the Production Method of Doped Tungsten

In addition to tungsten powder particle size by reducing temperature , humidity, hydrogen , hydrogen flow rate , the amount of loading the boat , push the boat speed and other factors , the dopants on the grain size is also affected. In general , doped tungsten oxide , to accelerate the reduction rate , the tungsten particles increases. In the tungsten oxide to tungsten powder by hydrogen reduction process, the reaction product should be doped with hydrogen , with the result that the potassium content of the tungsten powder decreased. Pickling tungsten powder is used in the 1960s began to produce , and its main purpose is to wash away excess tungsten powder dopant , ultrafine powder and some of the harmful impurities that can improve the processing performance , improve high temperature properties of tungsten . Production is generally pre-wash first with hydrochloric acid , and then washed with 5% hydrofluoric acid and then repeatedly washed to neutrality , and by low-temperature vacuum drying stage and two-stage reduction reduction reduction systems are different because the resulting tungsten powder particle size are different, the general particle size of the powder than D B fine powder . In actual production , after pickling , B and D pink powder mix to be reasonable , to ensure the match after producing tungsten powder particle size in the 3-4 m range. This is not only to control the average particle size , particle size optimization of composition, and, more importantly, to adjust the potassium content in the tungsten powder . Studies have shown that potassium tungsten particles mainly in the surface 100 within the tungsten powder with the particle size reduction therefore , surface area increases, the potassium content was increased.

However, if the potassium content of tungsten powder is too high, although the filament temperature performance is good, but the resulting processing performance deterioration . Must therefore be based on high temperature properties of tungsten required to determine the potassium content of the tungsten powder and the measured potassium content and particle size to match. Doped tungsten oxide , potassium powder only by the particle size distribution is adjusted , so the production process with powder a very important aspect . Doped tungsten powder pressing and sintering after pressing and sintering , you can get a dense doped tungsten billet . Is the use of force and the mold pressing the loose powder into a certain geometric shape, size , density and strength blanks . Compaction in many ways, the most common is steel cold forming and isostatic pressing ( see isostatic pressing ) . Since the powder between the former and the die and the powder and there is a large friction between the powder and thus the density compacts unevenly distributed within the parts . The latter compacts density distribution is uniform. Actual production , sometimes in order to reduce friction, reduce the pressing pressure , improving the quality of the green compacts . Kept suppressed to a small amount of tungsten powder forming agent or a lubricant ( such as glycerin and alcohol ) . The size of many compacts are generally square or circular cross-section , length 200-l000mm. The powder during the pressing behavior is very complex , which includes powders displacement, deformation or breaking, while it depends on the behavior of the powder particle shape , particle size , particle size and surface composition , these powders suppression characteristics of the tungsten powder process has a very important impact.


Tungsten Alloy Manufacturer & Supplier: Chinatungsten Online - http://www.tungsten-alloy.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com;sales@xiamentungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

 

• < Prev
• Next >