KINETICS OF SOLIDIFICATION

1956 ◽  
Vol 34 (5) ◽  
pp. 473-490 ◽  
Author(s):  
K. A. Jackson ◽  
Bruce Chalmers
Keyword(s):  
Free Energy ◽  
Kinetic Theory ◽  
Experimental Observation ◽  
Homogeneous Nucleation ◽  
Solid Phase ◽  
Equilibrium Temperature ◽  
Point Of View ◽  
Theory Of Melting ◽  
Kinetics Of ◽  
Thermodynamic Equations

The kinetic theory of melting and freezing is developed from consideration of atom movements at an interface between solid and liquid. The equations developed are shown to have the same form as the corresponding thermodynamic equations. The homogeneous nucleation of a solid phase in a liquid is then considered from the point of view of this theory. Agreement with experimental observation is obtained on the following points. (1) The supercooling at which homogeneous nucleation occurs is proportional to the absolute equilibrium temperature. (2) The surface free energy per atom used in the quasi-thermodynamic treatment of nucleation should be equal to one-half the latent heat per atom. (3) The amount of liquid supercooled has a very small effect on the temperature at which homogeneous nucleation occurs.

NUCLEATION AND GROWTH OF A SOLID PHASE IN A GAS EXPANDING INTO VACUUM

2007 ◽  
Vol 18 (04) ◽  
pp. 676-684 ◽  
Author(s):  
NIKOLAI V. BRILLIANTOV ◽  
JÜRGEN SCHMIDT ◽  
FRANK SPAHN
Keyword(s):  
Growth Rate ◽  
Phase Transformation ◽  
Homogeneous Nucleation ◽  
Solid Phase ◽  
Saturated Vapor ◽  
Nucleation And Growth ◽  
Gas Kinetic Theory ◽  
Long Channel ◽  
Kinetics Of ◽  
New Phase

We study kinetics of homogeneous nucleation in over-saturated vapor expanding from a reservoir through a long channel into vacuum. Assuming adiabatic conditions for the gas, we derive an equation of state which accounts for the phase transformation of vapor into the condensed phase. To describe the growth rate of particles of the new phase gas kinetic theory is employed. We find the size-distribution of these particles, the temperature and flux velocity along the channel. Calculations are performed for the particular case of water vapor expanding to vacuum from its equilibrium state at the triple point. These conditions correspond presumably to the formation of the gas-dust plume, recently detected at Enceladus – the icy moon of Saturn. Our results, therefore, shed some light on this interesting astrophysical phenomenon.

Benefits of Modeling of Melting for the Understanding of Solidification Processes

2010 ◽  
Vol 649 ◽  
pp. 53-59
Author(s):  
Markus Rettenmayr
Keyword(s):  
Free Energy ◽  
Phase Transformation ◽  
Diffusion Coefficients ◽  
Solid Phase ◽  
Local Equilibrium ◽  
Kinetic Equations ◽  
Thermodynamics And Kinetics ◽  
Solidification Processes ◽  
Kinetics Of ◽  
Melting And Solidification

Melting and solidification are both phase transformations involving a liquid and a solid phase. In a simplifying procedure melting could be treated as the inverse process of solidification. However, there are substantial differences in the thermodynamics and kinetics of melting and solidification. The elaboration of a model for melting of binary alloys has lead to the possibility to also describe solidification processes more consistently. Input parameters in the model are the Gibbs Free Energy curves and the diffusion coefficients in the liquid and solid phase, respectively. Assumptions about the thermodynamic state of the interface like local equilibrium are not necessary, recently developed interface thermodynamics is coupled with the kinetic equations. Simulations results for steady-state melting and solidification are compared. The treatment of both solidification and melting yields some insight in the proper¬ties of the liquid/solid interface and its role during the phase transformation.

STUDY OF THE FORMS OF MOISTURE IN A MATURE CHEESES

2020 ◽  
Vol 18 (4) ◽  
pp. 12-17
Author(s):  
V.A. Ermolaev ◽  
Keyword(s):  
Mass Transfer ◽  
Energy Consumption ◽  
Binding Energy ◽  
Solid Phase ◽  
Bound Water ◽  
Point Of View ◽  
Practical Point ◽  
Transfer Processes ◽  
Mass Transfer Processes ◽  
Kinetics Of

The work is devoted to the study of forms of moisture connection in Mature cheeses. The kinetics of mass transfer processes depends on the mobility and binding energy of water with the solid phase and solutes. Therefore, the removal of bound water is accompanied by both a deterioration in the kinetics and an increase in energy consumption. In this regard, information about the state of bound water in materials during dewatering is very important not only from a scientific but also from a practical point of view. Based on the conducted research, the forms of moisture binding in various types of cheese were determined by the strain-measuring and thermographic method. On the basis of which it is established that the forms of moisture binding in cheeses can be determined by strain and thermographic methods.

scholarly journals A Kinetic Theory Model of the Dynamics of Liquidity Profiles on Interbank Networks

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 363
Author(s):  
Marina Dolfin ◽  
Leone Leonida ◽  
Eleonora Muzzupappa
Keyword(s):  
Kinetic Theory ◽  
Network Formation ◽  
Transition Probabilities ◽  
Stochastic Game ◽  
Theory Model ◽  
Point Of View ◽  
Network Efficiency ◽  
Modelling Framework ◽  
Wide Range ◽  
Complex Adaptive

This paper adopts the Kinetic Theory for Active Particles (KTAP) approach to model the dynamics of liquidity profiles on a complex adaptive network system that mimic a stylized financial market. Individual incentives of investors to form or delete a link is driven, in our modelling framework, by stochastic game-type interactions modelling the phenomenology related to policy rules implemented under Basel III, and it is exogeneously and dynamically influenced by a measure of overnight interest rate. The strategic network formation dynamics that emerges from the introduced transition probabilities modelling individual incentives of investors to form or delete links, provides a wide range of measures using which networks might be considered “best” from the point of view of the overall welfare of the system. We use the time evolution of the aggregate degree of connectivity to measure the time evolving network efficiency in two different scenarios, suggesting a first analysis of the stability of the arising and evolving network structures.

scholarly journals A Study of the Impact of Graphite on the Kinetics of SPS in Nano- and Submicron WC-10%Co Powder Compositions

Ceramics ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 331-363
Author(s):  
Eugeniy Lantcev ◽  
Aleksey Nokhrin ◽  
Nataliya Malekhonova ◽  
Maksim Boldin ◽  
Vladimir Chuvil'deev ◽  
...  
Keyword(s):  
Activation Energy ◽  
Solid Phase ◽  
Continuous Heating ◽  
Diffusion Creep ◽  
Hard Alloys ◽  
Fine Grained ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
The Impact ◽  
Kinetics Of

This study investigates the impact of carbon on the kinetics of the spark plasma sintering (SPS) of nano- and submicron powders WC-10wt.%Co. Carbon, in the form of graphite, was introduced into powders by mixing. The activation energy of solid-phase sintering was determined for the conditions of isothermal and continuous heating. It has been demonstrated that increasing the carbon content leads to a decrease in the fraction of η-phase particles and a shift of the shrinkage curve towards lower heating temperatures. It has been established that increasing the graphite content in nano- and submicron powders has no significant effect on the SPS activation energy for “mid-range” heating temperatures, QS(I). The value of QS(I) is close to the activation energy of grain-boundary diffusion in cobalt. It has been demonstrated that increasing the content of graphite leads to a significant decrease in the SPS activation energy, QS(II), for “higher-range” heating temperatures due to lower concentration of tungsten atoms in cobalt-based γ-phase. It has been established that the sintering kinetics of fine-grained WC-Co hard alloys is limited by the intensity of diffusion creep of cobalt (Coble creep).

Effect of maturity of Napier grass (Pennisetum purpureum) hay on intake, digestibility, and rumen dynamics when given to zebu bulls

2000 ◽  
Vol 2000 ◽  
pp. 144-144
Author(s):  
A.J. Ayala-Burgos ◽  
F.D.DeB. Hovell ◽  
R.M. Godoy ◽  
Hamana S. Saidén ◽  
R. López ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Solid Phase ◽  
Napier Grass ◽  
Pennisetum Purpureum ◽  
Ad Libitum ◽  
The Tropics ◽  
Kinetics Of

Cattle in the tropics mostly depend on pastures. During dry periods the forage available is usually mature, constraining both intake and digestion. These constraints need to be understood, for intake and digestibility define productivity. Intake depends on the rumen space made available by fermentation and outflow. Markers such as PEG (liquid phase), and chromium mordanted fibre (solid phase) can be used to measure rumen volume and outflow, but have limitations. The objective of this experiment was to measure intake, digestibility, and rumen kinetics of cattle fed ad libitum forages with very different degradation characteristics, and also to compare rumen volumes measured with markers with those obtained by manual emptying.

Kinetics of arsenic-enhanced solid phase epitaxy in silicon

2004 ◽  
Vol 95 (8) ◽  
pp. 4427-4431 ◽  
Author(s):  
B. C. Johnson ◽  
J. C. McCallum
Keyword(s):  
Solid Phase ◽  
Solid Phase Epitaxy ◽  
Kinetics Of

Kinetics of Ion-Pair Effect of Aquation of Bromopentaammine Cobalt(III) Complex in Different Dicarboxylate Media

2011 ◽  
Vol 324 ◽  
pp. 166-169 ◽  
Author(s):  
Farah Zeitouni ◽  
Gehan El-Subruiti ◽  
Ghassan Younes ◽  
Mohammad Amira
Keyword(s):  
Free Energy ◽  
Solvent Effect ◽  
Compensation Effect ◽  
Ion Pairing ◽  
Reaction Rates ◽  
Ion Pair ◽  
Free Energy Of Activation ◽  
Different Types ◽  
Different Temperatures ◽  
Kinetics Of

The rate of aquation of bromopentaammine cobalt(III) ion in the presence of different types of dicarboxylate solutions containing tert-butanol (40% V/V) have been measured spectrophotometrically at different temperatures (30-600°C) in the light of the effects of ion-pairing on reaction rates and mechanism. The thermodynamic and extrathermodynamic parameters of activation have been calculated and discussed in terms of solvent effect on the ion-pair aquation reaction. The free energy of activation ∆Gip* is more or less linearly varied among the studied dicarboxylate ion-pairing ligands indicating the presence of compensation effect between ∆Hip* and ∆Sip*. Comparing the kip values with respect of different buffers at 40% of ter-butanol is introduced.

Free energy and kinetics of cAMP permeation through connexin26 via applied voltage and milestoning

2021 ◽  
Author(s):  
Wenjuan Jiang ◽  
Yi-Chun Lin ◽  
Wesley Botello-Smith ◽  
Jorge Contreras ◽  
Andrew L. Harris ◽  
...  
Keyword(s):  
Free Energy ◽  
Applied Voltage ◽  
Kinetics Of
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