The Manufacturing Method of Lanthanum Tungsten Electrode

Tungsten electrode material is one of the key materials in argon arc welding technology. Cerium tungsten electrodes have been developed to replace radioactive thorium tungsten electrodes in the field of TIG and PLASMA technology.

It has been proved that cerium tungsten electrodes successfully replace thorium tungsten electrodes in low current argon arc welding. However, in the field of AC polarity, gas discharge light source and cathode emission material, the thorium electrode is completely replaced, and there are defects such as repeated arcing and low life expectancy. The results show that the addition of lanthanum and yttrium can effectively improve the properties of the tungsten electrode, especially the lanthanum tungsten electrode has the characteristics of long life and good arc performance, and has a broad application prospect.

The methods of making lanthanum tungsten electrodes are as follows: 1000 grams of APT powder and 1000 grams of water are added, then mix together. Adding 60 grams of lanthanum acetate, continuous stirring, after heating and drying with steam, and sieving lanthanum tungsten coated powder. The lanthanum tungsten coated powder was loaded into a boat and placed in a hydrogen reduction furnace for the first reduction at a temperature of 600°C and the reduction time was 2 hours. Further heating up to 800°C for two reduction, the reduction time is controlled for 3.5 hours, and the hydrogen flow rate is 1.39×10-4m3/s. Then the lanthanum tungsten coated powder was mixed with alcohol and glycerol lubricant for 1 hours, then sieved, pressed, pre burned and pressed. The precalcining conditions are as follows: loading powder: 650-700g/ root, pressing pre sintering pressure: 60 ~ 80MPa, sintering temperature: 1050~1400°C, sintering time: 40~60 minutes. Then using the vertical melting sintering process, the process conditions are as follows: the vertical melting temperature: 2600~3000°C, heat preservation time: 20 minutes, cooling time: 2 minutes, cooling time: 3 minutes. Finally, the finished product is processed. After the billet inspection is qualified, the qualified blanks are put into the heating furnace with hydrogen protection, and the temperature is kept for 20 minutes according to the process requirements of the sample, and then rotary forging is made according to the requirements, and then processed to different specifications and finished products.

Lanthanum acetate reduces the decomposition temperature and simplifies the process. The decomposition of lanthanum salt in the hydrogen atmosphere makes the decomposition of lanthanum more fully and improves the conductivity of the material in the vertical melting process. It is an ideal method for manufacturing lanthanum tungsten electrode. 

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