Study on Rare Earth Tungsten Electrode Manufacturing Technology

To produce excellent performance composite rare earth tungsten electrode should optimize the manufacturing technology. After several industrial trials and understanding the role of rare earth in tungsten electrode summarized the following key points during manufacturing.

1. doping rare earth uniformly
Solid-liquid doping method can make rare earth be fully doped. APT and rare earth nitrate as raw materials and doped with solid-liquid method, rare earth nitrates can enter or adsorb on the surface of APT. It is conductive to help rare earth get into tungsten lattice to achieve uniformly doping during subsequent decomposition and restore process.

2. controlling reduced powder’s grain size
The grain size and distribution of reduced powder has a certain influence on the subsequent sintering and machining. The reduced powder which doped with rare earth has higher reduction temperature, so the powder grain size controlling is mainly by increasing the amount of powder loaded boat or increased reduction furnace temperature gradient, relying on high-temperature gaseous hydrated tungsten oxide quick migration to produce large and wide grain size. In addition, when sintering and subsequent processing can successfully operation, should as much as possible to reduce the reduction temperature which can obtain better rare earth grain size.

3. sintering curve
To develop a reasonable sintering curve can obtain good quality sintered blank. During sintering process, the electrode blank should keep warm at low temperature for long time and after rare earth diffusion to reach a balance can increase temperature. Sintering temperature too high can cause rare earth serious volatile, so to make a sintering process should take powder grain size, sintering temperature into consideration.

4. Processing System
Tungsten electrode doped with rare earth has a higher recrystallization temperature, so the processing temperature is also improved. However, rare earth will hinder tungsten grains to increases the recovery and recrystallization driving force, so as to increase the amount of deformation, the processing temperature should decrease. Beside the temperature decreasing range should great than thorium tungsten electrode, cerium tungsten electrode and other rare earth tungsten electrode which doped with single rare earth oxide.

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