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Preparation of Magnetic Particles

IP.com Disclosure Number: IPCOM000094294D
Original Publication Date: 1966-Aug-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Judge, JS: AUTHOR [+3]

Abstract

Magnetic metallic particles of high retentivity and high coercivity are made by the following processes:

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Preparation of Magnetic Particles

Magnetic metallic particles of high retentivity and high coercivity are made by the following processes:

1. An aqueous solution of a soluble salt of a magnetic metal is prepared.

2. A solution of a strong base is prepared.

3. A precipitate is formed by adding the solution of base to the metal salt solution, while the salt solution is agitated with continuous stirring.

4. The precipitate is washed with water.

5. The washed precipitate is heated in air at a temperature and for a time sufficient to raise it to its highest oxidation state.

6. The oxide is reduced with hydrogen gas at 400 degrees C for several hours or until the evolution of H(2)O ceases.

7. The reduced metal is allowed to cool in a nonoxidizing atmosphere and quenched with water before exposing it to air.

Using this procedure, magnet particles of cobalt, iron, nickel, cobalt-iron, cobalt-nickel, and iron-nickel and their alloys are formed.

More specifically, for example, a solution of 0.61 M FeSO(4) and of 0.068 M CoSO(4) is reacted with 2.7 M KOH as in step 3. Steps 4...7 are then followed. The resulting magnetic powder has a coercivity of 1100 oersteds with a squareness of 0.84 which corresponds to a residual induction of about 17,000 gauss.

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