Why Does the Cold Resistance of EB Tungsten Filament Unqualified?

In China, the main material of EB (electron beam) tungsten filament is Double spiral wire. Double spiral wire can heating the cathode evenly. What’s more, the Double spiral wire can eliminate the influence of the magnetic field which is cause by the cathode electron beam. However, the process to make the Double spiral wire is more complex, if the users cannot operate dissolution of molybdenum correctly, it will cause a lot of substandard products. Against to the unqualified phenomenon of the cold resistance of EB tungsten filament, people should try to improve the process of molybdenum core wire dissolution.

Molybdenum core wire dissolution is a pure chemical reaction process. Molybdenum has a strong chemical stability, so that people used a mixture of concentrated sulfuric acid, concentrated nitric acid and water as an etching solution. During the reaction, the temperature and time of the reaction should be to control by a strict operation. In addition, people should also pay attention to the phenomenon of the reaction, the reaction speed would change for the different temperature and the seasons. Due to the low temperatures in winter, the reaction is difficult to control the, it is more likely to cause the cold resistance of EB tungsten filament unqualified.

There exist the remaining acid in the surface of EB tungsten filament without washing cleanly. Oxidation would make the tails of EB tungsten filament become black. Molybdenum wire of cold resistance of EB tungsten filament is mainly caused by the incomplete reaction.

The cold resistance of EB tungsten filament unqualified will produce a lot of waste, causing serious environmental pollution. Therefore, people need to understand the reason to reduce pollution and improve the ecological environment.

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