Ternary Equilibrium Phase Diagram Research Articles

Study on the solid-liquid equilibrium and thermodynamic model of the L-phenylalanine + L-tryptophan + water system.

Amino acids hold significant importance in the diagnosis and treatment of various chronic diseases. Accurate solid-liquid equilibrium data are the key to drug synthesis and chemical production. However, the studies on the solid-liquid equilibrium of amino acids remain limited. In this work, the solid-liquid equilibrium of the L-tryptophan + L-phenylalanine + water ternary system under atmospheric pressure at temperatures of 278.15 K-318.15 K was explored via isothermal solution saturation. The isothermal equilibrium phase diagram of the ternary system was constructed. The obtained solid-liquid equilibrium data were correlated with a semi-empirical-model, yielding thermodynamic parameters pa, pb, pc, and k. Furthermore, the model can be used to effectively predict the solid-liquid equilibrium data of ternary systems at other temperatures, and the dY and dP are 0.005 and 4.34%, respectively. The solid-liquid equilibrium data and ternary equilibrium phase diagrams of the system were utilized for the separation and purification of an L-tryptophan and L-phenylalanine mixture. By employing thermodynamic models to calculate the relevant phase diagram data for mixtures with different proportions, effective separation and purification of the mixture could be achieved using the principles of variable temperature phase diagrams. These works are valuable for optimizing chemical processes and have practical implications in the field.

Study on the slagging tendency estimation of biomass fuel combustion with different additives and pretreatment processes

Grey fixed weight clustering (GFWC) method is studied to predict the slagging tendency of biomass fuels combustion. Then the results of the GFWC method were verified and compared with experimental results. In the experiment, bagasse was chosen as an example to prepare ash from three different pretreatment groups (non-washing (NW), water-washing (WW), acid-washing (AW)) and two samples adding kaolin and calcite respectively. The degree of slagging was determined by measuring the ash melting point temperature with the ash melting point analyzer and observing the structural morphology of the particles by the scanning electron microscope (SEM). The GFWC method was used to synthesize the five single slagging prediction indexes, and a mathematical model for the evaluation of slagging was proposed to improve the accuracy of the evaluation results. Furthermore, the accuracy and applicability of the GFWC method for the estimation of slagging tendency of 25 kinds of biomass were tested. Compared with SI method and ternary equilibrium phase diagram, the estimation of GFWC method can avoid the uncertainty and it agreed with the SEM characteristics and ash fusibility temperatures (AFT). This study provides a new reference for biofuel slagging trend estimation based on ash composition.

Mechanical Properties of Interface Layers in SiC/TiAl Composite

Although metal matrix composites (MMC) for the high temperature structural material have been investigated extensively for many years, applications of MMC have been still limited. Among many combinations between the ceramic fibers and the matrix materials, combination of SiC fiber and TiAl based intermetallic compounds has been expected to be one of the best combination, since both SiC fiber and TiAl have demonstrated the capabilities of the low density heat resistant materials. SiC fiber reinforced TiAl composites have been successfully fabricated using hot press method. Optimum temperature and pressure have been determined. SiC/TiAl composite having relatively low fiber volume fraction shows nearly an ideal elastic property applying the law of mixture. Effects of interface layers on the mechanical properties of composites have been studied in detail. Micro-indentation on a single fiber was carried out to examine the pull out strength of SiC fiber quantitatively. Estimated shear stress on the interface was 145-195MPa, those values are quite reasonable since the tensile strength of TiAl matrix was 420MPa and the maximum shear stress would be the half of tensile strength according to Schmid law. Three-point bending tests have been carried out to evaluate the mechanical properties of composites. Fiber volume fraction 8.9% specimen shows ideal bending stiffness compare with the calculated values based on the low of mixture. Reaction layers and the interface between SiC fiber and TiAl have been analyzed by SEM-EDS and XRD. At least two or more reaction layers have been identified. These reaction layers can be explained based on the Si-Ti-C ternary equilibrium phase diagram at 1373K. Optimum conditions of interface structure will be discussed

Slagging tendency estimation of aquatic microalgae and comparison with terrestrial biomass and waste

Due to their different growth environments, the slagging problem of aquatic biomass such as microalgae Chlorella vulgaris (C. vulgaris) is different from that of other fuels such as wood, herbaceous biomass and wastes. Three sample groups of microalgae C. vulgaris were made into ash after different pretreatment processes: non-washing (NW), water-washing (WW) and acid-washing (AW). The slagging-predictive indices (SI), the ash fusibility temperatures (AFT) and ternary equilibrium phase diagram SiO2–CaO–K2O (SCK) system were applied separately to estimate the slagging tendency of aquatic biomass C. vulgaris, six terrestrial biomasses and six wastes. The results showed that the elemental composition of ash for C. vulgaris differed from that of other biofuels, especially regarding the content of P2O5. The WW and AW methods were effective for potassium and sulfur removal from C. vulgaris. The results from SI, AFT and SCK system showed that the three groups of C. vulgaris ash had high slagging tendency caused by the high phosphorus content. The results of SCK were consistent with the SI results of RB/A and RFu for biomass and wastes.

Effect of sludge addition to coal on Na, K and S volatilisation in ashing process and ash fusibility

The effect of the addition of three types of sludge (L, O and F) on both the Na, K and S volatilisation and the slagging behaviour of a bituminous coal (H) was studied. Na, K and S volatilise in the coal, the sludges and their blends partially, and there exist linear relationships between their contents in ashes and the ratio sludge ash/blend ashes for each coal–sludge blend ash series. However, in blends with F (treated with FeCl3 and lime), S relationship is not linear due mainly to the following effects: a) sulphur retention by CaO to form CaSO4, and b) decrease of free CaO due to the formation of ferrites, silicates and phosphates. To determine the slagging tendency, the ash fusion temperatures (AFTs) were related with ash chemical and mineral composition by using the slagging factor, the base/acid ratio, the Fe2O3/CaO ratio, the P2O5 content, and the ternary equilibrium phase diagram SiO2–Al2O3–CaO. Sludge addition to coal produces a decrease in AFTs that depends on the percentage of sludge added, the sludge phosphorus content and additives (FeCl3 and/or lime), the fact that ash composition is near to those of the eutectics, and the formation of Si and P amorphous compounds.

Ash fusibility and compositional data of solid recovered fuels

Several approaches are established to analyse the fouling and slagging propensities of coal ashes, but the same cannot be said of solid recovered fuel (SRF) ashes. This work has been conducted by using some fouling and slagging indicators, which are commonly applicable to coal ashes, on SRF ashes to ascertain their applicability. In this work, laboratory prepared ashes derived from municipal solid waste (MSW), sewage sludge, demolition wood, shredded rubber tyres, and plastic/paper fluff are analysed for their fusibility leading to fouling and slagging using three approaches; the ash fusibility temperatures (AFT), ternary phase diagrams, and fouling/slagging indices. The results from each approach are examined to determine the inclination of the ashes toward fouling and slagging. A subsequent inter-comparison of the methods was conducted to validate the methods which are in agreement and are applicable to SRF ashes. The study showed that ternary equilibrium phase diagram SiO 2 –CaO–Al 2 O 3 , various fouling and slagging indices, and AFT can be used to complement each other to predict ash fusion properties, fouling and slagging propensities of SRF ashes.

Simple Model for the Capacity of Amorphous Silicon-Aluminum-Transition Metal Negative Electrode Materials

Thin-film libraries of (M=Cr, Fe, Mn, Ni) negative electrode materials were characterized using combinatorial and high-throughput techniques. Transition metal content had a large effect on capacity, such that alloys with more than ca. did not alloy with Li during room temperature or charge-discharge cycling. The contour line was used to separate those compositions that readily alloyed with Li from those that did not. This contour line also approximately connects the lowest content equilibrium crystalline phases. We propose that all crystalline equilibrium phases are inactive. The capacity of a given composition of can be approximated, to first order, using only the equilibrium ternary phase diagram. These results could have a large impact on the study of other, more complex, amorphous alloy negative electrode material systems.

Solidification and compositional convection of a ternary alloy

We present the results of an experimental study on the solidification of aqueous solutions of potassium nitrate and sodium nitrate cooled from below. Upon cooling, two distinct mushy layers form, primary and cotectic, separated by an approximately planar horizontal interface. A density reversal between the two mushes causes the residual liquid in the upper, primary mush to be more buoyant than the melt overlying it, while the cotectic mush is compositionally stable. The unstable concentration gradient between the melt and primary mush causes convection that keeps the melt well-mixed and reduces the concentration gradient to zero after a finite time. At this point, the cotectic mush overtakes the primary mush and a transition from a convective regime to a diffusive regime occurs. Our measurements show that this transition is rapid and alters the growth rate of the single (cotectic) mush layer that remains. Concentration measurements taken from within the melt during convection and from within the mush during the diffusive regime show good agreement with the concentration evolution predicted by use of the equilibrium ternary phase diagram. We describe a global conservation model for solidification of a ternary alloy in this regime. Predictions from our model forced with empirical data for the heat and solute fluxes are in good agreement with the measured data for the interface positions of the two mushy layers. We also discuss how solid fractions vary with different melt concentrations in a non-convecting alloy and examine the influence of vertical solute transport in the convecting case. The identification of a density reversal in the solidification of a ternary alloy begins to address the complexities in solidification processes of multi-component alloys.

Pathobiology of Cholesterol Gallstone Disease: From Equilibrium Ternary Phase Diagram to Agents Preventing Cholesterol Crystallization and Stone Formation

The primum movens in cholesterol gallstone formation is hypersecretion of hepatic cholesterol, chronic surpersaturation of bile with cholesterol and rapid precipitation of cholesterol crystals in the gallbladder from cholesterol-enriched vesicles. Associated events include biochemical defects (increased biliary mucin, and increased proportions of hydrophobic bile salts in the intestine and gallbladder), motility defects (gallbladder smooth muscle hypocontractility in vitro and gallbladder stasis in vivo, sluggish intestinal transit), and an abnormal genetic background. The study of physical-chemical factors and pathways leading to cholesterol crystallization in bile has clinical relevance and the task can be carried out in different ways. The lithogenicity of bile is investigated in artificial model biles made by three biliary lipids - cholesterol, bile salts and phospholipids - variably combined in systems plotting within the equilibrium ternary phase diagram; also, crystallization propensity of ex vivo incubated human bile is studied by biochemical analysis of precipitated crystals, polarizing quantitative light microscopy and turbidimetric methods. The present review will focus on the recent advances in the field of pathobiology of cholesterol gallstones, by underscoring the role of early events like water transport, lipid transport, crystallization phenomena - including a genetic background - in gallstone pathogenesis. Agents delaying or preventing precipitation of cholesterol crystals and gallstone formation in bile will also be discussed.

Pathobiology of Cholesterol Gallstone Disease: From Equilibrium Ternary Phase Diagram to Agents Preventing Cholesterol Crystallization and Stone Formation

The primum movens in cholesterol gallstone formation is hypersecretion of hepatic cholesterol, chronic surpersaturation of bile with cholesterol and rapid precipitation of cholesterol crystals in the gallbladder from cholesterol-enriched vesicles. Associated events include biochemical defects (increased biliary mucin, and increased proportions of hydrophobic bile salts in the intestine and gallbladder), motility defects (gallbladder smooth muscle hypocontractility in vitro and gallbladder stasis in vivo, sluggish intestinal transit), and an abnormal genetic background. The study of physical-chemical factors and pathways leading to cholesterol crystallization in bile has clinical relevance and the task can be carried out in different ways. The lithogenicity of bile is investigated in artificial model biles made by three biliary lipids - cholesterol, bile salts and phospholipids - variably combined in systems plotting within the equilibrium ternary phase diagram; also, crystallization propensity of ex vivo incubated human bile is studied by biochemical analysis of precipitated crystals, polarizing quantitative light microscopy and turbidimetric methods. The present review will focus on the recent advances in the field of pathobiology of cholesterol gallstones, by underscoring the role of early events like water transport, lipid transport, crystallization phenomena - including a genetic background - in gallstone pathogenesis. Agents delaying or preventing precipitation of cholesterol crystals and gallstone formation in bile will also be discussed.

Synthesis of Magnesium Aluminate Spinels from Bauxites and Magnesias

The synthesis of refractory Mg‐Al spinel aggregates from bauxites and magnesias was addressed by applying the alumina–magnesia–silica ternary equilibrium phase diagram as the fundamental basis. Four different alumina sources (bauxites) and four different magnesia sources were investigated. These were fired in air through 1700°C and their reactions were monitored using X‐ray diffraction. Evolution of their microstructure was observed by scanning electron microscopy. Initially, the periclase reacts with the free corundum of the bauxite to produce Mg‐Al spinel. The periclase then reacts with the mullite in the bauxites to yield additional spinel and also some forsterite. Spinels were produced for all sixteen different raw‐material combinations.

Cholesterol crystallization in model biles: effects of bile salt and phospholipid species composition

Cholesterol in human bile is solubilized in micelles by (relatively hydrophobic) bile salts and phosphatidylcholine (unsaturated acyl chains at sn-2 position). Hydrophilic tauroursodeoxycholate, dipalmitoyl phosphatidylcholine, and sphingomyelin all decrease cholesterol crystal-containing zones in the equilibrium ternary phase diagram (van Erpecum, K. J., and M. C. Carey. 1997. Biochim. Biophys. Acta. 1345: 269–282) and thus could be valuable in gallstone prevention. We have now compared crystallization in cholesterol-supersaturated model systems (3.6 g/dl, 37°C) composed of various bile salts as well as egg yolk phosphatidylcholine (unsaturated acyl chains at sn-2 position), dipalmitoyl phosphatidylcholine, or sphingomyelin throughout the phase diagram. At low phospholipid contents [left two-phase (micelle plus crystal-containing) zone], tauroursodeoxycholate, dipalmitoyl phosphatidylcholine, and sphingomyelin all enhanced crystallization. At pathophysiologically relevant intermediate phospholipid contents [central three-phase (micelle plus vesicle plus crystal-containing) zone], tauroursodeoxycholate inhibited, but dipalmitoyl phosphatidylcholine and sphingomyelin enhanced, crystallization. Also, during 10 days of incubation, there was a strong decrease in vesicular cholesterol contents and vesicular cholesterol-to-phospholipid ratios (~1 on day 10), coinciding with a strong increase in crystal mass. At high phospholipid contents [right two-phase (micelle plus vesicle-containing) zone], vesicles were always unsaturated and crystallization did not occur. Strategies aiming to increase amounts of hydrophilic bile salts may be preferable to increasing saturated phospholipids in bile, because the latter may enhance crystallization. —Moschetta, A., G. P. vanBerge-Henegouwen, P. Portincasa, G. Palasciano, and K. J. van Erpecum. Cholesterol crystallization in model biles: effects of bile salt and phospholipid species composition.

Predicting coal ash fusion temperature with a back-propagation neural network model

A novel technique, the back-propagation (BP) neural network, is presented for predicting the ash fusion temperature from ash compositions for some Chinese coals instead of the traditional techniques, such as the ternary equilibrium phase diagrams and regression relationships. In the applications of the BP networks, some modifications to the original BP algorithm are adopted to speed up the BP learning algorithm, and some useful advice is put forward for the choice of some key parameters in the BP model. Compared to the traditional techniques, the BP neural network method is much more convenient and direct, and can always achieve a much better prediction effect.

Rigid organic nanodisks of controlled size: A catanionic formulation

We show that organic rigid nanodisks of controlled size can be produced using a balanced pair of ionic surfactant molecules in a catanionic system. The counter-ion for the cationic surfactant is hydroxide. The counter-ion of the anionic surfactant is the hydronium ion. Close to equimolarity, counter-ions from water molecules: fluid solutions of ultra-low conductivity are obtained. This is solution contains rigid disks of thickness 4 nm: chains are frozen and surfaces are covered by ion pairs formed by the headgroups. The overall size of the disks is continuously adjustable from micrometer to nanometer size and is controlled by the excess of one of the two single chain surfactants involved. Unbound dispersed, nematic and lamellar structures are detected and located in the ternary equilibrium phase diagram at room temperature. Nous montrons que des nanoplaquettes rigides de taille contrôlable peuvent être obtenues en utilisant un mélange de tensioactifs catanioniques dont l'un porte un H + , l'autre un hydroxyde. On obtient des solutions diluées isotropes optiquement et qui contiennent des nanodisques rigides d'épaisseur 4 nm. Les chaînes hydrocarbonées sont dans l'état cristallin. La taille des nanoplaquettes organiques formées est continûment ajustable, de l'ordre du micromètre à quelques nanomètres. Les plaquettes sont constituées d'une partie centrale plate et rigide. Des paires d'ions stabilisent chacune des faces. Un premier diagramme de phase d'équilibre schématique comprend des zones isotropes, nématiques et lamellaires.

Solidification of ternary metal alloys—I. Model development

Building on previous treatments of transport phenomena occurring during the solidification of binary alloys, a model is constructed to simulate the casting of ternary alloys. Specifically, the continuum mixture equations for the transport of mass, momentum, energy and species are modified to account for a third component. To close the model, supplemental thermodynamic relations, which are taken from the ternary equilibrium phase diagram and which treat the several primary solid phases, binary eutectic troughs, ternary eutectic and peritectic reactions and the formation of an intermetallic compound, are presented. Finally, a calculation procedure is developed for the thermodynamic model. Numerical results based on the application of this model are discussed in a companion paper [Krane and Incropera, International Journal of Heat and Mass Transfer, 1997, 40, 3837–3847].

Calorimetric and structural analyses of mechanically alloyed and rapidly quenched Zr-Ni-Al alloys

Mechanical alloying and rapid quenching from the melt are used to form Zr-Ni-Al amorphous alloys. An experimental investigation of the amorphous to crystalline transformation is carried out using differential scanning calorimetry, X-ray diffraction and microprobe analysis. The experiments are managed to analyse and correlate the results both for mechanically alloyed powders and rapidly quenched ribbons: (i) a preliminary analysis of the kinetics of relaxation and crystallization, (ii) a connection between the final crystallized phases and the equilibrium ternary phase diagram.

Synthesis of [formula omitted] and [formula omitted] composites using displacement reactions in the TiSiC system

This paper reports on efforts to synthesize composites in the Ti-Si-C system. Selection of the composite system(s) was based on the Ti-Si-C ternary equilibrium-phase diagram. However, interest in the Ti-Si-C system was motivated by recent reports of not-so-brittle behavior of the complex ternary phase Ti{sub 3}SiC{sub 2}. Apparently, Ti{sub 3}SiC{sub 2} is a soft ceramic compound, like BN or graphite in its behavior. It has a layered crystal structure (D{sub oh}{sup 4}-P6{sub 3}/mmc, hexagonal), a melting temperature greater than 3000C, and a density of 4.53 g/cm{sup 3}. Reportedly, its microhardness as a function of load indicates ductile, or not-so-brittle, behavior, and is anisotropic. The Knoop hardness is about 3.5 GPa when measured along (hk0)(uv0) (parallel to soft, TiC-like orientation) and about 13 GPa when measured in other orientations (perpendicular to TiC-like orientation). Bulk, polycrystalline Ti{sub 3}SiC{sub 2} has a Vickers hardness of 6 to 7 GPa.

Calculation of isothermal sections of three ternary Ti-Zr-X systems

The equilibrium phase diagram of the binary system Ti-Zr shows complete solubility in both allotropic forms, the high temperature {beta}-phase (bcc structure) and the low temperature {alpha}-phase (hexagonal structure). In the present paper the influence of additions of a third element (X = Hf, Nb, Ta) on the relative stability of both phases has been analyzed. Hf does also exhibit the two allotropic forms, and both show complete solubility for Zr and Ti. The other two elements crystallize as bcc. Nb is completely soluble in {beta}-Ti, but only at higher temperatures in {beta}-Zr. Its solubility in the {alpha}-Ti and {alpha}-Zr phases is very limited. Ta is also completely soluble in {beta}-Ti but shows only limited solubility in {beta}-Zr, {alpha}-Zr and {alpha}-Ti. Calculated isothermal sections of these three ternary equilibrium phase diagrams as well as considerations concerning thermodynamic parameters are presented and discussed in this work.

Fe-C-Si系球状黒鉛鋳鉄の凝固組織予測のためのコンピュータ・シミュレーション

A model to predict the solidification of spheroidal graphite (SG) cast iron during the cooling process was developed. Using the model, we treated the problem of the ternary Fe-C-Si system and aimed at simulating the evolution of the solidifying microstructure. When the eutectic temperature was reached, eutectic grains were formed. The rate of nucleation depended on the melt characteristics and supercooling. The nucleation rate was assumed to be presented by power law function of undercooling. The growth of the austenite grain was controlled by carbon diffusion through austenite. Carbon and silicon concentrations at different interfaces were calculated from the Fe-C-Si equilibrium ternary phase diagram and the Scheil equation was applied to calculate the silicon content in the bulk liquid and the concentration of carbon in the liquid was determined to keep the eutectic reaction.The model was applied to a cylindrical sand casting with four-step diameters of 10, 20, 30 and 40 mm. The simulated results were compared with the experimental ones using a post processing program which was also developed to simulate the microstructural evolution graphically. The results showed relatively good agreement and the usefulness of the proposed model was confirmed.

Simulating Solidification of Spheroidal Graphite Cast Iron of Fe–C–Si System

A model to predict the solidification of spheroidal graphite (SG) cast iron during cooling process was developed. The model treated the problem of the ternary Fe-C-Si system and aimed at simulating the evolution of the solidifying microstructure. When the eutectic temperature is reached, eutectic grains are formed. The rate of nucleation depends on the melt characteristics and supercooling. The nucleation rate was assumed to be presented by power law function of undercooling. The growth of the austenite grain was controlled by carbon diffusion through austenite. Carbon and silicon concentrations at different interfaces are calculated from the Fe-C-Si equilibrium ternary phase diagram and Sheil equation was applied to calculate the silicon content in the bulk liquid and the concentration of carbon in the liquid was determined to keep the eutectic reaction. The model was applied to a four-step cylindrical sand casting which has a different diameter. The simulated results were compared with the experimental ones using a post processing program which was also developed to simulate the microstructural evolution graphically. The results showed relatively good agreement and the usefulness of the proposed model was confirmed.