Study of Condensed Phases, of Vaporization Temperatures of Aluminum Oxide and Aluminum, of Sublimation Temperature of Aluminum Nitride and Composition in an Air Aluminum Plasma

Abstract

International audienceWith the Gibbs free energy method, we determine the molar fraction in a plasma at and out of thermal equilibrium consisting of air and aluminum for several percentages in the temperature range of 500–6000 K. We take three temperatures into account (Trot = Th; Tvib; Tex = Te). We indicate the formulae and the numerical method used to perform the calculation taking three condensed phases AlN, Al, Al2O3 into account. We show that the air percentage plays a major role to create these phases. We clarify the role plays on the vaporization temperatures and on the sublimation temperatureby the non-thermal equilibrium of the plasma. This kind of plasma is found in arc roots, near a wall, in plasmas with a high value of electrical field,… The influence of the pressures until 30 9 105 Pa. is shown on molar fraction of the chemical species, on the vaporization temperatures and on the sublimation temperature. The vaporization temperatures are given versus the thermal non equilibrium versus various mixtures (air, aluminum) and versus the pressures (10^5 Pa–30 10^5 Pa)

Calculation of two-temperature plasma composition: II. Consideration of condensed phases

“…Very few previous works discussed the 2T plasma com position considering condensed phases. André et al [8] took three condensed species, AlN, Al and Al 2 O 3 , into account in determining the molar fraction of the 2T plasma consisting of air and aluminium. They used the method of Gibbs free energy minimization for the 2T plasma composition.…”

Graphite production in two‐temperature non‐LTE plasmas of C4F7N and C5F10O mixed with CO2, N2, and O2 as eco‐friendly SF6 replacements: A numerical study

“…[ 30 ] In such algorithms, the Lagrange multipliers are usually used to construct a nonlinear equation system representing Gibbs free energy minimization, chemical equilibrium, electrical neutrality, and Dalton's law. [ 28 ] As there have been a certain amount of previous works on the optimization algorithms for obtaining plasma compositions, [ 30–33 ] this study does not introduce the implementation of the algorithms in detail. Instead, we focus on how to calculate the Gibbs free energy of a plasma system with various mixtures using the parameters we can obtain from literature or by computation.…”

Calculation of two-temperature plasma composition: I. Mass action law methods and extremum searching methods

“…Instead of obtaining plasma composition by solving the equations of mass action laws simultaneously for all the reactions in plasmas, another kind of method is to obtain plasma composition by searching for an extremum in which the whole plasma system reaches the minimum Gibbs free energy or maximum entropy. The former is well known as the method of the Gibbs free energy minimization, which is widely used in the calculation of LTE plasma composition [3,[18][19][20][21] as well as 2T plasma composition [14,15]. However, it seems that researchers preferred to use the methods based on the law of mass action rather than the minimization of the Gibbs free energy.…”