We developed cerium-oxide-containing tungsten (CeO2-W) as an alternative for thorium-oxide-containing tungsten (ThO2-W) used as cathode of plasma torches. We evaluated the performance of neodymium-oxide-containing tungsten (Nd2O3-W), lanthanum-oxide-containing tungsten (La2O3-W) and CeO2-W as cathode electrodes for DC arcs under a nitrogen atmosphere and analyzed the consumption mechanism. Under a nitrogen atmosphere, CeO2-W showed lower erosion than ThO2-W. This is because the surface temperature of cathode of CeO2-W was lower than that of ThO2-W. On the other hand, the erosion rate using Nd2O3-W and La2O3-W as the cathode was higher than that using ThO2-W, unlike the results under argon atmosphere reported previously [1]. We inferred that this is caused by the decomposition of these oxides (Nd2O3, La2O3) by nitrogen radicals.
We compared the erosion rate using CeO2-W as a cathode under an argon atmosphere with the erosion rate of the cathode (Pure-W, Nd2O3-W, ThO2-W, La2O3-W) under an argon atmosphere in a previous report [1]. The erosion rate using CeO2-W as the cathode was also the lowest under an argon atmosphere.
The factors that cause consumption of electrodes are different in argon and nitrogen atmospheres. Among the tungsten materials currently used industrially, CeO2-W is the most effective material in terms of erosion resistance under both atmospheres.

3.Electrode_Performance_of_Oxide-Containing_Tungsten_Materials_in_Direct_Current_Arcs.pdf