Browse Prior Art Database

Manufacturing Alloy Particles Having Selected Coercivity

IP.com Disclosure Number: IPCOM000084034D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Tlaskal, RH: AUTHOR [+2]

Abstract

In U. S. Patents 3,726,664 and 3,859,130, it has been disclosed that finely divided magnetic alloy particles may be produced by reduction of salts of cobalt in a bath containing both hypophosphite and amine borane anion reducing agents. Additionally, U. S. Patent 3,756,866 has taught that magnetic cobalt-phosphorous particles having controlled coercivity, are provided by controlling the temperature at which chemical decomposition is initiated in a basic bath of the cobalt cation-hypophosphite anion type, which is free of strong complexing agents and in which the source of hydroxyl ions is a noncomplexing base.

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Manufacturing Alloy Particles Having Selected Coercivity

In U. S. Patents 3,726,664 and 3,859,130, it has been disclosed that finely divided magnetic alloy particles may be produced by reduction of salts of cobalt in a bath containing both hypophosphite and amine borane anion reducing agents. Additionally, U. S. Patent 3,756,866 has taught that magnetic cobalt- phosphorous particles having controlled coercivity, are provided by controlling the temperature at which chemical decomposition is initiated in a basic bath of the cobalt cation-hypophosphite anion type, which is free of strong complexing agents and in which the source of hydroxyl ions is a noncomplexing base.

In the system disclosed by the latter patent, control of the reaction temperature of the solution resulted in cobalt-phosphorous particles having coercivities, in the range of 750 to 1200 oersteds, with the coercivity exhibiting a marked inverse dependence upon temperature.

It has now been determined that in similar reaction baths containing both hypophosphite and amine borane anions as reducing agents for cobalt cations, coercivity of the resulting particles can be controlled as either a function of the reaction temperature of the system or as a function of the ratio of the hypophosphite anion to amine borane anion.

As the temperature of the reaction bath is increased, the coercivity of the resulting cobalt alloy particles is decreased. However, at a given bath temperature, as the ratio of hypophosp...