Electric Arc Research Articles

Mechanical and durability performance of self-compacting mortars made with different industrial by-products as fillers

This study evaluated the performance over time of Self-Compacting Mortars (SC mortars) with different industrial by-products simultaneously; Electric Arc Furnace Dust (EAFD) and fly ash, conforming (FA) or not conforming (NcFA), from coal-fired power plant or recovery filler from hot-mix asphalt plant (RF). Different SC mortars mixes were produced; three mixes with different EAFD ratio incorporation (0 %, 10 %and 20 %) for each the other industrial by-products (FA, NcFA and RF) substituted of cement at 30 %; and additional three mixes with 60 % of cement replacement by FA and the same EAFD incorporation ratios. To study the performance over time of these SC mortars, tests such as electrical resistivity, ultrasonic pulse velocity, drying shrinkage, capillarity, compressive and flexural strength were carried out up to 91 days of curing. The SC mortar compositions was evaluated by TGA/DTA and DRX analysis. Previously, the by-products used were characterized. The EAFD incorporation showed a strong influence in SC mortars, independently of the industrial by-product used. The initial inhibition of development of hardening in SC mortars due to the presence of ZnO in EAFD was lifted over time up to some extent. The simultaneous use of different industrial-by products in SC mortars in high volume content walks towards the sustainability in the construction sector.

Microstructure and mechanical properties in ultrasonic-magnetic field coaxial hybrid GTAW joints of Ti-6Al-4V

GTAW has less arc energy density and coarse joint microstructure. A novel method of Ultrasonic-Magnetic field coaxial hybrid GTAW (U-M-GTAW) was proposed, which improved upon the traditional GTAW torch. Under 140 A current and 4 mm/s speed, the results indicated that the U-M-GTAW depth-to-width ratio increased by 54.5 % compared to GTAW. Meanwhile, the surface of the joint showed a dense corrugation. The interior of the joints was all composed of martensite α', whose phase transformation obeyed the Burgers orientation relationship. The average martensite length in the U-M-GTAW weld zone was 14.8 μm, which was 33.6 % shorter than GTAW, and the length distribution was more uniform. Additionally, the U-M-GTAW joint orientation shifted from {01−10} to {−12−10}, revealing a higher texture density. The substantial precipitation of martensite in the weld zone resulted in the highest hardness, with an average microhardness of 396.8 ± 9.0 HV, marking a 12.1 % improvement over base metal. Moreover, U-M-GTAW exhibited an elongation of 9.3 %, representing a 10.7 % enhancement compared to GTAW, with deeper dimples in the fracture indicating superior plasticity. Notably, the improvements in microhardness and elongation in U-M-GTAW were primarily attributed to the reduction in martensite length and its uniform distribution under the action of ultrasonic and magnetic fields.

Effect of roasting process on the V (anti-tumor agent) recovery from the slag of the electric arc furnace (EAF)

Due to the lack of mineral sources of Vanadium (V) in many parts of the world and its recent applications in the field of medicine (as an anti-tumor agent), one of the biggest sources of V is the extraction of V as V2O5 from steel slag in melting process. In this study, the pyro-hydrometallurgical process has been investigated for the extraction of V from steel slag created in a convertor. To get an optimum process of salt roasting, the effect of roasting temperature, time, salt value, slag particle size, and cooling method have been investigated. For this purpose, slag samples were roasted with sodium carbonate and then dissolved in water. The amount of V2O5 obtained by optical spectrometry is the efficiency criterion of this process. Results showed that the optimum condition for the extraction of V2O5 from steel slag was 15 wt % of Na2CO3 as a salt roasting agent and hating for 60 min at 1100 °C.

Analysis of Steel Slag Sand – An Eco Friendly Fine Aggregate for Construction

Industrial waste slag is a major issue concerning the environmentalists today. The steel making industry produces a large amount of byproduct which is termed as Slag. Slag is produced during the steel-making operations that utilize Electric Arc Furnaces (EAF) and operate by smelting iron ore in the Basic Oxygen Furnace (BOF). Steel slag finds numerous uses in the construction industry e.g in the applications involving hot mixture asphalt, in Stone Matrix Asphalt (SMA), berms and embankments constructions, main ingredient in manufacturing of Portland cement, as fine and coarse aggregates, to name a few. But steel slag has a negative impact on the environment when disposed of. In that case a wide variety of use of steel slag becomes relevant. Steel Slag is a perfect candidate to replace the coarse and fine aggregates in the traditional concrete used in the construction industry. Most of the volume of concrete is aggregate. Steel Slag can be used as replacement to these aggregates in a more prominent way. In this research study, we will be making steel slag as substitution for raw fine aggregate. Fine aggregate would be replaced by these wastes in different proportions (20%, 40%, & 60 %) by weight of fine aggregate. The aim of this study is to investigate the compressive strength, split tensile strength and Material properties of concrete with partial replacement for fine aggregate. We will be performing pull off test on the applications of this modified concrete and checking the results for strength and durability.

Effect of EAF Slag on the Performance of Wollastonite Mixes Inspired by CO2 Curing Technology

Replacement of cement with electric arc furnace (EAF) slag at higher volumes causes volumetric expansion; therefore, such blends are not recommended in concrete production. In this study, the effect of this slag on the performance and microstructure of mortar samples based on wollastonite (CaSiO3) was examined. The samples were cured in a CO2-rich environment, resulting in the formation of non-expansive products, including aragonite, calcite, and traces of tobermorite in the microstructure. The addition of slag above 20% affected the workability and strength developments. However, the formation of pores above 100 nm reduced with increasing slag content to 60%, highlighting the beneficial effect of slag when used in higher volumes. EAF slag contains a higher amount of Fe2O3 which limits its disposal at landfills, but its increased use in the production of CO2 gas-cured wollastonite concrete can reduce the environmental burdens caused by the Portland cement and steel manufacturing industries.

Scrap Steel Recycling: A Carbon Emission Reduction Index for China

Accurately assessing carbon emissions from recycling scrap steel is essential for reducing emissions in the steel industry, especially in China, the world’s largest crude steel producer. In this study, a carbon emission reduction index was introduced to evaluate the effectiveness of recycling scrap steel in reducing emissions. The index considers the three processes used in scrap steel recycling: blast furnace ironmaking, converter steelmaking, and electric arc furnace steelmaking. This study developed an evaluation model using fuzzy analytic hierarchy process and iterative cluster analysis to determine the reduction of carbon emission. From a life cycle perspective, this study identified primary factors contributing to emissions, including fuel, raw materials, electric energy, and auxiliary materials. Then, the carbon emission reduction index for scrap recycling was developed by examining the production of one ton of steel and each additional ton of scrap steel, which can provide valuable insights into the environmental impact of scrap recycling. Finally, the study forecasts the future Carbon Emission Reduction Index for steel scrap recycling. The study indicates an increase in the carbon emission reduction index for scrap recycling prior to 2017, followed by a decrease about 11.8% from 2017 to 2018 and increases from 2018 to 2021. Finally, it dropped by 8.7% per cent in 2022. Similarly, the carbon emission reduction index for electric furnace steelmaking increased prior to 2019, then subsequently decreased. It is changing by ten per cent a year. Additionally, the scrap recycling index experienced a significant decrease of 90% in 2015, followed by a gradual increase until 2017 and then a consistent decrease every year thereafter. The index suddenly rose in 2021 and then decreased change for policy reasons. The forecast results suggest a gradual increase in the carbon emission reduction index per ton of steel scrap in the future. In conclusion, the practicable modeling methodology has the ability to assist government organizations and private enterprises in devising efficient green and low-carbon development tactics.

Effect of Nb Doping on the Electrical Contact Properties of AgNi Contact Materials

AgNi contact materials have received widespread attention with the acceleration of the process of replacing AgCdO contact materials. However, the practical applications of AgNi contact materials are limited due to its disadvantage of poor resistance to melting welding. Firstly, following the first principles of the density functional theory, we simulated and tested an interfacial model of AgNi doped with varying amounts of Nb. Next, we fabricated AgNi electrical contact materials. Subsequently, we conducted electrical contact tests. Finally, the impact of Nb doping on the arc erosion behavior of AgNi electrical contact materials was analyzed. The results indicate that, with an increase in Nb doping content, the electrical contact performance and the degree of arc erosion exhibit a trend of initially decreasing and then increasing, which aligns with the simulation results. The mean values of arc energy, arc duration, and welding force for the material doped with 4.55% Nb were 181.02 mJ, 9.43 mS, and 38.45 cN, respectively. Moreover, the anode is more responsive to changes in Nb content compared to the cathode. The introduction of Nb enhances the viscosity of the molten pool in the AgNi electrical contact. Furthermore, the mechanisms of grain boundary strengthening and solid solution strengthening by Nb improve the weld performance resistance of the contact.

Analysis of the melting process of carbon-bearing pellets in iron bath, slag bath and graphite crucible

Background With the increase in the amount of scrap steel in society, the proportion of electric furnace steelmaking is increasing year by year, especially in China. Due to the high Zn content, the electric furnace arc dust (EAFD) needs to be recovered by non-blast furnace process. Due to EAFD containing a large amount of zinc ferrite, it needs to be recovered by fire process. It is a promising process to melt the EAFD pellets to get the discount and zinc-rich secondary ash. Methods To clarify the melting behavior of pellets in the metallurgical process, the slag phase diagram and the effect of temperature and FeO on slag viscosity were calculated using FactSage, and the melting process of electric furnace arc dust (EAFD) pellets in a graphite crucible, iron bath, and slag bath were experimentally investigated. Results The experimental results show that the viscosity of the slag system decreases with increasing temperature and FeO content, and the effect of FeO on viscosity is greater. The viscosity decreased from 0.305 to 0.276 Pa·s when the FeO content in the slag was increased from 0 wt. % to 2 wt.% at 1773 K. The melting process of the EAFD pellets in an iron bath and graphite crucible was consistent, and after the formation of liquid-phase slag in the pellets, the liquid-phase slag was diffused to melt the pellets. Conclusions The iron bath improved the heat transfer conditions of the pellets, reducing the smelting time from 600 to 360 s. The slag bath promoted the slagging reaction of the contact part to change the pellet melting process and increase the pellet melting speed, and the EAFD pellets melted within 240 s in a slag bath.

Recycling the electric arc furnace waste after geopolymerization in bitumen: experimental analyses and LCA study

The conversion of solid waste materials into cleaner products for road paving. applications appears to be a promising and sustainable option. However, there is still a lack of attention given to quantifying the potential environmental benefits of recycling solid wastes in asphalt pavements, regarding the impact on asphalt performance. To address this gap, the present study investigates the effects of recycling electric arc waste based geopolymers on asphalt binder and mixture characteristics, as well as environmental outputs. For this purpose, geopolymers were incorporated into both neat and SBS-modified binders. A comprehensive rheological investigation was conducted using cutting-edge multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) analyses. Stability, Marshall quotient, and flow values, as well as dry and wetconditioned tensile strength were considered, to determine asphalt mixture properties. In the Life Cycle Assessment (LCA), greenhouse gases resulting from fuel and energy consumption in each inventory phase were determined. The varying service lifetimes, maintenance and rehabilitation plans, and production and construction requirements of the different asphalt schemes were taken into account. Subsequently, the environmental impacts of the asphalt mixtures, including global warming potential, acidification, eutrophication, and smog formation potential, along with the total energy demand, were calculated across different stages of the LCA. The results show that the geopolymerization process results in important contributions in terms of both environmental savings and pavement performance.

Modeling of Yb:YAG Laser Beam Caustics and Thermal Phenomena in Laser-Arc Hybrid Welding Process with Phase Transformations in the Solid State.

This paper focuses on the mathematical and numerical modeling of the electric arc + laser beam welding (HLAW) process using an innovative model of the Yb:YAG laser heat source. Laser energy distribution is measured experimentally using a UFF100 analyzer. The results of experimental research, including the beam profile and energetic characteristics of an electric arc, are used in the model. The laser beam description is based on geostatistical kriging interpolation, whereas the electric arc is modeled using Goldak's distribution. Hybrid heat source models are used in numerical algorithms to analyze physical phenomena occurring in the laser-arc hybrid welding process. Thermal phenomena with fluid flow in the fusion zone (FZ) are described by continuum conservation equations. The kinetics of phase transformations in the solid state are determined using Johnson-Mehl-Avrami (JMA) and Koistinen-Marburger (KM) equations. A continuous cooling transformation (CCT) diagram is determined using interpolation functions and experimental research. An experimental dilatometric analysis for the chosen cooling rates is performed to define the start and final temperatures as well as the start and final times of phase transformations. Computer simulations of butt-welding of S355 steel are executed to describe temperature and melted material velocity profiles. The predicted FZ and heat-affected zone (HAZ) are compared to cross-sections of hybrid welded joints, performed using different laser beam focusing. The obtained results confirm the significant influence of the power distribution of the heat source and the laser beam focusing point on the temperature distribution and the characteristic zones of the joint.

Improvement of tensile strength and anti-oxidation property of graphite electrode for electric arc furnace through heterogenization of binder pitch

Improvement of tensile strength and anti-oxidation property of graphite electrode for electric arc furnace through heterogenization of binder pitch

Fabrication of surface nanoscale axial photonics structures with electric arc discharge

The fabrication of surface nanoscale axial photonics (SNAP) microresonators, utilizing the approach of electric arc discharge (EAD), is accomplished, achieving a precision at the angstrom level. This paper thoroughly investigates the effects that discharge intensity and discharge duration have on SNAP microresonators, respectively, through the manipulation of relevant discharge parameters. The results indicate that, within a specified range of discharge intensity, a linear relationship is observed between the effective radius variation (ERV) and the discharge intensity, characterized by a slope of 0.325 nm/intensity unit. As the discharge duration is extended, the ERV gradually increases, eventually reaching a saturation value, which is inherently determined by the discharge intensity. Additionally, as the discharge intensity (or time) continues to increase, a “convex–concave–convex” shape is observed on the fiber, providing a method for fabricating bat microresonators. These discoveries derived from our study contribute toward providing a strong foundation for the progressive enhancement and refinement of EAD-based SNAP fabrication techniques.

Capacity of Ca-based slags for carbon capture

Efficiency in reutilization of Ca-based waste for carbon capture has gained high interest. Besides, the CO2 capture mechanism will be influenced by several operating parameters. Observation of carbonation by Ca-based slags (desulfurization slag/De-S, electric arc furnace/EAF slag, and bottom ash/BA) in this study indicated that De-S had the highest Ca(OH)2 content (73%) and largest surface area which led to the best slag utilization. This slag was further applied in the test under various operating conditions including temperature, space velocity, and the content of gas impurity (H2O and SO2). Higher temperature and lower space velocity promoted efficient carbonation. De-S endured the presence of ≤5% water vapor content in the simulated gas. Higher SO2 content in the simulated gas initiated the formation of CaSO4 and declined the CO2 capture capacity. Discussion in this study was complemented by the characterization of slags before and after carbonation process along with reaction kinetics analysis.

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

In this paper, we proposed an axially slow-variation microbubble resonator fabricated by an improved arc discharge method and applied to axial strain sensing. The prepared resonators are characterized by ultra-thin wall thickness and axial slow-variation. The wall thickness was experimentally measured to reach 938 nm and maintain a quality factor of an optical mode as large as 7.36 ×107. The main factors affecting the strain sensitivity of the microbubble resonators are investigated theoretically and experimentally. Experimentally, the maximum sensitivity measured was 13.08pm/µε, which is three times higher than the microbubble resonators without this method. The device is simple to prepare and possesses ultra-thin wall thickness. It is promising for applications in high-precision sensing, such as single molecule and biological sensing.

Thermal Cycling Test of Solar Salt in Contact with Sustainable Solid Particles for Concentrating Solar Power (CSP) Plants

Thermal energy storage (TES) is crucial in bridging the gap between energy demand and supply globally. Concentrated Solar Power (CSP) plants, employing molten salts for thermal storage, stand as an advanced TES technology. However, molten salts have drawbacks like corrosion, solidification at lower temperatures, and high costs. To overcome these limitations, research is focusing on alternative TES materials such as ceramic particles. These solids match molten salts in energy density and can withstand higher temperatures, making them well-suited for CSP systems. This study revolves around subjecting Solar Salt alone and Solar Salt alongside Volcanic Ash (VA) and Electric Arc Furnace Slag (EAFS) to a comprehensive thermal cycling test. This test is designed to assess the compatibility over the thermal cycles of the Solar Salt and the Solar Salt in contact with these solids in a CSP plant with a thermocline configuration. With a final thermal and chemical evaluation, our observations indicate that EAFS and VA demonstrate promising compatibility but an increase in the reduction rate of the Solar Salt due to a catalyst effect from EAFS in contact with the salt. No discernible alterations were detected in the properties of either the solid materials or solar salt when combined.

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.

Computational study of the effect of the number of splitter plates considering blow-out coil voltage in arc chamber of moulded case circuit breaker

To attain current limitation in low voltage circuit breaker (LVCB) apparatus, the approach involves elevating the arc voltage. This improvement is realised primarily in the arc chamber's splitter plates because of the higher drop voltages at the anode and cathode sheath areas. One of the most crucial ways to better describe arc behaviour in LVCB is to account for voltage in the vicinity of the electrodes. To reduce the current, LVCB works by raising the arc voltage. Voltage is raised in several ways, including increase in losses, elongating the arc, and multiplying the splitter plates. The aim of this research is to present readers with an additional technique for analysing electric arcs in moulded case circuit breaker (MCCB) which is one of the types of low voltage circuit breakers which is used to prevent overload and short circuit in electrical systems. 2-D model of MCCB with splitter plate has been developed and simulated using ANSYS software. Simulation results with the effect of increase in the number of Splitter plates considering blow-out coil voltage in arc chamber has been discussed. Modelling and simulation technologies provide the mechanism through which this understanding may be attained.

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.