US1651957A - Insulation of finely-divided magnetic material - Google Patents
Insulation of finely-divided magnetic material Download PDFInfo
- Publication number
- US1651957A US1651957A US158798A US15879827A US1651957A US 1651957 A US1651957 A US 1651957A US 158798 A US158798 A US 158798A US 15879827 A US15879827 A US 15879827A US 1651957 A US1651957 A US 1651957A
- Authority
- US
- United States
- Prior art keywords
- magnetic
- dust
- insulation
- magnetic material
- particles
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
- H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
- H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
- H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
- H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
- H01F1/20—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
- H01F1/22—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
- H01F1/24—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
- Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
- Y10T428/2991—Coated
- Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]
Definitions
- This invention relates to electrical insulation, and more particularly to the insulation of the particles used in the manufacture of magnetic dust cores for loading coils.
- Magnetic dust cores are belng extens ve- I ly used as the cores for loadlng co ls to improve the transmission characteristics of mgnaling lines.
- Certain magnetic alloys containing nickel and iron are now replacing 0 iron to a considerable extent for this purpose.
- These alloys, when formed into cores and properly heat treated, are peculiarly desirable for loading coil cores by virtue of roperties, some of which vary when the al- 16 0y material is strained, as 1s incidentally done by changing its form 1n compress1ng the dust into solid cores. It is, therefore, best to perform the heat treatment after the dust has been compressed into core form. 20
- the material used for insulating the finely divided magnetic material is a mixture ofmagnesium borate and silica.
- the invention is a meth- 'od of preparin magnetic structures and more particular y magnetic dust cores. As applied to cores, for example, this method,
- the magnetic material comprises mixing a mass of the magnetic material in finely dlvided form such as dust, dust with magnesium borate and silica to form an insulating coating on the particles, compressing the coated par- 40 ticles under high pressure to form a homo ge-' neous mass, and heat treating the core to improve the magnetic properties of the magnetic material.
- finely dlvided form such as dust, dust with magnesium borate and silica
- Fig. be ng a perspective view of a single magnetic ring and Fig. 2 illustrating a plurality of rings combined to form a magnetic core.
- the magnetic material is preferably prepared from an alloy containing nickel and iron.
- alloy contains78 nickel and 21 iron.
- the magnetic alloy which may be in slab form, is reduced to a finely divided state, such as dust, in any well known manner, as by crushing in a hammer mill or other suitable reducing apparatus and is subsequently rolled in a ball mill. The dust is passed through a sieve and the portion or dust passing through a 120 mesh sieve is suitable for magnetic core purposes. The dust is mixed with an insulator and pressed into core form.
- the insulator for the magnetic dust comprises magnesium borate and silica.
- One method of securing a definite refractory insulating coating on the particles comprises dissolving magnesium oxide in a concentrated solution of boric acid.
- the boric acid solution ma consist oi approximately 150 grams of oric acid in 500 cc. of Water to which is added 16 grams of magnesium oxide. This mixture is stirred while being heated at a temperature of approximately 90 C. until the oxide is dissolved.
- a suitable mixture for a core mass comprises 2000 grams of magnetic dust of nickel and iron alloy mixed with the boric acid solution of the magnesium oxide and 2% by volume of ground silica, the amount of the solution comprising approximately 4% of the mixture.
- the mixture is dried in an open vessel by stirring at a temperature of approximately 100 C. for one hour and then dried in an evacuated vessel at a temperature of 200 C. for two hours.
- the resulting material contains the nickel-iron alloy particles thoroughly coated with dry magnesium borate and silica dust.
- a mass of the coated particles is then placed in a mold and compressed into a core ring such as is shown in Fig. 1, with a pressure of approximately 200,000 pounds per square inch.
- the compression of' the particles into a homogeneous solid core necessarily produces strains in the ma etic dust and also causes the magnesium orate and silica insulating coating to be strained at the contact points of adjacent particles While the insulating coating on the flat surfaces of the particles is not subject to the same de-v gree of strain.
- the compressed core rings are then transferred to an electric furnace and given a heat treatment to improve the magnetic properties of the magnetic material. This treatment is carried on at temperatures between approximately 500 C. and 600 C. and the rings are thereafter cooled.
- a plurality of rings thus formed are stacked coaxially to form a complete core, as shown in Fig. 2, on which the usual toroidal winding is applied, the number of rings depending upon the existing electrical characteristics of the telephone clrcuit with which the loading coils are to be associated.
- magnesium borate and silica insulation may be employed in other forms of metallic structures which are subject to compression and heat treatment and the invention is only to be limited within the scope of the appended claims.
- a magnetic structure comprising magnetic material in a finely divided state, and an insulating coating on the particles of said material comprising magnesium borateand silica. 4
- a magnetic structure comprising magnetic material, an alloy in a finely divided state, said alloy including nickel and iron, and an insulating coating on the alloy partilc les comprising magnesium borate and s1 1ca.
- a magnetic structure comprising an allo in finely divided form, said alloy in cul ing nickeland iron, and an insulating coating on the particles consisting of mag nesium borate and silica, the entire mass being pressed into a homogeneous solid.
- a magnetic structure comprisin an alloy containin nickel and iron, in finely divided 'form,'t e division of the particles being such that they are capable of passing through a sieve having 120 meshes per inch, and an adherent insulating coating on the particles comlprising magnesium'borate and silica, the v0 ume of the magnesium borate being approximately 4% of the volume of the magnetic structure and the volume of the silica being approximately 2% of the volume of the magnetic structure.
- the method of making magnetic dust structures which comprises mixing a mass of magnetic dust particles with a boric acid solution containing magnesium oxide and silica dust, drying the mixture, and heat treating the mass to improve the magnetic properties.
- the method of making magnetic dust structures which comprises mixing magnetic dust with'a boric acid solution containing magnesium oxide and silica dust, drying the mixture, subjecting the mass to high pressure to form a homogeneous solid, and heat treating said solid to improve its magnetic properties.
Description
Dec. 6, 1927. 1,651,957
H. H. LOWRY INSULATION 0F FINELY DIVIDED MAGNETIC MATERIAL Filed Jan. 3, 1927 Wye/7f. Hamer Z awry,
Z ffomey Patented Dec. 6, 1927.
UNITED STATES 1,651,957 PATENT OFFICE.
HOMER H. LOWBY, OF MOUNTAIN LAKES, NEW JERSEY, ASSIGNOR TO BELL TELE- PHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 03' NEW YORK.
Application filed January '8, 1927. Serial No. 158,798.
' This invention relates to electrical insulation, and more particularly to the insulation of the particles used in the manufacture of magnetic dust cores for loading coils.
5 Magnetic dust cores are belng extens ve- I ly used as the cores for loadlng co ls to improve the transmission characteristics of mgnaling lines. Certain magnetic alloys containing nickel and iron are now replacing 0 iron to a considerable extent for this purpose. These alloys, when formed into cores and properly heat treated, are peculiarly desirable for loading coil cores by virtue of roperties, some of which vary when the al- 16 0y material is strained, as 1s incidentally done by changing its form 1n compress1ng the dust into solid cores. It is, therefore, best to perform the heat treatment after the dust has been compressed into core form. 20 Furthermore, it is necessary to insulate the individual particles prior to the core torming operation, to reduce eddy current losses in the completed core. It is therefore necessary to provide an insulation which will 85 withstand the high temperatures. of the heat treatment.
In accordance with this inventlon, the material used for insulating the finely divided magnetic material is a mixture ofmagnesium borate and silica.
In another aspect, the invention is a meth- 'od of preparin magnetic structures and more particular y magnetic dust cores. As applied to cores, for example, this method,
specifically stated, comprises mixing a mass of the magnetic material in finely dlvided form such as dust, dust with magnesium borate and silica to form an insulating coating on the particles, compressing the coated par- 40 ticles under high pressure to form a homo ge-' neous mass, and heat treating the core to improve the magnetic properties of the magnetic material.
A more detailed description of the invention follows, and the accompanying draw ing illustrates one embodiment, Fig. be ng a perspective view of a single magnetic ring and Fig. 2 illustrating a plurality of rings combined to form a magnetic core.
In carrying out the present invention the magnetic material is preferably prepared from an alloy containing nickel and iron.
preferred form of alloy contains78 nickel and 21 iron. For a description of this and other alloys which maybe used as core material, see patent to G. W. Elmen, No. 1,586,884. Obviously, other alloys also may be used. The magnetic alloy, which may be in slab form, is reduced to a finely divided state, such as dust, in any well known manner, as by crushing in a hammer mill or other suitable reducing apparatus and is subsequently rolled in a ball mill. The dust is passed through a sieve and the portion or dust passing through a 120 mesh sieve is suitable for magnetic core purposes. The dust is mixed with an insulator and pressed into core form. V
The insulator for the magnetic dust comprises magnesium borate and silica. One method of securing a definite refractory insulating coating on the particles comprises dissolving magnesium oxide in a concentrated solution of boric acid. For example, the boric acid solution ma consist oi approximately 150 grams of oric acid in 500 cc. of Water to which is added 16 grams of magnesium oxide. This mixture is stirred while being heated at a temperature of approximately 90 C. until the oxide is dissolved. A suitable mixture for a core mass comprises 2000 grams of magnetic dust of nickel and iron alloy mixed with the boric acid solution of the magnesium oxide and 2% by volume of ground silica, the amount of the solution comprising approximately 4% of the mixture. The mixture is dried in an open vessel by stirring at a temperature of approximately 100 C. for one hour and then dried in an evacuated vessel at a temperature of 200 C. for two hours. The resulting material contains the nickel-iron alloy particles thoroughly coated with dry magnesium borate and silica dust.
A mass of the coated particles is then placed in a mold and compressed into a core ring such as is shown in Fig. 1, with a pressure of approximately 200,000 pounds per square inch. The compression of' the particles into a homogeneous solid core, necessarily produces strains in the ma etic dust and also causes the magnesium orate and silica insulating coating to be strained at the contact points of adjacent particles While the insulating coating on the flat surfaces of the particles is not subject to the same de-v gree of strain. The compressed core rings are then transferred to an electric furnace and given a heat treatment to improve the magnetic properties of the magnetic material. This treatment is carried on at temperatures between approximately 500 C. and 600 C. and the rings are thereafter cooled. For a detailed account of heat treatments employed with nickelviron alloy structures reference is made to patents to G. W. Elmen, Nos. 1,586,884 and 1,586,889;
A plurality of rings thus formed are stacked coaxially to form a complete core, as shown in Fig. 2, on which the usual toroidal winding is applied, the number of rings depending upon the existing electrical characteristics of the telephone clrcuit with which the loading coils are to be associated.
While the invention has been described with respect to the insulation of magnetic dust which is subject to a heat treatment to improve the magnetic properties of the magnetic material, the invention is not limited to this particular aspect. The magnesium borate and silica insulation may be employed in other forms of metallic structures which are subject to compression and heat treatment and the invention is only to be limited within the scope of the appended claims.
What is claimed is:
1. A magnetic structure comprising magnetic material in a finely divided state, and an insulating coating on the particles of said material comprising magnesium borateand silica. 4
2. A magnetic structure comprising magnetic material, an alloy in a finely divided state, said alloy including nickel and iron, and an insulating coating on the alloy partilc les comprising magnesium borate and s1 1ca.
3. A magnetic structure comprising an allo in finely divided form, said alloy in cul ing nickeland iron, and an insulating coating on the particles consisting of mag nesium borate and silica, the entire mass being pressed into a homogeneous solid.
4. A magnetic structure comprisin an alloy containin nickel and iron, in finely divided 'form,'t e division of the particles being such that they are capable of passing through a sieve having 120 meshes per inch, and an adherent insulating coating on the particles comlprising magnesium'borate and silica, the v0 ume of the magnesium borate being approximately 4% of the volume of the magnetic structure and the volume of the silica being approximately 2% of the volume of the magnetic structure.
' 5. The method of making magnetic dust structures which comprises mixing a mass of magnetic dust particles with a boric acid solution containing magnesium oxide and silica dust, drying the mixture, and heat treating the mass to improve the magnetic properties.
6. The method of making magnetic dust structures which comprises mixing magnetic dust with'a boric acid solution containing magnesium oxide and silica dust, drying the mixture, subjecting the mass to high pressure to form a homogeneous solid, and heat treating said solid to improve its magnetic properties.
In witness whereof, I hereunto subscribe my name this 30th day of December, A. D.,
' j HOMER H. LOWRY.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US158798A US1651957A (en) | 1927-01-03 | 1927-01-03 | Insulation of finely-divided magnetic material |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US158798A US1651957A (en) | 1927-01-03 | 1927-01-03 | Insulation of finely-divided magnetic material |
Publications (1)
Publication Number | Publication Date |
---|---|
US1651957A true US1651957A (en) | 1927-12-06 |
Family
ID=22569748
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US158798A Expired - Lifetime US1651957A (en) | 1927-01-03 | 1927-01-03 | Insulation of finely-divided magnetic material |
Country Status (1)
Country | Link |
---|---|
US (1) | US1651957A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2518528A1 (en) * | 1981-12-23 | 1983-06-24 | Europ Composants Electron | Formation of magnetic castings - by cold forming followed by thermal treatment at 500 degrees Celsius in air |
US4543197A (en) * | 1982-04-27 | 1985-09-24 | Japan Metals & Chemicals Co., Ltd. | Process for producing magnetic metallic oxide |
-
1927
- 1927-01-03 US US158798A patent/US1651957A/en not_active Expired - Lifetime
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2518528A1 (en) * | 1981-12-23 | 1983-06-24 | Europ Composants Electron | Formation of magnetic castings - by cold forming followed by thermal treatment at 500 degrees Celsius in air |
US4543197A (en) * | 1982-04-27 | 1985-09-24 | Japan Metals & Chemicals Co., Ltd. | Process for producing magnetic metallic oxide |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US1669644A (en) | Magnetic material | |
US1647737A (en) | Magnetic core | |
US1669642A (en) | Magnetic material | |
US1651957A (en) | Insulation of finely-divided magnetic material | |
US1695041A (en) | Production of magnetic dust cores | |
US1809042A (en) | Magnet core | |
US2977263A (en) | Magnetic cores and methods of making the same | |
US1881711A (en) | Magnetic structure | |
US1297127A (en) | Magnet-core. | |
US1768443A (en) | Percent molybdenum | |
US1669643A (en) | Magnetic material | |
JPS63117406A (en) | Amorphous alloy dust core | |
US1651958A (en) | Insulation of finely-divided magnetic material | |
US2076230A (en) | Insulated magnetic core and method of making insulated magnetic cores | |
US1669665A (en) | Magnetic material | |
US1647738A (en) | Insulation of magnetic material | |
US1991143A (en) | Production of finely divided magnetic bodies | |
US1943115A (en) | Electrical insulation for magnetic bodies | |
USRE20507E (en) | Magnetic material | |
US1669646A (en) | Magnetic material | |
US1747854A (en) | Magnetic structure | |
US1669658A (en) | Magnetic core | |
US1840352A (en) | Process of producing magnetic bodies | |
US1714683A (en) | Electrical insulation | |
US1954102A (en) | Magnet core |