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CHEMICALLY ACTIVE COBALT

IP.com Disclosure Number: IPCOM000130391D
Publication Date: 2005-Oct-21
Document File: 1 page(s) / 22K

Publishing Venue

The IP.com Prior Art Database

Abstract

BACKGROUND Cobalt oxalate and related metal organic compounds such as cobalt formate, stearate, and citrate are well known precursors for finely divided, chemically active cobalt compounds. Randhawa showed that transition metal ferrites containing cobalt oxide could be prepared at 350-500°C, about 200°C lower than conventional methods by direct decomposition to cobalt oxide. Li defined preferred vacuum pyrolysis conditions to obtain fine cobalt used to advantageously sinter cemented tungsten carbide materials. Panpranot et al. describes several precursors for cobalt compounds used in cobalt Fischer-Tropsch synthesis catalysts. DESCRIPTION We report that finely divided cobalt can be produced on carbon surfaces, including crystalline carbon surfaces by pyrolysis of cobalt oxalate, CoC2O4.2H2O. Reagent grade cobalt oxalate di -hydrate, 99.9% metallic basis purity, was blended with 20-micron diameter carbon powders. The mixture, 1 weight % cobalt, was dried and pyrolized at 950°C in flowing hydrogen for 30 minutes. Scanning electron micrographs show cobalt particles less than a micron in diameter randomly distributed on the carbon particle surfaces. Other experiments with mixtures up to 10 % cobalt in carbon powders ranging up to 50 microns in diameter show the same finely divided and dispersed cobalt. We expect that similar results will be obtained on other size carbon particles, in other inert gases, and from the other metal-organic precursors cited above We also report that the presence of finely divided cobalt particles on carbon surfaces enhances cobalt infiltration of carbon powder beds at elevated pressures. The carbon and cobalt mixtures described above were variously exposed to molten cobalt at pressures over 50 atmospheres. Reliable infiltration was obtained in all cases.

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CHEMICALLY ACTIVE COBALT

BACKGROUND

Cobalt oxalate and related metal organic compounds such as cobalt formate, stearate, and citrate are well known precursors for finely divided, chemically active cobalt compounds.  Randhawa[1] showed that transition metal ferrites containing cobalt oxide could be prepared at 350-500°C, about 200°C lower than conventional methods by direct decomposition to cobalt oxide. Li[2] defined preferred vacuum pyrolysis conditions to obtain fine cobalt used to advantageously sinter cemented tungsten carbide materials.  Panpranot et al.[3] describes several precursors for cobalt compounds used in cobalt Fischer-Tropsch synthesis catalysts. 

DESCRIPTION

We report that finely divided cobalt can be produced on carbon surfaces, including crystalline carbon surfaces by pyrolysis of cobalt oxalate, CoC2O4.2H2O.  Reagent grade cobalt oxalate di –hydrate, 99.9% metallic basis purity, was blended with 20-micron diameter carbon powders.  The mixture, 1 weight % cobalt, was dried and pyrolized at 950°C in flowing hydrogen for 30 minutes. Scanning electron micrographs show cobalt particles less than a micron in diameter randomly distributed on the carbon particle surfaces.  Other experiments with mixtures up to 10 % cobalt in carbon powders ranging up to 50 microns in diameter show the same finely divided and dispersed cobalt.  We expect that similar results will be obtained on other size carbon particles, in other inert gases, and from the other metal...