Thermodynamic Equilibrium Conditions Research Articles

Inside Ceramics and Between MgO Grains: Solid-State Synthesis of Intergranular Semiconducting or Magnetic Spinels.

Configurations of composite metal oxide nanoparticles are typically far off their thermodynamic equilibrium state. As such they represent a versatile but so far overlooked source material for the intergranular solid-state chemistry inside ceramics. Here, it is demonstrated how the admixture of Fe3+ and In3+ ions to MgO nanoparticles, as achieved by flame spray pyrolysis, can be used to engage ion exsolution, phase separation, and subsequent spinel formation inside the network of diamagnetic and insulating MgO grains. Extremely high uniformity in the distribution of intergranular ferrimagnetic MgFe2O4 films and grains with resulting magnetic coercivity values that depend on the nanoparticles' initial Fe3+ concentration is achieved. Moreover, percolating networks of semiconducting MgIn2O4 are derived from MgO nanoparticles with admixtures of 20 at% In3+ that gives rise to an enhancement of dc conductivity values by more than five orders of magnitude in comparison to the insulating MgO host. The here presented approach is general and applicable to the synthesis of a variety of functional spinel nanostructures embedded inside ceramic matrices. Nanoparticle loading with aliovalent impurity ions, the level of nanoparticle powder density after compaction, and sintering temperature are key parameters for this novel type of solid-state chemistry in between the host grains.

Thermal Properties of Cu–Al–Ge Alloy PCM for Improving Thermal Energy Storage of Current CSP

Metallic phase change material was proposed and examined at melting/eutectic temperatures less than 600 °C for latent heat storage in concentrated solar power. The PCM alloy can potentially charge/discharge thermal energy as a sensible/latent heat at the temperature range of 414-527 °C. The working temperatures of PCM alloy are in operation temperatures of current molten-salt based CSP plant. In this study, thermal response testing of PCM alloy and sensible/latent storage unit that PCM alloy was loaded in a ceramic honeycomb were prepared in a laboratory scale. The thermal charging/discharging performance of PCM alloy and sensible/latent storage unit were experimentally examined and compared. The storage unit provided thermal release/absorption behaviour at close to temperatures of the thermodynamic equilibrium state.

Metastable CoCu2O3 Nanocrystals from Combustion-Aerosols for Molecular Sensing and Catalysis.

Metastable nanostructures are kinetically trapped in local energy minima featuring intriguing surface and material properties. To unleash their potential, there is a need for non-equilibrium processes capable of stabilizing a large range of crystal phases outside thermodynamic equilibrium conditions by closely and flexibly controlling atomic reactant composition, spatial temperature distribution and residence time. Here, the capture of metastable pseudo-binary metal oxides at room temperature is demonstrated with scalable combustion-aerosol processes. By a combination of X-ray diffraction, electron microscopy and on-line flame characterization, the occurrence of metastable CoCu2O3 is investigated with controlled crystal size (4-16nm) over thermodynamically stable CuO and Co3O4. Immediate practical impact is demonstrated by exceptional sensing and stable catalytic performance for air pollutant detection (e.g., 15 parts-per-billion benzene) shown for, at least, 21 days. This approach can be extended to various binary, ternary and high entropy oxides with even more components. Also, secondary phases can be loaded on such metastable nanocrystals to access novel materials promising for actuators, energy storage or solar cells.

Thermodynamic approach for designing processing routes of 4Mn quenching and partitioning steel

AbstractThe study addresses the design and optimization of chemical composition and processing routes of new quenching and partitioning medium-Mn alloy using theoretical and experimental approaches. The thermodynamic calculations using Thermo-Calc and JMatPro software were carried out to characterize the influence of Mn, Si and Al contents on cementite formation and precipitation processes. The evolution of individual phases as a function of temperature under thermodynamic equilibrium conditions was estimated. The investigations included the determination of continuous cooling transformation (CCT) and the time–temperature transformation (TTT) diagrams of a model 4Mn alloy. The calculated equilibrium diagrams were compared with the experimental diagrams determined using dilatometric tests. Microstructural observations were carried out to verify the results of dilatometric measurements. The results of thermodynamic calculations and experimental tests showed the moderate agreement. It is related to the inaccuracy of currently available models in the used software and/or non-equilibrium conditions of experimental tests.

A method to obtain the trapping energy and trapping range between hydrogen and defects at finite temperature

The binding energy between hydrogen (H) and defects in solid phase materials has been widely studied, which is of vital importance to understand the H retention effects and defect growth mechanisms. However, present studies of binding energy through density functional theory (DFT) or the molecular statics (MS) method were usually performed at 0 K, which could not take the influence of entropy into consideration. In this work, a thermodynamic method has been proposed to obtain the trapping energy between H and defects at finite temperatures. The method is based on the rate theory, which uses trapping energy (V) and trapping range (δ) to describe the trapping properties of defects. Ultimately, a parameterized H spatial cumulative distribution function at thermodynamic equilibrium state could be given. The trapping energy and trapping range parameters in the function can be determined by contrast with the results obtained from molecular dynamics or other methods. This method has been applied to calculate the trapping energies and trapping ranges of H to helium bubble and grain boundary, respectively. Further discussion has been made on the discrepancy between trapping energies obtained by this method and the conventional DFT/MS method.

Improved prediction of biomass gasification models through machine learning

Gasification of lignocellulosic biomass can be used to produce syngas used as a biorefinery feedstock. To facilitate the commercialisation of the gasification process, models are used to predict the outputs, simulate the impacts of irregular circumstances, and analyse process feasibility. This paper presents a hybrid model combining Aspen Plus and machine learning (ML) algorithms to enhance the prediction of gasification outputs. A base case gasification process flowsheet simulation was implemented in Aspen Plus based on assumed thermodynamic equilibrium conditions which can lead to inaccurate results. To address this, six ML algorithms were applied to collected experimental data and analysed for accuracy and efficiency. The feature importance, accuracy improvement, and the effect of implementing the ML predictions in the gasification block on the rest of the flowsheet were investigated. This paper emphasises the need of higher accuracy models and the great potential of ML approaches to offer high accurate predictions.

Current Status and Development Trend of Research on Polymer-Based Kinetic Inhibitors for Natural Gas Hydrates.

As the understanding of natural gas hydrates as a vast potential resource deepens, their importance as a future clean energy source becomes increasingly evident. However, natural gas hydrates trend towards secondary generation during extraction and transportation, leading to safety issues such as pipeline blockages. Consequently, developing new and efficient natural gas hydrate inhibitors has become a focal point in hydrate research. Kinetic hydrate inhibitors (KHIs) offer an effective solution by disrupting the nucleation and growth processes of hydrates without altering their thermodynamic equilibrium conditions. This paper systematically reviews the latest research progress and development trends in KHIs for natural gas hydrates, covering their development history, classification, and inhibition mechanisms. It particularly focuses on the chemical properties, inhibition effects, and mechanisms of polymer inhibitors such as polyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVCap). Studies indicate that these polymer inhibitors provide an economical and efficient solution due to their low dosage and environmental friendliness. Additionally, this paper explores the environmental impact and biodegradability of these inhibitors, offering guidance for future research, including the development, optimization, and environmental assessment of new inhibitors. Through a comprehensive analysis of existing research, this work aims to provide a theoretical foundation and technical reference for the commercial development of natural gas hydrates, promoting their safe and efficient use as a clean energy resource.

Spatial Distribution of C4H and c-C3H2 in Cold Molecular Cores

C4H and c-C3H2, as unsaturated hydrocarbon molecules, are important for forming large organic molecules in the interstellar medium. We present mapping observations of C4H (N = 9−8) lines, c-C3H2 (J Ka,Kb = 21,2–10,1), and H13CO+ (J = 1−0) toward 19 nearby cold molecular cores in the Milky Way with the IRAM 30 m telescope. C4H 9–8 was detected in 13 sources, while c-C3H2 was detected in 18 sources. The widely existing C4H and c-C3H2 molecules in cold cores provide material to form large organic molecules. Different spatial distributions between C4H 9–8 and c-C3H2 2–1 were found. The relative abundances of these three molecules were obtained under the assumption of local thermodynamic equilibrium conditions with a fixed excitation temperature. The abundance ratio of C4H to c-C3H2 ranged from 0.34 ± 0.09 in G032.93+02 to 4.65 ± 0.50 in G008.67+22. A weak correlation between C4H/H13CO+ and c-C3H2/H13CO+ abundance ratios was found, with a correlation coefficient of 0.46, which indicates that there is no tight astrochemical connection between C4H and c-C3H2 molecules.

Investigation on thermodynamic stability and electronic structure properties of Bi2CrO6 (0 0 1) surface using density functional theory

A density functional theory (DFT)-based thermodynamic approach was applied to investigate the stability and analyze the surface electronic structures of potential termination structures for the Bismuth chromate (Bi2CrO6) (001) surface. Five Bi2CrO6 (001) surface terminations can be stabilized under certain thermodynamic equilibrium conditions, according to the constructed Bi-Cr-O surface phase diagrams, which are based on calculated surface Gibbs free energies. Analysis of the surface electronic structure shows that O-Bi surface termination has high potential for photocatalytic applications. Additionally, the work functions exhibit substantial differences across various Bi2CrO6 surface terminations, implying that by selecting the thermodynamically more stable surface termination under suitable conditions, the performance of the direct Z-scheme heterostructure based on Bi2CrO6 can be optimized. These findings offer a valuable approach for subsequent experimental research on Bi2CrO6-based photocatalysts and facilitate the investigation of the intrinsic characteristics of Bi2CrO6 surfaces.

Application of coupled hydrodynamic and thermal Lattice–Boltzmann simulation on permeability estimation of hydrate-bearing sediment during hydrate dissociation processes

Natural gas hydrates, which are plentifully distributed in ocean floor sediments and permafrost regions, are considered a promising unconventional energy resource. The current hydrate production approaches aim at breaking the thermodynamic equilibrium state to stimulate hydrate dissociation that releases methane and water molecules, which causes formation porosity and permeability alteration. Efficient estimation of permeability during hydrate dissociation is essential to evaluate the economic feasibility for gas production from hydrate-bearing sediment. In this paper, we developed a coupled hydrodynamic and thermal Lattice–Boltzmann (LB) method to rigorously model the coupled processes of mass transfer, conjugate heat transfer, and fluid flow during the hydrate dissociation. We then carried out numerical simulation on the dissociation processes of hydrate formation with the three most common hydrate distribution morphologies, pore-filling, grain-coating and dispersed, under two production approaches that are depressurization, and depressurization with thermal intervention. Our simulation results indicated that the coupling of gas transport and heat transfer has significant impact on pore geometry evolution, especially pore connectivity, during hydrate dissociation processes due to the endothermic nature of the dissociation processes. Therefore, it is vital to consider the coupling effects for estimation of hydrate formation permeability through numerical simulations.

The Problem of the Influence of the Nature of Metal on the Electrocatalytic Process and Its Solution Based on a Combination of the Vacancy Thermodynamic Model and Equilibrium Statistical Thermodynamics

The Problem of the Influence of the Nature of Metal on the Electrocatalytic Process and Its Solution Based on a Combination of the Vacancy Thermodynamic Model and Equilibrium Statistical Thermodynamics

A Broad Line-width, Compact, Millimeter-bright Molecular Emission Line Source near the Galactic Center

A compact source, G0.02467–0.0727, was detected in Atacama Large Millimeter/submillimeter Array 3 mm observations in continuum and very broad line emission. The continuum emission has a spectral index α ≈ 3.3, suggesting that the emission is from dust. The line emission is detected in several transitions of CS, SO, and SO2 and exhibits a line width FWHM ≈ 160 km s−1. The line profile appears Gaussian. The emission is weakly spatially resolved, coming from an area on the sky ≲1″ in diameter (≲104 au at the distance of the Galactic center, GC). The centroid velocity is v LSR ≈ 40–50 km s−1, which is consistent with a location in the GC. With multiple SO lines detected, and assuming local thermodynamic equilibrium (LTE) conditions, the gas temperature is T LTE = 13 K, which is colder than seen in typical GC clouds, though we cannot rule out low-density, subthermally excited, warmer gas. Despite the high velocity dispersion, no emission is observed from SiO, suggesting that there are no strong (≳10 km s−1) shocks in the molecular gas. There are no detections at other wavelengths, including X-ray, infrared, and radio. We consider several explanations for the millimeter ultra-broad-line object (MUBLO), including protostellar outflow, explosive outflow, a collapsing cloud, an evolved star, a stellar merger, a high-velocity compact cloud, an intermediate-mass black hole, and a background galaxy. Most of these conceptual models are either inconsistent with the data or do not fully explain them. The MUBLO is, at present, an observationally unique object.

First Extragalactic Detection of Thermal Hydroxyl (OH) 18 cm Emission in M31 Reveals Abundant CO-faint Molecular Gas

The most abundant interstellar molecule, molecular hydrogen (H2), is practically invisible in cold molecular clouds. Astronomers typically use carbon monoxide (CO) to trace the bulk distribution and mass of H2 in our galaxy and many others. CO observations alone fail to trace a significant component of molecular gas known as “CO-dark” molecular gas, which can be probed with molecules such as OH and CH. We present an extremely sensitive pilot search for the 18 cm hydroxyl (OH) lines in the Andromeda galaxy (M31) with the 100 m Robert C. Byrd Green Bank Telescope. We successfully detected the 1665 and 1667 MHz OH lines in faint emission. The 1665/1667 MHz line ratio displays the characteristic 5:9 ratio predicted under conditions of local thermodynamic equilibrium. To our knowledge, this is the first detection of nonmaser 18 cm OH emission in another galaxy. We compare our OH and H i observations with archival CO (1–0) observations. Our OH detection position overlaps with the previously discovered Arp Outer Arm in CO. Our best estimates show that the amount of H2 traced by OH is 100%–140% higher than the amount traced by CO in this sight line. The amount of dark molecular gas implied by dust data supports this conclusion. We conclude that the 18 cm OH lines hold promise as a valuable tool for mapping of the “CO-dark” and “CO-faint” molecular gas phase in nearby galaxies, especially with upcoming multibeam, phased-array feed receivers on radio telescopes, which will allow for drastically improved mapping speeds of faint signals.

An improved and extended parameterization of the CO2 15 µm cooling in the middle and upper atmosphere (CO2_cool_fort-1.0)

Abstract. The radiative infrared cooling of CO2 in the middle atmosphere, where it emits under non-local thermodynamic equilibrium (non-LTE) conditions, is a crucial contribution to the energy balance of this region and hence to establishing its thermal structure. The non-LTE computation is too CPU time-consuming to be fully incorporated into climate models, and hence it is parameterized. The most used parameterization of the CO2 15 µm cooling for Earth's middle and upper atmosphere was developed by Fomichev et al. (1998). The valid range of this parameterization with respect to CO2 volume mixing ratios (VMRs) is, however, exceeded by the CO2 of several scenarios considered in the Coupled Climate Model Intercomparison Projects, in particular the abrupt-4×CO2 experiment. Therefore, an extension, as well as an update, of that parameterization is both needed and timely. In this work, we present an update of that parameterization that now covers CO2 volume mixing ratios in the lower atmosphere from ∼0.5 to over 10 times the CO2 pre-industrial value of 284 ppmv (i.e. 150 to 3000 ppmv). Furthermore, it is improved by using a more contemporary CO2 line list and the collisional rates that affect the CO2 cooling rates. Overall, its accuracy is improved when tested for the reference temperature profiles as well as for measured temperature fields covering all expected conditions (latitude and season) of the middle atmosphere. The errors obtained for the reference temperature profiles are below 0.5 K d−1 for the present-day and lower CO2 VMRs. Those errors increase to ∼1–2K d−1 at altitudes between 110 and 120 km for CO2 concentrations of 2 to 3 times the pre-industrial values. For very high CO2 concentrations (4 to 10 times the pre-industrial abundances), those errors are below ∼1 K d−1 for most regions and conditions, except at 107–135 km, where the parameterization overestimates them by ∼1.2 %. These errors are comparable to the deviation of the non-LTE cooling rates with respect to LTE at about 70 km and below, but they are negligible (several times smaller) above that altitude. When applied to a large dataset of global (pole to pole and four seasons) temperature profiles measured by MIPAS (Michelson Interferometer for Passive Atmospheric Spectroscopy) (middle- and upper-atmosphere mode), the errors of the parameterization for the mean cooling rate (bias) are generally below 0.5 K d−1, except between 5×10-3 and 3×10-4 hPa (∼85–98 km), where they can reach biases of 1–2 K d−1. For single-temperature profiles, the cooling rate error (estimated by the root mean square – rms – of a statistically significant sample) is about 1–2 K d−1 below 5×10-3 hPa (∼85 km) and above 2×10-4 hPa (∼102 km). In the intermediate region, however, it is between 2 and 7 K d−1. For elevated stratopause events, the parameterization underestimates the mean cooling rates by 3–7 K d−1 (∼10 %) at altitudes of 85–95 km and the individual cooling rates show a significant rms (5–15 K d−1). Further, we have also tested the parameterization for the temperature obtained by a high-resolution version of the Whole Atmosphere Community Climate Model (WACCM-X), which shows a large temperature variability and wave structure in the middle atmosphere. In this case, the mean (bias) error of the parameterization is very small, smaller than 0.5 K d−1 for most atmospheric layers, reaching only maximum values of 2 K d−1 near 5×10-4 hPa (∼ 96 km). The rms has values of 1–2 K d−1 (∼20 %) below ∼2×10-2 hPa (∼80 km) and values smaller than 4 K d−1 (∼2 %) above 10−4 hPa (∼105 km). In the intermediate region between ∼5×10-3 and ∼2×10-4 hPa (85–102 km), the rms is in the range of 5–12 K d−1. While these values are significant in percentage at ∼5×10-3–5×10-4 hPa, they are very small above ∼5×10-4 hPa (96 km). The routine is very fast, taking (1.5–7.5) ×10-5 s, depending on the extension of the atmospheric profile, the processor and the Fortran compiler.

A collision operator for describing dissipation in noncanonical phase space

The phase space of a noncanonical Hamiltonian system is partially inaccessible due to dynamical constraints (Casimir invariants) arising from the kernel of the Poisson tensor. When an ensemble of noncanonical Hamiltonian systems is allowed to interact, dissipative processes eventually break the phase space constraints, resulting in a thermodynamic equilibrium described by a Maxwell–Boltzmann distribution. However, the time scale required to reach Maxwell–Boltzmann statistics is often much longer than the time scale over which a given system achieves a state of thermal equilibrium. Examples include diffusion in rigid mechanical systems, as well as collisionless relaxation in magnetized plasmas and stellar systems, where the interval between binary Coulomb or gravitational collisions can be longer than the time scale over which stable structures are self-organized. Here, we focus on self-organizing phenomena over spacetime scales such that particle interactions respect the noncanonical Hamiltonian structure, but yet act to create a state of thermodynamic equilibrium. We derive a collision operator for general noncanonical Hamiltonian systems, applicable to fast, localized interactions. This collision operator depends on the interaction exchanged by colliding particles and on the Poisson tensor encoding the noncanonical phase space structure, is consistent with entropy growth and conservation of particle number and energy, preserves the interior Casimir invariants, reduces to the Landau collision operator in the limit of grazing binary Coulomb collisions in canonical phase space, and exhibits a metriplectic structure. We further show how thermodynamic equilibria depart from Maxwell–Boltzmann statistics due to the noncanonical phase space structure, and how self-organization and collisionless relaxation in magnetized plasmas and stellar systems can be described through the derived collision operator.

Multidimensional Electrochemistry Decodes the Operando Mechanism of Hydrogen Oxidation

AbstractBeing an efficient approach to the utilization of hydrogen energy, the hydrogen oxidation reaction (HOR) is of particular significance in the current carbon‐neutrality time. Yet the mechanistic picture of the HOR is still blurred, mostly because the elemental steps of this reaction are rapid and highly entangled, especially when deviating from the thermodynamic equilibrium state. Here we report a strategy for decoding the HOR mechanism under operando conditions. In addition to the wide‐potential‐range I–V curves obtained using gas diffusion electrodes, we have applied the AC impedance spectroscopy to provide independent and complementary kinetic information. Combining multidimensional data sources has enabled us to fit, in mathematical rigor, the core kinetic parameter set in a 5‐D data space. The reaction rate of the three elemental steps (Tafel, Heyrovsky, and Volmer reactions), as a function of the overpotential, can thus be distilled individually. Such an undocumented kinetic picture unravels, in detail, how the HOR is controlled by the elemental steps on polarization. For instance, at low polarization region, the Heyrovsky reaction is relatively slow and can be ignored; but at high polarization region, the Heyrovsky reaction will surpass the Tafel reaction. Additionally, the Volmer reaction has been the fastest within overpotentials of interest. Our findings not only offer a better understanding of the HOR mechanism, but also lay the foundation for the development of improved hydrogen energy utilization systems.

Multidimensional Electrochemistry Decodes the Operando Mechanism of Hydrogen Oxidation.

Being an efficient approach to the utilization of hydrogen energy, the hydrogen oxidation reaction (HOR) is of particular significance in the current carbon-neutrality time. Yet the mechanistic picture of the HOR is still blurred, mostly because the elemental steps of this reaction are rapid and highly entangled, especially when deviating from the thermodynamic equilibrium state. Here we report a strategy for decoding the HOR mechanism under operando conditions. In addition to the wide-potential-range I-V curves obtained using gas diffusion electrodes, we have applied the AC impedance spectroscopy to provide independent and complementary kinetic information. Combining multidimensional data sources has enabled us to fit, in mathematical rigor, the core kinetic parameter set in a 5-D data space. The reaction rate of the three elemental steps (Tafel, Heyrovsky, and Volmer reactions), as a function of the overpotential, can thus be distilled individually. Such an undocumented kinetic picture unravels, in detail, how the HOR is controlled by the elemental steps on polarization. For instance, at low polarization region, the Heyrovsky reaction is relatively slow and can be ignored; but at high polarization region, the Heyrovsky reaction will surpass the Tafel reaction. Additionally, the Volmer reaction has been the fastest within overpotentials of interest. Our findings not only offer a better understanding of the HOR mechanism, but also lay the foundation for the development of improved hydrogen energy utilization systems.

EMISSA: Exploring millimetre indicators of solar-stellar activity III. Comparison of Ca II indices and millimetre continua in a 3D model atmosphere

Amongst several spectral lines, some of the strongest chromospheric diagnostics are offered by the Ca II H K lines. These lines can be used to gauge the temperature stratification of the atmosphere since the line core and wings are formed in different regions of the solar atmosphere. Furthermore, the Ca II lines act as tracers for the magnetic structure of the solar atmosphere, as the line cores are formed in the upper chromosphere even though they are formed in non-local thermodynamic equilibrium (NLTE). In contrast, the formation of millimetre (mm) continuum radiation occurs under local thermodynamic equilibrium (LTE) conditions. As a result, the brightness temperatures obtained from observations with the Atacama Large Millimetre/Submillimetre Array (ALMA) offer a complementary perspective on the activity and thermal structure of stellar atmospheres. The overall aim is to establish more robust solar/stellar activity indicators using ALMA observations in comparison with classical diagnostics, such as the s index and infrared triplet (IRT) index. We employed the 1.5D radiative transfer codes RH1.5D and advanced radiative transfer (ART) to compute the synthetic spectra for the Ca II lines and the millimetre (mm) continua, respectively. These calculations were performed using an enhanced network atmosphere model, which incorporates non-equilibrium hydrogen ionisation generated by the state-of-the-art 3D radiation magnetohydrodynamics (rMHD) Bifrost code. To account for the limited spatial resolution of ALMA, we simulated the effect using a Gaussian point spread function (PSF). Additionally, we analysed the correlations and slopes of scatter plots between the Ca II indices and mm continuum for the original and degraded resolutions, focusing on the entire simulation box, quiet Sun regions, and enhanced network patches separately. The activity indices generated from these lines could further be used to compare the spectra of Sun-like stars with the solar spectrum. We present a comparative study between synthetic continuum brightness temperature maps at mm wavelengths (0.3 mm to 8.5 mm) and the Ca II activity indices; namely, the s index and infrared triplet (IRT) index. The Ca II activity indices and mm brightness temperatures are weakly correlated at the high resolution, with the highest correlation observed at a wavelength of 0.3 mm, corresponding to ALMA band 10. As the resolution decreases, the correlation consistently increases. Conversely, the slopes exhibit a decreasing trend with increasing wavelength, while the degradation of resolution does not noticeably affect the calculated slopes. As the spatial resolution decreases, the standard deviations of the Ca II activity indices and brightness temperatures decrease, while the correlations between them increase. However, the slopes do not exhibit significant changes. Consequently, these relationships could be valuable for calibrating the mm continuum maps obtained through ALMA observations.

АНАЛІЗ РОЗВИТКУ РЕАКЦІЇ ОКИСЛЕННЯ ВУГЛЕЦЮ НИЗЬКОВУГЛЕЦЕВОЇ СТАЛІ В КОВШІ ПІД ВАКУУМОМ

The object of research is the process of vacuuming steel in a ladle. The purpose of the study is to determine the degree of approach of degassing reactions to equilibrium and removal rates by articles. Research methods - theoretical studies are based on the basic provisions of physical chemistry and the theory of metallurgical processes, thermodynamic calculations of the non-equilibrium reactions of degassing. Scientific novelty - in vacuum degassing processes, the approximation of the corresponding reactions to equilibrium plays a significant role, in industrial vacuum installations, the equilibrium between carbon and oxygen dissolved in steel is not achieved due to ex-tremely small concentrations of interacting substances, the speed of the chemical reaction decreases so much that it does not allow for processing time to even approach the state of thermodynamic equilibrium. Practical significance - to ensure a high degree of implementation of the deoxidizing ability of carbon in vacuum conditions, it is neces-sary to: apply the main lining of steel pouring ladles; maintain a high basicity of slag and a minimum content of iron oxides in it; mix the melt in the ladle with an inert gas to facilitate the conditions for the nucleation of carbon oxidation reaction products.

Modeling of vacuuming of low-carbon steel in a ladle taking into account the approach of degasation reactions to equilibrium

The object of research is the process of vacuuming steel in a ladle. The purpose of the study is to determine the degree of approach of degassing reactions to equilibrium and removal rates by articles. Research methods - theoretical studies are based on the basic provisions of physical chemistry and the theory of metallurgical processes, thermodynamic calculations of the non-equilibrium reactions of degassing. Scientific novelty - in vacuum degassing processes, the approximation of the corresponding reactions to equilibrium plays a significant role, in industrial vacuum installations, the equilibrium between carbon and oxygen dissolved in steel is not achieved due to extremely small concentrations of interacting substances, the speed of the chemical reaction decreases so much that it does not allow for processing time to even approach the state of thermodynamic equilibrium. Practical significance - to ensure a high degree of implementation of the deoxidizing ability of carbon in vacuum conditions, it is necessary to: apply the main lining of steel pouring ladles; maintain a high basicity of slag and a minimum content of iron oxides in it; mix the melt in the ladle with an inert gas to facilitate the conditions for the nucleation of carbon oxidation reaction products.