COMPARISON OF TEMPERATURE AND WORK FUNCTION MEASUREMENTS OBTAINED WITH DIFFERENT GTA ELECTRODES

This work was carried out on one standard electrode (W-ThO2) and other electrodes developed by additions of La2O3, CeO2, and Y2O3. The effect of rare-earth metal oxides on GTAW electrode phenomena, concerning electrode temperature, emissivity, and work function, was analyzed and compared from the point of view of those oxides' behavior during arcing. The experimental results indicate that the electrode temperature, emissivity, and work function strongly depend on the behavior of the rare-earth metal oxides during arcing. The investigation demonstrates good stability of La2O3 during arcing compared with the other oxides. The temperature distributions along the electrode axis of these electrodes were measured by using infrared pyrometer and grooved electrodes. The W-La2O3 electrode showed the lowest temperature values, followed by W-CeO2 and W-ThO2 electrodes in that order. Also W-La2O3 electrodes have a higher emissivity and lower work function, followed by W-CeO2 and W-ThO2 electrodes in that order.