Melt Drop Research Articles

Relationship and Mechanism Analysis of Soft-Melt Dropping Properties and Primary-Slag Formation Behaviors of the Mixed Burden in Increasing Lump Ore Ratio

At present, cost reduction and environmental protection are the mainstream of blast furnace (BF) development and the high lump ore ratio is an effective means. Therefore, it is significant to explore the relationship and mechanism of burden soft-melt dropping and its primary-slag formation behaviors under increasing lump ore ratio. In this paper, the melt–drop test is carried out on the single ore and mixed burden, and obtained primary-slag properties are subjected to analysis. The experimental results show that the primary-slag of lump ore contains a large amount of FeO and SiO2, so it simply produces many low melting point compounds, which cause terrible soft-melt dropping properties and primary-slag formation behaviors. Notably, mixing with sinter and pellet can effectively improve both the properties. With the increase in lump ore ratio, the CaO in the primary-slag decreases, FeO and SiO2 increase, resulting in the melting temperature of the primary-slag sequentially decreasing and the cohesive zone moves to the low temperature zone. In addition, the maximum pressure difference increases, and the gas permeability deteriorates. Increasing the sinter ratio can overcome the defect of high lump ore ratio that can effectively improve the poor softening performance, melting performance and the position and thickness of the cohesive zone. However, because of the pulverization performance, the maximum pressure difference and gas permeability of the burden become worse.

Petrographic and mineral-glass chemical dataset of igneous rock clasts from Early Oligocene Aveto-Petrignacola Formation (Northern Italy).

This dataset article contains petrographic and mineral-glass chemical data of igneous rock clasts from Early Oligocene Aveto-Petrignacola Formation (APF; Northern Italy). Methods for obtaining the dataset include optical microscopy, scanning electron microscopy and electron probe microanalysis. The APF volcanic rocks are basalts, basaltic andesites, andesites, dacites and rhyolites. Rare gabbroic cumulate nodules complete the dataset. Basalts are porphyritic, with calcic plagioclase (An72–92Ab7–27Or0–1), ferroan enstatite (En59–68Fs29–37Wo3–4) and augite (En38–39Fs18–20Wo41–44) phenocrysts, in a hypocrystalline groundmass made up of bytownite (An71–85Ab14–28Or1), augite (En37–38Fs19Wo43–44), ferroan enstatite (En62–68Fs30–35Wo1–4) and rare pigeonite (En46–50Fs37–42Wo7–17). The basaltic andesites are porphyritic to glomeroporphyritic with phenocrysts of zoned plagioclase (An44–67Ab32–55Or1), orthopyroxene, Mg-rich augite (En38–42Fs15–17Wo43–45), rare pargasite to edenite amphibole (Mg# 69–59) and very rare biotite in a hypocrystalline to holohyaline groundmass. Andesites are highly porphyritic with phenocrysts of plagioclase (An47–79Ab20–52Or0–1), pargasite to magnesio-hornblende (Mg# 72–67), Mg-rich augite (En43–46Fs12–17Wo41–43), subordinate ferroan enstatite (En68–74Fs23–29Wo3–4), biotite (Mg# 53) and Ti-magnetite (Usp29–41). Dacites (massive lavas and ignimbrites) are porphyritic, with phenocrysts and phenoclasts of plagioclase (An33–79Ab20–62Or0–4), calcic amphibole (Ti-pargasite, Mg-hornblende and edenite; Mg# 81–46), biotite (Mg# 67–56), very rare Mg-rich augite (En41–42Fs16–18Wo40–43) and resorbed quartz in hypohyaline to holohyaline groundmass with a dense mat of anhedral quartz, labradorite-andesine (An36–66Ab33–61Or1–4) and rare anorthoclase (An22Ab66Or12). Rhyolitic compositions have been found both as volcanic clasts (massive lava and ignimbrites) with andesine to oligoclase phenoclasts (An25–38Ab61–71Or1–4), quartz, biotite (Mg# 55–53) and Ti-magnetite (Usp18–77), and as interstitial glasses (residual melt drops) in other APF volcanic rocks. The cumulate nodules are olivine-gabbro and amphibole-gabbro/gabbronorite with a mineral paragenesis dominated by plagioclase (An41–73Ab26–57Or1–3), olivine (Fo68–72), Mg-rich augite to ferroan diopside (En41–45Fs12–15Wo42–45; Mg# 79–74), ferroan enstatite (En65–74Fs24–33Wo2–3; Mg# 76–68), magnetite (Usp15–28) and titanian pargasite (Mg# 67–65). The main cumulus phases are plagioclase, olivine and pyroxene, while intercumulus/postcumulus phases are titanian pargasite and magnetite. The dataset can be used to compare petrographic features and chemical compositions of calc-alkaline rocks emplaced in other subduction-related settings. Above all, it can represent a useful contribution in solving the problem linked to the identification of a hidden Early-Oligocene source of the thick volcaniclastic APF succession in the Alpine-Apennine belt geodynamic evolution.

Thermochemical studies of X(NpO2)(PO4)(H2O)3 (X = K+, Rb+), neptunium analogs of the autunite/meta-autunite group

Actinide phosphate materials with autunite or meta-autunite type sheets consisting of vertex-sharing actinyl square bipyramids and phosphate tetrahedra have low aqueous solubility and potential applications for actinide immobilization in the environment. Neptunyl phosphates, X(NpO2)(PO4)(H2O)3, X ​= ​K+ and Rb+, have been synthesized by hydrothermal reactions and characterized for their structures and purities. Direct thermochemical studies were performed using high temperature oxide melt drop solution calorimetry. After correcting for the presence of residual fluorapatite from the synthesis, the formation enthalpies of K(NpO2)(PO4)(H2O)3 and Rb(NpO2)(PO4)(H2O)3 are determined to be −3235 ​± ​21 ​kJ/mol and −3270 ​± ​11 ​kJ/mol, respectively. The thermodynamic data presented here may be important for understanding neptunium mobility after disposal of nuclear waste in a geological repository.

2D MPS analysis of hydrodynamic fine fragmentation of melt drop with initial steam film during fuel–coolant interaction

The hydrodynamic fine fragmentation of melt drops, which increases the melt–coolant contact area and affects heat transfer and melt oxidation, is an important phenomenon during fuel–coolant interaction. The presence of a steam film surrounding the melt drops complicates the breakup simulation, including interface instabilities and high-density ratio. In this study, we modeled the breakup behavior of a melt drop with an initial steam film by using the meshless moving particle semi-implicit (MPS) method in the Lagrangian frame. Numerical models were validated step by step by simulating Kelvin–Helmholtz instability, Rayleigh–Taylor instability, and liquid drop breakup. The breakup behavior of a UO2 melt drop with and without initial steam film was simulated in 2D, and the fragment number, size distribution, and melt–coolant contact perimeter were comparatively analyzed. Results indicate that the initial steam film rapidly moved away from the melt drop and separated into two main bubbles, which had insignificant influence on either the melt drop deformation or the fragment number and the perimeter. The total number of fragments increased at the initial moments of the breakup process due to the flow inertia force and then decreased under the effect of surface tension. The number of small fragments (d/d0 = 0.01–0.03) increased and decreased in variations, but other relatively large fragments continuously increased in the entire duration. The perimeter contribution of small fragments was larger than those of other fragment groups in the initial duration of the melt drop breakup at We = 655, but it reversed subsequently. By contrast, the perimeter contribution by fragments with d/d0 = 0.01–0.02 and 0.02–0.03 was constantly larger than those of other groups at We = 2618. Moreover, the summations of perimeter contributions by all fragments in the present statistics were approximately 50% and 60%–80% for cases of We = 655 and 2618, respectively.

Experimental Modeling of a Micrometeorite Impact on the Moon

The shock-explosive processing of rocks by micrometeorite and meteorite bombardment on the surface of the Moon and other airless bodies of the solar system is a dominant geological and geochemical process that produces the loose layer of regolith. The paper presents results of modeling the process of a micrometeorite impact using a millisecond laser. The targets in the experiment were a sample of basalt of composition similar to those of basalts at Moon’s mare areas and a sample of basalt glass obtained by melting this basalt. At the laser “impact”, products ejected from the crater (glass spherules, droplets of various shapes, and condensates) and melting products in the crater were studied by electron microscopy, electron microprobe analysis with energy-dispersive spectrometers, X-ray diffraction, and X-ray fluorescence analysis. It has been shown that the glasses (melt drops) obtained in the experiment with the basalt target are characterized by a heterogeneous distribution of chemical composition. They were mixed in variable proportions as a result of melting the original minerals of the basalt. The spherules that have undergone significant evaporation differentiation in the experiment with a basalt target (crystalline basalt) make up about 25%. When the target was basalt glass, the proportion of the spherules (that have undergone profound evaporative differentiation) was ~90%. The glass was depleted in high- and medium-volatility components (Na2O, K2O, FeO, etc.). The most strongly differentiated glasses corresponded to high-alumina HASP glasses found on the Moon (Al2O3 > 34 wt %, SiO2 < 32 wt %).

Influence of Liquid Quenching on Phase Composition and Properties of Be-Si Eutectic Alloy

By the method of quenching from the liquid state (splat-quenching), it is first revealed the formation of mixture of metastable supersaturated substitutional solid solutions in the eutectic alloy Be-33at.% Si. Cast samples are obtained by pouring melt into a copper mold. High cooling rates during liquid quenching are achieved throw the well-known splat-cooling technique by spreading a drop of melt on the inner surface of a rapidly rotating, heat-conducting copper cylinder. The maximum cooling rates are estimated by the foil thickness. The melt cooling rates (up to 108К/s), used in the work, are sufficient to form amorphous phases in some eutectic alloys with similar phase diagrams, but it is found those rates are insufficient to obtain them in the Be-Si eutectic alloy. The X-ray diffraction analysis is carried out on a diffractometer in filtered Cobalt Ka radiation. Microhardness is measured on a micro-durometer at a load of 50 g. The electrical properties, namely the temperature dependences of relative electrical resistance, are studied by the traditional 4-probe method of heating in vacuum. The accuracy of determining the crystal lattice period of the alloy, taking into account extrapolation of the reflection angle by 900, is ± 3•10-4 nm. It is found that even at extremely high rate of quenching from the melt, instead of the amorphous phase formation, the occurrence of two supersaturated substitutional solid solutions, based on Beryllium and Silicon, is revealed. This fact is established by the obtained dependences of their lattice periods values on the alloying element content. So, during the formation of metastable eutectic structure, a supersaturated with Beryllium solid solution of Silicon has period a = 0.5416 nm, and a supersaturated with Silicon solid solution of low-temperature hexagonal Beryllium has periods a = 0.2298 nm, c = 0.3631 nm. The positive role of the liquid quenching method in increasing the level of mechanical characteristics (microhardness and microstresses) in rapidly cooled Be-Si films is shown. It has been demonstrated that the difference in the atomic radii of the elements significantly affects the distortion of crystal lattices of the formed supersaturated solid solutions, and a significant value of microstresses (second-order stresses) in the Silicon lattice supersaturated with Beryllium is estimated, which, of course, leads to a significant increase in the microhardness, namely: there is an increase in microhardness in the Be-Si alloy under the conditions of applied method of quenching from the liquid state by more than 1.7 times compared to cast eutectic alloy and more than 6 times higher in comparison with the eutectoid cast Iron-Carbon alloy. The obtained polytherm of electrical resistance of the alloy under conditions of continuous heating in vacuum confirms the metastable nature of obtained new phases during quenching from the liquid state.

МЕТАЛЛИЧЕСКИЕ ВОЛОКНА ДЛЯ НОВЫХ МАТЕРИАЛОВ АВИАЦИОННЫХ ДВИГАТЕЛЕЙ

Presents the results of work carried out at the Federal state unitary enterprise «VIAM» in the framework of a new material science direction – metallurgy of metal fibers. This work was made possible by the development of a method for producing metal fibers called the hanging melt drop extraction method (EUCR). This method is high-performance and allows you to obtain fibers from almost any material. Research has shown that it is possible to improve the performance and environmental characteristics of modern and advanced engines by introducing new classes of materials based on metal fibers.

Морфология и механические свойства микропроводов PrDyFeCoB

PrDyFeCoB microwires were obtained by pendant drop melt extraction (PDME). The diameter and cylindricality of microwires are controlled by the rotation speed of the cooling cylinder and depend on the solidification time of the drop on it. Variations in the cooling regime of the melt drop lead to a change in the shape of the cross section from a completely cylindrical to a semicircle, a crescent, and an almost flat plate. It was established that the cooling mode affects not only morphology, but also mechanical characteristics that are different for microwires of different shapes, and also changes the microhardness and Young's modulus of different surfaces of the same microwire.

Study of mechanical properties of rapidly quenched fiber from orthorombic alloy based on Ti2AlNb

The mechanical properties of a rapidly quenched Ti2AlNb-based alloy obtained by extraction of a hanging melt drop in the initial state and after heat treatment are investigated. It is stated that the rapidly quenched alloy has low tensile elongation, high strength and hardness, and a mechanism of brittle fracture during deformation. Heat treatment allows increasing the value of tensile elongation, reduces hardness, and results in tough fracture during deformation.

ГОРІННЯ ПАЛИВА НА ОСНОВІ АЛКАНІВ ПІД ДІЄЮ ЕЛЕКТРИЧНОГО ПОЛЯ

The relevance of research on the combustion processes of alkane-based fuels is due to the search for new, efficient, environmentally friendly fuels for the energy and aerospace industries. Paraffin (a mixture of alkanes) is a low-melting material that can be used as an environmentally friendly and high-energy fuel. An important task is to intensify the processes of fuel combustion in the reaction volume. One of the factors of intensification is the electric field. The purpose of this work is to study the laws of the influence of the electric field on the processes of high-temperature heat and mass transfer, melting and burning drops of liquid fuel based on alkanes.The paper developed a methodology for studying the kinetics of melting and burning of liquid fuel droplets using digital imaging of the object of study and computer processing of the images obtained.Studies have been conducted on the effect of a uniform electric field on the combustion of alkane particles in the air. The stages of heat and mass transfer in the combustion process are determined. It is shown that the melting of a particle is the main component of the induction period — the time during which the particle ignites. It was revealed that the melting rate significantly decreases if the electric field strength exceeds a certain critical value. It is established that the effect of the electric field on melting is more pronounced at high gas temperatures. It was found that when an octadecane particle melts in an electric field, the unmelted residual solid phase rotates in the melt. It is proved that this is a special case of the Quincke effect.The kinetics of combustion of octadecane drops of various initial diameters was studied. It has been proven that a linear law of variation of the square of the diameter of a droplet with time (Sreznevsky’s law) is fulfilled in a certain area of burning. The influence of the electric field on the burning rate of particles of different initial diameters was studied. It has been established that under the action of an electric field an increase in the rate of burning of alkane droplets occurs. In particular, for octadecane drops, the burning rate in a constant electric field increases by 10 ÷ 23% depending on the initial diameter of the drop. The burning rate constants of octadecane are found.The influence of the electric field on the geometric dimensions of the flame is studied. It is established that under the influence of the field the flame becomes asymmetrical and shifts towards the negatively charged plate of the capacitor. This reduces the height of the flame and increases its width. These phenomena are associated with the action of "ion wind" in the flame and the transformation of the energy of the electric field into heat. As a result of the action of these physical mechanisms, the combustion front approaches the surface of the drop, increasing its rate of evaporation.

The properties of flame retardant and heat conduction polyamide 66 based on melamine cyanurate/aluminum diethylphosphinate/graphene

In this present paper, melamine cyanurate (MCA)/aluminum diethylphosphinate (AlPi) were used as composite flame retardants, and with addition of graphene (Gr) served as thermal conductive filler for preparing flame-retardant and thermal conductive polyamide 66 (PA66). The effects of Gr on flame retardancy, as well as the thermal conductivity on the combustion behavior of PA66 under the heat environment were investigated. The results demonstrated that Gr could effectively inhibit phosphorus-containing radicals from AlPi into gaseous phase and improve its impact on the condensed phase. Additionally, as a physical carbon source, two-dimensional sheets of Gr provide excellent barrier shielding effects and increase the residue, thus significantly retarding the melt drops during the combustion process. The results showed that the specimens with 12 wt% composite flame retardants and 3.5 wt% Gr, passed UL-94 V-0 rating (1.6 mm of thickness) and the total heat release (THR) were decreased by 22% according to micro-scale combustion calorimetry (MCC). Additionally, the improved thermal conductivity due to the addition of Gr, effectively enhances the thermal heat dissipation rate and decreases the risk of self-ignition caused by local heat accumulation.

Fatigue Behavior of Non-Optimized Laser-Cut Medical Grade Ti-6Al-4V-ELI Sheets and the Effects of Mechanical Post-Processing

The study presented investigates the fatigue strength of the (α+β) Ti-6Al-4V-ELI titanium alloy processed by laser cutting with and without mechanical post-processing. The surface quality and possible notch effects as a consequence of non-optimized intermediate cutting parameters are characterized and evaluated. The microstructural changes in the heat-affected zone (HAZ) are documented in detail and compared to samples with a mechanically post-processed (barrel grinding, mechanical polishing) surface condition. The obtained results show a significant increase (≈50%) in fatigue strength due to mechanical post-processing correlating with decreased surface roughness and minimized notch effects when compared to the surface quality of the non-optimized laser cutting. The martensitic α’-phase is detected in the HAZ with the formation of distinctive zones compared to the initial equiaxial α+β microstructure. The HAZ could be removed up to 50% by means of barrel grinding and up to 100% through mechanical polishing. A fracture analysis revealed that the fatigue cracks always initiate on the laser-cut edges in the as-cut surface condition, which could be assigned to an irregular macro and micro-notch relief. However, the typical characteristics of the non-optimized laser cutting process (melting drops and significant higher surface roughness) lead to early fatigue failure. The fatigue cracks solely started from the micro-notches of the surface relief and not from the dross. As a consequence, the fatigue properties are dominated by these notches, which lead to significant scatter, as well as decreased fatigue strength compared to the surface conditions with mechanical finishing and better surface quality. With optimized laser-cutting conditions, HAZ will be minimized, and surface roughness strongly decreased, which will lead to significantly improved fatigue strength.

Estimation of the critical vitrification rate of pure metals using molecular dynamics simulation

A molecular dynamics simulation method was applied for estimation of critical cooling rates (vc) that required for amorphization of pure metals: Mg, Al, Ti, Fe, Co, Ni, Cu, Zr, Mo, Pd, Ag, Ta, W, Pt, Au, and Pb. The range of values vc was found to be from 7.9 × 1011 K/s for Al to 3.8 × 1013 K/s for Zr. The atomic structure obtained at different cooling rates is described. A dependence of the specific volume on temperature was investigated both during the amorphization and crystallization processes. The modelling shows, which metals have the highest temperature range of long-term stability of the amorphous phase (Fe, Mo, Ta, W). Estimates were given for the maximum radius of a melt drop that can be cooled at a rate of vc. The obtained simulation results were compared with available experimental data.

Estimating the Critical Glass Transition Rate of Pure Metals Using Molecular Dynamic Modeling

The critical cooling rates $${{{v}}_{{\text{c}}}}$$ at which pure metals Mg, Al, Ti, Fe, Co, Ni, Cu, Zr, Mo, Pd, Ag, Ta, W, Pt, Au, and Pb transit to an amorphous state (vitrify), have been calculated for some alloys using the method of molecular dynamic modeling. These rates range from 7.9 × 1011 for Al to 3.8 × 1013 for Zr. The atomic structures formed at different cooling rates are described. The temperature dependence of the specific volume is studied in the process of both glass transition and crystallization. The study of the thermal stability of metallic glasses has shown that the best stability is inherent in Fe, Mo, Ta, and W. Some estimates are given for the maximum radius of a melt drop, which can be cooled at the rate $${{{v}}_{{\text{c}}}}$$ . The comparison of the modeling results with the experimental data, which are currently known for Ta, Mo, and W, shows their good agreement.

Self-propagating high-temperature synthesis of macroporous B2+L12 Ni-Al intermetallics used in cylindrical radiant burners

The use of Ni-Al alloys proves to be highly relevant in advanced radiant burner production. The aim of this study is an in-situ fabrication of maсro-porous B2-L12 Ni-Al alloys by self-propagating high-temperature synthesis for a specified burner configuration. It has been revealed that the use of small amounts of special additives dramatically affects the synthesis of coarse-porous alloys. High-speed imaging and high-speed spectral pyrometry have demonstrated that a combustion wave consists of a set of short-lived superadiabatic drops of a melt, the temperature of which exceeds the liquidus temperature for a short time. In the formation of melt drops, up to 107 nickel and aluminum particles are involved. This makes it possible to synthesize porous alloys with Ni-Al elements of up to several millimeters in diameter, using Ni and Al powders with the size of fewer than 10 μm. The porosity structure of such alloys has been characterized in the paper. It has also been demonstrated that the structure can be controlled by changing initial synthesis conditions such as reaction mixture composition, an additive type and its amount, mixture relative density, and a preheating value. In addition, the article describes the conditions that allow obtaining alloys with Ni-Al elements in the range of 500–2500 μm in size. As for the phase composition of synthesized alloys, it has been examined by X-ray diffraction. Besides B2-L12 phases, the alloys may contain some martensite L10, which disappears if the alloys are annealed for an hour at a temperature of 1100 °C. To evaluate mechanical properties of the synthesized and annealed alloys, a compression test has been applied. The impact of the alloys phase composition on possible operation modes of Ni-Al radiant burners has been discussed in the work.

Numerical analysis of hydrodynamic fine fragmentation of corium melt drop during fuel-coolant interaction

Hydrodynamic fine fragmentation of melt drops is important in increasing melt-coolant contact area, and thus directly affects heat transfer, oxidation and solidification. The interfacial instabilities incurred by relative flow and density gradient are the dominant factors for melt drops deformation and fragmentation. In this study, we modelled melt drop breakup behavior using a meshless Lagrangian MPS method, and validated the numerical model with the experimental results. Then, the melt fragments amount, size distribution and normalized perimeter were analyzed under different Weber numbers. The results indicate that the melt drop breakup process could be divided into two phases: initial deformation and fragmentation phase governed by flow inertial force and the subsequent fragments coalescence phase under the impact of fluid surface tension. Fragments amount increased in fragmentation phase but decreased in coalescence phase. The amount of fragments with smaller size (d/d0 < 0.04) was significantly larger at high Weber number cases, but the amount of large-scale fragments (d/d0 > 0.05) was equivalent among different weber number cases. The maximum fragments perimeter reached 20 times of the initial melt drop perimeter for case of We = 2618, which was about 3.3 times of that at We = 291.

MELT DROPS MOVEMENT OVER SEMICONDUCTOR SURFACES CONTROLLED BY ELECTRIC FIELD

The problems of molten zones formation and their subsequent migration over material surface are of interest from the viewpoint of developing novel technological methods of forming microelectronic structures. Such drops can be used as primary working elements of microlenses and reflectors, displays, weighers. The aim of this work was experimental studying processes of electromigration of molten silver- and aluminum-based inclusions over surfaces of germanium and aluminum semiconductor crystals. The issues of formation and motion of molten drops over the surfaces of silicon and germanium semiconductor crystals are considered within the framework of the electrocapillary approach. It is shown by an example of Ge-Ag and Si-Al systems that accelerated migration is related to the contribution of an electrocapillary component that relates surface tension force of melt drops to electric potential difference at the interface. The experiment consisted in applying metal grain to the surface of the samples and vacuuming the chamber where excessive pressure and the surface temperature were created. Migration of inclusions by powerful current pulses was initiated. An analysis of the effect of direct current on a drop of melt deposited on the surface of a crystalline matrix was made. An analysis of the droplet composition was carried out using the AES method, the results of which showed the relationship between silver and germanium concentrations. Quantitative evaluations are given for migration rates in systems under direct current flow as well as under pulsed current loads. During the experiment, it was found that the energy required to detach the droplet from the rigid matrix was not consumed. The value of the surface charge transfer density was estimated. The results of the work can be used to develop new technological methods for the formation of microelectronic structures and their use for practical purposes.

Бистабильное и многодоменное состояния ферромагнитных микропроводов alpha-Fe/(PrDy)(FeCo)B

Microwire of α-Fe(50 at.%)(PrDy)(FeCo)B(48 at.%) was obtained by extracting a hanging melt drop of (PrDy)(FeCo)B in an electron beam. It was shown that a single microwire with a diameter of 50 μm and a length of 0.8 - 6 mm with an amorphous phase (PrDy)(FeCo)B content of ~ 48% and a polycrystalline α-Fe phase of ~ 52% has a rectangular narrow magnetic hysteresis loop and, accordingly, a bistable state with a switching field of ~ 100 Oe. The shortening of the wire to ~ 0.6 mm leads to a sharp deviation from the squareness of the loop, reducing the slope of the dependence of the magnetization on the field and the coercive force to 20 Oe. In the subsurface layers consisting of the amorphous phase (PrDy)(FeCo)B, oriented areas of reverse magnetization are observed. The role of the magnetic dipole interaction in the formation of a magnetic hysteresis loop of chaotic microwire assemblies of various compositions is discussed.

Explosive Fragmentation of Molten Salt in Subcooled Water

The present study examines the molten NaCl explosive fragmentation in subcooled distilled water. It is noted that the explosion occurred in all experiments performed. However, such a good reproducibility was not observed at a two-phase cooling of the molten metal. This fact can be explained by the lower value of the liquid salt viscosity in comparison with liquid metals viscosity. In addition, a description of explosion propagation in a group of melt drops is given.

Energetic Trends in Monomer Building Blocks for Uranyl Peroxide Clusters.

The uranyl triperoxide anionic monomer is a fundamental building block for uranyl peroxide polyoxometalate capsules. The reaction pathway from the monomer to the capsule can be greatly altered by the counterion: both the reaction rate and the resulting capsule structure. We synthesized and characterized uranyl triperoxides Mg2UO2(O2)3·13H2O (MgUT), Ca2UO2(O2)3·9H2O (CaUT), Sr2UO2(O2)3·9H2O (SrUT), and K4UO2(O2)3·3H2O (KUT) and compared their thermodynamic stabilities. The enthalpies of formation from oxides and elements of these compounds were calculated by thermochemical cycles from measurements by high temperature oxide melt drop solution calorimetry. Their formation enthalpies from oxides become more negative linearly as a function of the increasing basicity of the respective oxides on the Smith scale. This relationship holds for previously Li and Na analogues. Further affirming the trend, Δ Hf,ox of MgUT departs from linearity, due to the distinct bonding environment of Mg2+, as compared to the other alkalis and alkaline earths in the series.