Rare Earth Affected Tungsten Electrode Arc Static Characteristic

To learn tungsten electrode criticality arcing can understand the difficulty of arcing of electrode, which is one of the important property of the electrodes. However, currently, manufacturers usually using high-frequency for arcing, in general, as long as electrodes arc performance is similar to thorium tungsten electrode that arcing can be quite successful, but it hard to reflect rare earth tungsten electrode’s arcing advantage. Burning performance refers to the burned value of electrode under certain conditions, but it also differ greatly from the actual application operation, so only learned arc starting property and anti-burning property is not enough for complete  testing electrode welding property. The welding arcing IU curve also known as arc static characteristic curve which can be more comprehensive performance tungsten electrodes’ welding property.

During experiment, the cathode is water-cooled brass, argon gas flow rate 6L / min, welding load voltage 70V, the arc length 3mm, and the electrode extraction air guide nozzle length is 6mm. After arcing quickly adjusted loop current to 40A, to respectively record the steady-state voltage value, when the current is at 40A, 60A, 80A, 100A, 120A, 140A, 160A, 180A and 200A and the arcing is stable, to obtain static characteristic curve.

From the arc static characteristic curve can be found rare earth tungsten electrode and thorium tungsten electrode has three distinct curves characters including droop characteristic area, flat characteristic area and rising characteristic area. Compared to the thorium tungsten electrode, all rare earth tungsten electrodes exhibit good static characteristics, showing excellent electron emission ability, and they can achieve particular arc current at a lower voltage. Tungsten electrode doped with small amount of rare earth oxide can significantly reduce the work function of the electrode surface and increase electron emission rate, so it has excellent welding property, mainly excited stable static characteristics, superior arc starting and anti-burning property. Doped with La₂O₃, CeO₂ can improve electrode welding performance at small or medium current density. Doped with Y₂O₃ can improve electrode welding performance at high current density. Doped with a variety of rare earth oxides composite rare earth tungsten electrode has better welding performance than rare earth element tungsten electrodes doped with single rare earth oxide.

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