US950869A - Process of producing an amorphous tungsten powder. - Google Patents

Description

' JOHANNES SCHILLING, OF COLONIE 'GRUNEWALD, NEAR BERLIN, GERMANY.

PROCESS OF PRODUCING AN AMORPHOUS TUNGSTEN POWDER.

N Drawing.

Specification of Letters Patent. I

Application filed March 23, 1909. Serial No 485,306.

Patented Mar. 1, 1910.

To all whom "it may concern:

Be it known that I, JOHANNES SCHILLING,

, a subject of the King of Prussia, and resident of l \Vinklerstrasse, Colonic Grune- Wald, near Berlin, German Empire, have invented a new and useful Process forlroducing an Amorphous Tungsten Powder, of which the following is a specification.

The present invention'relates to a process for the production of a finely divided amorphous powder of tungsten or compounds of tungsten which are poor or comparatively poor in oxygen. Such finely' divided metallic powder is of special use in the manufacture of metallic filaments for incandescent electric lamps.

The present invention depends on the property of tungsten compounds to break up into small particles when brought to a high temperature in the presence of ammonia. \Vhen this process is carried out in the air or in any oxidizing medium-the ordinary trioxid of tungsten 0 is formed. If however the process is carried on in a non-oxidizing medium or atmosphere an exceedingly fine soft amorphous metallic powder is obtained as the result of the disruption on heating. This powder may be easily pressed and is specially suited for the manufacture of metallic filaments with any suitable binding agent in any known manner. \Vith this fine powder the filaments may be manufactured without encountering the usual di'fliculties of clogging or damaging of the nozzle through winch the material is forced when forming filaments. Further in consequence of the fine state of division of the powder it forms a much more intimate mixture with the bindingvagent and consequently produces a stronger filament which may be handled much more easily.

The tun sten owder roduced 15 either pure metallic tungsten or a mixture of the a metallic tungsten with loweroxids of tungsten,

In carrying the invention into effect, the substance. containing tungsten which is preferably employed, is one of the various metaor para-tungstates of'ammonium. The salt is heated in a closed tube or retort to a little above the temperature at which thedisruption of the tungstate takes place. Simultaneously a current of hydrogen and nitrogen or ammonia gas may be led over the mass.

When tungsten trioxid (WO is dissolved in ammonia water (NH at a moderate temperature, a salt 1S obtained which is approximately On heating thissalt as described above while leading ammoniagas over it, the am monia is driven out of the salt and at a suilicieu'tly high temperature this ammonia is wholly or' partly dissociated into hydrogen and nitrogen. The hydrogen in statu nascendi is exceedingly active as a reducing agent and reduces the oxid of tungsten from a higher oxid into a lower oxid or to the metallic tungsten. The amount of ammonia led over the heated mass while stirring is determined by the composition of the salt and the required degree of reduction of the tungsten oxids. It is also advisable to draw off the water of crystallization or the water formed by the reduction of the oxids of tungsten, and this may be done by leading a current of non-oxidizing gas, conveniently a 1'nixturc of nitrogen and hydrogen or dried ammonia gas over the mass. Vith care it is also possible to employ hydrogen gas for the purpose but the objection here is that a hard rough granular gray powder is obtained as discovered by Berzelius, and this substance is not suited for use in the formation of metallic filaments for lamps.

The powder produced according to the present invention may be further treated in any known manner as for instance in the manner described in my UnitedStates application Serial No. 349336 filed 24th. of December, 1906.

I claim i 1. The recess for the production of a fine amorp ous tungsten powder, consisting in heating a tungsten compound adapted to be dissociated by heat in a non-oxidizing atmosphere to a temperature above the disruption temperature whereby the reducing agents separated from the said tungsten compound act upon the oxids of tungsten pr'esent.-

2. The process for roducing a fine amorphous tungsten pow er, consisting in heating an ammonium salt of tungsten m a nonoxidizing atmosphere to a temperature slightly above the disruption temperature to cause the ammonia gas separated out by the heating to be itself dissociated and thereby act asia reducing agent on the oxids of tungsten remaining in the mass.

3. The process for producing a fine amorphous tungsten powder, consisting in heating an ammonium salt of tungsten in a non- OXldlZlllg atmosphere to a temperature slightly above the disruption temperature to cause the ammonia gas separated out by the heating to be itself dissociated and thereby act as a reducing agent on the oxids of tungsten remaining in the mass, passing a nonoxidizing gas over said heated mass to assist the reduction and draw off the moisture present, substantially as described.

4. In process of making metallic tungsten filaments for incandescent electric lamps the production of a fine amorphous tungsten powder consistin in heating a tungsten compound adapted to be dissociated by heat in a non-oxidizing atmosphere to a temperature slightly above the disruption temperature, separating thereby reducing agents from the dissociatin compound and allowing same to act on the oxid. of tungsten obtained by the dissociation whereby fine amorphous tungsten powder is obtained.

Signed at Berlin, Germany this 3rd day of I March 1909.

J OHANNES SCHILLING. WVitnesses:

HENRY HASPER, WOLDEMAR HAUPT.