English
The development and research status of tungsten electrode
materials are introduced The requirements of electrode materials are analyzed in
terms of the characteristics of the welding tip A comparative study is made
between W-ThO2 and pure tungsten electrode materials In
particular, the influence of rare-earth metallic oxides adding to tungsten electrode materials as replacements for ThO2 addition
are discussedThe studies show that tungsten electrodes activated with 2wt% of rare earth metallic oxides
have good form ability The operating characteristics of electrodes depend strongly on the rare-earth oxide additions;
their presence affects the operating, electrode temperature, work function, and the arc stability The equilibrium between the
supply and diffusion due to surface evaporation of rare-earth metallic oxides is
essential to arc stability, electrode lifetime The
rare-earth metallic oxides form tungstate or oxy-tungstate during arc burning
These newly formed relatively low melting point compounds melt, migrate, as well
as evaporate, during arc burning Rare-earth metallic oxides with various
components and ratios in the tungsten electrodes have different effects on this migration and
evaporation of the tungstate and oxy-tungstate compounds At the same time, they
affect the crystal structure upon recrystallization All of the above factors
combine to influence arc burning, electrode consumption,
and arc stability Among the tungsten electrodes activated with two or three types of rare-earth
metal oxides(CeO2, La2O3 and Y2O3), the electrodes with the ratio of CeO2∶La2O3∶Y2O3=1∶1∶3 show the lowest electrode temperature and the best thermal emission, and have
the best properties in terms of arc starting and electrode consumption
