Pure Zinc Powder Research Articles

Influence of zinc (Zn) powder on the microhardness characteristic and microstructure properties of stainless steel SS304 hybrid joint using low power microwave heating

AbstractMicrowave hybrid heating (MHH) process is a unique and novel approach of joint materials. Several lightweight materials (medium and high melting point) such as nickel, copper and aluminum have been successfully joined in the past research. However, small dimensions and low melting point of light weight materials such as zinc (Zn) metal or zinc (Zn) powder were always being a challenging mere for creating bond via any joining techniques. The sheets of stainless steel SS304 (17 mm×7.9 mm×0.2 mm) have been fabricated and joined at lap joint by using novel Microwave hybrid heating technique with mini heat chamber of 2.45 GHz of frequency and 200 W–360 W of microwave power, using pure zinc powder (99.9 %) as an interface material. Epoxy rate and exposure time have been varied from 10 % to 20 % and 2 min to 4 min, respectively. A developed heat chamber has been set in domestic microwave oven properly as proposed. To evaluate the microstructure correlation and microhardness at joint interface, the field emission scanning electron microscopy (FESEM – EDS), x‐ray diffraction (XRD) and Vickers hardness were used. For the experimental studies, it had found an excellent bonding was produced at interface layer between the upper and lower sections with good penetration rate of 360 W of microwave power, 4 min of exposure time and 20 % of epoxy rate as the 183.1 HV 0.05 of excellent microhardness and the intermetallic phase of iron‐zinc (FeZn11), nickel‐zinc (NiZn) and nickel‐zinc (NiZn3) were observed at interface layer.

Microstructural evolution and intermetallic formation in Zn-3Mg (wt%) powder mixture processed by high-pressure torsion

Severe plastic deformation (SPD) techniques have been used extensively over the past 40 years for producing strong metals and alloys. High-pressure torsion (HPT) is one of the most promising SPD techniques for achieving high strength through nanoscale grain refinement and phase transformation. In this research, a mixture of pure zinc (Zn) and magnesium (Mg) powders, Zn-3Mg (wt%), was HPT-processed under a pressure of 6 GPa for 1, 5, 10, 20, and 30 turns at room temperature to achieve a high strength biodegradable material. In order to understand the effects of pre-consolidation on the resulting microstructure and hardness, HPT processing was performed on loose powders placed in the die and also on a pre-compacted powder mixture and the resulting HPT disks were characterized by X-ray diffraction, scanning electron microscopy, atom probe tomography, and Vickers microhardness. In both cases, the HPT disk microstructures contained nanoscale grains, and stable and metastable strain-induced intermetallics, but an unusual softening appeared at large shear strains. Grain size, grain morphology, and the formation of different intermetallics were analyzed to explain the unusual hardness distribution, and it was found that an inverse Hall-Petch relationship between hardness and grain size exists. It is suggested that thermally-activated phenomena such as grain boundary sliding contributed to the strain-induced softening of this nano-structured biomaterial due to its low melting point. The current results are compared with those for HPT-processed cast alloys and hybrids of the same composition.

Controlled growth of Ag-ZnO thin films by thermal evaporation technique for optimized thermoelectric power generation

This manuscript is described the facile and cost-effective growth of silver Zinc Oxide (Ag-ZnO) thin films by simple thermal evaporation method for thermoelectric power generation applications. Growth of samples is started by making pellets of pure silver (Ag) and zinc (Zn) powders which are composed of 1:1 ration and evaporated in vacuum tube furnace. The other growth parameters are fixed as; evaporation time (45 min), evaporation temperature (1010 0C) and oxygen flow rate (60 sccm). Five samples are prepared at different source to substrate distances (6.5–8.5 in.) and post deposition annealing of all samples is carried out at 800 °C using semi-programable muffle furnace. Prepared thin films are analyzed using X-Ray Diffraction (XRD), Raman spectroscopy, Scanning Electron Microscope (SEM) and Seebeck measurements to study the impact of various source to substrate distances on the structural morphological and thermoelectric behavior of Ag-ZnO nanocomposite thin films. The obtained results are revealed that different source to substrate distances strongly influence the structural, morphological, and thermoelectric behavior of prepared thin films. Optimal values for electrical conductivity, Seebeck coefficient and powerful factor of synthesized thin films are calculated as 3.05 × 103 S/m, 645 µV/°C and 1.27 × 10−3 Wm−1 oC−2 respectively at source to substrate distance of 7.0 in.

STUDY TO MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Mg-Zn-Fe-Cu-Co AS HIGH ENTROPY ALLOYS FOR URETERAL IMPLANT APPLICATION

Magnesium and its alloys are promising candidates for degradable materials with good biocompatibility. Alloys based on Mg-Zn-Fe-Cu-Co compositions were designed using the equiatomic method of high entropy alloy. This paper discusses the microstructure and mechanical properties of these new high entropy alloys. Pure Magnesium (60 µm), Zinc (45 µm), Fe (10 µm), Cu (63 µm), and Co (1 µm) powder were mixed and milled using a shaker mill at 700 rpm for the 1800s. The resulting milled powders were compacted and sintered at 300 MPa for 180s and 600 MPa for 120s. Sintering was performed at 700oC for 2 hours in a tube vacuum furnace at a 5 °C/min heating rate under a high purity argon atmosphere. Microstructural analyses and mechanical tests were performed based on the American standard of testing and measurement. The alloys were basically multiphase and crystalline. The 20Mg-20Zn-20Fe-20Cu-20Co alloy consisted of the HCP phase and cubic phase. The physical and mechanical properties of Mg-Zn-Fe-Cu-Co were affected by the magnesium content in the matrix alloys. The presence of pores indicated uncomplete compaction and sintering process. The alloys have a medium hardness of between 286.06 HV - 80.98 HV, while the densities of the alloys were relatively moderate in the range of 3.057 g.cm-3 to 1.71 g.cm-3. Solid solution and intermetallic precipitation strengthening were believed the primary strengthening mechanics of the alloys. It is concluded that high entropy is a promising method for the processing of Mg alloys. Alloy with a chemical composition of 20Mg-20Zn-20Fe-20Cu-20Co had optimal mechanical properties that meet the minimum requirements of high entropy alloys as candidates for ureteral implant applications.

Effect of annealing temperature on the thermoelectric properties of ZnInO thin films grown by physical vapor deposition

This research work has been demonstrated the growth of ZnInO thin films using thermal evaporation technique for thermoelectric power generation applications. The pure zinc powder and indium metal were evaporated on the multi-crystalline Si substrate using the vacuum tube furnace. Deposited thin films were annealed at various temperatures (500–700 °C) for 30 min in a programmable muffle furnace. XRD data concluded that the sample annealed at temperature 500 °C, has a weak structure of ZnO. But as we have increased the annealing temperature, indium atoms get thermal energy from the annealing process and reacted with ZnO molecule to form ZnInO composite. The vibrational and rotational modes of the samples were studied by the Raman spectroscopic analysis and morphology of annealed samples was verified by SEM. The Seebeck coefficient data suggested that the value of Seebeck coefficient varies between (140.9–182.2) μV/oC. The maximum value of the Seebeck coefficient was obtained for the sample annealed at 600 °C because the mobility of carriers is highest at that temperature. But the value of electrical conductivity and power factor for the sample annealed at 600 °C is minimum due to low carrier concentration. Because of these conclusions, it may be suggested that this material can be a potential choice soon for thermoelectric power generation applications.

Wear Resistance Improvement of Copper Alloys Using a Thermochemically Obtained Zinc-Rich Coating

It has been developed a thermochemical process that has been applied on copper alloys: brass and bronze, using pure zinc powder, obtaining a zinc-rich wear protective coating. The layers obtained by a diffusion process, on brass (alloy C36000) and bronze specimens (alloy SAE 62), were characterized using a scanning electron microscope, EDAX microanalysis, Vickers microhardness, X-Ray diffraction analysis, and sliding wear test. The chemical analysis showed a layer composition of 62 % Zn and 38 % Cu, on average. The microhardness for thermochemical treated brass was 496HV and 598HV for bronze; thus, a microhardness increase for brass is 468% and 532% for bronze. It was made an X-Ray diffraction analysis, confirming the results obtained with the chemical analysis and crystalline structure for coating. It showed the presence of Cu64Zn36 and Cu5Zn8 phases. The wear tests demonstrated that treated specimens show better wear resistance than non-protected specimens.

Wear Resistance Improvement of Copper Alloys Using a Thermochemically Obtained Zinc-Rich Coating

It has been developed a thermochemical process that has been applied on copper alloys: brass and bronze, using pure zinc powder, obtaining a zinc-rich wear protective coating. The layers obtained by a diffusion process, on brass (alloy C36000) and bronze specimens (alloy SAE 62), were characterized using a scanning electron microscope, EDAX microanalysis, Vickers microhardness, X-Ray diffraction analysis, and sliding wear test. The chemical analysis showed a layer composition of 62 % Zn and 38 % Cu, on average. The microhardness for thermochemical treated brass was 496HV and 598HV for bronze; thus, a microhardness increase for brass is 468% and 532% for bronze. It was made an X-Ray diffraction analysis, confirming the results obtained with the chemical analysis and crystalline structure for coating. It showed the presence of Cu64Zn36 and Cu5Zn8 phases. The wear tests demonstrated that treated specimens show better wear resistance than non-protected specimens.

Preparation and Electrochemical Properties of Zinc Electrode for Alkaline Manganese Batteries Containing Ultrafine Zinc Powders

Submicron spherical zinc powders with high surface area, activity and low cost were prepared by DC arc plasma evaporation method. Based on the characterization of morphology, particle size and composition of ultrafine zinc powder, the effects of addition amount of PTFE and compounding of PTFE with PAAs and CMCs, electrolyte addition amount, compound mass ratio of flake and spherical zinc powder on the discharge performance of zinc electrode had been systematically studied. The results showed that ultrafine zinc powder was polycrystalline, spherical and its purity reached 99.96wt%. Under 0.2C, the discharge capacity reached 577.5mAh when addition of PTFE was 10wt.%. When 2.5wt.% PTFE was compound with 6.5wt.%(PAAs: CMCs = 2:1), the discharge capacity improved which reached 613.4 mAh. The discharge capacity was 580.3mAh when the electrolyte content was 38wt.%. When the mass ratio of special flake zinc powder to spherical zinc powder was 3:7, the discharge capacity reached 664.1 mAh, it was 13.5% higher than 584.9 mAh of pure spherical zinc powder and 22.6% higher than 541.5 mAh of pure flake zinc powder. Under 1.8C, compared with alkaline manganese battery prepared using flake zinc powders, the mass specific capacity increased by 57.12% and the volume specific capacity increased by 187.79%.

Evolution of Thermoelectric Properties of Zn4Sb3 Prepared by Mechanical Alloying and Different Consolidation Routes

In this research, a method combining the mechanical alloying with the vacuum sintering or hot pressing was adopted to obtain the compact of β-Zn4Sb3. Pure zinc and antimony powders were used as the starting material for mechanical alloying. These powders were mixed in the stoichiometry ratio of 4 to 3, or more Zn-rich. Single phase Zn4Sb3 was produced using a nominally 0.6 at. % Zn rich powder. Thermoelectric Zn4Sb3 bulk specimens have been fabricated by vacuum sintering or hot pressing of mechanically alloyed powders at various temperatures from 373 to 673 K. For the bulk specimens sintering at high temperature, phase transformation of β-Zn4Sb3 to ZnSb and Sb was observed due to Zn vaporization. However, single-phase Zn4Sb3 bulk specimens with 97.87% of theoretical density were successfully produced by vacuum hot pressing at 473 K. Electric resistivity, Seebeck coefficient, and thermal conductivity were evaluated for the hot pressed specimens from room temperature to 673 K. The results indicate that the Zn4Sb3 shows an intrinsic p-type behavior. The increase of Zn4Sb3 phase ratio can increase Seebeck coefficient but decrease electric conductivity. The maximum power factor and figure of merit (ZT) value were 1.31 × 10−3 W/mK2 and 0.81 at 600 K, respectively. The ZT value was lower than that reported in the available data for materials prepared by conventional melt growth and hot pressed methods, but higher than the samples fabricated by vacuum melting and heat treatment techniques.

Zinc Extraction from Zinc Plants Residue Using Selective Alkaline Leaching and Electrowinning

Annually, a great amount of zinc plants residue is produced in Iran. One of them is hot filter cake (known as HFC) which can be used as a secondary resource of zinc, cobalt and manganese. Unfortunately, despite its heavy metal content, the HFC is not treated. For the first time, zinc was selectively leached from HFC employing alkaline leaching. Secondly, leaching was optimized to achieve maximum recovery using this method. Effects of factors like NaOH concentration (C = 3, 5, 7 and 9 M), temperature (T = 50, 70, 90 and 105 °C), solid/liquid ratio (weight/volume, S/L = 1/10 and 1/5 W/V) and stirring speed (R = 500 and 800 rpm) were studied on HFC leaching. L16 orthogonal array (OA, two factors in four levels and two factors in two levels) was applied to determine the optimum condition and the most significant factor affecting the overall zinc extraction. As a result, maximum zinc extraction was 83.4 %. Afterwards, a rough test was conducted for zinc electrowinning from alkaline solution according to the common condition available in literature by which pure zinc powder (99.96 %) was successfully obtained.

One-step synthesis and excellent microwave absorption of hierarchical tree-like ZnO nanostructures

A large area of uniform and intriguing ZnO hierarchical tree-like nanostructures have been synthesized by a simple one-step chemical vapor deposition(CVD) process using pure zinc powder and O2 gas as source materials. ZnO nanowires grow on the silicon substrate while the reactions take place, and then regular nanorods grow uniformly on the ZnO nanowires to form tree-like nanostructures by increasing the flow rate of O2 only. Microwave absorption properties of the ZnO nanostructures have been investigated, the value of minimum reflection loss for the composite with 40vol% ZnO hierarchical tree-like nanostructures is −27.5dB at 5GHz with a thickness of 4.0mm.

Mechanisms of 1D Crystal Growth in Chemical Vapor Deposition: ZnO Nanowires

Abstract. ZnO nanowires synthesis throught oxidative evaporation of pure zinc powder without catalyst is studied in detail to understand the nucleation and growth mechanisms involved with the so-called “self-catalysis” schemes. The structural features associated with different growth stages were monitored using scanning electron microscopy (SEM), describe the direct observation of the nucleation and growth process. X-ray diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDS) demonstrate that the as-obtained sample can be indexed to high crystallinity with wurtzite structure and only contain Zn and O without the presence of any impurities.

Synthesis and characterisation of three-dimensional dendritic ZnO nanorods

Intriguing ZnO three-dimensional (3D) dendritic nanorods on silicon substrates have been successfully synthesised by thermal evaporation of pure zinc powder at a relative low temperature of 478°C without any metal catalyst. ZnO dendritic nanostructure exhibits unique shape and it is composed of stems and nanorod branches. It is found that the nanorods are single crystalline wurtzite structures, and each nanorod grows along the [0001] direction. At different growth temperatures, the shapes of ZnO nanostructures can be altered. System analysis reveals that the formation and morphology of ZnO dendritic nanostructures are sensitive to the growth temperature. Finally, room temperature photoluminescence spectrum is also investigated, revealing that the ZnO dendritic nanostructure could find application in UV optoelectronic devices; the nanostructure implies some potential applications for nanoscale functional devices.

Triple assembly of ZnO, large-scale hollow spherical shells with flower-like species consisting of rods grown on the outer surfaces of shells

Novel large-scale hollow ZnO spherical shells were synthesized by ionic liquids assisted hydrothermal oxidization of pure zinc powder without any catalyst at a relatively low temperature of 160 °C. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) patterns show that the shells are composed of ZnO and the structure of the shells is very unique. Textured flower-like ZnO consisting of ZnO rods is grown on the outer surfaces of shells forming a triple assembly. Room-temperature photoluminescence spectra of the oxidized material show a sharp peak at 379 nm and a wider broad peak centered at 498 nm. The possible growth mechanism of the triple assembly of ZnO is discussed in detail.

Growth and photocatalytic properties of one-dimensional ZnO nanostructures prepared by thermal evaporation

Aligned ZnO nanorods and nanotubes were grown on the silicon substrates by thermal evaporation of high pure zinc powders without any other metal catalyst. The morphology evolution of ZnO nanostructures with prolonged growth time suggested that the growth of the ZnO nanorods and nanotubes follows the vapor–liquid–solid mechanism. ZnO nanoneedle and nanoparticle films were also synthesized by the same way, and their photocatalytic performances were tested for the degradation of organic dye methylene blue. The ZnO nanoneedle films exhibited very high photocatalytic activities. The decomposition kinetics of the organic pollutant was discussed. Moreover, it is found that the ZnO nanoneedle films showed very stable photocatalytic activity.

Substrate Dependent Morphologies and Luminescence Properties of ZnO Nanostructures Prepared by Thermal Evaporation

High density ZnO nanostructures were fabricated on Au coated Si and quartz substrates through once and the same oxidative evaporation of pure zinc powder. The coated side of the substrate was intentionally positioned in two directions of face and back to the zinc sources. Structure, morphology and optical properties of the samples were investigated by scanning electron microscopy, X-ray diffraction, Raman spectra and room temperature photoluminescence measurements. The results showed that the samples on the different substrates with different directions have three different morphologies, including film-, rod- and comb-like nanostructures. Photoluminescence spectra of the samples showed the various bands centered in UV (380-390 nm), blue (470-490 nm), green (500-550 nm) and orange (610-620 nm) region. It demonstrates that the substrate material and the direction of substrate significantly affect the growth of ZnO nanostructures.

Morphology-controlled synthesis, growth mechanism, optical and microwave absorption properties of ZnO nanocombs

ZnO nanocombs and nanorods with different morphologies have been successfully synthesized through a simple metal vapour deposition route at 600–750 °C using pure zinc powder or zinc and graphite powders as source materials. The structures and morphologies of the products were characterized in detail by using x-ray diffraction, scanning electron microscopy, transmission electron microscopy and laser Raman spectrometer. The morphologies of the products can be easily controlled by tuning the following four factors: reaction temperature, the distance between the source and the substrates, the kinds of substrates and the kinds of precursors. Possible growth mechanisms for the formation of ZnO nanostructures with different morphologies are discussed. Photoluminescence studies show that there are sharp UV and broad defect-related green emissions for all products. Relative intensity of the UV to defect-related green emissions decreases from ZnO nanorods to nanocombs. Microwave absorption properties of these nanocombs are also investigated. The value of the minimum reflection loss is −12 dB at 11 GHz for the ZnO nanocomb composite with a thickness of 2.5 mm.

Thermoelectric Properties of ß-Zn4Sb3 Synthesized by Mechanical Alloying and Pulse Discharge Sintering

Thermoelectric power generation is a helpful method for harnessing waste thermal energy, particularly covering a middle temperature range between 500 and 800 K. A β-Zn 4 Sb 3 compound has become the focus of attention as a thermoelectric material applicable to thermoelectric power generation around 700 K. In this research, a method combining the mechanical alloying with the pulse discharge sintering was adopted to obtain the sintered compact of β-Zn 4 Sb 3 . Pure zinc and antimony powders were used as the starting material for mechanical alloying. These powders were mixed in the stoichiometry ratio of 4 to 3, or more Zn-rich. The mechanical alloying was carried out by planetary ball milling under conditions of fixed revolution speed and variable milling time. The influence of the milling time on the synthesis of β-Zn 4 Sb 3 was investigated. The sintering was executed at two sintering temperatures and under fixed conditions of sintering time, pressing pressure, and atmosphere. The influences of the sintering temperature of pulse discharge sintering on the polycrystalline grain size and the thermoelectric properties were also studied. The following results were clarified. The phases of ZnSb and Zn are easily obtained by mechanical alloying for 50 h or longer time. These phases change to a single phase of β-Zn 4 Sb 3 through pulse discharge sintering under the optimum condition of Zn-rich mixing. The sintered compact of β-Zn 4 Sb 3 with 1.17 of nondimensional figure of merit can be obtained at 673 K with the proposed mechanical alloying with pulse discharge sintering method.

Disc-Capped ZnO Nanocombs

Nanocombs with a disc cap structure of ZnO have been synthesized on Si substrates by using pure Zinc powders as the source materials based on a vapour-phase transport process. The morphology and the microstructure are investigated by a scanning electron microscopy and x-ray diffraction. Based on the transmission electron microscopy and selected area electron diffraction analysis, the growth directions of three representative parts, nanoribbon stem, nanorod branch and nanodisc cap of the nanocomb are revealed. The growth mechanism of the disc-capped nanocombs is discussed based on the self-catalyzed vapour-liquid-solid process.

Growth of amorphous SiO2 nano-wires on pre-oxidized silicon substrate via chemical vapor deposition

Without an additional silicon source, amorphous SiO2 nano-wires were grown on the pre-oxidized silicon substrate with the assistance of Ni-based catalyst under ambient pressure. The as-grown amorphous SiO2 nano-wires were characterized by X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy (HRTEM) and selected area diffraction. The micro-region chemical composition investigation on the as-grown amorphous SiO2 nano-wires was carried out using X-ray energy dispersion spectroscopy (EDS) on the HRTEM. The present work focuses on the formation of atomic H on the surface of pure zinc powder by introducing moisture (N2+H2O) into the furnace at high temperature. The growth mechanism has been discussed and attributed to the vapor–liquid–solid (VLS) mechanism instead of the adopted solid–liquid–solid (SLS) mechanism owing to the observed evidence of an etching reaction of atomic H at the SiO2 buffer layer and/or that of H at the Si substrate to form a gaseous hydro-silicon radical (SiHx) that is then transported to the growth sites. The intrinsic luminescent behavior of the amorphous SiO2 nano-wires in the range of 350–430nm was also reported and discussed. These results provide an alternative and simple procedure for nanostructures growth, which will be helpful to understand the growth mechanism of one dimensional SiO2 nanostructures.