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Square Loop Manganese-magnesium Ferrite Cores

IP.com Disclosure Number: IPCOM000097116D
Original Publication Date: 1962-May-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

DiMarco, HA: AUTHOR [+7]

Abstract

Square loop ferrite cores for memory applications are made using manganese-magnesium ferrites where the ferric oxide content is from 50 to 70 mol per cent. The cores, using this high ferric oxide composition, have higher Curie temperature and lower temperature sensitivity than comparable manganese-magnesium ferrite cores with a ferric oxide content of less than 50 mol per cent.

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Square Loop Manganese-magnesium Ferrite Cores

Square loop ferrite cores for memory applications are made using manganese-magnesium ferrites where the ferric oxide content is from 50 to 70 mol per cent. The cores, using this high ferric oxide composition, have higher Curie temperature and lower temperature sensitivity than comparable manganese-magnesium ferrite cores with a ferric oxide content of less than 50 mol per cent.

Mixes are prepared of the following ingredients in the proportions indicated by points A, B, C, D and E in the drawing and listed below: Fe(2)O(3) MnCO(3) MgO

A 55 10 35

B 55 35 10

C 65 10 25

D 65 25 10

E 60 20 20

The mixes are wet ballmilled to obtain a finely divided and thoroughly mixed composition and calcined between 700 and 900 degrees C. Small amounts of polyvinyl alcohol binder and magnesium stearate lubricant are added to the resultant powder. The material is pressed into toroidal shaped cores, inserted in a furnace maintained between 1280 to 1460 degrees C and sintered at that temperature for 3 to 15 minutes. The furnace is shut off after the sintering period and the cores are allowed to cool within the furnace at the natural rate of the furnace down to some previously selected temperature. The cores are then rapidly quenched from the selected temperature, which may be from 900 to 1050 degrees C, to room temperature.

The cooling technique just described, increases the squareness of the cores. By using this technique, squareness ratios...