Tungsten electrodes are used when arc welding with the Tungsten Inert gas (TIG) process or when plasma welding. In both processes the electrode, arc and weld pool are protected from atmospheric contamination by an inert gas. A tungsten electrode is used because it can withstand very high temperatures with minimal melting or erosion. Electrodes are made by powder metallurgy and are formed to size after sintering.

TIG welding electrodes usually contain small quantities of other metallic oxides which can offer the following benefits:-

• facilitate arc starting
• increase arc stability
• improve current-carrying capacity of the rod.
• reduce the risk of weld contamination
• increase electrode life

Oxides used are primarily those of zirconium, thorium, lanthanum, yttrium or cerium. Additions are usually of order 1%-4%. All 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 current (AC) TIG welding, normally for welding aluminium.