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UNIVERSITY OF NIFACULTY OF OCCUPATIONAL SAFETY IN NI

PROCEEDINGSThe 16th Conference of the series Man and Working Environment

INTERNATIONAL CONFERENCESAFETY OF TECHNICAL SYSTEMS IN LIVING AND WORKING ENVIRONMENT

Endorsed by:Government of the Republic of Serbia

MINISTRY OF EDUCATION AND SCIENCE

Ni, 27-28 October 2011

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UNIVERSITY OF NISFACULTY OF OCCUPATIONAL SAFETY IN NI

PROCEEDINGSThe 16th Conference of the series Man and Working Environment

INTERNATIONAL CONFERENCESAFETY OF TECHNICAL SYSTEMS IN LIVING AND WORKING ENVIRONMENT

PUBLISHED BY:FACULTY OF OCCUPATIONAL SAFETY IN NIS

arnojevi a 10a, 18000 Ni

FOR THE PUBLISHER:

Prof. dr Ljiljana ivkovi , dean

EDITORS OF PROCEEDINGS:Prof. Dejan Petkovi , PhD

Prof. Ivan Krsti , PhD

GRAPHIC DESIGN AND PREPRESS:Rodoljub Avramovi

PRINTED BY:M COPS CENTER, Ni

CIRCULATION:300 copies

CIP -

,

331.45/.46(082)

502/504(082)614.8.084(082)

INTERNATIONAL Conference of the Series Man

and Working Environment Safety of TechnicalSystems in Living and Working Environment (16; 2011 ; Ni)Proceedings / The 16th InternationalConference of the Series Man and WorkingEnvironment Safety of Technical Systems in

Living and Working Environment - [STS-11],Ni, 27-28 October 2011. ; [organizer Facultyof Occupational Safety in Ni ; editors DejanPetkovi , Ivan Krsti ]. - Ni : Faculty ofOccupational Safety, 2011 (Ni : M KopsCentar). - 493 str. : ilustr. ; 30 cm

Slike autora i beleke o njima. - Tira 300.- Bibliografija uz svaki rad.

ISBN 978-86-6093-035-61. Fakultet zatite na radu (Ni)a) - b)

- - c)-

COBISS.SR-ID 187155980

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NICOLAY BARBIN1

DMYTRI TERENTEV2

SERGEI ALEXEEV3

Ural Institute of State FireService of Emercom of Russia

1NMBarbin@yandex.ru

2svireppey@mail.ru33608113@mail.ru

THERMODYNAMIC SIMULATING OF

LIQUID AlCu ALLOY EVAPARATION

Abstract: In this work the pressure of the gaseous phase vapor above

melts of Al-Cu and Pb-Bi systems has been studied. The study has been

performed using the method of thermodynamic simulation (TS), aTERRA program package.

Key words: evaporation, AlCu, alloy, modeling.

INTRODUCTION

Systematic investigations into high-temperatureevaporation of liquid alloys in a wide range of

temperatures and concentrations of alloying elementshave been unavailable so far. Experimental studies onevaporation of liquid alloys at high temperatures andpressures are laborious, complicated, and erroneous.

Studies of this kind can be reasonably performed usingmethods of thermodynamic simulation; that is,mathematical modeling of equilibrium states inheterogeneous multi-component systems.

Correctness of thermodynamic calculations depends onthe choice of a mathematical model, which is close tothe real model as much as possible, and the accuracy ofthe thermodynamic parameters of all the constituent

components.In this work the pressure of the gaseous phase vaporabove melts of the Al-Cu system has been studied. Thestudy has been performed using the method ofthermodynamic simulation (TS), a TERRA programpackage.

METHOD

The thermodynamic analysis of the equilibrium state ofsystems as a whole (a full thermodynamic analysis) hasbeen performed.

The calculations of the thermodynamic equilibrium ofarbitrary systems (determination of all the parameters,the thermodynamic properties, chemical and phasecompositions) are performed by minimizing theentropy of the system taking into account all individualsubstances, which are potentially possible in theequilibrium state. The calculation methods haven beendeveloped on the basis of the variation principles ofthermodynamics:

1. Among all permissible moles of individualsubstances in a thermodynamic system, only those thatminimize the thermodynamic potential of the systemcorrespond to equilibrium values.

2. Among all permissible values of energy provided byeach independent component (atom), only those that

maximize the total contribution of energy fromindividual atoms to the system correspond toequilibrium values.

The extensive thermodynamic parameters of thesystem, i.e., those proportional to the number or themass of the substance in the system are the volume V,the entropy S, the internal energy U, the enthalpy H,the Helmholtz energy F (F = U - TS), and the Gibbsenergy G (G = H - TS). The intensive thermodynamicparameters, i.e., those independent of the quantity orthe mass of the system are the pressure P, thethermodynamic temperature T, the concentration, moleand specific thermodynamic values.

For any thermodynamic system to be presentedexplicitly, one has to assign two independentparameters out of V, S, U, H, P, T, F, and G and the

full initial chemical composition of the system. In thiscase, each pair of the independent parameters willdetermine a characteristic function, namely, "a functionof state of a thermodynamic system of thecorresponding thermodynamic parameters, with acharacteristic that this function and its derivatives withrespect to those parameters can be used to expressexplicitly all the thermodynamic properties of thesystem."

A criterion that a system reaches its equilibrium state isan extreme of its characteristic function. With theindependent parameters P and T, the characteristicfunction is the Gibbs free energy G, and a minimum of

this energy of the system (Gmin) is a criterion forreaching the equilibrium state. With the parameters Uand V, the characteristic function for an isolated systemis the entropy S, and a maximum of the entropy of thesystem, Smax is a criterion for reaching the equilibriumstate.

The calculation algorithm in the TERRA programpackage [1] was developed with the followingassumptions of the mathematical model:

- a consideration is given to closed and isolatedthermodynamic systems, in which the boundaries areimpermeable to exchange of matter, heat, and work

with the environment;- systems in a state of external and internalthermodynamic (full or local) equilibrium are analyzed;

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Safety of Technical Systems in Living and Working Environment - STS 2011, October 27-28, 2011, Ni, Serbia

- the system under study is assumed to beheterogeneous; it consists of several homogeneousparts (phases) separated by visible boundaries;- the presence of a gas phase in the system ismandatory;- all the gaseous individual substances (atoms,

molecules, atomic and molecular ions, and electrongas) are part of one gas phase;- the gas phase is described by the equation of ideal gasstate;- surface effects at the interface are disregarded; gasesdo not dissolve in condensed (liquid and solid) phases;condensed matter may be absent;- condensed matter forms single immiscible phases orenters into the composition of ideal condensedsolutions;- individual substances, which have the same chemicalformula, but are part of different phases, are assumed tobe different components;

- substances, which have the same chemical formula,but are in different polymorphous modifications, thecrystalline or liquid state, are assumed to be onecomponent whose properties change stepwise attransformation temperatures;- the volume of condensed components is negligiblysmall.In accordance with the second law of thermodynamics,the equilibrium of such systems is characterized by amaximum of the entropy relative to thermodynamicdegrees of freedom, which include the concentration ofcomponents in an equilibrium system (Mq, mole/kg),the temperature T, and the pressure P.

RESULTS AND DISCUSSION

The simulation was performed in argon at a totalpressure of 105 Pa. The study was carried out in thetemperature range of 1350 to 2500 K at the Cu-Alconcentration being 0.1 to 0.9. The simulation wasperformed taking into account the thermodynamicproperties of pure substances and compounds: gaseousAl, Al2, Cu, Cu2, Al

+, Cu+, e-, and Ar; condensed Al,Cu, CuAl2, Cu2Al3, Cu3Al, Cu4Al, and Cu9Al4.

Concentration dependences of the vapor pressure of thecomponents in the gas phase (Al, Al2, Cu, Cu2, Al

+,Cu+, e-, Ar) above Cu-Al melts were obtained. It wasfound that, as the Cu concentration of the Cu-Al systemrises, the pressure of Cu, Cu2, and Cu

+ vapor increases,and the pressure of Al, Al2, and Al

+ decreases. As thetemperature elevates from 1350 to 2700 K, the vaporpressure of all the components grows in the wholeconcentration range. The dependences lg(Pi, mPa) =f(1/T) are linear for all the components and aredescribed by the equation lg Pi = A + B/T.

Figure 1 has presented the temperature dependence ofthe logarithm of the partial pressures of the gas phasecomponents, which are formed upon heating of the Cu-

Al system (1:1). The partial pressures of all the vaporcomponents increase in the temperature range of 1400to 2700 K. At temperatures above 2700 K the vapor

pressure of Al and Cu changes insignificantly, whilethe vapor pressure of Al2 and Cu2 decreases due todissociation of molecules.

Figure 1. Composition of the gas phase in the Cu-Al

system (1:1)

REFERENCES

[1] G.K. Moiseyev, G.P. Vyatkin, N.M. Barbin: Applicationof thermodynamic modelling for studying of interactionwith participation of ionic melts, SUSU, 2002,Chelyabinsk.

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