US3014825A - Magnetic cores and methods of making the same - Google Patents

Magnetic cores and methods of making the same Download PDF

Info

Publication number
US3014825A
US3014825A US857087A US85708759A US3014825A US 3014825 A US3014825 A US 3014825A US 857087 A US857087 A US 857087A US 85708759 A US85708759 A US 85708759A US 3014825 A US3014825 A US 3014825A
Authority
US
United States
Prior art keywords
core
oil
particles
cores
magnetic
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
Application number
US857087A
Other languages
English (en)
Inventor
Harendza-Harinxma Alfred
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Western Electric Co Inc
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Western Electric Co Inc filed Critical Western Electric Co Inc
Priority to US857087A priority Critical patent/US3014825A/en
Priority to GB39189/60A priority patent/GB962631A/en
Priority to DE19601439912 priority patent/DE1439912A1/de
Priority to CH408565A priority patent/CH421215A/de
Priority to CH408465A priority patent/CH402206A/de
Priority to CH1350260A priority patent/CH408226A/de
Priority to JP4727960A priority patent/JPS3716779B1/ja
Priority to BE597724A priority patent/BE597724A/fr
Priority to ES0263399A priority patent/ES263399A1/es
Priority to DK524461A priority patent/DK108803C/da
Priority to DK482460A priority patent/DK104143C/da
Priority to US105836A priority patent/US3132952A/en
Application granted granted Critical
Publication of US3014825A publication Critical patent/US3014825A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
    • 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

Definitions

  • the present invention relates generally to magnetic cores and methods ⁇ of making the same. More particularly, the invention concerns certain improvements in the magnetic cores and methods of making them in accordance with the general principles of A. F. Bandur Patent 2,105,070, dated-January ll, 1.938, so as tol improve the physical and magnetic properties of the cores.
  • the cores may be use'd for many purposes, but are designed primarily for use in voice frequency telephone circuits.
  • An object of the invention is to provide new and improved magnetic cores.
  • Another object or the invention is to provide new and improved methods of making magnetic cores.
  • More .specic objects of the invention are to increase the magnetic permeability, decrease the core loss, and increase the physical strength of magnetic cores formed by compressing magnetic particles having an insulating coating including at least one alkali metal silicate.
  • magnetic cores are produced by coating nely divided magnetic particles with an insulating composition consisting of a refractory metal silicate, magnesium V"hydroxide and an alkali metal silicate.
  • the insulated particles are then compressed into a core and the core isiired at a temperature of 1000 to 1300" F. to -anneal the magnetic particles and cure the coating.
  • Another object of the invention is to provide improvements in the cores and methods of making them as generally disclosed in the Bandur patent, which improvements are directed primarily to producing cores having increased permeability, decreased core loss, or improved mechanical strength.
  • the cores As many reasons, it is ⁇ desirable to increase the permeability rating of the cores as much as possible to the eX- tent that this can be done without any substantial adverse electon the core loss.
  • by increasing the permeability of the cores it is possible to utilize cores which are smaller in size to accomplish a given result, thereby resulting in a saving both in space and in the materials used in the cores.
  • the same size core may be wound with fewer turns of Wire to obtain the same transformer action.
  • the cores functionL more eiiciently to transform voice-frequency alternating currents used in telephone transmission systems.
  • addi- Lion by decreasing the core loss resultant from using a given amonntof ⁇ insulation, it is possible to utilize cores having -a smaller amount of insulation than was heretofore possible and thus to produce cores having higher permeabilities.
  • the cores are impregnated with an alkali meta-l aluminate after the compression step and before the tiring step; With this additional step, the lcorev loss is substantially lower than that" resultant without the aluminate treatment and there is no substantial adverse effect on the' permeability or other properties.
  • the aluminate is sodium aluminate and the impregnating step is accomplished by dipping the compressed core in an aqueous solution thereof.
  • the insulated particles are treated with.. oil vapor prior to the compression step.
  • the oil vapor is absorbed by and reacts with the alkali metal silicate present inthe insulation to become ,a constituent of' the insulation.
  • the permeability may be substantially increased by using higher pressures than were heretofore practical andy the core loss is substantially 11e-l cuted with respect to. the core loss of cores produced by the same process but without the oil treatment.
  • the insulated particles are coated with a dilute solution of a light mineral oilI dissolved in a volatile solvent therefor, and the oil-containing particles: are heated. toa temperature sucient to driveot the solvent and vaporize at least a portion of the oil.
  • the aluminate treatment ofv the rst embodiment is; combined with the oil treatment of the, second embodiment.
  • the yaluminate reacts. with the alkali metal silicate and the oil ⁇ vapor to form a' ccramic-type reaction producnwhich becomes a ⁇ constituent of the insulation.
  • Cores producedl according to this; com bine-d process have a permeability of the samev order as that resultant from the oil treatment; alone, a core loss Iwhich is substantially lower than thatV achieved with either the aluminate or the oil treatmenty alone, and markedly superior mechanical strength.
  • the invention is also directed tothe magnetic cores produced in accordance with the foregoing processesfas new articles of manufacture having new and useful insulating materials separati-ng the magnetic particles.
  • Such insulating materials may include (l) the heat treated reaction product of an alkali metal silicate and an lalkali metal aluminate; (2.) the heat treated reactionproduct of an alkali metal silicate and oil vapor; and (3) the heattreated, ceramic-type reaction product of an alkali metal silicate, ⁇ oil vapor, and an alkali metal aluminate.
  • FIG. l illustrates graphically the typical effect of' the Y amount of insulation used on the magnetic permeability at 1800 cyclesper second in accordance ywith the prior process and Various of the improved processesl of this application;
  • FIG. 2 illus-trates the corresponding effect of the amount of insulation on the core loss; at 1800 cycles per second in various cases.
  • Such an alloy may be treated and' comminuted according to the general principles enunciated in P. Bcath et al. Patent 1,6691649, dated MayV 15, 1912-8. Accord'- ing to that patent, the'metallic constituents of the alloy are melted togetherv and oxidized in-l the molten state to embrittle the alloy. This treatment l produces a tine crystalline structure in the solidified alloy that facilitates reduction to a tiney powder by conventional' grinding and puverizing techniques.
  • TheV resultant magnetic powder is sieve'd through a mesh screen, and any oversize particles a're recycled;
  • the majority oli the particles are in the range* of about 3 200 to 300 mesh.
  • the sieved powder is next subjected to an annealing heat treatment at about 1500 to 1600 F. to remove stresses introduced into the magnetic material by the grinding operation.
  • the particles are then given an insulating coating comprising a refractory metal silicate, magnesium hydroxide and an alkali metal silicate.
  • the coating is made up of talc (a hydrated magnesium silicate), 1 part by weight; sodium silicate, 0.3 to 0.4 part by weight; and magnesium hydroxide, 0.06 to 0.08 part by weight.
  • talc a hydrated magnesium silicate
  • the optimum proportions embodied in the commercial process are talc, l part by weight; sodium silicate, 0.35 part by weight; and magnesium hydroxide, 0.07 part by weight.
  • the sodium silicate should have a high silicate to soda ratio, preferably about 1.6 to 3.0 parts silicate to one part soda.
  • Other refractory metal silicates, such as aluminum silicate may be used as well as other alkali metal silicates, such as potassium silicate.
  • the coating composition is preferably applied in at least three stages from an aqueous suspension of the conbeen encountered with the decreases tending to occur in cases where more insulating material is used.
  • the particles After the particles have been insulated, they are cornpressed into la core of a suitable shape, such as a ring, by molding at a pressure in the neighborhood of 150,000 to 200,000 pounds per square inch. During the application of this pressure, the magnetic particles are again subjectexl to ⁇ stresses which impair the magnetic properties thereof. Therefore, the cores are again subjected to an annealing heat treatment by firing at a temperature between about 1000 and 1300 F. The cores are preferably red in a hydrogen-containing atmosphere at about 1200 F. During this heat treatment, the insulating material is fully cured.
  • core rings are produced having an insulating coating as described above containing about 1.25 parts by weight of the insulating material to 100 parts by weight of the magnetic powder.
  • Such core rings have been found to exhibit an average magnetic permeability at 1800 cycles per second of 125 and an average core loss at 1800 cycles per second of 0.190 unit (ohms per unit of permeability per unit of inductance).
  • the present manufacturing limits on such core rings have been a permeability of at least 115 and a core loss no higher than 0.240 units.
  • magnetic particles containing an insulating coating including an alkali metal silicate, and particularly particles formed generally in accordance .with the prior process just described are impregnated with an alkali metal aluminate after the compression step and before the tiring step.
  • the core loss is substantially decreased without any substantial adverse effect on the permeability.
  • the pressed cores are dipped for a period of 10 to 60 minutes in a 5 to 10% aqueous solution of sodium aluminate'r- While the absolute value of the core loss may vary considerably depending on the process conditions, the core loss is decreased by the aluminate treatment in all cases.
  • the amount of insulation is preferably between vabout 0.5 and 1.5 parts by weight based on 100 parts by weight of the magnetic powder, and the process comprehends mixturesof lightly and heavily insulated powders.
  • the improved method has been found effective to lower the core loss Abetween about 15 and 80%, with the larger decreases being realized in cases where less insulating material is used and the core loss without treatment is higher.
  • the average permeability of cores treated according to the improved process is not substantially changed, although changes of plus or minus 5 units have proximately the same as that of the conventional process, indicated by curve A in FIG. 1.
  • maximum permeability in the typical example exists at about 0.55 part of the insulation, while the core loss decreases steadily over the range as indicated by the tapering curve B as the amount of insulation is increased.
  • the permeability maximum may occur between about 0.5 and about 0.8 part of the insulation depending on process conditions. From a manufacturing standpoint, it is highly desirable to use a smaller amount of insulation (0.5 to 0.9 part) than was heretofore used (1.2 to 1.3 parts) so as to achieve a permeability as near as possible to the maximum, to the extent that this can be accomplished with an acceptable core loss.
  • curve B the core loss is far too high when it is attempted to utilize only 0.5 to 0.9 part of the insulation by the standard method.
  • the aluminate treatment of the present invention depresses the core loss curve as indicated by curve C, it is possible to utilize more lightly insulated powder so as to achieve a higher perme ability, while maintaining the core loss within the manufacturing limit of 0.24 unit.
  • the aluminate solution penetrates through microscopic pores in the surface of the pressed core to impregnate the core.
  • the sodium aluminate then reacts with the sodium silicate in the insulation to form a gel which better insulates the particles and fills any minute voids that may exist in the mass.
  • the vcore is later fired, the water is driven olf and there remains as a constituent of the insulation the heat treated reaction product of the sodium silicate and the sodium aluminate.
  • Example I According to one specific example ofthe invention, several core rings produced according to the commercial process described hereinabove were taken as a sample. These core rings were insulated with 1.25 parts by weight of the insulation as previously described. Without any intermediate treatment, a rst group of core rings was pressed from this powder at a pressure of about 160,000 pounds per square inch, and the cores were red in a hydrogencontaining atmosphere at a temperature of 1200" F. The average permeability of these core rings was and the average core loss was 0.190 unit.
  • a second group of cores was produced from the same powder by exactly the same process, except that these cores were soaked in a 10% aqueous solution of sodium aluminate at about 210 F. for 60 minutes after the compression step and before the lfiring step.- These cores exhibited an average permeability of 121 (a 3.2% decrease) and an average core loss of 0.160 unit, a decrease of 0.03 unit or 15.8%. While this example demonstrates the applicability of the invention to standard methods, the prin- 3,01 geen f '51 cipal advantage thereof will bek indicated in the following examples as allowing the use of a lighter coating of insnlation.
  • Example II In the second example, anumber of coresv were produced. with and without the aluminate' dip as described in ⁇ Example I, except that the magnetic particles were insulated with only 0.9 part by weight of the. insulation.
  • the untreated cores had an average permeability of 177 and a core lossof 0.60 unit (curve BV), which is. Well beyoud; the manufacturing standardof 0.24 unit.
  • the treated cores exhibited a permeability ofr 174 and a core loss of only 0.19 unit (curve C), which is within the manufacturing standard.
  • the core loss was decreased by 0.41 unit or 68% by treatment in accordance With the invention, while a relatively high permeability was achieved.
  • Example III In this example, a mixture of insulated powders was used to provide a high permeability, while the core rings were treated with sodium aluminate after pressing and before tiring to decrease the core loss.
  • the insulated particles weremade up inv two distinct batches: batch A containing 0.8 part by weight of the insulation, and batch B containing the standard 1.25 parts ⁇ by weight of insulation.' These batches were otherwise produced according to the process described hereinbefore.
  • a series of cores was pressed from a uniform mixture of 74% of the lightly insulated particles from batch A and '26%Y of the standard particlesof batch B. Without further treatment, some of these cores were red'-, Cores produced from the mixed powders according to conventional pressing andy tiring techniques exhibited an average permeability of about 165 and a core loss of 0.28. unit.
  • the advantages of using a mixture of lightly and heavily insulated powders is that the resultant permeability tends to approximate the weighted' average of the two constituents, while the core loss is much closer to that of the heavily insulated powder than the average figure.
  • magnetic particles containing an insulating coating includ'- ing an alkali metal silicate, and particularly particles formed generally in accordance with the prior process described hereinbefore are treated with oil vapor prior to the compression step.
  • the insulated particles are coated with a thin tilm of oil, and are then heated to vaporize at least a portion of the oil.
  • the oil vapor is absorbed by and reacts with the alkali metal silicate to become a constituent of the insulation.
  • the permeability ofthe finished core l may beV substantially increased by using higher pressures than were heretofore practical and the core lossr is substantially decreased in any case.
  • a light. mineral oil is. added by mixing. the particles with a dilute solution of the ⁇ oil in a. volatile solvent therefor.
  • the dilute solution is used; so that. the small amount. ofy oil used, preferably about 0.2 part by Weight, is extended to cover substantially all of the insulated particles with an exceedingly thin iilm of oil. This iilm of oil may have a thickness of approximately 0.001 mill.
  • the dilute solution ⁇ of oil ⁇ may range between. about 1 and about 3.5% oil, with the remainder'being solvent.
  • a surface-active agent such as -Aerosol (dihexylsodiumsulfosuccinate.) or Levapon,v to the oil-solvent mixture so as. to. lower the: surface tension thereof and facilitate. coating of the particles with a thin film of oil.
  • a surface-active agent such as -Aerosol (dihexylsodiumsulfosuccinate.) or Levapon,v
  • oil a light mineral oil. having the following. properties: specific gravity, 0.887; viscosity at 11009 E. (S.S.U.), 10G-1351; flash paint 310 F.; boiling point., 250 F.; volatile matter 0.35% maximum at 212 F.; neutralization No., 0.10 milligram of KOH- t'oneutralize 1 gram of oil; and. ash, 0.01% maximum.
  • solvent must be capable of dissolving the required amount of the oil, up to about 3.5%, and must be vaporized at'a temperature substantially below that where the oil begins to vaporize.
  • Acetone which has a low. viscosity and vaporizes'at about 134"v F.,.is suitable for application with ay wide variety of oils.
  • suitable solvents include methyl. chloroform, carbon tetrachloride and toluol.
  • 'Ille amount of oil used is dependentA on the. amount of sodium silicate in the insulation, and the more ⁇ heavily insulated particles are capable of absorbing a larger amount of oil since more sodium silicate is present..
  • the oil-coated particles should be heated. to atemperature at which the oil begins to vaporize, preferably to about 260 F. for the specitic oil described which boils at about 250 F. This temperature should be-maintained for a suicient time, preferably about 5 to 15 minutes, to vaporize a substantial portion of ther oil, at leastl a portion of the oilv vapor being absorbed. by the sodium silicate. When the core is later tired, any remaining oil is vaporized and the heat-treated reaction product of the sodium silicate and the oil vapor remains as a. con.- stituent of the insulation. j
  • this treatment permits the use of a higher pressure than was heretofore possible, which results. in a denser core having a higher permeability; and second, by drastically reducing the core loss as. indicated. by curve E in FIG. 2,. the method allows the use. of a smaller amount of insulation, between about 0.5 v and 1.0 part. byweight, tov take advantage of they phenomenon of maximum permeability. s
  • Example IV'y tion tends to: be broken down and the resultV is an exi cessive core. loss;
  • a second groupv of cores' was made. from the same powder in the same mannenexceptthat the pressure was approximatelyl 200,000. pounds per squarev inch. and the insulated particles were coated with a 2.5% solutionI of the light mineral oil described hereinbefore dissolved in acetone and containing a minor amount of AerosoL ApproximatelyS milliliters of the solution were used for 100 grams of the insulated powder, sufficient to yield 0.2 part by weight of the oil per 100y parts by weight of the insulated powder. The oil-containing mixture was then heated to a temperature of 260 F. for about 10 minutes to drive off the solvent and vaporize a substantial portion of the oil. These oil-coated particles were then compressed into cores and ired according to the standard procedure.
  • the cores thus formed exhibit an average permeability of 217 (curve D) and an average core loss of 0.150 unit (curve E), which is well within the manufacturing limit.
  • the permeability was raised 40 units or 22.6%, while the core loss was lowered 0.45 unit or 75%.
  • Example V In this example, a series of cores was produced as described in Example lV, except that only 0.7 part by weight of the insulation was utilized. This percentage of insulation is designed to achieve a near maximum permeability, as indicated in FG. l (curve D). Without the oil treatment, these cores had a permeability of 210 (curve A) and a core loss of 1.05 units (curve B). The cores treated with oil, however, showed a permeability of 233 (curve D) and a core loss of only v0.175 unit (curve E).-
  • the aluminate treatment described hereinbefore is combinedwith the oil treatment just described to produce further improvements in the physical and magnetic properties of the cores.
  • Cores produced according to the combined method have a permeability about the same as that realized by the oil treatment alone (curve D, FIG. l), a core loss lower than that produced with either the aluminate treatment or the oil treatment alone (curve F, FIG. 2), and markedly improved physical strength and resistance to breaking.V
  • Example AVI A number of the cores containing 0.9 part by Weight of insulation were given an loil treatment as described in Example IV and were also given an aluminate treatment as described in Example II.
  • the cores treated according to this combined process had a permeability of 215 and a core loss of 0.115 unit, as compared with 217 and 0.150 for the oil treatment alone, 174 and 0.19 for the aluminate treatment alone, and 177 and 0.60 without any of these treatments.
  • the cores manufactured in accordance with the combined process were substantially harder and more difficult to break than those produced by any of the other methods, probably due to the presence of the ceramictype constituent in the insulation.
  • the insulated particles did not crumble; instead, the metal rubbed ott on the surface of the insulated particles.
  • the powder crumbled in response to scratching by metallic Permalloy.
  • the cores produced by the combined process were much more diicult to fracture than any of the other cores.
  • Example VII A number of cores were produced as described in Example V with 0.7 part by weight of the insulation, except that the sodium aluminate treatment as in Example II was added to the oil treatment. These cores displayed a permeability of 228 and a core loss of 0.125 unit, as compared to a permeability of 233 and a core loss of 0.175'resultant with the oil treatment alone. These cores were also substantially harder and more resistant to breakage than the cores treated with oil alone.
  • all of the core rings formed in accordance with the present invention may be soaked in water after the firing operation and then retired in a hydrogen atmosphere at about 1200 F. so as to increase the permeability by about 20 additional units without any substantial change in the core loss.
  • the improved method which comprises vthe additional step-of impregnating the core with an alkali metal aluminate after the compression step and before the firing step.
  • the improved method which comprises the additional step of dipping the compressed core in an aqueous solutionof sodium aluminate after the compression step and before the ring step.
  • the insulated powder is prepared in two distinct batches, a iirst containing between 0.50 and 0.90 part by weight of the insulation per 100 parts of the metal and the second containing between 1.2 and 1.5 parts Vby weight of the insulation per 100 parts of the metal; and wherein a uniform mixture of 70 to 80% particles from the irst batch with 30 to 20% particles ⁇ from the second batch is compressed into the core.
  • the improved method which comprises the additional step of treating the insulated particles with oil vapor prior to the compression step, the oil vapor being absorbed by and antenas reacting with the alkali metal silicate to become a constituent of the insulation.
  • the improved method which comprises the additional steps of coating the insulated particles with a thin lm of oil prior to the compression step; and heating the oil-containing particles prior to the compression step to vaporize at least a portion of the oil, the oil vapor being absorbed by and reacting wtih the alkali metal silicate to become a constituent of the insulation.
  • the improved method which comprises the additional steps of coating the insulated particles prior to the compression step with between 0.05 and 0.35 part by weight, based in 100 parts by weight of the insulated powder, of an oil by mixing the particles with a dilute solution of the oil in a volatile solvent therefor; and heating the oilcontaining particles prior to the compression step to a temperature suiiicient to drive off the solvent and vaporize at least a portion of the oil, the oil vapor being absorbed by and reacting with the alkali metal silicate to become a constituent of the insulation.
  • iinely divided magnetic metal particles are given an insulating coating of between 0.5 and 1.0 part by weight, based on 100 parts of the metal, of a composition consisting essentially of talc, 1 part by weight, sodium silicate, 0.3 to 0.4 part by weight, and magnesium hydroxide, 0.06 to 0.08 part by weight; wherein the insulated particles are then compressed into a core; and wherein the core is tired at a temperature of 1000 to l300 F.: the improved method which comprises the additional steps of coating the insulated particles prior to the compression step with between 0.05 and 0.35 part by weight, based on 100 parts by weight of the insulated powder, of a light mineral oil by mixing the particles with a 1 to 3.5% solution of the oil dissolved in acetone and containing a minor amount of a surface active agent; and heating the oil-containing particles prior to the compression step to a temperature between 5 and 15 F. above the temperature at which the oil begins to vaporize to drive off the acetone and
  • the improved method which comprises the additional steps of treating the insulated particles with oil vapor prior to the compression step, the oil vapor being absorbed by and reacting with the alkali metal silicate; and impregnating the core with an alkali metal aluminate after the compression step and before the tiring step, the aluminate reacting with the silicate and the oil vapor upon firing to form a ceramic-type reaction product which becomes a constituent of the insulation.
  • the improved method which comprises the additional steps of coating the insulated particles with a thin film of a light mineral oil prior to the compression step by mixing the particles with a dilute solution of the oil in a volatile solvent therefor; heating the oil-containing particles prior to the compression step to a temperature sufiicient to drive oit the solvent and vaporize at least a portion of the oil, the oil vapor being absorbed by and reacting with the alkali metal silicate; and dipping the compressed core in an aqueous solution of sodium aluminate after the compression step and before the firing step, the sodium aluminate reacting with the alkali metal silicate and the oil vapor upon ring
  • the improved method which comprises the additional steps of coating the insulated particles prior to the compression step with between 0.05 and 0.35 part by weight, based on 100 par-ts by weight of the insulated powder, of a light mineral oil by mixing the particles with a 1 to 3.5% solution of the oil dissolved in acetone and containing a minor amount of a surface active agent; heating the coated particles prior to the compression step to a temperature about 5 to 15 F.
  • a magnetic core composed of particles of a magnetic material separated by an insulating material comprising the heat treated reaction product of an alkali metal silicate and an alkali metal aluminate.
  • a magnetic core composed of particles of a magnetic material separated by an insulating material comprising the reaction product of sodium silicate and sodium aluminate when heat treated at a temperature of 1000 to 1300 F.
  • a magnetic core composed of particles lot a magnetic material separated by an insulating material comprising the heat treated reaction product of an alkali metal silicate and oil vapor.
  • a magnetic core composed of particles of a magnetic material separated by an insulating material comprising the ceramic-type reaction product of sodium silicate, having the vapor of a 'light mineral oil absorbed thereby, and sodium aluminate when heat treated at a temperature of 1000 to 1300" F.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Soft Magnetic Materials (AREA)
US857087A 1959-12-03 1959-12-03 Magnetic cores and methods of making the same Expired - Lifetime US3014825A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
US857087A US3014825A (en) 1959-12-03 1959-12-03 Magnetic cores and methods of making the same
GB39189/60A GB962631A (en) 1959-12-03 1960-11-15 Magnetic materials
DE19601439912 DE1439912A1 (de) 1959-12-03 1960-11-25 Magnetkerne und Verfahren zu ihrer Herstellung
CH408465A CH402206A (de) 1959-12-03 1960-12-02 Verfahren zur Herstellung eines Magnetkernes und ein nach diesem Verfahren hergestellter Magnetkern
CH1350260A CH408226A (de) 1959-12-03 1960-12-02 Verfahren zur Herstellung eines Magnetkerns und nach dem Verfahren hergestellter Magnetkern
JP4727960A JPS3716779B1 (de) 1959-12-03 1960-12-02
CH408565A CH421215A (de) 1959-12-03 1960-12-02 Verfahren zur Herstellung eines keramischen Isolationsmaterials sowie Anwendung des Verfahrens
BE597724A BE597724A (fr) 1959-12-03 1960-12-02 Noyaux magnétiques et procédés pour leur obtention
ES0263399A ES263399A1 (es) 1959-12-03 1960-12-02 Procedimiento de fabricaciën de nucleos megneticos
DK524461A DK108803C (da) 1959-12-03 1960-12-03 Fremgangsmåde til fremstilling af en magnetkerne.
DK482460A DK104143C (da) 1959-12-03 1960-12-03 Fremgangsmåde til fremstilling af en magnetkerne.
US105836A US3132952A (en) 1959-12-03 1961-02-27 Ceramic composition comprising an alkali metal silicate, oil vapor, and and alkali metal aluminate

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US857087A US3014825A (en) 1959-12-03 1959-12-03 Magnetic cores and methods of making the same

Publications (1)

Publication Number Publication Date
US3014825A true US3014825A (en) 1961-12-26

Family

ID=25325150

Family Applications (1)

Application Number Title Priority Date Filing Date
US857087A Expired - Lifetime US3014825A (en) 1959-12-03 1959-12-03 Magnetic cores and methods of making the same

Country Status (4)

Country Link
US (1) US3014825A (de)
JP (1) JPS3716779B1 (de)
CH (2) CH408226A (de)
GB (1) GB962631A (de)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3523881A (en) * 1966-09-01 1970-08-11 Gen Electric Insulating coating and method of making the same
US4158580A (en) * 1978-04-14 1979-06-19 Westinghouse Electric Corp. Method of making pressed magnetic core components
US4265681A (en) * 1978-04-14 1981-05-05 Westinghouse Electric Corp. Method of producing low loss pressed magnetic cores from microlaminations
US4486641A (en) 1981-12-21 1984-12-04 Ruffini Robert S Inductor, coating and method
US5418811A (en) * 1992-04-08 1995-05-23 Fluxtrol Manufacturing, Inc. High performance induction melting coil
US5470399A (en) * 1993-06-30 1995-11-28 Samsung Electro-Mechanics Co., Ltd. Process for manufacturing MPP core forming powder, and process for manufacturing MPP core using the powder
US20070203051A1 (en) * 2004-04-21 2007-08-30 Hildmar Vidarsson Method For Making Compacted Products And Iron-Base Powder Comprising Lubricant
US20080019859A1 (en) * 2004-06-23 2008-01-24 Hilmar Vidarsson Lubricants For Insulated Soft Magnetic Iron-Based Powder Compositions
CN109453774A (zh) * 2018-10-16 2019-03-12 华东师范大学 一种镍系双金属纳米材料的制备方法及其电催化应用

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531445A (en) * 1945-11-23 1950-11-28 Int Standard Electric Corp Manufacture of magnetic bodies from compressed powdered materials
US2744040A (en) * 1952-03-25 1956-05-01 Gen Aniline & Film Corp Process of preparing iron powder for magnetic cores
US2827384A (en) * 1954-07-01 1958-03-18 Philadelphia Quartz Co Waterproof coatings and adhesives
US2919996A (en) * 1957-04-26 1960-01-05 Montedison Spa Aqueous dispersions of high molecular weight fibrils of amorphous silicates

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2531445A (en) * 1945-11-23 1950-11-28 Int Standard Electric Corp Manufacture of magnetic bodies from compressed powdered materials
US2744040A (en) * 1952-03-25 1956-05-01 Gen Aniline & Film Corp Process of preparing iron powder for magnetic cores
US2827384A (en) * 1954-07-01 1958-03-18 Philadelphia Quartz Co Waterproof coatings and adhesives
US2919996A (en) * 1957-04-26 1960-01-05 Montedison Spa Aqueous dispersions of high molecular weight fibrils of amorphous silicates

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3523881A (en) * 1966-09-01 1970-08-11 Gen Electric Insulating coating and method of making the same
US4158580A (en) * 1978-04-14 1979-06-19 Westinghouse Electric Corp. Method of making pressed magnetic core components
US4265681A (en) * 1978-04-14 1981-05-05 Westinghouse Electric Corp. Method of producing low loss pressed magnetic cores from microlaminations
US4486641A (en) 1981-12-21 1984-12-04 Ruffini Robert S Inductor, coating and method
US5588019A (en) * 1992-04-08 1996-12-24 Fluxtrol Manufacturing, Inc. High performance induction melting coil
US5418811A (en) * 1992-04-08 1995-05-23 Fluxtrol Manufacturing, Inc. High performance induction melting coil
US5470399A (en) * 1993-06-30 1995-11-28 Samsung Electro-Mechanics Co., Ltd. Process for manufacturing MPP core forming powder, and process for manufacturing MPP core using the powder
US20070203051A1 (en) * 2004-04-21 2007-08-30 Hildmar Vidarsson Method For Making Compacted Products And Iron-Base Powder Comprising Lubricant
US7758804B2 (en) 2004-04-21 2010-07-20 Höganäs Ab Method for making compacted products and iron-based powder comprising lubricant
US20100186551A1 (en) * 2004-04-21 2010-07-29 Hoganas Ab Coarse Iron or Iron-Based Powder Composition Containing Specific Lubricant
US7871453B2 (en) 2004-04-21 2011-01-18 Höganäs Ab Coarse iron or iron-based powder composition containing specific lubricant
US20080019859A1 (en) * 2004-06-23 2008-01-24 Hilmar Vidarsson Lubricants For Insulated Soft Magnetic Iron-Based Powder Compositions
US7718082B2 (en) * 2004-06-23 2010-05-18 Höganäs Ab Lubricants for insulated soft magnetic iron-based powder compositions
CN109453774A (zh) * 2018-10-16 2019-03-12 华东师范大学 一种镍系双金属纳米材料的制备方法及其电催化应用
CN109453774B (zh) * 2018-10-16 2021-05-25 华东师范大学 一种镍系双金属纳米材料的制备方法及其电催化应用

Also Published As

Publication number Publication date
CH421215A (de) 1966-09-30
CH408226A (de) 1966-02-28
GB962631A (en) 1964-07-01
JPS3716779B1 (de) 1962-10-18

Similar Documents

Publication Publication Date Title
US2484214A (en) Method of making magnetic cores
US2601212A (en) Heat resistant magnetic cores and method of making
US3014825A (en) Magnetic cores and methods of making the same
US1924311A (en) Insulating material
US2796364A (en) Method of forming an adherent film of magnesium oxide
US2977263A (en) Magnetic cores and methods of making the same
US2214876A (en) Method of fabricating electrolytic capacitor
US2858235A (en) Method of coating
US1292206A (en) Magnet-core.
US3132952A (en) Ceramic composition comprising an alkali metal silicate, oil vapor, and and alkali metal aluminate
US2999777A (en) Antimonide coated magnetic materials
US3241008A (en) Formation of electrode
US1991143A (en) Production of finely divided magnetic bodies
KR101620032B1 (ko) 내열 산화물절연막이 형성된 FeSiAl 연자성복합체 분말 및 이를 이용한 분말 코아
US2139529A (en) Process of treating palladium
US1297127A (en) Magnet-core.
US1383703A (en) Method of insulating metal particles
US1829635A (en) Method of making alloys
USRE20507E (en) Magnetic material
JPS61222207A (ja) 鉄心の製造方法
US1669643A (en) Magnetic material
US3180809A (en) Tantalum capacitor manufacture
JP2000223308A (ja) 被覆を有する軟磁性粉末およびこの粉末から製造した磁芯
US1855562A (en) Method of insulating bodies
US1714683A (en) Electrical insulation