Lanthanum Tungsten Electrode Production Process

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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