Eutectic Phase Diagram Research Articles

Preparation and characteristics of lauric acid-myristic acid-based ternary phase change materials for thermal storage

Latent heat energy storage technology is an important measure in the field of energy conservation. In this work, lauric acid and myristic acid were used as binary matrix, two ternary phase change materials of lauric-myristic-palmitic acid and lauric-myristic-paraffin section were prepared by introducing palmitic acid and paraffin section. Two ternary eutectic phase diagrams were obtained by analyzing the binary system, the optimal quality proportions of lauric-myristic-palmitic acid and lauric-myristic-paraffin section were 59:26:15 and 51:28:21, respectively, the phase transition temperatures were 32.24 °C and 31.50 °C, the difference between the theoretical predicted temperature and the experimental results is 0.95 ℃ for lauric-myristic-palmitic acid, which is basically consistent with the theoretical values. The enthalpies were 160.41 J/g and 172.37 J/g for the two groups of ternary phase change materials, and the research indicated that they were physically mixed and had good thermal stability at working temperature. After 500 thermal cycles, lauric-myristic-palmitic acid exhibited better thermal reliability compared to lauric-myristic-paraffin section. The results show that both groups of ternary phase change materials have excellent thermal properties and can be used in engineering applications over a long period of time.

Solid-Liquid Equilibrium and Phase Diagram of Organic System Forming Simple Eutectic

The study of phase diagram guided with solid-liquid equilibrium (SLE) data at different molar composition in two component systems serve as a basic roadmap for the material synthesis, and also provide in-depth study of physicochemical and thermochemical properties of synthesized materials. The solid-liquid equilibrium data of binary organic system, acetanilide – acetamide (ACN-ACT) is determined by thaw melt method. The system exhibits simple eutectic type phase diagram at 0.20 molar composition of ACN with congruent melting temperature 52oC.

Determination and modeling of binary solid-liquid equilibria of para-xylene/meta-xylene, para-xylene/ortho-xylene by DSC method

Solid-liquid equilibria of three binary mixtures consisting of para-xylene, ortho-xylene, meta-xylene and ethylbenzene were investigated in this study using differential scanning calorimetry (DSC) method, the mixtures were cooled to -120 °C and then heated to 20 °C at different heating rates, eutectic phase diagrams were observed for para-xylene/ortho-xylene and para-xylene/meta-xylene binary systems. The freezing point of pure ethylbenzene at atmospheric pressure is around -95 °C, but due to the effect of induction time, the observed freezing temperature is lower than -120 °C, the operation temperature of industrial xylene crystallization separation process is higher than -80 °C traditionally, therefore ethylbenzene will not crystallize in practical process, the phase diagram for para-xylene/ethylbenzene was not achieved. The experimental data were compared with data from other literatures and new features were found. The data were well correlated by Apelblat equation and λH equation, it is significative to provide important engineering data for the separation and purification of xylene mixtures.

Active learning of eutectic phase diagram in engineering courses

The present article shows a new strategy used to cover phase diagrams for undergraduate mechanical engineering students. It is based on active learning in which students are required to investigate experimentally three different eutectic alloys by using X-ray diffraction and metallography. The first technique allows students to use Rietveld analysis to obtain the mass fraction of the present phases and they must compare their results with those obtained theoretically whilst the second one is used to characterize those phases and measured their area fractions. From these results, they can also compare them with those obtained theoretically, but considering the density of different phases. The results have shown that students understood more clearly concepts such as the lever rule, and the very interpretation of phase diagram: the liquidus and solidus curve and finally the eutectic point.

New thermodynamic interpretation of T0 curves in glass forming alloys

This study presents a new thermodynamic interpretation of T0 curves in eutectic phase diagrams. By analyzing the Gibbs energy variation of liquid-solid transition in energy-composition schematics, we illustrated the thermodynamic particularities of the T0 curves. They are experimentally observed to be boundaries between the partitionless crystallization and amorphous areas in phase diagrams. Our interpretation basically rationalizes the capability of T0 curves in predicting new glass forming systems and their glass forming regions. Good agreements between the thermodynamic indicator “phase diagram + T0 curves” for metallic glasses and the experimental information were obtained in typical systems.

Physical characterization of Bis(2,2-dinitropropyl) acetal and Bis(2,2-dinitropropyl) formal

ABSTRACT Bis(2,2-dinitropropyl) acetal (BDNPA) and bis(2,2-dinitropropyl) formal (BDNPF) are two commonly used energetic plasticizers in explosive and propellant composites. However, some of their physical properties are rather scattered and inconsistent in the open literature. For example, there are at least two widely different values, 14.5ºC and −15ºC, for the melting point of eutectic BDNPA/F with 1:1 mass ratio (called NP here). The eutectic phase diagram of BDNPA/F mixtures are not well documented. Furthermore, the effect of temperature on the miscibility between water and eutectic BDNPA/F eutectic is rarely reported. To fill these knowledge gaps, a large set of BDNPA/F mixtures with BDNPA concentration ranging from 0 to 100% was analyzed using DSC techniques. In addition to confirming the eutectic melt point as −25.9ºC, a phase diagram of the BDNPA/F system was constructed from −30ºC to 45ºC. To study the miscibility between NP and water, a large set of NP/water samples with water concentration ranging from 500 ppm to 5800 ppm was fully characterized using coulometric Karl Fischer titration, TGA, DSC, and Near-IR Spectroscopy. As a result, a phase diagram of the NP and rich NP-water system was constructed from −90ºC to 130ºC. To further support these efforts, the effects of temperature on the NP viscosity, specific heat capacity, and thermal conductivity are reported here as well.

Effect of Ta addition on solidification characteristics of CoCrFeNiTax eutectic high entropy alloys

Effect of Ta addition on solidification characteristics of CoCrFeNiTax (x = 0.1–0.7) eutectic high entropy alloys were investigated. With increasing Ta content, CoCrFeNiTax alloys changed from hypoeutectic alloys with primary γ phase to eutectic alloy (x = 0.43) and to hypereutectic alloys with primary Laves phase. Consequently, Ta content in primary phase significantly increased, while the content of Ta element in γ/Laves eutectic phases slightly decreased. Meanwhile, the solidification path and solidification characteristic temperatures of CoCrFeNiTax alloys both agreed with typical binary eutectic phase diagram, and obvious microsegregation of Ta element was only found in CoCrFeNiTa0.1 alloy. Furthermore, the contents of Co, Cr, Fe and Ni elements in primary phases and distribution behaviors of Co, Cr, Fe and Ni elements were both different in CoCrFeNiTax alloys, which indicated that CoCrFeNiTax alloys cannot be simplified as (CoCrFeNi)–Ta pseudo binary system when analyzing distribution behaviors of Co, Cr, Fe and Ni elements.

X-ray scattering study on the crystalline and semi-crystalline structure of water/PEG mixtures in their eutectic phase diagram.

Mixtures of water and PEG exhibit a well known eutectic phase diagram. While the thermodynamic properties like eutectic and liquidus temperatures as well as the eutectic concentration are intensely investigated almost nothing is known about the structural properties of water and PEG in the different regions of the phase diagram. Therefore, we report on a combined DSC, SAXS and WAXS study over the full range of polymer water compositions in order to elucidate the crystalline and semi-crystalline structure. Throughout the whole phase diagram no signatures of a mixed-crystalline phase of PEG and water can be found. Below the eutectic temperature, both components demix microscopically into hexagonal ice and crystalline PEG with its well known crystalline structure. In the region between eutectic and liquidus temperature, the solid component is composed of a single phase of either pure semi-crystalline PEG (PEG rich side of the phase diagram) or pure ice (water rich side). The semi-crystalline structure of PEG, in contrast, is changed by the presence of water. Its long spacing dac increases due to the incorporation of water molecules in the amorphous regions, while the formation of crystalline regions seems to be enhanced, resulting in an almost unaffected crystallinity.

Localization of Melt Components in a Crucible as a Result of Inserting Anisothermic Rod with Non-wettable Boundaries

Concentration-induced convection of a binary metal melt in a rectangular crucible has been studied numerically in the case of a mixture with a eutectic phase diagram. The calculations are performed for realistic parameters which correspond to the pair of metals Sn-Pb. A solid rod with non-wettable boundaries and a non-uniform longitudinal temperature distribution on the surface is immersed into the melt vertically at the center of the crucible. The condition of complete non-wetting allows us to consider the interface between the melt and the rod to be free. The temperature non-uniformity leads to inhomogeneity of the surface tension. As a result, the thermocapillary force generates a steady convective flow first on the surface of the rod and then in the volume. Due to this motion, the heavy component of the alloy is transferred along the rod’s surface to the butt-end. At the boundary patches with the excess of concentration it has been extracted into the volume by means of the desorption mechanism. In the presence of weak convection in the volume, this component is partially accumulated near the bottom of the crucible under the butt-end. Thus, there takes place a process of separation of heavy admixture for the two-component metal melts.

PEG hydration and conformation in aqueous solution: Hints to macromolecular crowding

The molecular structural dynamics of PEG in aqueous solution has been addressed with a series of experimental data correlating macroscopic solution properties of PEG with structural and hydration properties at molecular level, by using thermodynamic, UV Brillouin and Raman spectroscopy data. Water activity measured in PEG 600 solutions by a novel dynamical calorimetry approach shows that data reveal some non-equilibrium process for dilute solutions. Brillouin scattering data on aqueous solutions in the UV range made possible the measurement of the viscoelastic relaxation of the system with a characteristic temperature, TM, as precursor of the glass transition process at lower T, while at constant temperature, the addition of water to liquid PEG 600 first lead to a slight decrease and then to an increase in the solution viscoelastic relaxation consistent with the slowest polymer dynamics observed in the concentrated solution. Specific Raman bands corresponding to trans and gauche conformations of the C–C and C–O bonds and their sequences in the PEG chain have been identified and their relative intensities as a function of concentration evidence non-monotonous variations with a rather unusual concentration dependence for the frequency of C–O bonds in the range of physiological temperatures.The heuristic result is that the extended time-space domains approach suggests an overall quasi-regular solution behavior of semidilute PEG, with opposite concentration dependence at low and at high water content, similar to discontinuities observed in excess thermodynamic properties and eutectic phase diagram. The cross-over of these distinct behaviors occurs at the concentration close to that usually employed to mimic the cellular crowding in biomolecular systems, highlighting the interplay of water molecules in solute-solute interactions.

Investigation on the Phase Diagram of LiCl-KCl-NdCl3 Pseudo-Ternary System

The ternary phase diagram of LiCl-KCl-NdCl3 system has been investigated by differential thermal analysis (DTA), followed by characterization of the coexisting phases in the solid state by x-ray diffraction, in order to understand the interactions in the NdCl3-LiCl-KCl ternary system. The results of these experiments showed that LiCl and K2NdCl5 form a non binary join section. This divides the LiCl-KCl-NdCl3 system into two quasi-ternary sections, namely (1) LiCl-KCl-K2NdCl5 and (2) LiCl-K2NdCl5-NdCl3 systems. Both are simple eutectic ternary phase diagrams. The ternary eutectic temperatures and eutectic compositions are determined to be 316 ± 3 °C and 53.9 mol.% LiCl-38.7 mol.% KCl-7.4 mol.% K2NdCl5 in the LiCl-KCl-K2NdCl5 quasi-ternary section, while the other eutectic temperature and composition are determined to be 376 ± 9 °C and 46.2 mol.% LiCl-32.5 mol.% K2NdCl5-21.3 mol.% NdCl3 in the LiCl-K2NdCl5-NdCl3 quasi-ternary section. A quasi-ternary peritectic reaction is observed at 37.7 mol.% LiCl-36.2 mol.% KCl-26.1 mol.% K2NdCl5 at 445 ± 1°C. The primary and secondary crystallization temperatures for the samples are deduced from the heating runs of DTA traces, and the phases responsible for the various thermal events are ascertained. Isothermal sections at chosen temperatures and polythermal liquidus projection with isothermal contours are drawn over the ternary phase field.

Calculation of the state diagrams of binary Sn-Pb and Pb-Sb solutions in the framework of the generalized lattice model

This paper is devoted to a theoretical study of mono- and non-invariant equilibria in binary Sn-Pb and Pb-Sb solutions. Modeling of Sn-Pb and Pb-Sb solutions was carried out within the framework of the generalized lattice model, corresponding eutectic phase diagrams were obtained.

Diagram Fase dan Sifat Termodinamik Campuran Biner Ketoprofen-Asam Suksinat

The equilibrium phase diagram and thermodynamic properties of a mixture of drugs and additives are information related to various possible interaction processes between components. Therefore, we conducted a study of the phase diagrams and thermodynamic properties of binary mixtures of ketoprofen-succinic acid to estimate the types of interactions that may occur between these materials. The solid-liquid phase diagram of ketoprofen-succinic acid binary mixtures was determined by differential scanning calorimetry and composition of eutectic system was determined accurately using a Tamman diagram. The measurement of binary mixtures of ketoprofen-succinic acid with differential scanning calorimeter obtained the value of melting temperature and heat of fusion of ketoprofen- succinic acid system. The solid-liquid phase diagram of ketoprofen- succinic acid showed the formation of eutectic type phase diagram. The Tamman diagram showed accurately composition of the eutectic system of the Kp-SA binary mixtures at the mole fraction of Kp 0.87 and temperature 96.9oC.Keywords: ketoprofen, phase diagram, eutectic system, Tamman diagram

Phase diagrams and crystal-fluid surface tensions in additive and nonadditive two-dimensional binary hard-disk mixtures.

Using density functionals from fundamental measure theory, phase diagrams and crystal-fluid surface tensions in additive and nonadditive (Asakura-Oosawa model) two-dimensional binary hard-disk mixtures are determined for the whole range of size ratios q=smalldiameter/largediameter, assuming random disorder (lattice points or interstitial occupied by large or small disks at random) in the crystal phase. The fluid-crystal transitions are first order due to the assumption of a periodic unit cell in the density-functional calculations. Qualitatively, the shape of the phase diagrams is similar to the case of three-dimensional hard-sphere mixtures. For the nonadditive case, a broadening of the fluid-crystal coexistence region is found for small q, whereas for large q a vapor-fluid transition intervenes. In the additive case, we find a sequence of spindle-type, azeotropic, and eutectic phase diagrams upon lowering q from 1 to 0.6. The transition from azeotropic to eutectic is different from the three-dimensional case. Surface tensions in general become smaller (up to a factor 2) upon addition of a second species and they are rather small. The minimization of the functionals proceeds without restrictions and optimized graphics card routines are used.

Interpretation of the global heat of melting in eutectic binary systems

Starting from ten eutectic binary phase diagrams, the heat absorbed to melt completely a binary mixture from its solid state was plotted as a function of the mole fraction of one of the two components of the system. Surprisingly, a linear relationship was found for all the studied systems. The extrapolated total heat values at pure component composition (i.e. x = 0 and x = 1) obtained via the heat capacity experimentally determined for each compound were interpreted as the melting enthalpies of the pure components at the eutectic temperature, for each binary system. A mathematical model is proposed that takes into account an ideal liquid state and an enthalpy in the liquid state independent of the temperature.

Electric Field Effects During Solidification of the Ternary Oxide Eutectic Al2O3‐YAG‐ZrO2

AbstractLHPG and zone melting solidification of Al2O3‐YAG‐ZrO2:Y eutectic samples is performed in order to investigate intrinsic and extrinsic electric field phenomena. An intrinsic electric field is measured during solidification. Its decay with distance from the interface, and its relaxation with time, show that it is induced by the accumulation of positive electric charges at the solid‐liquid interface, that diffuse away when pulling is stopped. Under extrinsic electric field, a significant modification of the eutectic phase diagram is observed. The charged diffusive boundary layer interacts with the field and the microstructure is impacted. Those observations suggest that the segregating species is zirconium ions.

Quantification of the liquid window of deep eutectic solvents.

Deep eutectic solvents (DESs) have been considered as a new class of green solvents with tunable physical properties based on the selective combination of their individual components. As the liquid window of a DES identifies the range of feasible applications, it is essential to determine, quantify, and predict their phase behavior. Phase diagrams were measured for systems consisting of tetrapentylammonium bromide and erythritol or succinic acid. Regular solution theory is applied to quantitatively describe the liquid window of DESs. The succinic acid mixture shows a larger deviation from ideal behavior, caused by the stronger hydrogen bond forming acid groups. The interaction parameter between the two DES components in regular solution theory could be determined directly from the eutectic temperature of the mixture and this enables quantification of the degree of non-ideality of DESs.

Solid–Liquid Equilibria of Nine Binary Systems with Dicarboxylic Acids

In this study, solid–liquid equilibria of dicarboxylic acids for binary mixtures, hexanedioic acid (1) + octanedioic acid (2) (eutectic temperature TE = 390.54 K, eutectic composition x1E = 0.419); hexanedioic acid (1) + nonanedioic acid (2) (TE = 372.52 K, x1E = 0.269); hexanedioic acid (1) + decanedioic acid (2) (TE = 387.43 K, x1E = 0.514); heptanedioic acid (1) + octanedioic acid (2) (TE = 365.81 K, x1E = 0.782); heptanedioic acid (1) + nonanedioic acid (2) (TE = 352.50 K, x1E = 0.558); heptanedioic acid (1) + decanedioic acid (2) (TE = 367.07 K, x1E = 0.753); octanedioic acid (1) + decanedioic acid (2) (TE = 387.97 K, x1E = 0.465); nonanedioic acid (1) + octanedioic acid (2) (TE = 367.62 K, x1E = 0.712); and nonanedioic acid (1) + decanedioic acid (2) (TE = 370.49 K, x1E = 0.687), are measured using differential scanning calorimetry and correlated using Clarke-Glew equation. An observation here is simple eutectic phase diagrams for these systems. It can be noted that experiment results, correlated wi...

Pluronic F127 as a suitable carrier for preparing the imatinib base solid dispersions and its potential in development of a modified release dosage forms

In recent years, considerable attention focuses on making sustained release dosage forms also containing solid dispersions. The objective of this study is evaluation of imatinib base (IMA) solid dispersion physicochemical properties which can be useful to controlled release solid dosage formation. The solid dispersions were obtained by kneading method, containing of 10–90% w/w Pluronic F127 (PLU). Drug dissolution test was determined by rotating-disc system method in 0.1 M hydrochloric acid (pH 1.2) and phosphate buffer (pH 6.8). XRD, DSC, FTIR, and SEM observations were performed to evaluate the physical characteristics of solid dispersions. These studies showed that there was no chemical interaction of the IMA with PLU in the solid state and revealed that IMA and PLU form a simple eutectic phase diagram. Our research has shown that the dynamics of the release of imatinib base from solid dispersions with Pluronic F127 depends on the pH of dissolution medium. At pH 1.2, the presence of polymer in solid dispersion causes delaying of drug release due to formation a viscous gel layer, whereas at pH 6.8 significant enhancement of the drug dissolution rate from solid dispersions has been observed compared to pure IMA. The highest improvement was observed in solid dispersions containing 20 and 30% w/w polymer. The present investigation confirmed that the hydrophilic polymer Pluronic F127 could be applied as a suitable matrix to design modified release formulations of imatinib base.

A numerical model for a hypoeutectic alloy droplet deposition with non-equilibrium solidification

A numerical model is developed to study the splat morphology and solidification characteristics of a molten hypoeutectic alloy droplet impinging and solidifying on a substrate. The study finds application in optimization and improvement of metal additive manufacturing processes such as solder jetting, microcasting, sputtering and 3D printing. The major mathematical and numerical challenges include solution of multiphase flow governing equations, interface tracking and modeling the non-equilibrium (rapid) solidification on a macroscopic domain. The free surface is tracked using a volume of fluid method with a piecewise linear interface construction while the mushy phase is modelled as a pseudo porous medium. An enthalpy formulation of the energy equation is coupled with the solute transport equation and the system is solved simultaneously for the temperature and concentration profiles until the eutectic point is reached; beyond which a special treatment is employed till complete solidification. Segregation models (with back diffusion) and eutectic phase diagram are incorporated in the solution procedure. The splat morphology, concentration profiles and microstructural properties are closely examined with emphasis on the convective effects and eutectic formation.