Rare Earth Doped Tungsten Electrode Performance Effect by Rare Earth Doping Quantity

With the development of welding industry, modern industry has higher requirements on electrode welding property, welding stability and pollution standard. Thoriated tungsten electrodes have good welding properties, but it has radioactive contamination, gradually being replaced by other rare earth tungsten electrodes, such as ceriated tungsten electrodes and lanthanated tungsten electrodes. Rare earth oxides having low work function and excellent thermal electron emission property so rare earth doped tungsten electrode has good welding stability and welding ability. However, at AC TIG welding (tungsten argon-arc welding), there are some shortages including poor arcing property, short life and other issues. Tungsten electrode doped with three rare earth oxides is produced for improving these shortages. In general, tungsten electrode doped with three rare earth oxides has better arcing property and welding stability than tungsten electrode doped with two rare earth oxides. In the tungsten electrode doped with three rare earth oxides, different rare earth doping quantity has a certain influence on rare earth doped tungsten electrode welding  performance.

Using powder metallurgy method to produce two different rare earth content tungsten electrodes doped with three rare earth oxides, and the electrodes will be divided into A electrode and B electrode. A electrode rare earth oxide ratio is La₂O₃: CeO₂: Y₂O₃ = 1: 2: 1, B electrode rare earth oxide ratio is La₂O₃: CeO₂: Y₂O₃ = 1: 1: 3. Comparing these two electrodes with ceriated tungsten electrodes, we will more comprehensive understanding he use performance of electrodes.

These three electrodes were placed on the TIG welding machine, high frequency arcing to test electrode’s welding property and burning loss property, in TIG welding tungsten electrode as a negative electrode, a water-cooled purple copper as the positive electrode. During arc experiments, electrode current is 60A / 120A and arcing duration is 10s / 20min, repeated 10 times in each electrode. From experiment data we knew that B electrode and ceriated tungsten electrodes has better arcing performance and welding performance. A electrode arc performance is general. But burning loss rate of tungsten electrode doped with three rare earth oxides is smaller than ceriated tungsten electrode, so it has better burning resistance property, and B electrode is better than A electrode.

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