TIG welding electrodes usually contain small quantities of metallic oxides which can offer the following benefits:
- Facilitate arc starting
- Increase arc stability
- Improve current carrying capacity of the electrode
- Reduce the risk of weld contamination
- Increase electrode life
Oxides used are primarily zirconium, thorium, lanthanum or cerium. Additions are usually 1% - 4%. These oxides greatly improve arc initiation, especially when direct current (DC) welding is employed. Thorium oxide (thoria) has been used for many years, having been found effective in terms of long life and thermal efficiency. Zirconium oxide (zirconia) has been commonly used for alternating (AC) TIG welding, normally for welding aluminum.