Rare Earth Affected Tungsten Electrode Workability

Adding different content of rare earth elements into tungsten electrode may have different effects on the workability of the electrode. Rare earth particles can hinder tungsten grain deformation. Adding rare earth elements into tungsten electrode, the deformation resistance of the electrode will increase which need to reduce the amount of processing pass in processing. Further, the crystallization temperature of rare earth tungsten electrode is higher than pure tungsten electrode, so during processing need to appropriate increase processing temperature.

In rare earth tungsten electrode, rare earth phase particle size is about 1 ~ 2um and tungsten particle size is about 10 ~ 20um. During processing, tungsten particle will first to deformation showing flat structure. With the in-depth processing, tungsten particle continue flattening showing fibrous structure. With deeper processing, rare earth particle started to deformation and the structure extends along the direction of deformation. At this time larger rare earth particles break into small particles distributed parallel to the deformation direction. At the drawing stage, rare earth particles break into 1um small particles. The rare earth particle became finer making the structure of rare earth tungsten electrode more uniform, so during processing, electrodes can compatible deformation and can withstand greater deformation.

To understand the impact of rare earth on tungsten electrodes hardness the manufacturers use nano-hardness tester for testing. Putting the pressure head in tungsten substrate the hardness curve peak value is about 6.4GPa, and then to decrease. With the increase of the amount of pressure, the curve is decline, indicating that the mechanical characteristic of rare earth particles proportion is growing. When the penetration depth is 900um, showing rare earth hardness value is about 5.4GPa. From this we can see that the hardness of rare earth particle is less than the tungsten particles’. Therefore, under the same conditions, the rare earth particles more easily to deform. Compared to the tungsten particles, with further processing, rare earth particles more easily break into small particles, which is good for subsequent processing.

• < Prev
• Next >