New Cathode Materials for Inert and Oxidizing Atmosphere Plasma Application

This study has been carried out to develop new cathode materials for two types of thermionic cathode. First is concerning to the tungsten electrodes for the plasma furnace and welding torches. The second one is the electrodes for air plasma cutting torch. Tungsten electrodes activated with a single and combined additives of rare earth metal oxides, such as La203,Y203 and Ce02,are produced and pared with pure and thorLated tungsten electrode conventionally used, from the point of view of electrode consumption and deformation due to heavy loading, behavior of oxide during arc burning,etc.The results indicated excellent durability and properties of the newly developed electrodes than that of the conventional one. Concerning to the cathode materials for air plasma cutting torch,the consumptions of Re-Y203 and Ru-Y203 electrodes were compared with those of Hf and Zr electrodes which have been widely used. Ru including 10-35wt% Y203 showed lower consumption rates rather than Hf and Zr electrodes in the continuous and periodic operations.