scholarly journals Design of Composites by Infiltration Process: A Case Study of Liquid Ir-Si Alloy/SiC Systems

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6024
Author(s):  
Rada Novakovic ◽  
Simona Delsante ◽  
Donatella Giuranno
Keyword(s):  
Liquid Phase ◽  
Thermophysical Properties ◽  
Free Volume Theory ◽  
Infiltration Process ◽  
Reactive Infiltration ◽  
Structures And Properties ◽  
Energy Of Mixing ◽  
Predicted Values ◽  
Free Energy Of Mixing

The design of processing routes involving the presence of the liquid phase is mainly associated with the knowledge of its surface and transport properties. Despite this need, due to experimental difficulties related to high temperature measurements of metallic melts, for many alloy systems neither thermodynamic nor thermophysical properties data are available. A good example of a system lacking these datasets is the Ir-Si system, although over the last fifty years, the structures and properties of its solid phases have been widely investigated. To compensate the missing data, the Gibbs free energy of mixing of the Ir-Si liquid phase was calculated combining the model predicted values for the enthalpy and entropy of mixing using Miedema’s model and the free volume theory, respectively. Subsequently, in the framework of statistical mechanics and thermodynamics, the surface properties were calculated using the quasi-chemical approximation (QCA) for the regular solution, while to obtain the viscosity, the Moelwyn-Hughes (MH) and Terzieff models were applied. Subsequently, the predicted values of the abovementioned thermophysical properties were used to model the non-reactive infiltration isotherm of Ir-Si (eutectic)/SiC system.

scholarly journals Design of Composites by Infiltration Process: A Case Study of Liquid Ir-Si Alloy/SiC Systems

2021 ◽  
Author(s):  
Rada Novakovic ◽  
Simona Delsante ◽  
Donatella Giuranno
Keyword(s):  
Liquid Phase ◽  
Thermophysical Properties ◽  
Free Volume Theory ◽  
Infiltration Process ◽  
Reactive Infiltration ◽  
Structures And Properties ◽  
Energy Of Mixing ◽  
Predicted Values ◽  
Free Energy Of Mixing ◽  
S Model

The design of processing routes involving the presence of the liquid phase is mainly associated with the knowledge of its surface and transport properties. Despite this need, due to experimental difficulties related to high temperature measurements of metallic melts, for many alloy systems neither thermodynamic nor thermophysical properties data are available. A good example lacking these datasets represents the Ir-Si system, although over the last fifty years, the structures and properties of its solid phases have been widely investigated. To compensate the missing data, the Gibbs free energy of mixing of the Ir-Si liquid phase was calculated combining the model predicted values for the enthalpy and entropy of mixing using Miedema’s model and Free Volume Theory, respectively. Subsequently, in the framework of statistical mechanics and thermodynamics, the surface properties were calculated using the Quasi Chemical Approximation (QCA) for the regular solution, while to obtain the viscosity, the Moelwyn-Hughes (MH) and Terzieff models were applied. Subsequently, the predicted values of the abovementioned thermophysical properties were used to model the non-reactive infiltration isotherm of Ir-Si (eutectic) / SiC system.

scholarly journals OPTIMIZATION OF DRUG SOLUBILITY USING ASPEN PLUS: ACETYLSALICYLIC ACID (ASPIRIN) SOLUBILITY – A SECOND CASE STUDY

2020 ◽  
pp. 178-184
Author(s):  
KAMAL I AL-MALAH
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Stable Solution ◽  
Aspen Plus ◽  
Liquid Solution ◽  
Flow Sheet ◽  
Molar Gibbs Free Energy ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

Objective: The objective of the study is to optimize the solubility of a drug or a drug-like molecule using Aspen Plus simulation platform. Aspirin (solute) was taken as the second case study. The following solvents were used in our dry (virtual) laboratory experiment: Water, acetone, ethanol, and ethylene-glycol-mono-propyl-ether (PROPGLYC). Methods: A simplified process flow sheet made of a single mixing tank where it has five feed streams, representing the solute, the water, and the set of three organic solvents, and one product stream where aspirin is either solubilized (liquid solution) or remains as solid crystal. Minimization of the molar Gibbs free energy of mixing, ΔGmix, was used as an objective function from an optimization point of view. The Non-random Two-liquid property method was used to analyze the solution properties. Results: Using the molar Gibbs free energy of mixing, ΔGmix, as a criterion of solution thermodynamic stability, it was found that the most stable solution is the quinary mixture made of 24.42% aspirin, 10.22% water, 21.08% acetone, 19.51% ethanol, and 24.77 mole % PROPGLYC. Conclusions: Exploiting Aspen Plus can be extended to handle the solubility of a new drug-like molecule once it is defined within its molecular editor with a little knowledge such as density and/or melting point.

Interionic Pair Potential, hard sphere diameter and entropy of mixing of NaCd compound forming binary molten alloys under the framework of Pseudopotential theory

2014 ◽  
Vol 10 (6) ◽  
pp. 2843-2852
Author(s):  
Sujeet Kumar Chatterjee ◽  
Lokesh Chandra Prasad ◽  
Ajaya Bhattarai
Keyword(s):  
Nearest Neighbor ◽  
Effective Interaction ◽  
Pair Potential ◽  
Sphere Diameter ◽  
Compound Formation ◽  
Pseudopotential Theory ◽  
Energy Of Mixing ◽  
Asymmetric Behaviour ◽  
Statistical Mechanical ◽  
Free Energy Of Mixing

The observed asymmetric behaviour of mixing of  NaCd liquid alloys around equiatomic composition with smaller negative values for free energy of mixing at compound forming concentration, i.e. GMXS = -4.9KJ at Ccd =0.66 has  aroused our interest to undertake a theoretical investigation of this system.A simple statistical mechanical theory based on compound formation model has been used to investigate the energetics of formation of intermetallic compound Cd2Na in the melt through the study of entropy of mixing.Besides, the interionic interactions between component atoms Na and Cd of the alloys have been understood through the study of interionic pair potential фij(r), calculated from pseudopotential theory in the light of CF model.Our study of фij(r) suggest that the effective interaction between Na-Na atoms decreases on alloying with Cd atom, being minimum for compound forming alloy( Cd 0.66 Na 0.34 ).The nearest neighbor distance between Na-Na atoms does not alter on alloying. Like wise Na-Na,  effective interaction between  Cd-Cd atom decreases from pure state to NaCd alloys, being smaller at compound forming  concentration Cd 0.66 Na 0.34.The computed values of SM from pseudopotential theory are positive at all concentrations, but the agreement between theory and experimental is not satisfactory. This might be happening due to parameterisation of σ3 and Ψcompound.

Higher Order Conditional Probabilities and Thermodynamics of Binary Molten Alloys

1997 ◽  
Vol 11 (02n03) ◽  
pp. 93-106 ◽  
Author(s):  
O. Akinlade
Keyword(s):  
Free Energy ◽  
Experimental Evidence ◽  
Cluster Model ◽  
Excess Free Energy ◽  
Higher Order ◽  
Thermodynamic Quantities ◽  
Equiatomic Composition ◽  
Conditional Probabilities ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The recently introduced four atom cluster model is used to obtain higher order conditional probabilities that describe the atomic correlations in some molten binary alloys. Although the excess free energy of mixing for all the systems studied are almost symmetrical about the equiatomic composition, most other thermodynamic quantities are not and thus, the study enables us to explain the subtle differences in their physical characteristics required to describe the mechanism of the observed strong heterocoordination in Au–Zn or homocoordination in Cu–Ni within the same framework. More importantly, we obtain all calculated quantities for the whole concentration range thus complimenting experimental evidence.

scholarly journals Thermodynamic, structural, transport and surface properties of Pb-Tl liquid alloy

BIBECHANA ◽  
2015 ◽  
Vol 13 ◽  
pp. 100-113 ◽  
Author(s):  
SK Yadav ◽  
LN Jha ◽  
D Adhikari
Keyword(s):  
Liquid Alloy ◽  
Surface Concentration ◽  
Heat Of Formation ◽  
Concentration Fluctuation ◽  
Heat Of Mixing ◽  
Long Wavelength ◽  
Wavelength Limit ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Experimental Values

Thermodynamic properties, such as free energy of mixing, heat of mixing, entropy of mixing, activities and the microscopic structural properties, such as concentration fluctuation in long-wavelength limit and chemical short-range order parameter of Pb-Tl liquid alloy at 773 K have been studied on the basis of regular associated solution model. We have estimated the mole fractions of the complex and the unassociated atoms assuming the existence of  complex as energetically favoured in the liquid state. The compositional contributions of the heat of mixing of the species Pb and Tl and the heat of formation of the compound to the net enthalpy change have also been studied. The transport properties such as, viscosity and the ratio of mutual and intrinsic coefficients have been studied using different approaches. The surface concentration of Tl atoms has been computed and it has been employed to calculate the surface tension of Pb-Tl liquid alloy. Both the theoretical and the experimental values of the concentration fluctuation in long-wavelength limit are found to be less than the ideal value, revealing that the concerned system is hetero-coordinating in nature. The interaction energies are found to be temperature dependent and respective alloy is found to be weakly interacting system. BIBECHANA 13 (2016) 100-113

Diffusion-Induced Grain Boundary Migration and Role of Defects

1993 ◽  
Vol 319 ◽  
Author(s):  
T.K. Chaki
Keyword(s):  
Free Energy ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Solute Concentration ◽  
Grain Boundary Migration ◽  
Thermally Activated ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Liquid Film Migration ◽  
Lattice Diffusivity

AbstractA model is presented to explain various aspects of diffusion-induced grain boundary migration (DIGM). The driving energies of DIGM are identified as the free energy of mixing and the interface free energy, the former being predominant in most cases of DIGM. The grain boundary migrates due to thermally activated motion of atoms across the interface under the influence of the driving energies. An expression for the velocity of migration is derived. It is shown that this depends parabolically on the solute concentration, in agreement with experimental observations in the case of liquid film migration (LFM), which is analogous to DIGM. Furthermore, the velocity is proportional to lattice diffusivity ahead of the boundary. Recent results of enhancement of DIGM by ion bombardment is explained by radiation-enhanced lattice diffusivity due to introduction of point defects by the ions. The model also explains that diffusion-induced recrystallization (DIR) is due to a free energy decrease associated with the transformation from the amorphous phase in the grain boundary layer to the crystalline phase.

Dolomite Decomposition to (Ca,Mg)O Solid Solutions: An X-Ray Diffraction Study.Part II.

1984 ◽  
Vol 39 (10) ◽  
pp. 981-985 ◽  
Author(s):  
G. Spinolo ◽  
U. Anselmi Tamburini
Keyword(s):  
Free Energy ◽  
Low Temperatures ◽  
Particle Sizes ◽  
Diffusional Process ◽  
X Ray Diffraction ◽  
High Iron Content ◽  
X Ray ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Low Pressures

Abstract The full decomposition of dolomites with low and high iron content at low temperatures and low pressures is discussed with reference to the free energy of mixing of the ternary system Ca. Fe, Mg/O. The actual products of the primary step are a couple of rock salt structured oxides close to the spinodal compositions and with very small particle sizes. A subsequent diffusional process can produce large crystallites with equilibrium compositions, but it is effective only when either a low-iron dolomite is used as starting material or higher temperatures are employed.

Calculation on the Free Energy of Mixing of some Silane Systems

2011 ◽  
Vol 391-392 ◽  
pp. 1017-1021
Author(s):  
Ru Zhang ◽  
Yan Fen Wu ◽  
Ping Hu
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Activity Coefficients ◽  
Influence Factors ◽  
Critical Parameters ◽  
Model Parameters ◽  
Free Energies ◽  
Wilson Model ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

Six binary silane systems were chosen to calculate the activity coefficients (γ) and free energies of mixing (ΔGm). These systems included: methyldichlorosilane + methyltrichlorosilane, methyldichlorosilane + methylvinyldichlorosilane, methyldichlorosilane + toluene, methyltrichlorosilane + methylvinyldichlorosilane, methyltrichlorosilane + toluene, methylvinyldichlorosilane + toluene. Based on the Antoine constants, critical parameters of the pure components and Wilson model parameters, γ and ΔGmwere calculated. The influence factors of these thermodynamic properties were also discussed.

Calculation of Darken Stability Functions of Al-In and Bi-Zn Binary Liquid Alloys

2021 ◽  
Vol 14 (2) ◽  
pp. 111-116
Keyword(s):  
Free Energy ◽  
Activity Ratio ◽  
Binary Alloys ◽  
Concentration Fluctuation ◽  
Nearest Neighbour ◽  
Stability Function ◽  
Energy Of Mixing ◽  
Neighbour Shell ◽  
Free Energy Of Mixing ◽  
The Ideal

Abstract: The thermodynamic model based on clustering of two atoms is considered with the view to obtain the concentration-concentration fluctuation, Scc(0) and the darken stability function. The thermodynamic properties of these alloys were evaluated based on clustering of two atoms (A & B) or (B & A). Each system has the view of obtaining concentration-concentration fluctuation, Scc(0) enumerating the low-order atomic correlation in the nearest neighbour shell of liquid binary alloys. The highlights of reciprocals of Scc(0) of these alloys were noted . The values of Scc(0) for Al-In alloy throughout the entire concentration were positive and higher for activity ratio and lower than the ideal solution values for free energy of mixing at specific Al composition. The values of darken stability function of Al-In alloy fall below the ideal darken stability function for activity ratio and free energy of mixing . The indication of the reciprocal of Scc(0) for all the alloys is in support of homocoordination / heterocoordination in the nearest neighbour shell. The Scc(0) and darken stability function of Bi-Zn binary alloys were noted with fluctuations. Keywords: Concentration-concentration fluctuation, Darken stability function, Ordering energy.

Sign in / Sign up

Export Citation Format

Share Document