Liquid Metal Phase Research Articles

Gallium-rich Pd-Ga phases as supported liquid metal catalysts.

A strategy to develop improved catalysts is to create systems that merge the advantages of heterogeneous and molecular catalysis. One such system involves supported liquid-phase catalysts, which feature a molecularly defined, catalytically active liquid film/droplet layer adsorbed on a porous solid support. In the past decade, this concept has also been extended to supported ionic liquid-phase catalysts. Here we develop this idea further and describe supported catalytically active liquid metal solutions (SCALMS). We report a liquid mixture of gallium and palladium deposited on porous glass that forms an active catalyst for alkane dehydrogenation that is resistant to coke formation and is thus highly stable. X-ray diffraction and X-ray photoelectron spectroscopy, supported by theoretical calculations, confirm the liquid state of the catalytic phase under the reaction conditions. Unlike traditional heterogeneous catalysts, the supported liquid metal reported here is highly dynamic and catalysis does not proceed at the surface of the metal nanoparticles, but presumably at homogeneously distributed metal atoms at the surface of a liquid metallic phase.

Silicon-aluminum additives assisted hydrothermal process for stabilization of heavy metals in fly ash from MSW incineration

Hydrothermal treatment (HT), as a novel promising technology, still could not make fly ash (FA) from municipal solid waste incineration (MSWI) meet the standard of non-hazardous waste, due to the unsuccessful formation of aluminosilicate minerals caused by the lack of Si and Al in FA. In this research the mechanism of zeolites formation and stabilization/migration of heavy metals during hydrothermal process affected by external addition of coal fly ash (CFA), bentonite, and kaolin as silicon-aluminum source, were studied. Tobermorite could be synthesized, attributing to the proper element proportion of Ca/(Si+Al) adjusted by 30% of additives addition. Heavy metals were detected on the surface of tobermorite crystalline. The leaching toxicity of Pb, Zn, Cu, Cd, Cr in FA were significantly reduced after HT, associated with the transformation into the residue fraction. The decrease of heavy metals in liquid phase and the decrease of leaching toxicity in solid phase were observed, indicating that heavy metals were really stabilized in the treated FA, rather than transferred into liquid. Higher reaction temperature could promote the formation of tobermorite, but increase the leaching toxicity and migration of heavy metals. Addition of 30% of CFA and temperature of 150°C would be the recommended technological parameters.

Experimental Determination of Partitioning in the Fe-Ni System for Applications to Modeling Meteoritic Metals.

Experimental trace element partitioning values are often used to model the chemical evolution of metallic phases in meteorites, but limited experimental data were previously available to constrain the partitioning behavior in the basic Fe-Ni system. In this study, we conducted experiments that produced equilibrium solid metal and liquid metal phases in the Fe-Ni system and measured the partition coefficients of 25 elements. The results are in good agreement with values modeled from IVB iron meteorites and with the limited previous experimental data. Additional experiments with low levels of S and P were also conducted, to help constrain the partitioning behaviors of elements as a function of these light elements. The new experimental results were used to derive a set of parameterization values for element solid metal-liquid metal partitioning behavior in the Fe-Ni-S, Fe-Ni-P, and Fe-Ni-C ternary systems at 0.1 MPa. The new parameterizations require that the partitioning behaviors in the light-element-free Fe-Ni system are those determined experimentally by this study, in contrast to previous parameterizations that allowed this value to be determined as a best-fit parameter. These new parameterizations, with self-consistent values for partitioning in the end-member Fe-Ni system, provide a valuable resource for future studies that model the chemical evolution of metallic phases in meteorites.

A Mathematical Model for Reactions During Top-Blowing in the AOD Process: Derivation of the Model

In an earlier work, a fundamental mathematical model was proposed for side-blowing operation in the argon–oxygen decarburization (AOD) process. The purpose of this work is to present a new model, which focuses on the reactions during top-blowing in the AOD process. The model considers chemical reaction rate phenomena between the gas jet and the metal bath as well as between the gas jet and metal droplets. The rate expressions were formulated according to a law of mass action-based method, which accounts for the mass-transfer resistances in the liquid metal, gas, and slag phases. The generation rate of the metal droplets was related to the blowing number theory. This paper presents the description of the model, while validation and preliminary results are presented in the second part of this work.

回转窑处理钢铁厂含锌粉尘结圈机制的研究

针对回转窑处理含锌粉尘过程中的结圈问题，采用XRF、SEM和EDS等测试方法对窑中结圈物的化学组成和矿相组成进行分析，研究了窑中结圈物的形成机理。结果表明，结圈物的最主要的化学成分是铁和铁的氧化物，CaO、SiO2、Al2O3的含量也相对较高。内层结圈物以铁的浮氏体、钙长石为主，内层结圈以固相固结为主，液相粘结为辅。中层结圈物中液相的含量很高，铁的浮氏体和黄长石、尖晶石类物质次之。中层结圈主要是液相粘结造成的。粘结相主要是橄榄石类液相和铝酸盐类液相。外层结圈物以液相、铁的浮氏体和硅酸钙为主，主要是液相粘结，粘结相主要是金属铁液相和硅酸盐液相。导致结圈最主要的原因是煤灰的堆积和物料中各种氧化物反应形成的低熔点化合物在窑中高温的作用下形成了液相，在此基础上，提出了抑制窑内结圈的措施。 The study focuses on ring formation of rotary kiln in the process of treating Zn-bearing dusts from ironmaking and steelmaking process. The chemical composition and phase composition of the ring were analyzed using XRF, SEM and EDS. The results show that the ring consists of iron and iron oxides, and have relative high contents of CaO, SiO2, and Al2O3. The internal layer is mainly composed of iron wustite and calciclase, and mainly caused by solid phase sintering, complemented liquid phase bonding. The middle layer contains much liquid phase, and some iron wustite, the melilite and the spinel. The outer layer is mainly composed of liquid phase, iron wustite and calcium silicate. It is mainly caused by liquid phase bonding. The bond phase is predominantly liquid metallic iron and silicate liquid phase with low melting point. Based on the above results, proposing the following formation mechanism of ring: the accumulation of coal ash and the various oxides in the material form a low melting point compounds in the kiln, in turn the liquid and solid particle form high viscosity fluids adhere to the wall of rotary kiln. On the basis of the results, the measures to suppress the knot in the kiln are put forward.

Process Improvement for Liquid-Phase Metal Reduction from Steelmaking Dump Slags

Background/Objectives: This work was aimed at experimental studying the laboratory process and the results of liquidphase carbon (coke) reduction of the steelmaking slag conducted to obtain the metal and oxide phases which can be used in the metallurgical industry and building materials industry. Methods: The slag from the slag dumps of Zlatoust Metallurgical Plant (the Russian Federation) was an object of the study. The composition of the experimental samples of metal and slag was determined by electron probe microanalysis. Findings: The conducted experiments give grounds to assert that the process allows recovering almost completely iron, chromium and nickel contained in the slag. Major part of manganese, as well as some other components, including valuable elements – tungsten, molybdenum, titanium and vanadium, also passes into the molten metal. It has been shown that liquid-phase recovery of slag is acceptable to be carried out at temperatures of about 1500-1550°C. In this case, the slag reduction time (after heating the mixture up to the operating temperature) should not exceed 30 minutes. For a more complete recovery of valuable metals it is recommended to use the moment of the ‘boiling’ (intensive separation of gaseous carbon oxides) period completion as an indicator of the isothermal time end. Improvements/Application: Useful products of the recovery process are liquid metal and heavy metal-depleted oxide melt consisting mainly of calcia, silica, magnesia and alumina which may be used in cement manufacturing.

Geochemistry: Large gem diamonds from metallic liquid in Earth's deep mantle

The redox state of Earth's convecting mantle, masked by the lithospheric plates and basaltic magmatism of plate tectonics, is a key unknown in the evolutionary history of our planet. Here we report that large, exceptional gem diamonds like the Cullinan, Constellation, and Koh-i-Noor carry direct evidence of crystallization from a redox-sensitive metallic liquid phase in the deep mantle. These sublithospheric diamonds contain inclusions of solidified iron-nickel-carbon-sulfur melt, accompanied by a thin fluid layer of methane ± hydrogen, and sometimes majoritic garnet or former calcium silicate perovskite.The metal-dominated mineral assemblages and reduced volatiles in large gem diamonds indicate formation under metal-saturated conditions. We verify previous predictions that Earth has highly reducing deep mantle regions capable of precipitating a metallic iron phase that contains dissolved carbon and hydrogen.

Thermal Conductivity and Thermoelectric Power of Some Transition Metals in Liquid Phase

Thermal Conductivity and Thermoelectric Power of Some Transition Metals in Liquid Phase

Time and temperature dependency of carbon dioxide triggered metal(loid) mobilization in soil

Assessing the influence of CO2 on soil and aquifer geochemistry is a task of increasing interest when considering risk assessment for geologic carbon sequestration. Leakage and CO2 ascent can lead to soil acidification and mobilization of potentially toxic metals and metalloids due to desorption or dissolution reactions. We studied the CO2 influence on an Fe(III) (oxyhydr)oxide rich, gleyic Fluvisol sampled in close vicinity to a Czech mofette site and compared the short-term CO2 influence in laboratory experiments with observations on long-term influence at the natural site. Six week batch experiments with/without CO2 gas flow at 3 different temperatures and monitoring of liquid phase metal(loid) concentrations revealed two main short-term mobilization processes. Within 1 h to 1 d after CO2 addition, mobilization of weakly adsorbed metal cations occurred due to surface protonation, most pronounced for Mn (2.5–3.3 fold concentration increase, mobilization rates up to 278 ± 18 μg Mn kgsoil−1 d−1) and strongest at low temperatures. However, total metal(loid) mobilization by abiotic desorption was low. After 1–3 d significant Fe mobilization due to microbially-triggered Fe(III) (oxyhydr)oxide dissolution began and continued throughout the experiment (up to 111 ± 24 fold increase or up to 1.9 ± 0.6 mg Fe kgsoil−1 d−1). Rates increased at higher temperature and with a higher content of organic matter. The Fe(III) mineral dissolution was coupled to co-release of incorporated metal(loid)s, shown for As (up to 16 ± 7 fold, 11 ± 8 μg As kgsoil−1 d−1). At high organic matter content, re-immobilization due to resorption reactions could be observed for Cu. The already low pH (4.5–5.0) did not change significantly during Fe(III) reduction due to buffering from sorption and dissolution reactions, but a drop in redox potential (from > +500 mV to minimum +340 ± 20 mV) occurred due to oxygen depletion. We conclude that microbial processes following CO2 induction into a soil can contribute significantly to metal(loid) mobilization, especially at optimal microbial growth conditions (moderate temperature, high organic carbon content) and should be considered for carbon sequestration monitoring and risk assessment.

Influence of Forced Convection on the Solidification of Metal in Cast-Iron and Ceramic Ingot Molds

A nonstationary problem of solidification of an ingot in molds with walls of varying thermal conductivity has been solved by the variational method with account taken of forced convection in the liquid phase of the metal. A formula for the temperature distribution in the liquid phase and the dependence of the time of advance of the solidification front on its coordinates have been obtained. Numerical calculations of the time of solidification of the ingot in castiron and ceramic molds have been done at different convection rates.

Liquid-Phase Recovery of the Metallurgical Slag Using Induction Heating Installation

Processing of dump slag steelmaking to extract a metal component should include the stage high-temperature recovery oxide components. The efficiency of the recovery phase depends on both temperature conditions and the composition slag, and introduced additions. The exploration of the possibility and feasibility of the liquid-phase restoration for steelmaking waste slag of the Zlatoust Metallurgical Plant applying the induction heat installation is the aim of this study. Application of induction heating was tested by laboratory research for implementation of the process of the liquid-phase metal restoration from various structure dump slags of the steel-smelting production. The parameters of the reconstruction process corresponding to the maximum extraction of a metal component from the waste slag have been identified. The design of industrial induction plant for liquid slag processing with a separate periodic metal release and a depleted slag melt was developed.

Study of the Inner Phase Interface Structure in an Indium Freezing Fixed Point Cell

Methods are considered for initiation of the inner interface between metal liquid and solid phases. The dependence of structure and temperature in an indium fixed point cell on initiation method is studied. Estimates are obtained for the density of heat flow with different inner boundary initiation methods. Optimum initiation conditions are determined in order to exclude undesirable thermal connections between a thermometer channel and cell walls.

High rate in situ laser-induced synthesis of copper nanostructures performed from solutions containing potassium bromate and ethanol.

The synthesis of copper nanostructures from solutions in the presence of oxidizing additives on the surface of opaque and transparent substrates was performed upon laser irradiation at 532nm. Organic alcohols such as ethanol and ethylene glycol were used as the reducing agents whereas potassium bromate was employed in order to demonstrate the influence of inorganic oxidizing additives on the process of the copper laser-induced synthesis from aqueous solutions. The presence of these additives increases the copper deposition rate during the synthesis which is a grand challenge of implementation of laser-induced liquid-phase metal deposition technique. The scanning electron microscopy, energy-dispersive analysis and impedance spectroscopy reveal that the synthesized copper structures from solutions containing potassium bromate composed of densely agglomerated nanocrystals.

Thermodynamic Optimization of the Ca-Fe-O System

The present study deals with the thermodynamic optimization of the Ca-Fe-O system. All available phase equilibrium and thermodynamic experimental data are critically assessed to obtain a self-consistent set of model parameters for the Gibbs energies of all stoichiometric and solution phases. Model predictions of the present study are compared with previous assessments. Wustite and lime are described as one monoxide solution with a miscibility gap, using the random mixing Bragg-Williams model. The solubility of CaO in the “Fe3O4” magnetite (spinel) phase is described using the sublattice model based on the Compound Energy Formalism. The effect of CaO on the stability of the spinel phase is evaluated. The liquid CaO-FeO-Fe2O3 slag is modeled using the Modified Quasichemical Formalism. Liquid metal phase is described as a separate solution by an associate model.

Tuning bad metal and non-Fermi liquid behavior in a Mott material: Rare-earth nickelate thin films.

Resistances that exceed the Mott-Ioffe-Regel limit (known as bad metal behavior) and non-Fermi liquid behavior are ubiquitous features of the normal state of many strongly correlated materials. We establish the conditions that lead to bad metal and non-Fermi liquid phases in NdNiO3, which exhibits a prototype bandwidth-controlled metal-insulator transition. We show that resistance saturation is determined by the magnitude of Ni eg orbital splitting, which can be tuned by strain in epitaxial films, causing the appearance of bad metal behavior under certain conditions. The results shed light on the nature of a crossover to a non-Fermi liquid metal phase and provide a predictive criterion for Anderson localization. They elucidate a seemingly complex phase behavior as a function of film strain and confinement and provide guidelines for orbital engineering and novel devices.

Термодинамическое моделирование фазовых равновесий с оксидными системами, содержащими РЗМ. Сообщение 3. Диаграммы состояния оксидных систем с Ce2O3 и CeO2

Binary and ternary oxide systems, containing cerium oxides (III and IV) as independent components have been researched. The forms of binary and ternary phase diagrams, conjugated with the region of iron-based liquid metal phase existence were established. The calculation of liquidus curve coordinates for binary phase diagrams of Ce2O3–MgO, CeO2–MgO, Ce2O3–СaO, CeO2–СaO, Ce2O3–SiO2, CeO2–SiO2, Ce2O3–Al2O3, CeO2–Al2O3 systems was carried out using selected energy parameters of theory of subregular ionic solutions. Thermodynamic dependencies of equilibrium constants of reactions of cerium aluminates (Ce2O3·Al2O3, Ce2O3·11Al2O3) and silicates (SiO2, 7Ce2O3·9SiO2, Ce2O3·2SiO2) formation from ionic melt components were defined. Phase diagrams of ternary oxide systems FeO–CeO2–SiO2, FeO–Ce2O3–SiO2 were created for the first time on the basis of thermodynamic data on oxide compounds, melting heat of oxides forming the systems researched, values of energy parameters of theory of subregular ionic solutions. The calculation of liquidus curve coordinates for ternary systems FeO FeO–Ce2O3–CeO2, FeO–Ce2O3–CaO, FeO–CeO2–CaO, CeO2–Ce2O3–CaO, FeO–Ce2O3–MgO, FeO–CeO2–MgO, CeO2–Ce2O3–MgO is based on the theory of ideal ionic solutions. Phase diagrams of FeO–Ce2O3, Ce2O3–CeO2, FeO–Ce2O3–CeO2, FeO–Ce2O3–Al2O3 systems were redetermined and re-calculated.

The Role of Quantum Interference Effects in Normal-State Transport Properties of Electron-Doped Cuprates

The normal-state resistivity of thin films of the infinite-layer electron-doped cuprate Sr 1−x La x CuO 2±δ has been investigated. Under-doped samples, which clearly show a metal-to-insulator transition (MIT) at low temperatures, have allowed the determination of the fundamental physical mechanism behind the upturn of the resistivity, namely the quantum interference effects (QIEs) in three-dimensional systems. The occurrence of weak localization effects has been unambiguously proven by low-frequency voltage spectral density measurements, which show a linear dependence of the 1/f noise on the applied bias current at low temperatures. The identification of the QIEs at low temperatures has therefore allowed the determination of the high-temperature non-Fermi liquid metallic phase, which is dominated by a linear temperature dependence of the resistivity for all of the samples investigated.

Mechanical properties and microstructure of Ti(C, N) based cermet cutting tool materials fabricated by microwave sintering

A type of Ti(C, N) based cermet cutting tool materials was fabricated by microwave sintering. The effects of metal content and sintering temperature on the mechanical properties and microstructure were thoroughly investigated. The experimental results showed that sufficient metal liquid phase can significantly improve densification and fracture toughness of cermet. However, high metal content, on one hand, reduced the hardness of cermets, and on the other resulted in the micro-defects of materials. The activate mechanisms of microwave can lower the temperature required for the metal liquid phase formation and enable the densification of cermet at low temperatures without external pressure. But low sintering temperature suppressed the flow of metal liquid phase which caused the pores among the grains cannot be fully filled. High temperature may lead to the coarsening of the particles and the decreasing of mechanical properties. A Ti(C, N) based cermet cutting tool material with 15% Co–Ni content which was sintered at 1550°C for 10min exhibited the optimum mechanical properties. Its hardness and fracture toughness were 15.49±0.21GPa and 10±0.55MPam1/2 respectively.

High ramp rate thermogravimetric analysis of zirconium(II) hydride and titanium(II) hydride

Zirconium and titanium hydride are utilized in liquid phase metal foam processing techniques. This application results in immediate exposure to molten metal and almost immediate decomposition at high temperatures. Most decomposition characterization techniques utilize slow heating rates and are unable to capture the decomposition behavior of hydrides under foam processing conditions. In order to address this issue a specialized high ramp rate thermogravimetric analyzer was created from a xenon arc image refiner. In addition to thermogravimetry, complimentary techniques including X-ray diffraction and scanning electron microscopy were used to characterize hydride decomposition and compare the results to literature. Hydrides were partially oxidized and separated into particles size ranges to evaluate the influence of these factors on decomposition. Oxidizing treatments were found to decrease decomposition rate only at temperatures below 933K (660°C) while particle size effects appeared to be negligible. Several improvements to the unique TGA apparatus presented in the current work are suggested to allow reliable kinetic modeling and analysis.

Nanodrilling of fused silica using nanosecond laser radiation

The fast laser drilling of dielectric surfaces with hole diameters in the sub-μm range and a high aspect ratio is a challenge for laser methods. In this study, a novel laser structuring method for the production of randomly and periodically distributed holes in a fused silica surface will be presented using a self-assembling process. A fused silica surface was covered with a 10nm thick magnetron-sputtered molybdenum film. The metal film was irradiated by a KrF excimer laser (wavelength λ=248nm, pulse duration Δtp=25ns) with low laser fluences (Φ<1J/cm2) and the laser-induced heating resulting in a melting of the metal film and finally in a self-assembled formation of randomly distributed metal droplets due to the surface tension of the metal liquid phase using a top hat beam profile. Furthermore, the usage of a periodically modulated laser beam profile allows the fabrication of periodically distributed droplet pattern. The multi-pulse irradiation of the laser-generated metal droplets with higher laser fluences results in a stepwise evaporation of the metal and in a partial evaporation of the fused silica near the metal droplets. Finally, the laser-induced stepwise evaporation process results in a formation of cone-like holes in the fused silica surface where the resultant holes are dependent on the size of the generated metal droplets and on the laser parameters. The “drilling” process allows the fabrication of holes with a depth up to 1μm at a hole radius in the sub-μm range. Furthermore, the hole density can be adjusted by the laser fluence where a hole density up to ∼1.3μm−2 can be achieved. Furthermore, the process was simulated by finite element method using a simple thermodynamic model and the theoretical results were compared with the experimental findings.