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Publication numberUS2330590 A
Publication typeGrant
Publication dateSep 28, 1943
Filing dateMay 18, 1940
Priority dateMay 19, 1939
Publication numberUS 2330590 A, US 2330590A, US-A-2330590, US2330590 A, US2330590A
InventorsKurt Kaschke
Original AssigneeKurt Kaschke
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Dust iron core
US 2330590 A
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Description  (OCR text may contain errors)

Sept. 28, 1943. sc 2,330,590

DUST mon CORE Filed May 18, 1 946 May/refit Cm, tomprllfl'ay Ivdered/ran, panderedd/l'can 'md lho'ulaflhq wafer/4A Patented Sept. 28, 1943 DUST IRON CORE- Kurt Kaschke, Berlln-Neukolln, Germany; vested in the Alien Property Custodian Application May 18, 1940, Serial No. 336,018 In Germany May 19, 1939 2 Claims.

This invention relates to a dust iron. core of the type used in particular for high frequency, for instance, of the order of 100 kcs. and especially for frequencies beyond 200 kcs.

Such dust iron cores mostly consist of a ferromagnetic powder, for instance, iron powder, especially carbonyl iron powder and the like, of a particle size of 0.01 mm. and less, and a binder. In many instances, the magnetic particles are surrounded by a solid insulating skin. It is an important object of the present invention to provide a dust iron core, of the type referred to, in which only a certain percentage of the solid powder contained in the core consists of ferromagnetic material, the balance being nonmagnetic material.

Another object of the invention is to provide means for regulating the permeability and losses of the core material and to vary the composition of the magnetic powder which is being used, in accordance with the specified permeability and losses.

Still another object of the invention is to pro-' vide a non-magnetic solid admixture increasing the mechanical strength of the core and its accuracy regarding dimensions and ensuring low wear of the pressing tools.

In the drawing, a core is shown in elevation which may be made in accordance with the invention. The particular core shown in the drawing is a so-called plug core of the screw type, having a screw thread on its surface and operating slots at both ends. Cores of this type are advantageously used for tuning coils in radio receivers, since they permit accurate adjustment of the coil inductance by screwing them more or less into the coil.

With the above mentioned objects in view. I- use silicon powder as an admixture of filling powder in the core, in addition to the iron or other magnetic powder and the binder. Of course, silicon is an electric conductor and, therefore, it might be expected that the eddy current losses are increased by the admixture of silicon powder, compared to the conventional use of nonconductive powder, such as quartz powder and the like. I have found, however, that the silicon powder, if sufficiently comminuted, does not cause any additional losses compared to non-conductive powders. While it is not intended to oiIer a deflnite theoretical explanation for this fact, it may be that owing to the small size of the individual particles and the relatively high specific resistance of silicon, the loss currents formed in each particle are so small as to be negligible compared to the iron losses.

Advantageously, the silicon powder is ground to a similar size as the magnetic particles, 1. e., to a diameter of a few microns. The amount of silicon powder admixed to the magnetic powder depends on the specified permeability and loss data and may range from a few percent up to 80% weight of the core. The great advantage of this filling material compared to the conventional filling powders resides in the fact that the cores become extremely hard and solid andthat resilient action of the filler which, for instance. may occur with quartz powder and would cause subsequent changes of dimensions and electrical data after the pressing operation, and low mechanical strength, is absolutely eliminated. The cores are very hard, strong and true to specified dimensions.

Example In order to make a screw type plug core for short wave coils, 50% by weight of carbonyl iron powder is mixed with 50% of silicon powder of substantially the same particle size. ,It is not necessary for the silicon powder to be absolutely pure (for instance, 98% silicon, 2% iron). Now, a varnish consisting of the condensation products of phenol and formaldehyde is admixed as a binder and the moist powder thus obtained is compressed in a cold or thermoplastic state to the cores of the required shape. It is also contemplated that the compression may be carried out in two steps, comprising an initial cold pressing and a subsequent pressing under heat, followed by a hardening step in 'a suitable furnace.

I claim:

1. A high-frequency ferromagnetic core consisting of a pressure-formed body consisting essentially of discrete particles of ferromagnetic powder and .of silicon powder in substantially equal amounts by weight, said particles being held together solely by means of a therm'o-setsubstantially the same particle size and being' held together solely by means of a thermo-setting insulating binder.


Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US2419847 *Jun 2, 1944Apr 29, 1947Gen ElectricPowdered iron magnetic core
US2475321 *Jun 22, 1943Jul 5, 1949Henry L CrowleyMolded core
US2597236 *Oct 24, 1947May 20, 1952Rca CorpComminuted ferromagnetic cores
US2791561 *Apr 27, 1950May 7, 1957Gen Aniline & Film CorpMagnetic powders and method of making the same
US4006479 *Feb 4, 1969Feb 1, 1977The United States Of America As Represented By The Secretary Of The Air ForceMethod for dispersing metallic particles in a dielectric binder
US4048280 *Sep 17, 1971Sep 13, 1977Jury Gordeevich BorzyakMethod of manufacturing electrotechnical articles
US4543208 *Dec 23, 1983Sep 24, 1985Tokyo Shibaura Denki Kabushiki KaishaMagnetic core and method of producing the same
US7510766Feb 4, 2004Mar 31, 2009Corporation Imfine Inc.Silicon oxide coatings; metallurgy; heat treatment; dielectrics; low hysteresis losses and low eddy current losses
US8416044 *Nov 16, 2009Apr 9, 2013Denso CorporationReactor and method of producing the reactor
U.S. Classification252/62.54, 336/233, 106/403, 252/62.55, 75/255, 524/440
International ClassificationH01F1/12, H01F1/26
Cooperative ClassificationH01F1/26
European ClassificationH01F1/26