green emission at 510 nm appears in the ZnO crystals with increasing the content of ZnO shell on the surface of Zn spheres. Furthermore, a possible formed mechanism of ZnO shells on the Zn core is discussed.

Sintering Characteristics of Micro-Zn Paste Containing Sn-3.0Ag-0.5Cu Nanoparticles

The transient liquid-phase sintering behavior of micro-Zn/nano-Sn-3.0Ag-0.5Cu (SAC) pastes was examined at a temperature of 190 °C as a function of the volume of ultrafine (~12.4 nm) SAC nanoparticles present. SAC nanoparticles have lower melting point drop than the bulk SAC particles. Although successful linkage at the interface between all Zn particles was not accomplished in all sintered samples, the number of linkages increased marginally with a decrease in the SAC content. As a result, the electrical resistivity of the sintered samples decreased with the decrease in the SAC content; however, the resistivities were still very high in all samples. Microstructural observations indicated that the observed results were mainly due to the short lifespan of the liquid phase caused by the coarsening of SAC nanoparticles during heating.

Metal removal via particulate material in a lowland river system

Twelve month surveys of acid-soluble and dissolved trace metal concentrations in the lower Waikato River (in 1998/9 and 2005/6) showed abnormally low particulate Fe, Mn, Cu, Pb and Zn concentrations and mass flux in autumn, when the suspended particulate material (SPM) had a relatively high diatom and organic carbon content, and low Fe and Al content. Dissolved Mn, Cu and Zn concentrations also decreased in autumn, while dissolved Fe and Pb concentrations were unaffected. While SPM settlement under the low river flow conditions present in autumn can explain the removal of particulate metals, it does not explain dissolved metal removal. SPM-metal interaction was therefore investigated using seasonal monitoring data, experimental adsorption studies, sequential extraction and geochemical modelling. Pb binding to SPM occurred predominantly via Fe-oxide surfaces, and could be reliably predicted using surface complexation adsorption modelling. Dissolved Mn concentrations were controlled by the solubility of Mn oxide, but enhanced removal during autumn could be attributed to uptake by diatoms. Zn and Cu were also adsorbed on Fe-oxide in the SPM, but removal from the water column in autumn appeared augmented by Zn adsorption onto Mn-oxide, and Cu adsorption onto the organic extracellular surfaces of the diatoms.

Preparation and Characterization of Antibacterial Zn-Coated High Density Polyethylene Films by Vacuum Evaporation Technology

Zn-coated HDPE films with different amount of zinc deposition were prepared via vacuum evaporation technology. AFM images showed that the size of Zn particles was decreasing evidently with the increase of the amount of Zn deposition on HDPE substrate. The Zn-coated HDPE films exhibited excellent antibacterial activity, especially for S. aureus. Compared with the HDPE film, the improvement of the barrier properties of the Zn-coated HDPE films was observed. Moreover, the barrier properties of the Zn-coated HDPE films were increasing with the elevation of the Zn content on HDPE films. The as-prepared Zn-coated HDPE films have a promising foreground applied in food packaging.

Formation of zinc oxide films using submicron zinc particle dispersions

The thermal oxidation of submicron metallic Zn particles was studied as a method to form nanostructured ZnO films. The particles used for this work were characterized by electron microscopy, x ray diffraction, and thermal analysis to evaluate the Zn-ZnO core shell structure, surface morphology, and oxidation characteristics. Significant nanostructural changes were observed for films annealed to 400 °C or higher, where nanoflakes, nanoribbons, nanoneedles, and nanorods were formed as a result of stress induced fractures arising in the ZnO outer shell due to differential thermal expansion between the metallic Zn core and the ZnO shell. Mass transport occurs through these defects due to the high vapor pressure for metallic Zn at temperatures above 230 °C, whereupon the Zn vapor rapidly oxidizes in air to form the ZnO nanostructures. The Zn particles were also incorporated into zinc indium oxide precursor solutions to form thin film transistor test structures to evaluate the potential of forming nanostructure...

Microanalysis of the Elemental Distribution in Particlesof Zn(OH)2 Obtained by Chemical Precipitation.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Optimization of magnetron deposition process for formation of high-quality oriented ZnO films

The thickness distribution and structure of ZnO films deposited by DC-magnetron sputtering of a zinc target in argon-oxygen gaseous medium at substrate temperature of 27°C and gas pressure in the chamber within 5×10−3 − 5×10−2 mm Hg was investigated. It was revealed that the use of a target with a certain depression in the sputtering zone allows depositing high quality c-oriented films at lower gas pressure than with a flat target. The dependence of film quality on geometric factors is interpreted on the basis of theoretical computations with the assumption that the film structure is improved when the flux of deposited Zn particles decreases while their energy increases.

Fabrication of zinc coatings on alumina balls from zinc powder by mechanical coating technique and the process analysis

Abstract Mechanical coating technique was used to fabricate zinc (Zn) coatings on alumina (Al 2 O 3 ) balls. The detailed evolution of the coatings was examined. The effect of the rotation speed of planetary ball mill on the evolution was investigated by experiments and modeling. The results showed that continuous and high dense Zn coatings with the average thickness of about 100 μm were formed during the milling operation at 300 rpm. To form continuous Zn coatings, a critical collision pressure corresponding to a critical minimum rotation speed was necessary to produce a critical plastic strain of Zn particles. Exponential relations between the required time to form continuous Zn coatings and the collision strength or the collision power were established. The relations showed that the required time was determined by the collision stress or the work done on Zn particles on unit area in unit time. The evolution of the coatings can fall into nucleation, formation and coalescence of discrete islands, formation and thickening of continuous coatings, and exfoliation of continuous coatings.

Interdiffusion in InSb/Zn/InSb System

Interdiffusion in Zn/InSb system has been investigated under high (0.59×106 G) and low (1 G) gravity conditions at 673, 593 and 573K, respectively. Samples annealed at 0.59×106 G, 673K for 60 hours, indicated the formation of a periodic reaction layer structure. Since such structures can be formed in solid state reactions of ternary systems [, the effect of high gravitational field and high hydrostatic pressure (approximately 3kbar) in the formation of periodic patterns was investigated. Systematic investigations at ambient pressure and low gravitational field were carried out at 593 and 573 K in sandwich geometry. SEM and EDX analysis had shown that there are different phases between the initial components. Starting from the Zn side of the specimen there is a very thin single-phase with high (about 90%) In content. Next to it is a thin two-phase layer, containing mainly 50-50% InSb and some elongated Zn particles and then there is a thick phase with the composition of Zn5In2Sb4 which is followed by a similar two-phase mixture (InSb+Zn) similar to the Zn side of the sample. Although the diffusion zone is not a well developed periodic structure, but every layer (clearly distinguishable form the others and was either a single-or multiphase layer) grows with the time.

Investigation of the properties of conductive hydrogel composite containing Zn particles

In this work, the conductive hydrogel composites containing Zn particle synthesized and their electrical and thermal properties were investigated. Polyacrylamide/Zn composites were synthesized by free radical polymerization in aqueous solution. The effect of preparation conditions such as the influence of crosslinker amount, initiator amount, Zn amount, and water absorbency on electrical conductivity of hydrogel was investigated. The effect of preparation conditions on thermal properties has been characterized using thermogravimetric analysis (TGA) method. The structures of metal-composites were evaluated by FTIR and scanning electron microscopy (SEM) methods. SEM revealed a more uniform pore size when Zn particles were used when compared with pure polyacrylamide. TGA curves showed that both hydrogels were stable upto 600°C. The Zn/polyacrylamide hydrogels have a good conductivity of 4.30 mS cm−1. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Dispersed mineralization in granitic rocks in the Dukat ore field, the Russian Northeast: Sources and relationship with epithermal gold-silver and silver-base-metal ores

The dispersed mineralization in the Late Cretaceous leucogranite of the Dukat ore field comprises melanocratic high-sulfide epidote-feldspar, pyroxene-feldspar and low-sulfide allanite-fluorite-feldspar inclusions in greisenized intrusions. The silver-base-metal mineralization is composed of pyrite, pyrrhotite, small particles of Pb, Zn, Sn, Ag, and Sb sulfides and oxides, their native species, and intermetallic compounds; the rare-metal mineralization consists of REE, Th, U, Ti, Zr, Nb, Ta, and W oxides, silicates, and aluminosilicates. The isotopic Nd, Sr, and Pb isotopic compositions and geochemical characteristics of the mineralized inclusions, rock-forming minerals of granitoids, hydrothermal minerals of preore metasomatic propylites and orebodies at the Dukat deposit show that their components have been taken from heterogeneous domains of the Paleozoic juvenile continental crust of the Siberian Platform.