Liquid Bath Research Articles

Development of electroslag remelting technology for obtaining multilayer billets

The paper analyzes the methods of external influence on the electroslag remelting process in order to obtain multilayer ingots. The method of electroslag remelting with rotation of the consumable electrode is proposed, which leads to the appearance of centrifugal force that affects the heat pattern in the metal bath by changing the place of delivery of electrode metal droplets and form the crystallization front, providing greater crystalline homogeneity in the axial direction. Application of the electrode rotation technology allows to obtain multilayer ingots with a minimum transition zone between layers of different chemical composition. For realization of this method it is necessary to give the electrode unidirectional or reversible rotation around its axis or the axis of the bath at asymmetric location of the electrode. The rotation speed of the electrode depends on its diameter. For electrodes with a diameter of 40–250 mm it is 30–90 rpm. Rotation of the consumable electrode has a complex positive effect on remelting performance: it increases productivity without increasing the suitable power for the slag bath; it increases refining capacity; it changes the place of electrode metal delivery into the metal bath and forms the crystallization front, providing greater crystalline homogeneity in the axial direction. Application of the technology of rotation of the consumable electrode makes it possible to introduce chemical composition-correcting additives into the liquid metal bath from the ingot surface by applying a coating consisting of filler material and water-based non-stick paint to the remelting electrode.

Realisation of the triple-point of Argon: comparison between two devices

A new cryostat for the realization of the triple-point of the argon (83.8058 K), a defining fixed point of the International Temperature Scale of 1990 (ITS-90), was acquired at Italian National Metrological Institute (INRiM). The new system, manufactured by Fluke, is intended to substitute the current National reference, a model developed at BNM-INM in the 1975. The main difference between the two system is in the way to control the temperature. In the BNM-INM device the temperature is controlled adjusting the pressure of liquid nitrogen bath, in the Fluke system instead, an electrical heater wrapped around the argon cell is used, following cryogenic practice. This paper describes the result of the direct comparison and shows typical phase transitions obtained with the two argon systems. Then, a complete uncertainty budget is evaluated for the new Fluke system and compared with the National standard.

Numerical analysis and industrial practice of single-flow post-combustion oxygen lance with high oxygen supply intensity

The oxygen supply process is a vital operation in converter steelmaking, which is to inject oxygen and kinetic energy into the liquid bath with an oxygen lance. Herein, a single-flow post-combustion oxygen lance (SF-PCL) with four primary holes and six secondary holes was designed to increase the oxygen supply intensity of a 60-ton converter in a steel plant. The attenuation and coalescence behaviors of supersonic jets for the conventional four-hole oxygen lance (COL) and the newly designed SF-PCL were studied by numerical simulation. And then, their metallurgical effects were verified by industrial practice. The simulation results indicated that the SF-PCL effectively suppresses the attenuation and coalescence of supersonic jets as well as simultaneously increases both the impact area and penetration depth. In industrial practice, compared with the COL, the newly designed SF-PCL increases the oxygen supply intensity from the original 4.89 m3 (t·min)−1 to 5.43 m3 (t·min)−1, rises the dephosphorization rate by 1.4%, shortens the blowing time by 34 s, reduces the ferrous charges consumption by 7 kg t−1 and decreases the total iron content in final slag by 0.85%.

Dynamic density functional theory with inertia and background flow.

We present dynamic density functional theory (DDFT) incorporating general inhomogeneous, incompressible, time-dependent background flows and inertia, describing externally driven passive colloidal systems out of equilibrium. We start by considering the underlying nonequilibrium Langevin dynamics, including the effect of the local velocity of the surrounding liquid bath, to obtain the nonlinear, nonlocal partial differential equations governing the evolution of the (coarse-grained) density and velocity fields describing the dynamics of colloids. In addition, we show both with heuristic arguments, and by numerical solution, that our equations and solutions agree with existing DDFTs in the overdamped (high friction) limit. We provide numerical solutions that model the flow of hard spheres, in both unbounded and confined domains, and compare with previously derived DDFTs with and without the background flow.

A protocol for accurately calibrating thermocouples at cryogenic temperatures

To study the quenching characteristics of materials in a cryogenic liquid bath transient temperature measurements of high accuracy are necessary. Thermocouple is an ideal tool for this application because of its low self-heat capacity. However, they require calibration before usage that require multiple fixed-point temperatures. The common fixed-point temperatures are the water-ice melting temperature, the dry ice sublimation temperature, and the boiling temperature of liquid nitrogen. It is important to note that there are uncertainties associated with dry ice sublimation and liquid nitrogen boiling temperature inherent to the heat and mass transport phenomenon at their phase-changing interface or inside the bulk medium. The dry ice temperature is influenced by the mass transport phenomenon occurring at the interface between the dry ice and the ambient surrounding it. In a typical lab environment, dry ice temperature is significantly lower than the commonly quoted sublimation temperature of -78.5 °C at 1.013 bar. In the case of liquid nitrogen stored in a cryostat, temperature gradients develop in the liquid bath. This paper describes a protocol for calibrating thermocouples by accurately defining and using fixed-point temperatures of dry ice in a saturated environment and a liquid nitrogen slush.

DarkSide-20k Veto Photon-Detector Units: construction and characterization

DarkSide-20k is a global direct dark matter search experiment situated underground at LNGS (Italy), designed to reach a total exposure of 200 tonne-years nearly free from instrumental backgrounds. The core of the detector is a dual-phase Time Projection Chamber (TPC) filled with 50 tonne of low-radioactivity liquid argon.The entire TPC wall is surrounded by a gadolinium-loaded polymethylmethacrylate (Gd-PMMA), which acts as a neutron veto, immersed in a second low-radioactivity liquid argon bath enclosed in a stainless steel vessel. The neutron veto is equipped with large-area Silicon PhotoMultiplier (SiPM) array detectors, placed on the outside of the TPC wall. SiPMs are arranged in a compact design meant to minimize the material used for PCBs, cables and connectors: the so-called Veto Photon-Detector Units (vPDUs).A vPDU comprises 16 vTiles, each containing 24 SIPMs, together with front-end electronics, and amotherboard, which distributes voltage and control signals, sums vTiles channels, and drives theelectrical signal transmission. The neutron veto will be equipped with 120 vPDUs. The paper willfocus on the production of the first vPDUs, describing the assembly chain in the U.K. institutes, inorder to underline the rigorous QA/QC procedures, up to the final characterization of the firstcompleted prototypes. Tests will be extensively performed in liquid nitrogen baths either for thesingle vTiles and for the assembled vPDUs, with the purpose of assigning a “quality passport” toeach component.

Six years’ experience of the XFEL 2K operation

The European X-Ray Free Electron laser (XFEL) has successfully been operated for more than 5 years. The superconducting cavities and magnets being key components of the cryomodules constituting the XFEL linac and injector are operated at 2 K in a liquid helium bath. A four stages cold compressor system is used to return the vapor to the XFEL helium refrigerator with the capability of pumping up to 110 g/s for compensating static and dynamic heat losses at 2 K.In this paper technical challenges with regard to the cold compressor system such as availability, 2K pressure stability and contamination of the 2K circuit are summarized. Influence of hydrostatic head on operation of all cooling circuits is analyzed. Issues related to the use of some kinds of instrumentation as pressure transmitters, flow meters and level sensors are discussed. The experiment regarding the future XFEL project as doubling of safety valves is described.

Study of Assimilation of Cored Wire into Liquid Steel Baths

Cored wire is a widespread technology used for performing additions into liquid metal baths as an alternative to bulk-additions. A laboratory-scale study was performed in which the kinetics of assimilation of cored wire in liquid steel baths were studied. An original dataset of positions of the wire/melt interface of cored wire as a function of the time and steel bath temperature was produced. The dataset was compared against results of simulations made with a transient 1D (radial) thermal model of the assimilation of cored wire, and demonstrated reasonable agreement. Hence, this paper provides a dataset that can be used as a resource for the validation of future developments in the field of modeling cored wire injection into liquid metal baths.

A diffusion model for liquid metal dealloying. Application to NiCu precursors dealloyed in liquid Ag

Liquid metal dealloying is a promising technique to elaborate porous metallic materials with potential applications for catalysis and energy storage. It consists in the selective dissolution of an element out of a precursor alloy by immersing it in a liquid bath. To model this process, we introduce a one-dimensional diffusion model that relies on the thermodynamic properties of the ternary system, and on a maximum velocity criterion of the reaction front. The model is compared to experimental measurements conducted on NiCu samples dealloyed in liquid Ag. Regarding the kinetics, the model enables to reach experimental time-scales, replicate experimental trends, and reveal the influence of the ligament structure on the dealloying rate. Also, by assuming thermodynamic equilibria between solid and liquid phases in the dealloyed region, the microstructure gradient obtained numerically is in satisfactory agreement with experimental measurements. These numerical results are obtained without adjustable parameters, which opens the possibility to predict dealloyed microstructures as function of the process parameters (precursor and bath composition, dealloying time and temperature, etc.).

Antibubble formation through single drop impact: Effect of density difference

The antibubble has emerged as a promising tool for the microdroplet manipulation since the intermediate air film can protect the inner globule from external contaminants. Moreover, the antibubble structure allows the convenient package and release of microdroplets since the intermediate air film would not hinder the separation between the inner globule and the liquid surface. Despite the development of various methods for antibubble formation, the initial approach involving single drop impact on a free liquid surface has received limited attention in subsequent studies, partly due to the challenges in replicating this phenomenon in practical applications. This paper presents an experimental investigation into antibubble formation via single drop impact on a liquid surface. Experimental results imply that antibubble formation requires the droplet to penetrate deeply into the liquid bath before the intermediate air film collapses or the deformed liquid surface contracts. A theoretical analysis is introduced to emphasize the crucial role of the density difference between the droplet and the liquid bath. A higher density of the droplet results in an increased penetration speed into the liquid bath, facilitating the formation of antibubbles. Notably, this study repeats the experimental results reported by Hughes and Hughes in 1932. Moreover, the method provides a means to control antibubble parameters such as diameter and air film thickness. This control offers valuable insight for subsequent investigations on antibubbles, establishing a foundation for further exploration and application of this intriguing phenomenon.

Nanostructuring of Ferritic Steel: A Review on Enhanced Surface Properties Using Ultrasonic Shot Peening

Nanostructuring of ferritic stainless steel refers to the process of intentionally reducing the grain size of the material at the nanoscale level. By manipulating the microstructure of the steel, it is possible to enhance its mechanical, physical, and chemical properties. Nanostructuring can significantly improve the strength, hardness, and wear resistance of ferritic stainless steel, while still maintaining its corrosion resistance. The increased density of grain boundaries and the complex dislocation network within the nanostructured material contribute to these improved properties. Moreover, the nanostructured ferritic stainless steel exhibits enhanced thermal stability, leading to better high-temperature performance and resistance to creep deformation. The small grain size also allows for increased precipitation of secondary phases, such as carbides, nitrides, or intermetallic compounds, which can further improve the material's properties. There are several methods to achieve nanostructuring in ferritic stainless steel, such as severe plastic deformation (SPD) techniques like high-pressure torsion, equal channel angular pressing, and accumulative roll bonding. These techniques impose extreme plastic deformation on the material. Leading to grain refinement below the micrometre range. Also, a novel method of surface nanostructuring ultrasonic shot peening (USP) is discussed in detail. Shot peening is a process in which small, spherical media, typically made of steel or ceramic, called "shots," are propelled onto the surface of a material at high velocities. Ultrasonic shot peening enhances the traditional shot peening process by introducing high-frequency vibrations to the shots. These vibrations are generated by an ultrasonic transducer, which is immersed in a bath of shots and liquid. The vibrations are transmitted through the liquid to the shots, causing them to collide with the surface of the ferritic steel at even higher velocities and energy levels than in traditional shot peening. In summary, nanostructuring of ferritic stainless steel offers great potential for tailoring the material's properties to meet specific application requirements, including improved strength, hardness, wear resistance, corrosion resistance, and high-temperature performance. USP is an effective surface treatment method for ferritic steel, offering advantages in terms of fatigue life, stress corrosion cracking resistance, surface hardness, and wear resistance.

Heterogenous Grain Nucleation in Al-Si Alloys: Types of Nucleant Inoculation

The objective of the current work is to establish, on the one hand, the conventional mechanisms of grain refining and, on the other hand, the effect of the refining-modification interaction in Sr-modified Al-Si alloys on the achieved grain refining and the modification of eutectic silicon. For this purpose, the hypereutectic alloy A390.1 (~17%Si) was used. Various grain refiners were used, namely, Al-10%Ti, Al-5%Ti-1%B, and Al-4%B. After the preparation of the liquid metal, several concentrations of these master alloys were added to the liquid bath according to the desired objective. The different melts prepared were heated at 750 °C and cast in a preheated graphite mold with a solidification rate of around 0.8 °C/s. The liquid metal was. The presence of strontium (added in the form of Al-10%Sr master alloy) and boron completely affects the microstructure of the alloy. An atom of Sr unites with 6 atoms of B to form a compound whose stoichiometric formula is of the SrB6 type, leading to a significant reduction in the modification. A strong relationship exists between the addition of B and the recovery level of Sr. The affinity between titanium and boron is stronger than the affinity between boron and strontium. Both B and TiB2 phase particles do not react with Si; it is only the Ti part of the Al-Ti-B master that forms (Al, Si)3Ti. Regardless of the amount of Si content in the alloy, the Al-4%B master alloy achieves the best grain refining compared to Ti-containing master alloys.

High temperature spin selectivity in a quantum dot qubit using reservoir spin accumulation

Employing spins in quantum dots for fault-tolerant quantum computing in large-scale qubit arrays with on-chip control electronics requires high-fidelity qubit operation at elevated temperature. This poses a challenge for single spin initialization and readout. Existing schemes rely on Zeeman splitting or Pauli spin blockade with typical energy scales of 0.1 or 1 meV for electron-based qubits, so that sufficient fidelity is obtained only at temperatures around or below 0.1 or 1 K, respectively. Here we describe a method to achieve high temperature spin selectivity in a quantum dot using a reservoir with a spin accumulation, which deterministically sets the spin of a single electron on the dot. Since spin accumulation as large as 10 meV is achievable in silicon, spin selection with electrically adjustable error rates below 10−4 is possible even in a liquid He bath at 4 K. Via the reservoir spin accumulation, induced and controlled by a nearby ferromagnet, classical information (magnetization direction) is mapped onto a spin qubit. These features provide the prospect of spin qubit operation at elevated temperatures and connect the worlds of quantum computing and spintronics.

Formulation of babadotan (Ageratum conyzoides) leaf extract natural liquid soap

Babadotan leaf has an antibacterial agent which able to protect the skin from types of infectious diseases. The antibacterial agent is potential to be developed as an antibacterial agent in soap preparation also potential replaced the SLS soap. The purpose of this study is to determine the best concentration extract of babadotan on liquid soap based SNI 06-4085-1996. The concentration treatment of babadotan leaf extract consisted of 9 levels (0-40%). Observations made included the degree of acidity (pH), specific gravity, foam stability, total plate count, sensory test consisting of a scoring test and a hedonic test. Then the data were analyzed using the Least Significant Difference (LSD) test at the 5% level. The result is the best babadotan extract liquid bath soap at an extract concentration of 25%. Babadotan extract liquid soap produces the best characteristics with a score color 3.32 (typical babadotan), aroma 3.67 (fresh), texture 2.95 (less viscous), foam 3.32 (like), and overall acceptability 3.52 (like). The 25% extract treatment resulted in a pH value of 6.59, a specific gravity is 1.03 and a total plate number of 3.4x104. The stability of the resulting foam is at 94.35%, antibacterial inhibition formed was 18.41 mm.

Drop impact on a heated liquid bath: Formation of antibubbles

As a ubiquitous phenomenon, drop impact on a liquid bath has been widely studied. This paper demonstrates a systematical study on the collision between the volatile drops and a heated liquid bath. In the experiments, water, alcohol, and hydrogen fluoride ether (HFE-7100) were used to generate drops. The experimental results vary with the impact parameters and liquid properties. Despite the common phenomena, like bouncing and coalescence, antibubble was observed at an intermediate impact velocity with the HFE-7100 drops. A regime map is built based on the experimental results. A qualitative model is proposed to elucidate the stability of the air film separating the impinging droplet and the surrounding liquid during collision. This study should stimulate further investigation on the surfactant-free antibubbles and the control of antibubble lifetime.

Impact of Injection Rate on Flow Mixing during the Refining Stage in an Electric Arc Furnace

During the refining stage of electric arc furnace (EAF) operation, molten steel is stirred to facilitate gas/steel/slag reactions and the removal of impurities, which determines the quality of the steel. The stirring process can be driven by the injection of oxygen, which is carried out by burners operating in lance mode. In this study, a computational fluid dynamics (CFD) platform is used to simulate the liquid steel flow dynamics in an industrial-scale scrap-based EAF. The CFD platform simulates the three-dimensional, transient, non-reacting flow of the liquid steel bath stirred by oxygen injection to analyze the mixing process. In particular, the CFD study simulates liquid steel flow in an industrial-scale EAF with three asymmetric coherent jets, which impacts the liquid steel mixing under different injection conditions. The liquid steel mixing is quantified by defining two variables: the mixing time and the standard deviation of the flow velocity. The results indicate that the mixing rate of the bath is determined by flow dynamics near the injection cavities and that the formation of very low-velocity regions or ‘dead zones’ at the center of the furnace and the balcony regions prevents flow mixing. This study includes a baseline case, where oxygen is injected at 1000 SCFM in all the burners. Two sets of cases are also included: The first set considers cases where oxygen is injected at a reduced and at an increased uniform flow rate, 750 and 1250 SCFM, respectively. The second set considers cases with non-uniform injection rates in each burner, which keep the same total flow rate of the baseline case, 3000 SCFM. Comparison between the two sets of simulations against the baseline case shows that by increasing the uniform flow rate from 1000 to 1250 SCFM, the mixing time is reduced by 10.9%. Moreover, all the non-uniform injection cases reduce the mixing time obtained in the baseline case. However, the reduction in mixing times in these cases is accompanied by an increase in the standard deviations of the flow field. Among the non-uniform injection cases, the largest reduction in mixing time compared to the baseline case is 10.2%, which is obtained when the largest flow rates are assigned to coherent jets located opposite each other across the furnace.

Nitriding layer depth detection based on mixing frequency nonlinear ultrasonic parameters

Nitriding treatment can improve the surface properties of workpieces, thus increasing the service life of the workpiece. The depth of nitriding layer is not only one of the important indexes for evaluating the nitriding effect, but also an important factor affecting the end-use performance of the workpiece. While the existing hardness and metallographic methods cannot meet the needs for non-destructive testing of nitriding layer depth in shaft parts. Therefore, a method using non-linear ultrasonic testing technology is proposed for non-destructive evaluation of nitriding layer depth. In this study, 1045 steel shaft specimens with different nitriding layer depths were prepared by a liquid salt bath nitriding method. The total depth of the nitriding layer was measured using a microhardness tester, and metallographic microscopy was applied to observe microstructure changes before and after nitriding treatment. With the proposed non-destructive method, the longitudinal critically refracted (LCR) wave mixing detection model was established and the ultrasonic nonlinear coefficients were used for characterizing the nitrided layer depths. Experimental results show that the LCR wave sum frequency (LCRWSF) detection model better characterizes the nitriding layer depth of 1045 steel and has higher sensitivity. As a result, the LCRWSF model is more suitable to efficiently estimate the nitrided layer depth.

Infinite-memory classical wave-particle entities, attractor-driven active particles, and the diffusionless Lorenz equations.

A classical wave-particle entity (WPE) can materialize as a millimeter-sized droplet walking horizontally on the free surface of a vertically vibrating liquid bath. This WPE comprises a particle (droplet) that shapes its environment by locally exciting decaying standing waves, which, in turn, guides the particle motion. At high amplitude of bath vibrations, the particle-generated waves decay very slowly in time and the particle motion is influenced by the history of waves along its trajectory. In this high-memory regime, WPEs exhibit hydrodynamic quantum analogs where quantum-like statistics arise from underlying chaotic dynamics. Exploration of WPE dynamics in the very high-memory regime requires solving an integrodifferential equation of motion. By using an idealized one-dimensional WPE model where the particle generates sinusoidal waves, we show that in the limit of infinite memory, the system dynamics reduce to a 3D nonlinear system of ordinary differential equations (ODEs) known as the diffusionless Lorenz equations (DLEs). We use our algebraically simple ODE system to explore in detail, theoretically and numerically, the rich set of periodic and chaotic dynamical behaviors exhibited by the WPE in the parameter space. Specifically, we link the geometry and dynamics in the phase-space of the DLE system to the dynamical and statistical features of WPE motion, paving a way to understand hydrodynamic quantum analogs using phase-space attractors. Our system also provides an alternate interpretation of an attractor-driven particle, i.e., an active particle driven by internal state-space variables of the DLE system. Hence, our results might also provide new insights into modeling active particle locomotion.

Bio-inspired sustained entrainment in immiscible liquid–liquid systems for collecting floating oil

Entrainment, where a solid object in a liquid bath moves towards the air phase, is common in industry and daily-life.

Ultra-Chaos in the Motion of Walking Droplet

A liquid bath vibrating vertically can lead to the emergence of a self-propelled walking droplet on its free surface, which can exhibit chaotic motion. It is well-known that trajectories of a chaotic system are sensitive to its initial condition, known as the “butterfly-effect”, while its statistics normally remain stable to small disturbances: this type of chaos is called “normal-chaos”. However, a concept called “ultra-chaos” has been recently introduced, whose statistical features are unstable, i.e. extremely sensitive to small disturbances. Up to now, a few examples of ultra-chaos have been reported. In this paper, the influence of tiny disturbances on the motion of walking droplet is investigated. It is found that both normal-chaos and ultra-chaos exist in the motion of the walking droplet. Different from the normal-chaotic motion, even the statistical properties of the droplet’s ultra-chaotic motion are sensitive to tiny disturbances. Therefore, this illustrates once again that ultra-chaos indeed exists widely and represents a higher disorder compared with normal-chaos. The ultra-chaos as a new concept can widen our knowledge about chaos and provide us with a new point of view to study chaotic properties. It should be emphasized that, for an ultra-chaos, it is impossible to repeat any results of its physical experiments or numerical simulations even in the meaning of statistics! Unfortunately, reproducibility is a corner stone of modern science. Thus, the paradigm of modern scientific research might be invalid for an ultra-chaotic system.