Zinc Vapor Research Articles

Prediction of zinc evaporation in the snout of high-temperature hot-dip zinc-aluminum-magnesium coating line

The internal flow field of snout affects the quality of hot-dip zinc products significantly. The prediction of zinc evaporation is a key issue of analyzing the atmosphere flow in the snout. In this paper, simulations of the atmosphere flow with zinc evaporation considered are carried out in the snout of a high temperature hot-dip zinc-aluminum-magnesium coating line. In order to eliminate the false diffusion in numerical calculation of zinc evaporation, a strategy of high-order scheme combined with local orthogonal grids at the zinc vaporization boundary is proposed. The simulation is validated by available experimental data. The effects of operation parameters such as the temperature of snout wall, the width and the speed of the strip on the zinc vapor flow are studied. It is found that with the increased temperature gradient between the snout wall and strip wall, the concentration of zinc vapor in the snout is also increased. Therefore, the method of heating the snout wall can reduce the temperature gradient between the snout wall and strip wall, so it is beneficial to reduce the evaporation of zinc liquid in the snout.

Zinc Vaporization Induced Formation of Desired Ni Nanoparticles Coated with Ultrathin Carbon Shells for Efficient Electrocatalytic H2 Production Coupling with Methanol Upgrading.

The integration of the hydrogen evolution reaction (HER) with the methanol oxidation reaction (MOR) has been demonstrated to be a viable strategy for the energy-saving generation of H2 and value-added formate, which relies primarily on highly active and cost-effective bifunctional electrocatalysts. Herein, an efficient electrocatalyst consisting of controllable Ni nanoparticles (NPs) coated with ultrathin graphitic carbon shells was obtained by the pyrolysis of a Ni-Zn metal-organic framework. Intriguingly, we found that zinc vaporization not only resulted in the relatively small Ni NPs but also ultrathin carbon shells (≤3 layers). The density functional theory simulations confirmed that these ultrathin carbon shells significantly influenced electrocatalytic activity by facilitating electron transfer from the Ni core to the carbon shell. The optimized Ni1(Zn)@C demonstrated high catalytic activity for both HER and MOR, and only a low potential of 97 mV at 10 mA cm-2 was required for HER and 1.48 V at 30 mA cm-2 for MOR. In a two-electrode electrocatalytic cell measurement, a cell voltage of 1.63 V was observed at 10 mA cm-2 in the presence of methanol, 240 mV lower than that without methanol.

An Experimental Study of Zinc Evaporation from Bottom Zinc Dross at Atmospheric Pressure and in Inert Atmosphere with Integrated CFD Modelling.

In the present study, the recycling process of bottom zinc dross was performed by evaporation and subsequent condensation at 800 °C for 30 min with an observed argon flow rate of 100-400 mL/min to ensure an inert atmosphere, to observe the evaporation rate and final form of the product. Under the set conditions of over 98% zinc purity, products in the form of nanofibres (thickness 500 nm), powder (size of spherical particles 2-5 μm), dendrites, and metallic forms were obtained. The employed mathematical modelling (via Ansys 2023R1 software) predicted the behaviour of the argon flow current in the quartz tube, as well as the temperature gradient in the quartz tube and in the close vicinity of the zinc sample. Via Inventor 2014 software, the rate of zinc sample heating was calculated. All the simulations were compared with the physical measurements and correlation was proven.

Numerical study of gas-solid two-phase flow in the snout of continuous hot-dip galvanizing process

In the hot-dip galvanizing process for strip steel, zinc vapor oxidizes and forms zinc ash in the snout. Given that the snout connects the annealing furnace, the zinc ash will return to the annealing furnace with the gas, affecting the upstream process. The gas-solid two-phase flow regularity in the snout is the key issue for zinc ash control. In this paper, the snout of a hot-dip galvanizing production line was taken as the physical model. The two-phase flow was simulated by the Euler-Lagrange method and the zinc ash particles were simulated via the discrete phase model (DPM). The results show that several vortex regions exist in the snout due to the forced convection caused by the moving strip and changes in flow channel sizes. There exist differences in the movement of zinc ash with different diameters. Small zinc ash has a strong tracking performance with the gas. Large zinc ash is easy to remain in the snout. In addition, orthogonal analysis was conducted to determine the optimal parameter combination. The research results provide theoretical guidance for the operation scheme of the gas circulation system.

Experiments to Improve the Efficiency of Obtaining Brass Nanoparticles by Evaporation by a Continuous Beam of High-Energy Electrons

Composite, copper and zinc containing nanoparticles and brass nanoparticles have been obtained by a high-performance method of evaporation of substances by a relativistic electron beam. The change in the stoichiometry of nanopowders produced by stepwise irradiation of a brass ingot placed in a single-zone graphite crucible is considered. It was found that the production of such particles depends on the concentration of saturated vapors of zinc and copper. A two-zone configuration of the crucible has been developed, which makes it possible to realize the simultaneous evaporation of the constituent components, thereby providing the conditions for the formation of uniform brass nanoparticles with a uniform distribution of elements and a high yield of nanopowder. X-ray diffraction analysis (XRD), Transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDX) were carried out, and the specific surface of the obtained nanoparticles was determined. The mechanism of formation of composite nanoparticles is discussed.

Deep penetration welding of brass with subsequent wire filling process by laser beam with combined core and ring beam

Brass is an important copper alloy and plays a crucial role in component production. Laser welding of brass offers promise for high-quality seams and productivity. Challenges include irregular surfaces, pores, and spatters due to melt pool and keyhole instabilities, intensified by zinc evaporation. Smooth surfaces are crucial for aesthetic applications, requiring solutions to address welding challenges and ensure optimal outcomes in various industrial contexts. Recent advancements in high-brilliance near-infrared laser beams with adjustable profiles aim to stabilize welding processes.This study focuses on the welding of CuZn37 (508L) brass alloy using a 6000 W laser beam with a core and ring profile. High-quality deep penetration welds are for 2 mm thickness are shown with a subsequent wire filling process to address underfills. By feeding a brass wire into the seam and melting it with the laser beam, parameters are identified to produce smooth, pore-free welds with reinforcement and strong bonding.

Investigating impact of zinc vapor jet on keyhole dynamics and liquid ejection from molten pool during remote laser welding of zinc-coated steel in zero-gap lap joint configuration

When Zn-coated steels are laser welded in a zero part-to-part gap lap joint configuration, highly pressurised Zn vapors are readily produced, generating spatters in the weld. The best practice is to set a non-zero gap to facilitate vapor degassing; however, this necessitates additional operations, escalating production costs. This paper aims to investigate the keyhole dynamics and the ejections from the molten pool due to the interaction between high-pressure Zn vapors and the liquid metal, during remote laser welding of Zn-coated DX57D+Z steel sheets at zero nominal part-to-part gap in lap joint configuration. This is achieved by complementing experimental trials with multi-physics Computational Fluid Dynamics (CFD) simulations. The findings showed that the interplay between heat-affected zone, Zn evaporation zone, size/shape of the laser beam are critical factors for controlling the effect of Zn vapors jet on keyhole stability and liquid ejections. Opportunities for laser beam shaping are discussed throughout the paper.

Reduction of zinc and iron in dust removal ash by H2 generated from lignite pyrolysis

The article describes a process based on the hydrogen recovery of dust removal ash from lignite pyrolysis. The high volatile components in lignite will produce a large amount of H2 during the pyrolysis process, which can replace part of C to reduce zinc and iron oxides in dust removal ash, thereby achieving the goal of reducing carbon consumption. Two methods were used to study the different pyrolysis behaviors of lignite, and it was found that the peak of H2 release was reached at 700 °C. After 1000 °C, the pyrolysis of lignite basically ended, and the final pyrolysis gases were mainly H2, CO, CO2, CH4, and a small amount of CxHy. In addition, the proportion of H2 generated by the full pyrolysis of lignite at 1000 °C in H2–H2O is 84.4 %, and the proportion of CO in the CO–CO2 system is 74 %, which can meet the reduction of zinc and iron oxides in dust removal ash. Based on the principle of minimum free energy and laboratory experiments, zinc oxide is completely reduced to zinc vapor above 906 °C, while the Fe obtained from iron oxide reduction increases with the increase of H2/CO in the system above 810 °C, further confirming the feasibility of this process. The effects of temperature, lignite added amount and holding time on iron reduction and zinc volatilization during the reduction process of dust removal ash was investigated. The results indicate that due to the fast diffusion rate of H2, the reaction rate is greatly increased, which can quickly increase the metallization rate of dust removal ash to over 95 % and the dezincification rate also increases from 19.60 % to about 98.76 % with the increase of carbon content under low temperature (1000 °C) and low carbon content (10 wt %) conditions.

Phase and formation mechanism of the brittle layer of ASC castable in blast furnace hearth

An Al2O3-SiC C castable BF was dissected and investigated in the present work. The phase composition and microstructure of the brittle layer of castable and the original castable after service were analyzed by XRD, chemical analysis, and SEM-EDS. The results show that a brittle layer of castable with a thickness of about 50–300 mm is found at the bonding surface between the carbon brick and castable on the sidewall of the hearth. Zn enrichment was found in the brittle layer of castable. In the high-temperature environment of the furnace sidewall, the evaporation of water and formation of mullite phase in the process of phase transformation at high-temperature lead to the formation of pores and microcracks in the castable. Stress concentration in the joint area of the castable and carbon brick was produced due to their different expansion coefficient, and the microcracks in the castable gradually develop and expand under the action of thermal stress. In addition, the diffusion of CO, alkali metal steam, and Zinc vapor in the blast furnace hearth and the expansion caused by the reaction product with the original phase of castable accelerated the propagation of microcracks in castable and finally formed the macro-brittle layer.

Zinc Evaporation from Brass Scraps in the Atmosphere of Inert Gas.

A description of the process of metal evaporation from liquid alloys at an atmospheric pressure has a practical value for both the smelting and remelting of their scraps. The quantities of volatile components that are eliminated in these processes depend on many factors of which the type of melting device, the method and conditions of the process performance, the alloy composition and the kind of applied atmosphere are of the greatest importance. In this paper, the results of the research on zinc evaporation from brass scraps containing 10.53 wt% Zn are presented. The experiments were conducted using the thermogravimetric method at 1080 ÷ 1240 °C in a helium atmosphere. In the research, the levels of zinc removal from copper ranged between 82% and 99%. The values of the overall mass transfer coefficient for zinc kZn, determined based on the experimental data, ranged from 4.74 to 8.46 × 10-5 ms-1. The kinetic analysis showed that the rate of the analysed process was determined by mass transfer in the gas phase.

Self-Templated Formation of Carbon Nanotubes Interpenetrating Ordered Microporous Carbon Nanospheres for High-Performance Li-S Batteries.

Lithium-sulfur (Li-S) batteries are known as a prospective new generation of battery systems owing to their high energy density, low cost, non-toxicity, and environmental friendliness. Nevertheless, several issues remain in the practical application of Li-S batteries, such as low sulfur usage, poor rate performance, and poor cycle stability. Ordered microporous carbon materials and carbon nanotubes (CNTs) can effectively limit the diffusion of polysulfides (LiPSs) and have high electrical conductivity, respectively. Here, inspired by the evaporation of zinc at high temperatures, we constructed CNTs interpenetrating ordered microporous carbon nanospheres (CNTs/OMC NSs) by high-temperature calcination and used them as a sulfur host material. With the benefit from the excellent electrical conductivity of CNTs and OMC achieving uniform sulfur dispersion and effectively limiting LiPS dissolution, the S@CNTs/OMC NS cathodes show outstanding cycling stability (initial discharge capacity of 879 mAh g-1 at 0.5 C, maintained at 629 mAh g-1 for 500 cycles) and excellent rate performance (521 mAh g-1 at 5.0 C). Furthermore, the current study can serve as a significant reference for the synthesis of CNTs that interpenetrate various materials.

High yielded Co–C derived from polyester-Cobalt carbothermal reduction for efficient activation of peroxymonosulfate to degrade levofloxacin

A kind of high yield and recyclable Cobalt–Carbon composite (Zn1Co5/PnC) was prepared by carbothermal reduction process, in which the cobalt acetate and zinc acetate were considered as Zn and Co precursors, and the polyester waste was evolved as the carbon precursor. The morphology, structure and composition of the composite were characterized using scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Results showed that evaporation of zinc contributed to the formation of porous carbon structure, and the Co nanoparticles were wrapped and protected by the porous carbon matrix. The Zn1Co5/PnC activated peroxymonosulfate (PMS) system (Zn1Co5/PnC/PMS) was constructed to degrade the levofloxacin (LEV). The activity and mechanism of LEV degradation was understood. The LEV degradation efficiency was high to 96.60% within 90 min in the presence of Zn1Co5/P4C. Moreover, the Zn1Co5/P4C still maintained favorable PMS activation performance after five-cycle runs. The results show that the Zn1Co5/P4C played positive role in activating the PMS, it may be due to the facts that the polyester derived carbon could supported the Co while the evaporated Zn could increase the surface area of Zn1Co5/P4C, leading to the increased activity. The possible degradation pathways were proposed by identifying the intermediate products through liquid chromatography-mass spectrometry analysis. This study put forward a promising method to use polyester waste to synthesize high yield cobalt-carbon composite for degrading the antibiotic in wastewater.

Ni, Zn Co-doping ZIF-67-derived electrocatalyst based on CNT film for efficient overall water splitting

Water electrolysis has been acknowledged as a renewable, scalable, and effective way of producing hydrogen. However, for water splitting, efficient and noble metal-free electrocatalysts were lacking. Here, a Co–Ni–Zn porous three-dimension N-doped carbonization structure on the carbon nanotube film (CNTF) was synthesized through a metal organic frameworks (MOFs) annealing procedure. The porous morphology, caused by the evaporation of zinc at high temperatures, enhances the interaction between the catalysts and electrolyte, and the self-supporting structure minimizes the contact resistance between the catalysts and the substrate, which reduces obstructions during current flow. More active sites, multiple mesopores, and high conductivity are all features of this composite structure. It can achieve a small overpotential of 112 mV and 270 mV at a current density of 10 mA cm−2, respectively, for hydrogen and oxygen evolution reactions (HER and OER). At a current density of 10 mA cm−2, the Co–Ni–Zn/NCNTF has an external voltage of 1.58 V and is very durable for overall water splitting.

Characterization of galvanized steel-low alloy steel arc stud welded joint

This paper investigates the possibility of successfully welding a Low Alloy Steel (LAS) stud to Galvanized Steel (GS) plate.Arc Stud Welding (ASW) was performed on joining LAS studs to GS plates. Welding parameters were selected based on weld trails. The first tests of the welded joints were based on visual inspection for welding defects such as lack of fusion and undercut welding defects. The good quality should be free of these defects and have full weld reinforcement. Other weld qualifications included torque strength test, microhardness test, and microstructure examination.The LAS studs have been successfully welded to a galvanized steel plate using the arc stud welding process. Higher welding current with adjusted welding time (800 A, 0.3 s) gave full weld reinforcement, the best joint appearance, and strength. Martensite phase was detected in the weld area and heat affected zone (HAZ), affecting the joint mechanical properties. Hardness property varied across the welded joint, and maximum hardness was recorded at the HAZ at the stud side. Hardness increased with the increasing welding current. At 800 A, welding current hardness was 10% higher than at 400 and 600 A. Torque strength was affected by weld reinforcement, and 800 A gave the best weld reinforcement that produced the highest torque strength.The main research limitation is the difficulty of welding LAS studs and GS plates. In conventional welding methods, such as gas metal arc welding, it is hard to get full weld penetration due to the geometry restrictions of the joint, which results in partial weld penetration between the studs and the plates. Furthermore, the issue of zinc evaporation during welding can be reduced by the advantage of the very high welding speed (in milliseconds) of ASW that overcomes the problem of continuous welding that usually results in the formation of harmful porosities and poor weldability.In this research, galvanized steel plates were successfully welded to LAS studs using the ASW process. The welding parameters for this dissimilar welding joint were carefully selected. Microstructure changing due to the welding process was investigated. The joint mechanical properties were evaluated.

Zinc ash deposition pattern and structural optimization in the continuous hot-dip galvanizing vertical furnace

In a continuous hot-dip galvanizing vertical furnace for strip steel, zinc vapor oxidizes in the snout of the furnace to form zinc ash. The zinc ash adheres and agglomerates on the inner walls of the snout. If the zinc ash falls off and adheres to the surface of the strip, zinc ash defects will be formed, thereby affecting the surface quality of the galvanized layer. Given that the snout connects the annealing furnace and the zinc pot, the zinc ash will be transported into the annealing furnace and form nodulation on the roller, affecting the normal operation of the equipment. To study the deposition pattern of zinc ash inside the snout, a model of particle movement and deposition is established in this work to predict the movement and deposition characteristics of zinc ash particles, and it is verified by literature. On this basis, the zinc ash deposition patterns of three improvement cases of snout structure are compared. Results show that all three improvement schemes can effectively reduce the deposition rate of the zinc ash particles in the annealing furnace. In the case of slotted-baffle-added-only, although adding slotted baffles reduces the deposition of zinc ash in the furnace, it also increases the deposition rate in the snout and entry sections. In the case of exhaust-duct-added-only, the addition of the exhaust duct not only reduces the overall deposition rate in the furnace, but also effectively reduces the deposition rate in the snout and the entry section. By contrast, the scheme with slotted baffles and exhaust ducts is the most effective in inhibiting the diffusion of zinc ash.

Effect of ZnO on sintering and microwave dielectric properties of 0.5CaTiO3-0.5 (Li0.5La0.5) TiO3 ceramics

The novel calcium titanate-lithium lanthanum titanate doped with zinc oxide (0.10, 0.30, and 0.50 mol. %) ceramic samples were prepared by solid-state reaction route. The phase formation, microstructure, densification, and microwave dielectric properties were investigated. It was found that the doping with zinc oxide led to a decrease in sintering temperature by 25 oC as compared with pure calcium titanate lithium lanthanum titanate due to the liquid phase effect. Also, the calcium titanate lithium lanthanum titanate (10ZCTLLT&30ZCTLLT)) doped with lower zinc oxide (0.10 and 0.30 mol. %) led to higher densification parameter. This was followed by increasing the zinc oxide doping up to (0.50 mol. %) which resulted in a decrease in densification and microwave dielectric properties which may be attributed to increase in porosity and grain growth upon the evaporation of zinc and oxygen vacancy. This led to the increase in dielectric loss (≈10 × 10−4) value with 50ZCTLLT. Hence, the best result of microwave dielectric characteristics was obtained for 0.5CaTiO3–0.5(Li0.5La0.5)TiO3 with (0.10 and 0.30 mol. % ZnO) 10ZCTLLT and 30ZCTLLT ceramic samples sintered at 1175 oC/2h, with low dielectric constant (εr) = 4.4–10.5, very low dielectric loss = 1.07-2.23 × 10−4 and high quality factor (Q x ƒ) ≈59-55 × 104 at 8 GHz. Consequently, they can be used not only in wireless satellite communications technology but also can be used in the fifth-generation telecommunication 5G technology construction.

Photoconductivity of gamma-irradiated Znse (Te)/ZnO:O and ZnSe(Te)/ZnO:O,Zn nanogeterojuctions

Possibility of enhancing the photoconductivity of ZnSe (0.2%Те)/ZnO:O nanoheterojunction was investigated under effect of thermo-treatment in zinc vapor followed by 60Сo gamma-irradiation in air to the dose of 106 Gy by means of generation of impurity-defect complexes. The obtained ZnSe (0.2%Te)/ZnO:O,Zn nanoheterojunction had an electron conductivity with the activation energy 0.33 eV that is caused by thermo-stimulated transfer of charge carriers on the stable resonance level Γ6v= 5.76 eV in the conducting band. The significant photoconductivity growth from 10-10 to 10-5 Ω-1 was achieved at 300 K, and also a broad band (480-1100 nm) light scattering at free carriers occurred due to formation of additional stable associates (OSe0TeSe0VZn-), (OSe0VZn-)- or (OSe0VZnMeZnIIIZni) at the interface between the matrix crystal p-ZnSe(0.2%Te):O,Zn and nanocrystallite n-ZnO of 40 nm size, where amorphous phase layer of 1.2 nm was also grown.

Theoretical and Practical Evaluation of the Feasibility of Zinc Evaporation from the Bottom Zinc Dross as a Valuable Secondary Material

This study presents a theoretical and practical evaluation of zinc evaporation from bottom zinc dross (hard zinc) as a secondary zinc source (zinc content approximately 94-97%), which originates in the batch hot-dip galvanizing process. The thermodynamics of the zinc evaporation process were studied under the normal pressure (100 kPa) in the inert atmosphere, using argon with flow rate 90 mL/min. Samples were subjected to the evaporation process for 5, 10 and 20 min under the temperature of 700 °C and 800 °C, respectively. For the theoretical thermodynamic study, HSC Chemistry 6.1 software was used and final products, as well as residuals after the evaporation process, were analyzed by SEM (Scanning Electron Microscopy) and EDX (Energy Dispersive X-ray). Calculated and experimental argon consumption in the process of zinc evaporation has been compared. A high purity zinc with efficiency over 99% was reached. Due to a dynamic regime, argon consumption at the temperature of 700 °C and 800 °C were 7 times and 3 times, respectively, less than calculated.

Polymer infiltration synthesis of inorganic nanoporous coatings: Does polymer template affect their properties?

Synthesis of all-inorganic metal oxide architectures using polymer templates offers control over their thickness, porosity, and composition. Here, we provide insights into the synthesis of nanoporous zinc oxide films as a model system via infiltration of polymers that have different mechanisms of interaction with metal oxide precursors such as a polymer of intrinsic microporosity (PIM-1) and representative of the block-copolymers family (polystyrene-polyvinyl pyridine block copolymer). We investigated polymer infiltration process with both gas (diethyl zinc, DEZ, and water vapors) and solution (zinc acetylacetonate, Zn(acac)2, dissolved in ethanol) phase precursors. Using quartz crystal microbalance (QCM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) analyses, we systematically studied the effect of polymer template and the form of the metal oxide precursors on the properties of synthesized metal oxide thin coatings. We demonstrate that the infiltration of polymer templates can be efficiently achieved using both gas phase and solution phase precursors. We show that the crystallinity of the synthesized 200 nm ZnO films is mainly affected by the state of the precursor (gas or solution phase) and does not depend on the polymer template type. In turn, the polymer type affects the surface termination of ZnO films. We demonstrate that the surface of porous ZnO coatings synthesized with BCP (here PS-P4VP) is more accessible than the surface of ZnO synthesized with PIM; however, despite the lower surface accessibility for ethanol molecules, ZnO synthesized via infiltration of PIM-1 with solution-phase precursors demonstrates the largest change in resistivity upon its exposure to ethanol vapor at room temperature.

Autogenous and Tunable CNTs for Enhanced Polarization and Conduction Loss Enabling Sea Urchin-Like Co3ZnC/Co/C Composites with Excellent Microwave Absorption Performance.

ZIF-67-derived magnetic metal/carbon composites are considered prospective candidates for use as microwave absorption (MA) materials owing to their magnetoelectric synergy. However, the structure of ZIF-67-derived MA materials mainly depends on the morphology and composition of pristine metal-organic frameworks (MOFs), and their microstructures lack a rational design. Herein, a multidimensional sea urchin-like carbon nanotubes (CNTs)-grafted carbon polyhedra-encapsulated Co3ZnC/Co nanoparticle composite was prepared by one-step catalytic pyrolysis of ZIF-67/ZnO using a rational structural design. The autogenous and tunable CNTs obtained with the assistance of zinc evaporation not only overcome the limitation of homogeneous dispersion but also endow the Co3ZnC/Co/C composite with outstanding MA properties owing to the conduction loss provided by CNTs, polarization loss caused by multiple components, and electromagnetic wave trap composed of a special sea urchin-like structure. Consequently, the minimum reflection loss of ZZ0.1-600 reaches -60.3 dB at 1.6 mm, the maximum absorption bandwidth of ZZ0.05-600 is 6.24 GHz (covering nearly the entire Ku band) at 1.9 mm, and the structure has a low weight ratio (30 wt %). Compared with Z-600 and pure ZnO, the MA performance of the sea urchin-like Co3ZnC/Co/C composite obtained by rational structural design has been greatly improved; this strategy offers a new approach for optimizing the MA performance of materials according to their structural design.