Phase Triangle Research Articles

Thermodynamic Diagram Analysis and Smelting of Complex Fe-Cr-Mn-Si Ferroalloy

A state diagram of the Cr-Mn-Si-Fe metallic system, which simulates the compositions of complex chromium-manganese-silicon-containing ferroalloy (Fe-Cr-Mn-Si), has been constructed using thermodynamic-diagram analysis. Theoretical investigations have determined that the system comprises eight elementary tetrahedra. The sum of the relative volumes of the elementary tetrahedra equals one (1.00000), confirming the accuracy of the tetrahedration conducted. Analytical expressions for each tetrahedron have been derived. Calculations have determined the tetrahedron characterizing the phase composition of the ferroalloy. This tetrahedron is identified as the most voluminous phase triangle in the Cr-Mn-Si-Fe metallic system, implying that its significant volume facilitates the smelting process of chromium-manganese-silicon-containing ferroalloy, i.e., there is the possibility of freely regulating the charge compositions to achieve the required alloy grade. Based on the obtained results, an experimental smelting of the Fe-Cr-Mn-Si ferroalloy was conducted using a charge composed of chromium ore, low-grade manganese ore, and coke, resulting in a sample with the following composition, %: 44.07 Cr, 13.97 Fe, 12.48 Mn, 9.48 Si, 4.45 C. The microstructure comprises a complex silicide (Cr, Fe, Mn)3Si and Cr3C2 carbides.

Описание химического взаимодействия в системе CaO-Al 2O3-SiO2

In this study the construction of a phase tree and the description of the chemical interaction for the ternary oxide system CaO-Al 2O3-SiO2 are given. Particular interest to a system consisting of oxides of calcium, aluminum and silicon is associated with the production of highly demanded functional materials with desired properties. Melts of the CaO-Al2O3-SiO2 system are of great theoretical and applied importance. This is due to the significant role of melts of these oxides and their mixtures in metallurgy, ceramics production, and other industries. Phase relationships in the system with the complete disappearance of liquid in the CaO-Al2O3-SiO2 system has made it possible to construct a phase tree of the system, which includes a linear part and two cycles. The construction of the phase tree is given taking into account the formation of four double compounds in the CaO-SiO2 system, five double compounds in the CaO-Al2O3 system, one double compound in the Al2O3-SiO2 system, and two ternary compounds. The stable complex includes fifteen secondary phase triangles, interconnected by sixteen stable secants. For mixtures corresponding to equivalence points (points of intersection of unstable and stable secants), the chemical interaction is described in accordance with the law of equivalents. It is concluded that for all mixtures corresponding to equivalence points, interactions are thermodynamically possible under standard conditions. The prediction of crystallizing phases is made.

Influence of composition and cooling rate of alumocalcium slag on its crumblability

The main components of metallurgical slags are iron compounds, which are extracted by reduction smelting. There are several types of this process with obtaining various products based on iron and slags of various compositions (aluminum-calcium self-disintegrating), etc. The mode of smelting and cooling of alumocalcium slag, formed during melting in the furnace, should ensure the most complete spontaneous crumbling of it, as well as high rates of extraction of REM from it. Synthetic slags similar in phase composition to industrial samples after smelting of iron-containing ores were selected for the experiments. The simulated samples correspond to the region of primary crystallization of bicalcium silicate on the triple state diagram of CaO – SiO2 – Al2O3 system. The slag after crumbling was subjected to a sieve analysis using a mechanical sieve. In the experiments, slags with a silicon module k = 2.0 were used, which actively crumbled during their cooling. With an increase in the silicon module, the crumbling deteriorates. It was established that it is impossible to precisely limit the areas of compositions of crumbling slags at certain cooling rates. The conducted studies showed that the crumblability of slags improves as it approaches the center of the bicalcium silicate region. The composition of slags close to composition of the intersection points of the lines 2CaO·SiO2 – 2CaO·Al2O3 and 2CaO·SiO2 – 12CaO·7Al2O3 with the lines of the permanent silicon module granulometric composition almost does not depend on the cooling rate. The temperature mode from smelting to cooling affects the slags crumblability. The most promising are slags with a silicon module in the range of 2.85 – 3.00, close to the phase triangle 12CaO·7Al2O3 – 2CaO·SiO2 – 2CaO·Al2O3 .

Древо фаз, прогноз кристаллизующихся фаз и описание химического взаимодействия в системе KCl–CaCl 2–BaCl2

The construction of a phases tree of a ternary system with three binary compounds KCaCl3, K2BaCl4, CaBaCl4 is given. The phase tree includes four secondary phase triangles CaCl2–KCaCl3–СаBaCl4, CaBaCl4–KCaCl3–BaCl2, KCaCl3–BaCl2–K2BaCl4 and KCaCl3–CaBaCl4–KCl. These triangles are connected by three stable secants KCaCl3–СаBaCl4, KCaCl3–BaCl2, KCaCl3–K2BaCl4. Crystallizing phases in stable and secant elements correspond to the simplex tops. The presence of binary compounds on adjacent sides of the composition triangle made it possible to reveal, in addition to addition reactions, the reactions of mutual exchange. The description of the main reactions for mixtures corresponding to the intersection points of unstable and stable secants is carried out. The possibility of these reactions has been confirmed by thermodynamic calculation of thermal effects and Gibbs energies for standard conditions. Using the constructed tree of phases for any mixtures in a triangle of compositions, including 2...6 salts, a description of the chemical interaction by the ion balance method is carried out. The ion balance method allows you to determine the final composition after reaction in a secant or stable element. Complex gross-reactions are presented as a set of simpler reaction equations. The proposed method for description the chemical interaction can be used for other types of ternary systems with exchange reactions (metathesis) – with ion-exchange processes and with displacement reactions.

Improving CPT-InSAR Algorithm with Adaptive Coherent Distributed Pixels Selection

The Coherent Pixels Technique Interferometry Synthetic Aperture Radar (CPT-InSAR) method of inverting surface deformation parameters by using high-quality measuring points possesses the flaw inducing sparse measuring points in non-urban areas. In this paper, we propose the Adaptive Coherent Distributed Pixel InSAR (ACDP-InSAR) method, which is an adaptive method used to extract Distributed Scattering Pixel (DSP) based on statistically homogeneous pixel (SHP) cluster tests and improves the phase quality of DSP through phase optimization, which cooperates with Coherent Pixel (CP) for the retrieval of ground surface deformation parameters. For a region with sparse CPs, DSPs and its SHPs are detected by double-layer windows in two steps, i.e., multilook windows and spatial filtering windows, respectively. After counting the pixel number of maximum SHP cluster (MSHPC) in the multilook window based on the Anderson–Darling (AD) test and filtering out unsuitable pixels, the candidate DSPs are selected. For the filtering window, the SHPs of MSHPC’ pixels within the new window, which is different compared with multilook windows, were detected, and the SHPs of DSPs were obtained, which were used for coherent estimation. In phase-linking, the results of Eigen decomposition-based Maximum likelihood estimator of Interferometric phase (EMI) results are used as the initial values of the phase triangle algorithm (PTA) for the purpose of phase estimation (hereafter called as PTA-EMI). The DSPs and estimated phase are then combined with CPs in order to retrievesurface deformation parameters. The method was validated by two cases. The results show that the density of measuring points increased approximately 6–10 times compared with CPT-InSAR, and the quality of the interferometric phase significantly improved after phase optimization. It was demonstrated that the method is effective in increasing measuring point density and improving phase quality, which increases significantly the detectability of the low coherence region. Compared with the Distributed Scatterer InSAR (DS-InSAR) technique, ACDP-InSAR possesses faster processing speed at the cost of resolution loss, which is crucial for Earth surface movement monitoring at large spatial scales.

Investigation of the Ternary Reciprocal System Na,Ba||Br,MoO4

Theoretical partition of the ternary reciprocal system Na,Ba||Br,MoO4 into simplexes was performed, the stable diagonal of the system was determined, and the heat of the reaction at the conversion point was calculated. The chemical interaction in the system and the phase equilibria were described, and the crystallization fields of phases were delimited. The validity of the theoretical partition was confirmed by experimental investigation of the stable diagonal and two stable elements of the ternary reciprocal system Na,Ba||Br,MoO4 by differential thermal analysis. It was found that the system Na,Ba||Br,MoO4 is a singular irreversible reciprocal system with eutectic melting. The system is divided by the stable cutting diagonal NaBr–BaMoO4 into two stable phase triangles, NaBr–BaBr2–Na2MoO4 and NaBr–BaMoO4–Na2MoO4. The results of the partition were corroborated by the X-ray powder diffraction analysis data. In the stable cutting diagonal, a saddle quasi-binary eutectic point, e 721°C, was revealed. The coordinates (melting point and composition) of two ternary eutectics, E1 586°C and E2 525°C, were found. The maximum crystallization field in the composition square corresponds to high-melting barium molybdate.

Mechanism of three phase separation in the ternary system of a polymer in a mixed solvent

Abstract The three phase separation due to contact between binodals was observed for the ternary system nitroethane(NE) + methylcyclohexane(MCH) + polystyrene(PS) with the molecular weight (Mw = 9.64 × 104 g/mol). A phase equilibrium experiment was made to determine binodals and three phase triangles on a composition triangle. With decreasing temperature a binodal spreads out from the MCH-PS side of a composition triangle at 48.4 °C and reaches the NE-MCH side at 23.6 °C. Another binodal spreads out from the NE-PS side at 43.6 °C and makes contact with the binodal running between the MCH-PS and NE-MCH sides at 3.3 °C. Simultaneously with the contact the three phase separation appears. The contact occurs at the critical point of the former binodal and at a noncritical point of the latter. The three phase separation usually occurs due to projection of a new binodal from the two phase region.

Characteristics of three phase separation in the ternary system of a polymer in a mixed solvent

The three phase separation was obtained for the ternary system of ethylene glycol diacetate (EGDA) + methylcyclohexane (MCH) + polystyrene (PS) with the molecular weight (Mw = 4.8 × 104 g/mol). A phase equilibrium experiment was carried out to determine binodals and three phase triangles. With decreasing temperature the three phase separation appears at 35.0 °C in the two phase region spreading from the EGDA-MCH side protruding a new binodal with a critical point on a composition triangle. The binodal spreading from the EGDA-PS side merges with the binodal from EGDA-MCH side at 34.0 °C via a critical point, while the binodal from MCH-PS side merges with the new binodal at 32.9 °C. Thus, the binodal surface in a prism diagram of composition triangle and temperature has two saddle points at which a critical line has a minimum.

Unraveling the Origin of Instability in Ni-Rich LiNi1–2xCoxMnxO2 (NCM) Cathode Materials

In this work, phase stability of Ni-rich LiNi1–2xCoxMnxO2 (NCM) (x Ni2+Mn4+ > Ni3+Mn4+ > Co3+Mn4+ > Co2+Mn4+ > Ni2+Ni4+) is then predicted by bond model and subsequently used to understand the intricate layered LiTMO2 (TM = Ni, Co, Mn) phase triangle. Our results also show that Co and Mn ions segregate to form clusters within the Ni environment when x < 0.1 (Ni ≥ 80 at. %), and such segregation is responsible for the electrochemical degradation during cycling. The obtained results agree excellently with the validation experiment in the present work and also other experiments in the ...

Isothermal decomposition kinetics of nickel (II) hydroxide powder

Nickel (II) hydroxide powder was investigated by thermogravimetry for isothermal decomposition kinetics and verification of the Ni–O–H ternary phase diagram at low temperatures. The activation energy and frequency factor were measured as Ea=134kJ/mol and A=1.27×1010s−1, respectively. The validity of the first-order random nucleation model was confirmed, as opposed to diffusion and or moving-boundary models. The dependence of TGA results on specimen size was noted. The Ni–Ni(OH)2–NiO phase triangle was confirmed. Accordingly, a thermodynamic description of the system was established in the Ni-rich corner, and the isotherm at room temperature is calculated.

Direct phase selection of initial phases from single-wavelength anomalous dispersion (SAD) for the improvement of electron density and ab initio structure determination.

Optimization of the initial phasing has been a decisive factor in the success of the subsequent electron-density modification, model building and structure determination of biological macromolecules using the single-wavelength anomalous dispersion (SAD) method. Two possible phase solutions (φ1 and φ2) generated from two symmetric phase triangles in the Harker construction for the SAD method cause the well known phase ambiguity. A novel direct phase-selection method utilizing the θ(DS) list as a criterion to select optimized phases φ(am) from φ1 or φ2 of a subset of reflections with a high percentage of correct phases to replace the corresponding initial SAD phases φ(SAD) has been developed. Based on this work, reflections with an angle θ(DS) in the range 35-145° are selected for an optimized improvement, where θ(DS) is the angle between the initial phase φ(SAD) and a preliminary density-modification (DM) phase φ(DM)(NHL). The results show that utilizing the additional direct phase-selection step prior to simple solvent flattening without phase combination using existing DM programs, such as RESOLVE or DM from CCP4, significantly improves the final phases in terms of increased correlation coefficients of electron-density maps and diminished mean phase errors. With the improved phases and density maps from the direct phase-selection method, the completeness of residues of protein molecules built with main chains and side chains is enhanced for efficient structure determination.

Li, K‖Br, VO3 ternary mutual system

Phase equilibria in the Li, K‖Br, VO3 ternary mutual system were studied by differential thermal analysis. The composition square of the ternary mutual system is divided into two phase triangles, LiVO3-KBr-KVO3 and LiBr-LiVO3-KBr. The ternary eutectics E1 at 331°C and E2 at 330°C have the compositions 40.0 mol % LiVO3, 6.0 mol % KBr, 54.0 mol % KVO3 and 58.0 mol % LiBr, 3.2 mol % LiVO3, 38.8 mol % KBr, respectively. The fields of phases crystallizing in the system were delimited.

Cd4Cu7As, The First Representative of a Fully Ordered, Orthorhombically Distorted MgCu2Laves Phase

The ternary Laves phase Cd(4)Cu(7)As is the first intermetallic compound in the system Cu-Cd-As and a representative of a new substitution variant for Laves phases. It crystallizes orthorhombically in the space group Pnnm (No. 58) with lattice parameters a = 9.8833(7) Å; b = 7.1251(3) Å; c = 5.0895(4) Å. All sites are fully occupied within the standard deviations. The structure can be described as typical Laves phase, where Cu and As are forming vertex-linked tetrahedra and Cd adopts the structure motive of a distorted diamond network. Cd(4)Cu(7)As was prepared from stoichiometric mixtures of the elements in a solid state reaction at 1000 °C. Magnetic measurements are showing a Pauli paramagnetic behavior. During our systematical investigations within the ternary phase triangle Cd-Cu-As the cubic C15-type Laves phase Cd(4)Cu(6.9(1))As(1.1(1)) was structurally characterized. It crystallizes cubic in the space group Fd3m with lattice parameter a = 7.0779(8) Å. Typically for quasi-binary Laves phases Cu and As are both occupying the 16c site. Chemical bonding, charge transfer and atomic properties of Cd(4)Cu(7)As were analyzed by band structure, ELF, and AIM calculations. On the basis of the general formula for Laves phases AB(2), Cd is slightly positively charged forming the A substructure, whereas Cu and As represent the negatively charged B substructure in both cases. The crystal structure distortion is thus related to local effects caused by Arsenic that exhibits a larger atomic volume (18 Å(3) compared to 13 Å(3) for Cu) and higher ionicity in bonding.

SCFT Study of Nonfrustrated ABC Triblock Copolymer Melts

The phase behavior of ABC triblock copolymer melts is studied by self-consistent-field theory (SCFT). We focus on “nonfrustrated” triblocks, in which the Flory−Huggins interaction parameter χAC between the end blocks is significantly larger than that between the middle and either end block, i.e., χAC ≫ χAB ∼ χBC. Such systems tend to form ordered structures with no AC interface. Complete phase triangles at fixed values of the products χijN are presented for a model with χAB = χBC ≪ χAC and for a model with parameters chosen to represent poly(isoprene-b-styrene-b-ethylene oxide) copolymers that have recently been studied experimentally. Particular attention is paid to the structure of the orthorhombic O70 network phase and the reasons for its existence as well as to the sensitivity of the predicted phase behavior to changes in the χ parameters.

Spinel ferrites of the quaternary system Cu-Ni-Fe-O: Synthesis and characterization

The decomposition of the freeze dried Cu(II)-Ni(II)-Fe(III) formate precursors at 1000°C in air yields complex oxides CuxNi1−xFe2O4±δ (0 ≤ x ≤ 1) with a cubic spinel structure. For x < 0.7, single phase spinels are formed at 1000°C. However, for 0.7 ≤ x ≤ 1, Copper oxide (CuO) is identified as a second phase and the formation of a pure spinel phase requires an increase of the iron content in the mixture. For example, Cu0.81Ni0.1Fe2.09O4 is a single phase at 1000°C/air. Other single spinel phases Cu0.5+yNi0.5−y−zFe2+zO4±δ, 0 ≤ (y + z) ≤ 0.5, in the phase triangle Cu0.5Ni0.5Fe2O4–CuFe2O4–Cu0.5Fe2.5O4 have been synthesized under special p(O2)/T—synthesis conditions. The increase of the iron content requires an increase of the reaction temperature and/or a decrease of the p(O2) in the reaction gas stream. The oxygen exchange between Cu0.9Fe2.1O4.02 and the reducing gaseous phases shows that the non stoichiometry δ of copper ferrite is only about ±0.03. Significant changes in the oxygen content lead to the separation in different phases. The electrical and magnetic properties of copper ferrite samples depend on their chemical composition and preparation conditions.

PHASE BEHAVIOR OF THE ETHANOL-BIODIESEL-DIESEL MICRO-EMULSION SYSTEM

The use of ethanol blended with regular diesel fuel was a subject of research in the 1980s. It was shown that such blends were technically acceptable for existing diesel engines without modifications. Biodiesel as well as ethanol-blended E-diesel yielded substantial reductions in urban emissions of carbon monoxide (CO), greenhouse gases (primarily CO2), sulfur oxides (SOx), and particulate matter (PM). The major drawback of E-diesel is that ethanol is immiscible in diesel over a wide range of temperatures. This study attempts to use biodiesel as a potential amphiphile in the ethanol-biodiesel system. The study looks into the phase behavior of the ethanol-biodiesel-diesel ternary system in order to identify key areas within the phase diagram that are stable isotropic micro-emulsions that could be used as potential biofuels for compression-ignition engines. The instantaneous phase behavior indicated that the system formulates stable micro-emulsions over a fairly large region of the phase triangle, depending on the concentrations of different components. The single-phase area of the three-component system was widest at higher biodiesel concentrations. The phase diagram indicated that at higher diesel concentrations, in order to formulate a stable micro-emulsion, the ratio of biodiesel to ethanol in the system should be greater than 1:1. The results of the study suggested that biodiesel could be effectively used as an amphiphile in an ethanol-diesel blend.

Systematic Research on Insertion Materials Based on Superlattice Models in a Phase Triangle of LiCoO2 ­ LiNiO2 ­ LiMnO2: I. First-Principles Calculation on Electronic and Crystal Structures, Phase Stability and New Material

The first-principles calculations on the lithium insertion materials have been done to give the rationale for materials research on advanced lithium-ion batteries. To apply the computational methods, the model crystals are constructed by assuming in-plane two-dimensional superlattices based on -type structure for three sides of a phase triangle of Model crystals consisting of a superlattice gives two transition metal elements in the ratio of 3 to 1 and a superlattice model gives 2 to 1. For the ratio of 1 to 1, two model crystals are assumed, i.e., so-called “straight” and “zigzag” models. The first-principles calculations for these model crystals indicate that (i) is a solid solution between and (ii) is not expected to be a solid solution between and (unstable, phase separation is expected), and (iii) is not a solid solution between and is expected to be a stable phase). Among these compounds calculated, having a layered structure may be a new compound consisting of and in their formal charges, which is neither a solid solution between and nor between NiO and From these theoretical results, materials design toward the implementation of novel lithium insertion materials for advanced lithium-ion batteries is discussed. © 2004 The Electrochemical Society. All rights reserved.

Prediction of a stable microemulsion formulation for the oral delivery of a combination of antitubercular drugs using ANN methodology.

The aim of this project was to develop a colloidal dosage form for the oral delivery of rifampicin and isoniazid in combination with the aid of artificial neural network (ANN) data modeling. Data from the 20 pseudoternary phase triangles containing miglyol 812 as the oil component and a mixture of surfactants or a surfactant/cosurfactant blend were used to train, test, and validate the ANN model. The weight ratios of individual components were correlated with the observed phase behavior using radial basis function (RBF) network architecture. The criterion for judging the best model was the percentage success of the model prediction. The best model successfully predicted the microemulsion region as well as the coarse emulsion region but failed to predict the multiphase liquid crystalline phase for cosurfactant-free systems indicating the difference in microemulsion behavior on dilution with water. A novel microemulsion formulation capable of delivering rifampicin and isoniazid in combination was created to allow for their differences in solubility and potential for chemical reaction. The developed model allowed better understanding of the process of microemulsion formation and stability within pseudoternary colloidal systems.

HF-CVD of B, C, N containing layers on various substrates by the decomposition of Triethylborazine

In the BCN phase triangle many interesting compounds are located, e.g. h-BN, c-BN, BC 2N, graphite and diamond. For layers with composition in this area interesting qualities can be expected. To fix the B:C:N stoechiometry 2,4,6-Triethylborazine (C 6H 18B 3N 3) was used and decomposed in a hot-filament equipment. Pre-carburised Ta-filaments and hydrogen or argon for the gas atmosphere were used. Untreated, etched and diamond coated WC–Co hardmetal inserts were used as substrates. The deposition parameters filament temperature (1800–2200 °C), precursor flow rate and gas atmosphere were varied. The layer growth rates increased with the precursor flow rate and showed less influence of the substrate material. Layer morphology was of the pyrolytic type. When the layers became thick they tended to eliminate from the substrate. Due to the atomic hydrogen produced at the filament the deposition rate decreased in case of H 2/Ar atmosphere compared to the experiments in argon atmosphere. This can be explained by etching reactions of the atomic hydrogen. Due to the etching reactions of the atomic hydrogen the IR-spectra also looked different. Nevertheless, it was not possible to identify a cubic phase from the IR or XRD measurements.

Thermodynamics of pseudo-ternary systems as a tool to predict the morphologies of cellulose acetate/polystyrene blends cast from tetrahydrofuran solutions

The demixing behavior of the ternary system THF/CA/PS (tetrahydrofuran/cellulose acetate/polystyrene) was investigated at 25 °C. Cloud point measurements show that the system exhibits a large miscibility gap caused by the incompatibility of CA and PS. Both ends of the experimentally determined tie lines are located inside the two-phase area of the phase diagram. By means of the measured critical composition of the ternary system and the Flory–Huggins interaction parameters published for two of the binary subsystems ( χ CA/THF=0.442 and χ PS/THF=0.475) the polymer/polymer interaction parameter was adjusted (directly minimizing the Gibbs energy) to χ CA/PS=0.057. These thermodynamic data were used to calculate the extension of the metastable and the unstable regions of the phase diagram. This procedure permits a realistic prediction of the morphologies of the (solvent-free) blends from the location of the starting composition of the casting solutions in the Gibbs phase triangle, as demonstrated by means of optical micrographs and field emission scanning electron micrographs.