The study of arc behavior with different content of copper vapor in GTAW

In order to understand the effects of different content of copper vapor entering the arc plasma on the arc behavior, the tungsten-copper materials with copper contents of 0%, 10%, 20% and 30% were made into special tungsten electrodes, which replaced the melting electrode to generate copper vapor. The effects of different content of copper vapor on the arc morphology, arc voltage, arc pressure, current density and arc axial temperature were studied. When copper vapor was transported into the arc plasma, the arc consisted of two parts: a high brightness arc core and the surrounding green luminous area. Through the observation and measurement of the stabilized arc, the results showed that as the content of copper vapor increased, the radius of the greenish region gradually increased, the brightness and size of the core area gradually decreased, the axial temperature of the arc gradually decreased and arc voltage gradually increased with a maximum difference of 1.5 V. This is because the increase of copper vapor concentration changes the net emission coefficient, resulting in a decrease in arc temperature and electrical conductivity. The distribution of arc pressure and current density showed unimodal distribution on the anode surface, and as the content of copper vapor increased, the distribution curves were gradually flattening. A factor contributing to this is that with the increase of copper vapor concentration, the current tends to flow through the edge of the electrode, which expands the conductive path and makes the arc disperse. And the coupling mathematical model of tungsten electrode and arc were established to further explain the experimental results.