Lanthanum Tungsten Electrode of The Origin And Development

Stainless steel electrode melting point of pure tungsten (3650K), the electron emission capability, high modulus , low vapor pressure , the first to be used as an electron -emitting material , but the pure tungsten emission efficiency is low , and at a high temperature to form equiaxed recrystallized shaped grains become brittle and easy to break. To overcome these shortcomings , countries Materials workers dedicated to research and development of new electrode materials , tungsten -based doping several high melting point, low power electronic escape rare earth metal oxides, can improve the recrystallization temperature , and can activate the electron emission . However, in the rare earth tungsten electrodes on the basis of research , despite some achievements , but the current global market, replace the use of tungsten electrodes still a long way .

In our country the 1990s, in order from the system with excellent performance and pollution tungsten electrode, tungsten trioxide powder of lanthanum oxide is added , after reduction , suppression, melt down , swaging , stretching lanthanum tungsten electrode was obtained . After analysis, the lanthanum of the tungsten electrode electrical performance than cerium tungsten and tungsten thorium , lanthanum, tungsten and lanthanum oxide evaporation rate is low migration rate , to form a better lap dovetail microstructure , has good high temperature resistance creep. High-energy ball milling and vacuum hot pressing sintering prepared bulk nanocrystalline tungsten - lanthanum oxide electrode materials, the effects of different lanthanum oxide nanocrystalline tungsten content on the electrical properties of the electrode material , while using scanning electron microscopy and energy dispersive spectrometer measured fuel La arc electrode tip distribution and microstructure . The results showed that: nanocrystalline tungsten - lanthanum oxide electrode was superior to the conventional powder metallurgy coarse-grained tungsten electrodes . When the lanthanum oxide content of 6% to 8% , the thermal electron emission capability and stability of the best , but with increasing the content of rare earth lanthanum oxide , lanthanum tungsten electrode moldability and processability more difficult.


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