Electric Arc Research Articles

Effect of activator type and Pozzocrete waste on the mechanical and microstructural properties of eco-friendly geopolymer incorporating electric arc furnace slag

ABSTRACT The precursor type and activator are two primary factors that significantly affect the properties of geopolymers. Most of the previous studies used byproduct materials such as fly ash (FA) and slag as geopolymer precursors, while too limited studies used electric arc furnace slag (EAFS) for this purpose. The EAFS is a type of steel slag, which can be produced when scrap steel is melted. The preliminary usage of EAFS as a precursor in the geopolymer system has not been sufficiently highlighted. To make this come true, the current procedure employed EAFS as a precursor material for the geopolymeric system. Due to superior properties, EAFS was partially replaced with 10–50 wt% pozzocrete (Pz). Two different types of alkaline activators, NaOH and Na2CO3, were used to activate EAFS slurries supported by Pz. The results indicated that the optimal ratio of Pz to be replaced by EAFS to achieve the target properties varies according to the type of activator. The inclusion of 10% Pz exhibited maximum compressive strength when Na2CO3 was used, whilst 50% Pz exhibited maximum compressive strength when NaOH was used. The coexistence between N-A-S-H from Pz and C-(A)-S-H gel from EAFS is the main reason for the enhanced strength.

Serum Plasminogen Activator Inhibitor-1, α 1-Acid Glycoprotein, C-Reactive Protein, and Platelet Factor 4 Levels—Promising Molecules That Can Complete the “Puzzle” of the Biochemical Milieu in Severe Burns: Preliminary Results of a Cohort Prospective Study

Background: Burns represent a serious health problem, associated with multiple-organ failure, prolonged hospitalization, septic complications, and increased rate of mortality. The main aim of our study was to evaluate the levels of various circulating molecules in children with severe burns (more than 25% TBSA), in three different moments: 48 h, day 10, and day 21 post-burn. Materials and Methods: This study included 32 children with burns produced by flame, hot liquid, and electric arc and 21 controls. Serum plasminogen activator inhibitor-1 (PAI-1), α 1-acid glycoprotein (AGP), C-reactive protein (CRP), and platelet factor 4 (PF4) were detected using the Multiplex technique. Several parameters, such as fibrinogen, leucocyte count, thrombocyte count, triiodothyronine, thyroxine, and thyroid-stimulating hormone were also determined for each patient during hospitalization. Results: Significant statistical differences were obtained for CRP, AGP, and PF4 compared to the control group, in different moments of measurements. Negative correlations between CRP, AGP, and PF4 serum levels and burned body surface, and also the hospitalization period, were observed. Discussions: CRP levels increased in the first 10 days after burn trauma and then decreased after day 21. Serum PAI-1 levels were higher immediately after the burn and started decreasing only after day 10 post-burn. AGP had elevated levels 48 h after the burn, then decreased at 7–10 days afterwards, and once again increased levels after 21 days. PF4 serum levels increased after day 10 since the burning event. Conclusions: Serum CRP, AGP, PAI-1, and PF4 seem to be promising molecules in monitoring patients with a burn within the first 21 days.

High-sensitivity strain sensor based on an asymmetric tapered air microbubble Fabry-Pérot interferometer with an ultrathin wall

A Fabry-Pérot interferometer (FPI) with an asymmetric tapered structure and air microbubble with an ultrathin wall is designed for high-sensitivity strain measurement. The sensor contains an air microbubble formed by two single-mode fibers (SMF) prepared by fusion splicer arc discharge, and a taper is applied to one side of the air microbubble with a wall thickness of 3.6 µm. In this unique asymmetric structure, the microbubble is more easily deformed under stress, and the strain sensitivity of the sensor is up to 15.89 pm/µɛ as evidenced by experiments.The temperature sensitivity and cross-sensitivity of the sensor are 1.09 pm/°C and 0.069 µɛ/°C in the temperature range of 25-200°C, respectively, thus reducing the measurement error arising from temperature variations. The sensor has notable virtues such as high strain sensitivity, low-temperature sensitivity, low-temperature cross-sensitivity, simple and safe process preparation, and low cost. Experiments confirm that the sensor has good stability and repeatability, and it has high commercial potential, especially strain measurements in complex environments.

Characterization of Asphalt Filler Mastics with Industrial By-Products as Fillers under the Coupled Effect of Aging and Moisture

An asphalt mix comprises asphalt binder and aggregates of different sizes (coarse and fine) and filler. Even with a smaller share, filler plays a crucial role in the performance of asphalt-filler mastics. The study is motivated by the growing need to preserve natural resources and aims to investigate the utilization of four different industrial by-products/wastes (electric arc furnace slag filler, basic oxygen furnace slag filler, tire pyrolysis char filler, and plastic pyrolysis char filler, and one conventional natural stone aggregate filler (NSAF) in asphalt-filler mastics. Four conditioning environments were used to characterize the chemo-rheological properties of the mastics formulated by these five different fillers: unaged, long-term aged, freeze-thaw, and freeze-thaw of long-term aged mastics. To understand the significance of filler attributes in the filler-asphalt mastic performance, a correlation between various filler characteristics (specific surface area, Rigden voids, methylene blue value, and hydrophilic coefficient) and the mastic properties (multiple stress creep and recovery, linear amplitude sweep, binder yield energy test, and Fourier transform infrared spectroscopy) was also attempted. The fatigue life and elastic recovery of the mastics were negatively affected by the combined effects of aging and moisture. The filler characteristics showed a negligible-to-low association with fatigue parameters and a good correlation with rutting performance. The use of these industry co-products/by-products as fillers is supported by the superior rutting and fatigue performance of steel slag and pyrolytic char fillers compared with the traditional NSAF.

The Waelz Slag from Electric Arc Furnace Dust Processing: Characterization and Magnetic Separation Studies

The Waelz slag generated during electric arc furnace dust processing is an iron-rich product with significant amounts of iron, zinc and copper. About 600–800 kg of the Waelz slag is generated per ton of the dust processed. The Waelz slag samples from two different plants were thoroughly characterized using inductively coupled plasma optical emission spectroscopy (ICP-AES), X-ray diffraction analysis (XRD), chemical phase analysis, Mössbauer spectroscopy and other supporting methods. The phase distribution of iron, zinc and copper was determined in the Waelz slag samples. Low-intensity wet magnetic separation was tested for the iron recovery from the Waelz slag samples. It was found that the Waelz slag samples have complex chemical and mineralogical compositions, which can impede the selective recovery of valuable elements. The obtained results indicate that the chemical and mineralogical composition of the Waelz slag samples has a considerable effect on the magnetic separation indexes. The experiments showed that the iron concentrates with Fe contents of 73% and 46.8% with the metallization degrees of 87.2% and 57.5% and the iron recovery degree of 54.8% and 52.9% were obtained at optimal conditions for two different samples, respectively, without selective segregation of Cu and Zn in the magnetic or non-magnetic fraction.

Waste to wealth: Efficient wet desulfurization of electric arc furnace dust (EAFD) and recycling of desulfurization solid residue

In this study, we used calcined hazardous waste electric arc furnace dust (EAFD) as a desulfurizer for an effective wet desulfurization process. Testing for desulfurization efficacy revealed that the calcined EAFD, particularly when treated at 800 °C in an oxygen (O2) environment (termed EAFD-O2), achieved an unprecedented breakthrough sulfur capacity (BSC) of 3.71 gSO2·g−1 at 55 °C-the highest to date for EAFD applications in desulfurization efforts. Further investigation indicated that the calcination method expels certain volatile contaminants, thereby enhancing the crystallinity and lattice oxygen content of zinc oxide, the strong active phase of desulfurization in EAFD, which is principally responsible for the superior desulfurization results of EAFD-O2. Moreover, the observed reduction in the desulfurization slurry’s activity primarily stems from the depletion of the strong active phase of desulfurization (ZnO) and the resultant rise in the liquid phase’s sulfate concentration. Notably, the deactivated slurry’s solid residue predominantly consists of high-purity ZnFe2O4, a form of zinc ferrite utilized extensively for its proficiency in photocatalytic. Following straightforward processing, this substance displayed exceptional performance in photocatalytic-Fenton degradation tests on tetracycline (TC). In sum, the study not only turns hazardous EAFD into a powerful agent for removing SO2, a gaseous pollutant but also converts it into a value-added material, ZnFe2O4, thus proposing an integrated and efficient approach to solid waste management.

Electrical arc discharge in air between Pt-coated NEMS electrodes at nanoscale separation

A thorough understanding of arc discharge mechanism as well as determination of arc discharge voltage at the nanometer scale remains challenging due to the complexities associated with electrode preparation and precisely maintaining nanoscale separations in experiments. This work addresses this challenge through a novel approach by accurately measuring electric breakdown/discharge voltages between Pt-coated Si electrodes with separations ranging from ∼5 nm to 370 nm using a combination of fixed and flexible nano-electrodes while inherently creating an ideal environment to mitigate the effect of mechanical vibrations on the measurement results. For separations of 10, 100, and 300 nm, the corresponding discharge voltages are ∼15, 75, and 160 V, respectively, with the apparent electric field for the 10 nm separation exceeding 1.5 GV m−1. The results acquired from the investigated electrode configuration closely resembling the laterally actuated nanoelectromechanical system (NEMS) cantilever relays reveals strong agreement with NEMS relay breakdown characteristics, emphasizing the importance of arc discharge considerations while designing micro/nano electromechanical devices. Furthermore, deliberately applied arc discharge is shown to provide electrode nano-welding for realization of configurable NEMS circuits.

Enhancing purity and crystallinity of carbon nanotubes by magnetically assisted arc discharge and thermal purification and their field emission characteristics

This study used a magnetically assisted arc discharge (AD) method and thermal purification to enhance the purity and crystallinity of multi-walled carbon nanotubes (MWCNTs). CNT synthesis in the presence of a magnetic field increased the densities of ionic carbon species and the arc plasma temperature, thereby improving CNT production. AD-MWCNTs produced at an optimal magnetic strength exhibited enhanced purity, crystallinity, and thermal stability. Thermal purification was also conducted to increase the purity of the AD-MWCNTs further. Purity was evaluated using Raman spectroscopy. AD-MWCNTs were homogenized to overcome limitations in light-penetration depths to ensure accurate evaluation. The calculated purities were consistent with the analytical results, confirming the reliability of Raman spectroscopy for purity assessment. The number of working CNT emitters on the film surface was directly related to the purity. Highly pure crystalline AD-MWCNTs exhibited high-performance field-emission properties, namely a high current density of 2.7 A/cm2 and long-term emission stability (12 h at a current density of 500 mA/cm2), with no performance reduction.

Mechanical and corrosion performance of WAAM printed steel structure

Wire plus arc additive manufacturing (WAAM) is rapidly growing into a popular and cost-effective technology for manufacturing medium-large complex structured components. WAAM is a novel metal additive manufacturing method that deposits material layer by layer using an electric arc as a heat source, allowing the creation of metal components with high mechanical characteristics. The procedure allows for the construction of a near-net-shape structure at a rapid pace of production (50–130 gm/min) and material utilization efficiency (80–90 %). The present study mainly focuses on the fabrication of the WAAM structure and a detailed investigation of the mechanical and corrosion performance of multi-layer fabricated wall components. The most versatile and widely applicable stainless steel SS316L material is employed to build multi-layered wall structures. The average micro-hardness of the WAAM-built structure along the building direction was found to be 197.43±1.46 HV0.3 and that of the commercially available counterpart was found to be 187.26±1.17 HV0.3. Moreover, the maximum hardness was observed close to the bottom region (201.86±1.44 HV0.3) which further reduces with the building height. The ultimate tensile strength, and yield strength of the WAAM printed wall obtained as 573.81±2.3 MPa, and 275.41±1.1 MPa respectively found to have improved mechanical strength to that of wrought counter-part however the ductility in the form of percent elongation gets slightly reduced. Furthermore, comparable corrosion resistance was observed for the WAAM fabricated wall structure and conventionally manufactured SS316L structure. The bottom region experiences better corrosion resistance compared to the upper region in both saline environment and acidic corrosion solution with an average corrosion rate of 0.0276 mm/yr, and 0.0366 mm/yr respectively.

Axially slow-variation microbubble resonators fabricated by an improved arc discharge method for strain sensing applications

Axially slow-variation microbubble resonators fabricated by an improved arc discharge method for strain sensing applications

Ionization layer with collision-free atoms at the edge of partially to fully ionized plasmas

When a hot arc spot has just formed on the cathode surface, e.g. in the course of arc ignition on a cold cathode, a significant part of the current still flows in the glow-discharge mode to the cold surface outside the spot. The near-cathode voltage continues to be high at all points of the cathode surface. The mean free path for collisions between the atoms and the ions within the plasma ball near the spot is comparable to, or exceeds, the thickness of the ionization layer, which is a part of the near-cathode non-equilibrium layer where the ion current to the cathode is generated. The evaluation of the ion current to the cathode surface under such conditions is revisited. A fluid description of the ion motion in the ionization layer is combined with a kinetic description of the atom motion. The resulting problem admits a simple analytical solution. Formulas for the evaluation of the ion current to the cathode for a wide range of conditions are derived and the possibilities of using these formulas to improve the accuracy of existing methods for modeling high-pressure arc discharges in relation to glow-to-arc transitions are discussed.

Rapid synthesis of ZnO nanoparticles via gliding arc discharge: unveiling the impact of discharge time on particle properties and photocatalytic performance.

Herein, we present a novel approach for the synthesis of ZnO nanoparticles (ZnO NPs) using a non-thermal plasma source generated by the gliding arc discharge-air system. The effect of discharge time on the physical and optical properties, as well as the photocatalytic performance of the as-fabricated ZnO NPs, was investigated. The characterization techniques revealed that the as-synthesized ZnO exhibit hexagonal Wurtzite structure, with a wide energy gap and peak intensities of UV-vis absorption with longer discharge times. A decrease in particle size from 29 to 25 nm was also observed with increasing discharge time, while all samples were thermally stable between 25 and 700 °C. The photocatalytic performance of the ZnO NPs was evaluated by degrading Congo Red (CR) dye with a concentration of 20 ppm under sunlight at a dose of 1 mg/mL. The as-synthesized ZnO NPs revealed exceptional photocatalytic performance by degrading ~ 97% of CR dye after irradiation for 150 min. This work presents an easy and simple method for synthesizing NPs in a short time and pave the way for other potential ideas on the application of plasma gliding arc discharge.

Tailoring microstructure, mechanical properties, and biocompatibility of Zr alloys via the addition of Ag

This study focuses on the preparation of zirconium (Zr) -silver (Ag) alloys through the alloying of pure Zr with a specific content of Ag using an electric arc furnace. Subsequently, the mechanical and biological properties of these alloys were examined. The analysis conducted, including XRD, OM, SEM, and TEM, confirms the well-established understanding that the Zr-Ag alloy matrix exhibits an α-phase. Furthermore, the addition of Ag elements leads to a gradual refinement of the laths, accompanied by the presence of AgZr2 compounds within the α-Zr matrix. Compression tests demonstrate that the inclusion of Ag components significantly enhances the mechanical properties of the alloys. Notably, the compressive strength of Zr-8Ag reaches an impressive 1932 MPa, while exhibiting an elongation of 22.2%. Furthermore, analysis conducted using an electrochemical workstation reveals that the self-corrosion potentials of Zr-xAg (where x=2, 4, 6, 8 at.%) tend to exhibit more positive values compared to pure Zr. Additionally, the corrosion current densities of Zr-6Ag and Zr-8Ag are lower, indicating an improved corrosion resistance. Upon conducting an examination of the antimicrobial test and hemolysis test, it was ascertained that the inclusion of Ag elements significantly augments the antimicrobial characteristics of the alloy. Furthermore, the Zr-Ag alloys exhibit hemolysis rates below 5%, rendering them appropriate for implementation in biological research endeavors.

Durability and performance characteristics of eco-friendly geopolymer binders based on electric-arc-furnace slag and dealuminated kaolin

The pursuit of sustainable development is an essential aspect of modern society's progress, aiming to achieve goals without causing waste, pollution, harm, or environmental degradation. The study focused on developing environmentally friendly binders by utilizing two industrial solid wastes: electric arc furnace slag (EAFS) and dealuminated kaolin (DK). The investigation aimed to assess the physio-mechanical, chemical properties, and durability of the binders against elevated temperatures and exposure to seawater, thereby contributing to sustainable practices. The eco-friendly geopolymer binders, EAFS and DK were blended in various proportions and mixed with alkaline activators. The resulting binders were cured at 40°C and a relative humidity of 98±2% for 180 days. Some of the binders were subjected to temperature increments in the order of 200, 400, 600, 800, and 1000°C, while the other geopolymer binders were immersed in seawater for upto 180 days. Setting times, compressive strength tests, evaluation of free slag and combined water contents, and analysis of the effects of elevated temperatures and seawater exposure on the phase composition of the geopolymer binders were conducted using XRD, TGA/DTG, and SEM/EDX. The finding showed the replacement of 10–20% of EAFS with DK resulted in a reduction in both the initial and final setting times. Increasing the amount of alkali activation content of EAFS upto (1.00 mol/Kg Na2O) (ES3 mix) leads to an increase in the values of compressive strength. Further increase in the alkali content (1.50 mol/Kg Na2O) reduces the compressive strength. The incorporation of DK enhanced the compressive strength value upto 30% DK (ES-DK3 mix). The increase in DK content beyond 30% resulted in reduced compressive strength values. ES-DK3 mix improved the thermal stability of the geopolymer matrix as well as demonstrated higher relative compressive strength values, especially at 1000°C. In addition to the mix, ES-DK3 showed superior durability against the attack of seawater. The compressive strength showed a sharp increase for specimens submerged in seawater for upto 180-days, this is attributed to the high reactivity of DK which acts as a nucleating agent that fills the open matrix preventing the penetration of SO42- and Cl- ions to inhibit the formation of nonbinding material.

Enhancing Weld Quality: A Review of Optimization Techniques for Electric Arc Welding Parameters in Mild Steel Grade Fe 500 Using Taguchi Method

Abstract: Electric arc welding stands as a cornerstone in various industries for its efficacy in joining metal components. The paramount importance of achieving impeccable welds cannot be overstated, as they are pivotal for maintaining structural integrity and performance. This review meticulously scrutinizes optimization techniques tailored for electric arc welding parameters, with a specific focus on mild steel grade Fe 500, leveraging the Taguchi method. Renowned for its efficiency in experimental design and optimization, the Taguchi method has been extensively harnessed to refine weld quality by mitigating defects such as porosity, cracks, and lack of fusion. Offering a comprehensive insight, this paper first delineates the pivotal parameters inherent to electric arc welding and elucidates their profound impact on weld quality.

A comparative study on the effectiveness of pollutants control measures adopted in the steel industry to reduce workplace and environmental exposure: a case study

Our understanding of the environmental and occupational health implications of pollutants emitted in steel production is still lacking, despite the considerable amount of research devoted to this topic. Given the significance of steel recycling and the need to reduce greenhouse gas emissions, many steel factories are adopting electric arc furnace (EAF) technology. The use of a technological system designed for the capture of pollutants emitted through EAF steel production is highly ecological because of its utilization of iron scrap and low investment cost. Despite this, the main issue with the EAF is the environmental impact it poses, specifically the release of pollutants into the air, such as dust and organic substances, chlorinated dioxins and furans, dioxin-like polychlorinated biphenyls and brominated dioxins and furans. As a result, workers in this field have a considerable rate of morbidity. The main challenge for EAFs is to optimize the capture of powders produced during the techno-logical process, both from the EAF and the workplace. A state-of-the art solution for managing pollutants in modern steel manufacturing is highlighted in this paper, featuring a method used in Romania that employs the Best Available Techniques (BAT) reference document for iron and steel production to directly collect pollutants from the EAF. The system included a cylindrical fitting, a heat exchanger to cool the gases and a hood to collect contaminants. In comparison to other ventilation options, this equipment boasts lower investment and lower operational costs because of its effective and minimal air flow. Through the use of cutting-edge technology and progressive strategies, we can move closer toward our objective of a workplace free from injuries in the steel industry.

Optimization of Welding Parameters for Minimizing Defects and Porosity in Electric Arc Welding of Mild Steel Grade Fe 500 Using of Taguchi Method

Abstract: Electric arc welding is a widely used technique in industrial applications for joining metals, including mild steel grade Fe 500. However, the process is susceptible to defects such as porosity, which can compromise the integrity and quality of welds. In this study, we investigate the optimization of welding parameters to minimize defects and porosity in electric arc welding of mild steel grade Fe 500, utilizing the Taguchi method. The Taguchi method, known for its efficiency in optimization studies, is employed to systematically identify the most influential welding parameters and their optimal levels. Through a series of experiments based on the Taguchi orthogonal array design, we vary parameters such as current amperage, voltage, and electrode size to explore their effects on weld quality. The experimental results reveal significant insights into the relationship between welding parameters and defect formation. By analyzing signal-to-noise ratios and ultimate tensile strength, we quantify the effects of parameter variations on weld quality. The Taguchi analysis enables us to identify the optimal combination of welding parameters that minimizes defects and porosity while maximizing weld strength.

Carbon Quantum Dots: Properties, Preparation, and Applications.

Carbon quantum dots are a novel form of carbon material. They offer numerous benefits including particle size adjustability, light resistance, ease of functionalization, low toxicity, excellent biocompatibility, and high-water solubility, as well as their easy accessibility of raw materials. Carbon quantum dots have been widely used in various fields. The preparation methods employed are predominantly top-down methods such as arc discharge, laser ablation, electrochemical and chemical oxidation, as well as bottom-up methods such as templates, microwave, and hydrothermal techniques. This article provides an overview of the properties, preparation methods, raw materials for preparation, and the heteroatom doping of carbon quantum dots, and it summarizes the applications in related fields, such as optoelectronics, bioimaging, drug delivery, cancer therapy, sensors, and environmental remediation. Finally, currently encountered issues of carbon quantum dots are presented. The latest research progress in synthesis and application, as well as the challenges outlined in this review, can help and encourage future research on carbon quantum dots.

The Phenomenon of a Cathode Spot in an Electrical Arc: The Current Understanding of the Mechanism of Cathode Heating and Plasma Generation

A vacuum arc is an electrical discharge, in which the current is supported by localized cathode heating and plasma generation in minute regions at the cathode surface called cathode spots. Cathode spots produce a metallic plasma jet used in many applications (microelectronics, space thrusters, film deposition, etc.). Nevertheless, the cathode spot is a problematic and unique subject. For a long time, the mechanisms of spot initiation, time development, instability, high mobility, and behavior in magnetic fields have been described by approaches that caused some controversy. These spot characteristics were discussed in numerous publications over many years. The obscurity and confusion of different studies created the impression that the cathode spot is a mysterious phenomenon. In the present work, a number of typical representative publications are reviewed with the intention of clarifying problems and contradictions. Two main theories of cathodic arcs are presented along with an analysis of the experimental data. One of the approaches illustrates the cathode heating by Joule energy dissipation (volume heat source, a sharp rise in current density, etc.), nearly constant cathode potential drop, and other certain initial conditions. On the other hand, a study using a mathematically closed approach shows that the spot initiation and development are determined not by electron emission current rise but by a rise in arc power density, affecting heat sources including the energy of ion flux to the cathode (surface heat source).

Deposition of a‐C:H:SiOx Coatings Using Low‐Frequency Inductively Coupled Plasma

This article investigates the plasma‐enhanced chemical vapor deposition of a‐C:H:SiOx coatings in a non‐self‐sustaining arc discharge plasma with a hot cathode in combination with a low‐frequency (200 kHz) inductively coupled plasma. It is shown that increasing the inductor power from 0 to 600 W leads to a twofold increase in the ion current density on the substrate. An increase in ion bombardment intensity results in a 1.3‐fold reduction in the coating's growth rate due to the resputtering phenomenon, a 1.5‐fold reduction in surface roughness, and an improvement in the mechanical properties of the coatings. The hardness of the coating is increased by 9–11%, the plasticity index by 10–17%, and the resistance to plastic deformation by 32–49%.