General view about Tungsten Electrode

Electrodes are generally accessible in pure tungsten or tungsten with oxide additions of thorium, zirconium, and lanthanum.

Oxide additions decrease the electron emission energy of the electrode:

• pure tungsten (5.36 eV)

• thoriated tungsten (2.62 eV)

For AC welding pure tungsten or zirconiated tungsten are used, whereas for DC welding thoriated tungsten or tungsten electrodes with rare earth oxide additions are optional (thorium is radioactive).

Thoriated electrodes are not optional for AC welding; since the electrode tip does not form the necessary hemispherical bulb thus gives an unstable arc and unsatisfactory cleaning action. For DC welding thoriated electrodes offer for a stable arc, improved electrode life span, greater current carrying capability along with better arc ignition.