Views: 2 Author: Site Editor Publish Time: 2022-02-23 Origin: Site
Pure tungsten electrode is an electrode product with refractory metal tungsten as the main raw material. It is the earliest electrode used in argon arc welding. However, due to the high electron work function, high tip temperature and easy grain growth of the electrode, Therefore, it is difficult to start the arc, the arc beam is unstable and the service life is short, and the application field is limited, and it is basically used in AC welding. In response to the above problems, some researchers pointed out that some modifiers such as rare earth oxides can be appropriately added in the production process of pure tungsten, which will enable the prepared electrode products to have higher comprehensive performance and wider application range.
Specifically, the main reasons for adding a certain amount of rare earth oxides to pure tungsten are: (1) rare earth oxides have low electron work function, so they can improve the recrystallization temperature and electron emission capability of tungsten electrode products ; (2) Rare earth particles can improve the arc starting performance, arc column stability and ablation resistance of the electrode because it will hinder the deformation of tungsten grains. At present, common rare earth oxides are cerium oxide, lanthanum oxide and yttrium oxide.
According to the difference of rare earth oxides, rare earth tungsten electrodes can be divided into cerium tungsten electrodes, lanthanum tungsten electrodes and yttrium tungsten electrodes. Due to the different modifiers added, they differ slightly in physicochemical properties and applications.
Cerium tungsten electrode: The color-coded coating head is gray. It has the characteristics of no radiation, low burning rate, low evaporation rate and long welding life. It can replace the radioactive thorium tungsten electrode. It is suitable for direct current or alternating current welding, mainly welding carbon steel, Silicon copper, titanium and other materials.
Lanthanum tungsten electrode: The color-coded coating head has black, golden yellow and sky blue. It has the characteristics of easy arc starting under low current, good arc column stability, good ductility and creep resistance, etc. It is suitable for AC welding.
Yttrium tungsten electrode: The color-coded coating head is blue, and it has the characteristics of good arc starting performance, high arc column stability and low burning loss rate. It is mainly used for welding military and aerospace parts.