Tungsten pin can be divided into pure tungsten pin, rare earth tungsten pin and doped tungsten pin. Tungsten pin is mainly used to make electrode for arc tube of high intensity gas discharge lamp.
Due to the characteristics of tungsten, it is very suitable for TIG welding and other electrode materials similar to this kind of work. Adding rare earth oxide to tungsten metal to stimulate its electron work, the welding performance of tungsten electrode can be improved: better arc starting performance, higher stability of arc column, less electrode burning rate. Common rare earth additives include ceria, lanthanum oxide, zirconia, yttrium oxide and thorium oxide.
Tungsten has a high melting point (3683 ℃ ± 20 ℃), strong electron emission ability, high elastic modulus and low vapor pressure, so it has been used as a hot electron emission material for a long time. The emission efficiency of pure tungsten electrode is very low, and the equiaxed grain structure formed by Recrystallization at high temperature makes the tungsten wire sag and fracture. In order to overcome the above shortcomings and adapt to the development of modern industrial new technology and new process, material workers in various countries are committed to research and develop various new electrode materials. Doping some rare earth oxides with low electron work can not only raise recrystallization temperature, but also activate electron emission. Rare earth metal oxides have excellent thermal electron emission ability, and the rare earth tungsten electrode material has been the development direction of replacing the traditional radiothorium tungsten electrode material.
