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Making Ferrite Cores

IP.com Disclosure Number: IPCOM000097949D
Original Publication Date: 1961-Oct-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Leaycraft, EC: AUTHOR

Abstract

In the manufacture of manganese ferrite cores, the characteristics of the finished cores are effected by the particle size of the oxide mixture from which the cores are produced. Therefore, closer process control is achieved, and more uniform cores are produced, if the particle size of the material is measured and controlled during processing. Since calcining time and temperature and milling conditions have a marked effect upon particle size, it is important to check the particle size of the material after calcining and milling operations. Heretofore, particle size measurement of the calcined material has been considered impractical because of the fact that the material is rendered magnetic by calcining, which is carried out at temperatures between 650 degrees C and 900 degrees C.

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Making Ferrite Cores

In the manufacture of manganese ferrite cores, the characteristics of the finished cores are effected by the particle size of the oxide mixture from which the cores are produced. Therefore, closer process control is achieved, and more uniform cores are produced, if the particle size of the material is measured and controlled during processing. Since calcining time and temperature and milling conditions have a marked effect upon particle size, it is important to check the particle size of the material after calcining and milling operations. Heretofore, particle size measurement of the calcined material has been considered impractical because of the fact that the material is rendered magnetic by calcining, which is carried out at temperatures between 650 degrees C and 900 degrees C. The magnetic particles tend to cling together and cannot readily be dispersed, and accurate measurement of particle size distribution is extremely difficult and time consuming.

Calcined manganese ferrite material can be decomposed and rendered non- magnetic, if it is cooled slowly from the calcining temperature to room temperature, rather than rapidly quenched in the normal manner. This slow cooling step following calcining is introduced into the manganese ferrite core manufacturing process to provide a non-magnetic calcined material which is readily measured for particle size distribution.

In the manufacture of materials of the manganese ferrite system, which inclu...