thermal

The lifetime of tungsten cathodes used in plasma spray torches is limited by processes leading to a loss of cathode material. It was reported in the literature that the mechanism of their erosion is the evaporation. A model of the ionization layer of a cathode is developed to study the diffusive transport of evaporated tungsten atoms and tungsten ions produced due to ionization by electron impact in a background argon plasma.

The work is concerned with the effect of a spatially fluctuating heating of Al_2O_3 particles with diameters of 5–120 μm during a plasma spray process. A plasma jet is generated in a mixture of Ar (40 NLPM) and H_2 (14 NLPM) and in pure Ar at an electric current of 600 A. The tracing of the injected particles in the plume region of the plasma jets is considered in the framework of a three-dimensional model taking into account a turbulent fluid flow.

The data set is related to a two-dimensional and stationary magneto-hydrodynamic model of a plasma spray torch operated with argon, which is developed to predict the plasma properties in a steady operating mode. The model couples a submodel of a refractory cathode and its non-equilibrium boundary layer to a submodel of the plasma in local thermodynamic equilibrium in a self-consistent manner. The Navier-Stokes equations for a laminar and compressible flow are solved in terms of low- and high-Mach number numerical approaches.

An appropriate coupling of an arc plasma column in the state of local thermodynamic equilibrium to a refractory
cathode necessarily involves the non-equilibrium boundary layer between them. A model has been developed that

This dataset contains plasma parameters of microarcs generated between a cooled copper anode and a ceriated tungsten cathode by means of a one-dimensional unified non-equilibrium model for gap lengths between 15 and 200 µm and current densities from 2x10^5 up to 10^6 A/m^2. The data show that the decrease of the gap length down to a few tens of micrometers for a given current density results in a progressive shrinking of the quasineutral bulk in the microplasma and its complete disappearance.

Recent research of gas metal arc welding (GMAW) has proven that the sheath voltage dominates the total voltage fall in the current circuit and delivers most of the energy, which is finally transferred to the wire and the weld pool. This data set provides the results for droplet temperatures and the energy delivered to the wire anode in comparison with the sheath voltages. These quantities have been studied experimentally for a typical pulsed GMAW process in the one drop per pulse mode for mild steel under Ar with 2.5% CO2 with different peak currents from 350 to 650 A.

The relation between the voltage and the arc length in gas metal arc welding (GMAW) is an important characteristic. It depends on a complex distribution of the electric conductivity along the current path and does not depend on the arc length only. Based on electric measurements and the arc length determination from high-speed arc images, a simplified electrical model is introduced for a pulsed GMAW process. It shows the relation of voltage, current, arc length and free wire length and considers also their temporal evolution during the process in particular during the high-current phase.