Study on Gas-Tungsten-Arc Electrode

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A comparative study has been made of characteristics of gas-tungsten-arc (GTA) cathodes, consisting of tungsten mixed with a small quantity of La-, Y-, Ce-, Th, Mg-oxides respectively and pure-tungsten. Arc starting characteristics, arc pressure, electrode consumption, change in shape due to heavy loading and incompleteness of inert gas shielding, and electrode temperature are compared in D.C.E.N. porarity, and it is shown the superiority of La-oxide, Y-oxide and Ce-oxide electrodes in those characteristics. Electrodes containing two of these three kinds of oxides are also examined and it is shown those electrodes have very superior properties similarly. Direct observation of cathode tip by microscope during arc burning is carried out and important phenomena concerning the formation of tungsten "rim" at the periphery of cathode area, which governs the stability of arc, studied. Copper coverd electrode is produced and it is shown the ability of supression of consumption of tungsten in the Argon-Oxygen mixed gas.