Abstract
The thermodynamic and transport properties of magnesium oxide crystal arc plasma have been researched under local thermodynamic equilibrium in this paper. The pure CO2 plasma in the arc initiation stage and Mg-CO mixtures plasma in the stable melting stage were selected. The parameter-variation method combined with Levenberg–Marquardt algorithm (PVM-LMA) is used to solve the plasma equilibrium compositions model established by mass action law from higher to lower temperature in sequence. Taking Mg50%-CO50% plasma as an example, the plasma number density of 7500 K is calculated according to 8000 K. The results show that the PVM-LMA algorithm has the advantages of fast and high precision. The comparisons to the results of pure CO2 in previous literature are displayed and our work shows better agreement with theirs. The results of Mg-CO mixtures indicate that the chemical properties of Mg atoms are more active and easier to ionize, which can effectively improve the electrical conductivity and thermal conductivity of plasma and reduce its viscosity.
Highlights
Magnesium oxide crystals have the characteristics of high purity, good calcium-silicon ratio, large crystal size and stable physical and chemical properties
The equilibrium composition model was constructed and solved, the collision integral was calculated according to the principle of interaction between particles, and the transport parameters were obtained by the Chapman–Enskog method
The number densities of pure CO2, Mg0%-CO100%, Mg1%-CO99%, Mg5%-CO95%, Mg10%-CO90%, Mg20%-CO80%, Mg30%-CO70%, Mg40%-CO60% and Mg50%-CO50% mixtures at temperatures ranging from 300 to 30000 K, under atmospheric pressure were calculated, and the results are illustrated in Figure 5 and Figure 6
Summary
Magnesium oxide crystals have the characteristics of high purity, good calcium-silicon ratio, large crystal size and stable physical and chemical properties. The presence of metal vapor in arc welding has a major influence on the thermodynamic, transport and radiative properties of the arc It determines the size and shape of the weld pool [8], and the distributions of the temperature, current density, and heat flux of the arc area. The equilibrium composition model was constructed and solved, the collision integral was calculated according to the principle of interaction between particles, and the transport parameters were obtained by the Chapman–Enskog method. The Chapman–Enskog method is applied to calculate the transport parameters of the plasma based on the number density and collision integral. The results of pure CO2 plasma are compared with those obtained in literature, and the influence of Mg metal on transport parameters was analyzed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
