US1857879A - Metal powder - Google Patents

Description

' ticles.

.g atcnted May i0, @032 Ni FFICE WALTER SCHUBARDT, or

TBIE AKTIENGESELLSCHAFT, OF FRANKFORT-ON-THE-MAIN,

RATION 0F GERMANY GERMANY, A. CORPO- METAL POWDER No Drawing. Application filed June 29,

The present invention relates to the production of heavy metal powders from spongy or pulverulent metals of low weight per unit of volume produced from metal carbonyls.

In the manufacture and production of metal powders by the decomposition of metal carbonyls by heat, products are obtained which depending on the decomposition conditions differ quite appreciably in their lensity andmostly also in the size of their secondary particles, that is to say, the aggregates built up of the smallest metal par- Thus, for example, on the one hand, a metal powder may be obtained having a weight of 4500 to 5000 grams per liter or a flocculent product like cotton wool having a weight of 100 grams per liter on the other hand, may be obtained, the last-mentioned product, in particular, when operating in mall decomposition furnaces and with great output.

For many purposes, especially for working up metal powders into very dense shaped articles, which are only slightly porous, if at all, a metal powder with a low weight per unit of volume is less suitable than a heavy powder having uniform small particles.

I have now found that spongy or pulverulent metals having a low weight. per unit of volume obtained from carbonyls and which, if-desired, may also have been subjected to i any subsequent treatment, for example to decarbonization, are converted into heavy powders having granules of uniform size, in a simple manner and without great working expense by subjecting them to mechanical comminution,preferably by grinding. The coirminution' is preferably carried out in a ball mill, if desired in a non-oxidizing, that is to say in an inert or reducing atmosphere.

In this manner the separate particles do not agglomerate or consolidate to form'larger granules or laminae, as do for example spongy metals prepared from the corresponding metal oxides on grinding.

Vhcu carrying out the comminution of metal powders, for example of the undesirable iron fiakes-frequently obtained in the decomposition of iron carbonyl, the comminution device may be directly attached to 1929, Serial No. 374,984, and in Germany July 11, 1928.

the carbonyl decomposition apparatus, the further advantage results that the voluminous, and frequently pyrophoric product, which can only be removed continuously from the apparatus with difficulty, is converted while excluding the air into a heavy powder no longer pyrophoric which may be removed from the apparatus continuously, for example by means of a worm conveyor.

The following example will further illustrate the nature of this invention, but the invention is not restricted thereto.

E'avample Flocculent iron having a weight of 100 grams per liter as obtained by the decomposition of iron carbonyl at 320 0., is shortly ground in a'ball mill in an atmosphere of nitrogen, an extremely fine powder having a weight of 4300 grams per liter showin a uniform size of the ains being obtaine What I claim is:

1. A process of producin heavy metal powders, which comprises su jecting flocculent, cotton-like metal of low weightper unit of volume obtained by thermal decomposition of a metal carbonyl to mechanical comminution in a ball mill.

2. A. process of producing heavy metal owders, which comprises subjecting floccuent, cotton-like metal of low weight per unit of volume obtained by thermal decomposition of a metal carbonyl to mechanical comminution in a ball mill in a. non-oxidizing atmosphere.

3. A process of producing heavy metal powders, which comprises decomposing a metal carbonyl by heat and subjectingthe spongy or pulverulent metal-of low weight per unit of volume obtained to mechanical comminution before bringing the metal powder into contact with the air. In testimony whereof I have hereunto set my hand.

WALTER SCHUBARDT.