Lanthanum tungsten electrode manufacturing method relates to a method mainly used for TIG ( tungsten inert gas welding ) and PLASMA ( plasma ) technology for metal welding , cutting, spray coating , smelting a method of manufacturing the tungsten electrode . Wherein : a, and include use of lanthanum acetate APT, tungsten and tungsten trioxide powder made ​​of solid material slurry water mixed to prepare lanthanum tungsten-coated powder ; b, lanthanum tungsten-coated powder decomposition of lanthanum the process is carried out in a hydrogen atmosphere . The method of the present invention can be more fully decomposed lanthanum , significant improvement in the melt down process Chinese conductivity material , and the decomposition of the lanthanum salt and reduction process in the same equipment at the same time , simplify the process, which can effectively reduce the hours of work, saving energy.

Lanthanum tungsten electrode welding in alternating current outstanding performance . Also, because the end of the electrode in the welding process spherical, contamination resistance is very strong, very suitable for welds shall be subjected to serious pollution of the occasion . Lanthanum tungsten electrode is a hundred years European countries have introduced a class of products , the purpose is expected to replace with radioactive thorium tungsten electrode . Once launched , lanthanum tungsten electrode will by the international community praised the welding , and its export volume has considerable tungsten electrodes with thorium . Lanthanum tungsten electrode is characterized by conductive properties closest to 2% thoriated tungsten electrodes , durable high burning rate of the current minimum .

Lanthanum oxide, lanthanum component comprising tungsten oxide, lanthanum into 2 %, 1.5% , 1%, three levels . Lanthanum is a rare earth, and no radioactive , it is known as lanthanum tungsten electrodes substituted products thoriated tungsten electrode . Lanthanum tungsten electrode is mainly used for DC welding, AC welding can also play a good effect . 1.5% lanthanum tungsten electrode , low current, easy arc starting and stable low current arc . 2% lanthanum tungsten thorium tungsten electrode life longer than in most use arcing easier . Especially good (a) to prevent thermal shock , (b) short cycle repeated ignition welding case , the welding good (c) to avoid contamination.


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Case 1.

Take APT powder 1000 grams , adding 1000 grams of water , stir , add 60 grams of lanthanum lanthanum continue to stir , steam heated and concentrated , dried and sieved to obtain lanthanum tungsten-coated powder . The prepared lanthanum tungsten-coated powder loaded boat , put through a hydrogen reduction furnace , heated to conduct a reduction temperature of 600 ℃, the reduction time is 2 hours. Then continue to a second temperature to 800 ℃ restore , restore time control in 3.5 hours , the hydrogen flow rate during 0.5m3 / h. Then lanthanum tungsten-coated powder into alcohol , glycerin lubricant mixing one hour after sifting , pressing, burn , pressing, calcining process conditions: loading powder quantity :650-700g / root , repression burn pressure : 60 ~ 80MPa sintering temperature : 1050 ~ 1400 ℃, sintering time : 40 ~ 60 minutes. Then using a conventional vertical melt sintering process , process conditions are as follows : vertical melt temperature : 2600 ~ 3000 ℃, holding time : 20 minutes Cooling time: 2 minutes , cooling time: 3 minutes . Finally finished processing , vertical melt billets after passing inspection , will be qualified blanks , into protected with a hydrogen furnace , then the sample temperature for 20 minutes to process requirements , as required swaging , and then processed to the desired product with different specifications .

Example 2.

Take tungsten powder 700 g , add 700 grams of water , stir , add 55 grams of lanthanum lanthanum continue to stir , steam heated and concentrated , dried and sieved to obtain lanthanum tungsten-coated powder . The prepared lanthanum tungsten-coated powder loaded boat , put through a hydrogen reduction furnace , heated to conduct a reduction temperature of 650 ℃, the reduction time 2 hours . Then continue to a second temperature to 900 ℃ restore , restore time control in four hours , during the hydrogen flow 0.5m3 / h. Other conditions are the same in Example 1 .

Example 3.

Take tungsten trioxide powder 850 g , add 850 grams of water , stir , add 58 grams of lanthanum lanthanum , continue stirring evenly, by steam heated and concentrated , dried and sieved to obtain lanthanum tungsten-coated powder . The prepared lanthanum tungsten-coated powder loaded boat , put through a hydrogen reduction furnace , heating get in a reduction temperature of 670 ℃, the reduction time 2.5 hours . Continue to warm to 970 ℃ for secondary reduction, reduction time control in five hours , during the hydrogen flow 0.5m3 / h. Other conditions are the same in Example 1 .


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In order to take power system with excellent performance and no radioactive contamination of tungsten electrode, tungsten trioxide powder of lanthanum oxide was added , after reduction, vertical melt , swaging , drawing obtained Φ2.7mm lanthanum tungsten electrode with the same specifications cerium tungsten, tungsten thorium power level for the electrical performance comparison , while a scanning electron microscope , measuring the electrical performance test tungsten lanthanum , cerium tungsten electrodes lanthanum , cerium content and microstructure of the distribution . The results showed that: Lanthanum tungsten electrode tungsten electrical performance than cerium , thorium tungsten ; lanthanum oxide, lanthanum tungsten migration rate , evaporation rate is low , to form a better lap dovetail organization with high temperature creep performance.

Lanthanum tungsten electrode manufacturing method with the use of lanthanum nitrate lanthanum tungsten-coated powder preparation methods, in common with the reduction of time is prolonged, the lanthanum average particle size of the tungsten powder coated grow . The lanthanum nitrate reduction by more sensitive to the impact of time , the average increase in grain size range. The method of the present invention , lanthanum tungsten-coated powder particle size by reducing the influence of time fluctuation is small, in the particle size range within a certain time basically converge. These two different approaches are eventually encapsulated in the form of La2O3 tungsten , plays the role of grain refinement , but due to their respective decomposition temperature differences inevitably lead to the difference in outcome . The method of the present invention , the specific process conditions, the particle size range of less volatile , and in accordance with repression, burn process requirements , which can effectively reduce gasification process , helping to eliminate harmful gases nitrogen oxide pollution is a more ideal method for preparing lanthanum tungsten electrodes .


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1. Experimental Materials : APT, tungsten oxide , tungsten powder: purity of more than 99.5% ( by weight ) ; iron : content is less than 0.0025% ; Molybdenum : less than 0.01 % ; arsenic: content is less than 0.0025% ; alumina : content is less than 0.005% ; phosphorus: content is less than 0.01% ; oxidation residue traces of material size APT: 25 ~ 36μm; WO3: 8 ~ 9μm; tungsten powder : 2 ~ 2.5μm;

2. Lanthanum tungsten-coated powder Preparation: Materials used by Solid : H2O = 1:1 ratio mixing thoroughly stirred and then the prepared tungsten electrodes grade requirement ratio quantity of lanthanum acetate was added uniformly continued mixing uniformly , heated and concentrated by means of steam , drying, sieving step before being sent to restore.

3 Restore the prepared lanthanum tungsten-coated powder loaded boat after reduction furnace temperature decomposition and a secondary reduction, a reduction temperature of 600 ~ 700 ℃ , the restore time is 2 to 3 hours . Second reduction temperature : 800 ~ 970 ℃, time is 3-5 hours. These processes are carried out in a hydrogen atmosphere , the hydrogen flow control : 0.5 ~ 1.5m3 / h.

4 It will be restored after pressure type lanthanum tungsten powder coated aggregate batches for 2-5 hours , then physical and chemical analysis , to be lanthanum tungsten-coated powder has an average particle size of lanthanum oxide content and uniformity are in compliance with technical requirements , the addition of alcohol , glycerine lubricant mixing one hour after sifting , pressing, burn , pressing, calcining process conditions: loading powder quantity :650-700g / root , repression burn pressure : 60 ~ 80MPa, the sintering temperature : 1050 ~ 1400 ℃, sintering time : 40 ~ 60 minutes.

5 Vertical melt using conventional vertical melt sintering process , process conditions are as follows : vertical melt temperature : 2600 ~ 3000 ℃, holding time : 20 minutes Cooling time: 2 minutes , cooling time: 3 minutes .

6 Finished processing vertical melt billets after passing inspection , will be qualified blanks , into the furnace with hydrogen protection , according to the technological requirements of the sample temperature for 20 minutes , according to the requirements swaging , and then processed to different specifications of the finished product desired .


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