Ecological Material - Multi Composite Rare Earth Tungsten Electrode

Multi composite rare earth tungsten electrode is an ecological material. It can achieve low emissions, no pollution, which can completely replace the serious environmental pollution thorium tungsten electrode used in welding, plasma welding, and spraying and cutting technical and as key heat source material used in metallurgical industry. Currently, the total annual world consumption of tungsten electrodes can up to thousands of tons and the market demand increasing with economic steady development the amount of consumption continues to rise, where thorium tungsten electrode consumption accounts for more than 70%. Thorium is a natural radioactive element and the half-life period is more than 1.39x 10¹⁰ year, so the thorium tungsten electrode is harm to human health and environment. As countries increasing attention to environmental issues, will significantly restrict the production and use of thorium tungsten electrodes.

Multi composite rare earth tungsten electrode has low work function, high melting point, good high temperature mechanical properties and chemical stability and there are abundant raw materials, thus becoming the new alternative material of thorium tungsten electrode. In multi composite electrode, rare earth oxides can refine tungsten grain size to improve the performance of the electrode. After welding testing found it has better arcing performance and anti-burning properties. Besides, the arc static characteristic curve is small than Th-W electrode indicated that it has lower surface electrode work function and electrons are easily escape from the surface, which has better welding performance. Multiple composite rare earth tungsten electrodes at 1300 ℃ the effective work function is 2.76eV and Th-W electrode effective work function is 3.08eV, so composite electrode has low thermal electron emission capability. Electron work function has certain impact on the arc performance. At the beginning of arcing and during arcing, the electrode surface has not been heated to enough temperature, so it can not work as a hot cathode at the first. If the electrode surface has low work function, then the electrode to produce the hot electrons temperature is lower and the electrode is easy to produce thermionic emission. At certain voltage the welding circuit current to generate arc discharge current required time is less, which is arcing easier.

Through the above indicators we will see, multiple composite tungsten electrode is an ecological material. Compared to the thorium tungsten electrode it has good weldability and it can replace Th-W electrode as new welding materials.

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