EP0931322A1 - Soft magnetic, deformable composite material and process for producing the same - Google Patents

Soft magnetic, deformable composite material and process for producing the same

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Publication number
EP0931322A1
EP0931322A1 EP98948761A EP98948761A EP0931322A1 EP 0931322 A1 EP0931322 A1 EP 0931322A1 EP 98948761 A EP98948761 A EP 98948761A EP 98948761 A EP98948761 A EP 98948761A EP 0931322 A1 EP0931322 A1 EP 0931322A1
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EP
European Patent Office
Prior art keywords
composite material
compound
material according
soft magnetic
silicon
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EP98948761A
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German (de)
French (fr)
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EP0931322B1 (en
Inventor
Wilfried Aichele
Hans-Peter Koch
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Robert Bosch GmbH
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Robert Bosch GmbH
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Priority to EP00119956A priority Critical patent/EP1061534A3/en
Publication of EP0931322A1 publication Critical patent/EP0931322A1/en
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Publication of EP0931322B1 publication Critical patent/EP0931322B1/en
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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
    • H01F1/26—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 by macromolecular organic 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
    • H01F41/0206—Manufacturing of magnetic cores by mechanical means
    • H01F41/0246—Manufacturing of magnetic circuits by moulding or by pressing powder

Definitions

  • the invention relates to a soft-magnetic, mouldable composite material which contains powders which have soft-magnetic properties and have a non-magnetic coating according to independent claims 1, 5, 13 and 16, and to a method for producing the same according to independent claims 19 and 23.
  • Soft magnetic materials are required for the manufacture of temperature, corrosion and solvent resistant magnetic components in the electronics sector and especially in electromechanics. These soft magnetic components require certain properties: they should have a high permeability (Umax '' e: Lne high magnetic saturation (B s ), a low coercive field strength (H c ) and a high specific electrical resistance (p S p e z ' The combination of these magnetic properties with a high specific electrical resistance results in high switching dynamics, ie the magnetic saturation and demagnetization of such a component take place within a short time. So far, for example, soft iron sheets have been glued to form lamellar packets in order to serve as an anchor for electric motors. However, the layer insulation only works in one direction.
  • thermosetting resins for example epoxies or phenol resins
  • thermosetting resins for example epoxies or phenol resins
  • soft magnetic powder grains By coating soft magnetic powder grains with a non-magnetic thermoplastic compound, it is possible to increase the proportion of soft magnetic powder in the composite material in an advantageous manner and to achieve good temperature and solvent resistance of the molded part produced therefrom by using stable thermoplastic compounds.
  • Coating the soft magnetic powder with compounds of boron or aluminum, which merge into corresponding ceramics during pyrolysis, is a further preferred possibility of increasing the solvent resistance and the temperature resistance of the soft magnetic composite material and the molded parts produced therefrom.
  • thermoplastic connection is made from a solution onto the powder grains upset.
  • the powder grains are introduced into the polymer solution and the solvent is drawn off with constant movement of the powder at elevated temperature or in vacuo.
  • the powder grains are given a thin polymer coating in a simple manner, so that complicated process processes are eliminated.
  • the temperature after shaping the material is advantageously chosen such that the coating material turns into a ceramic , metallic or even intermetallic end product, whereby a high magnetization and a temperature and solvent resistance is achieved.
  • Silicon compounds selected from the group consisting of binary hydrogen compounds of silicon, polydialkylsilanes, carbosilanes, polysilazanes, alkoxyalkylsilanes, alkylpolysiloxanes, alkylsilanols and compounds of alkylsilanols with elements of the first main group are particularly preferably used as the coating material.
  • the corresponding ceramic can be used Influence on the magnetic field strength and the switching time of the soft magnetic connections can be selected. It is also possible to select the temperature range for the application accordingly.
  • boron compounds selected from the group consisting of borazole, pyridine or other ⁇ -donor-borane adducts, for example borane-phosphine, borane-phosphinite, borane-sulfur or borane-nitrogen adducts, borosilazanes and polyborazanes, can be used to coat the soft magnetic powder are used so that various boron-containing ceramics can be made available in a simple manner after the thermolysis
  • a polyazalan as the aluminum precursor compound, which can be used in very small quantities of 0.2-2% by weight, based on the total weight.
  • Aluminum-nitrogen ceramics are thus produced as a coating for the soft magnetic powder, the proportion by weight of the soft magnetic powder being particularly high.
  • PPA polyphthalamide
  • NMP N-methylpyrrolidone
  • Thermoplastics with a high heat resistance have one essential advantage compared to low-melting thermoplastics less cold flow.
  • a mixture of magnetic powder with small proportions of thermoplastic powders is pressed, a sufficient insulation layer is created around the magnetic particles only with ductile thermoplastic powders.
  • high-melting thermoplastics are not commercially available as powders with the necessary small grain size of ⁇ 5 micrometers. Both difficulties are avoided by the invention in that the magnetic powder is coated with a polymer solution before the axial pressing. If the solubility of the polymer is only given at a higher temperature, the dissolving of the polymer and the coating of the magnetic powder must take place under protective gas in order to avoid thermooxidative damage to the thermoplastic material.
  • the cold pressing of the coated magnetic powder is followed by a heat treatment of the compact under protective gas above the melting point of the polymer (PPA, 320 ° C).
  • the samples obtained have a strength of approx. 80 N / mm 2 and a specific electrical resistance of at least 400 ⁇ Ohm * m.
  • a better demoldability of the pressed components from the molding press is achieved by surface treatment of the coated powder with a lubricant.
  • the lubricant is added in a substantially smaller proportion than the thermoplastic coating in order to reduce the density of the pressed parts as little as possible and it should be so volatile that it volatilizes before the polymer melts during the subsequent heat treatment and does not with the polymer reacts chemically.
  • suitable lubricants are, for example, punching oils, such as those used for punching sheet metal, or rapeseed oil methyl ester and stearic acid amide in additions of about 0.2%, based on the weight of the magnetic powder.
  • the inorganic, or silicon, boron and organoaluminum compounds used for coating the soft magnetic powders with a predominantly polymeric character have good sliding or lubricating properties. After hardening, they thus represent a thermosetting binder, which is converted into a ceramic or into alloy additives for ferrous metals by subsequent thermal decomposition (pyrolysis). In connection with oxidation-sensitive magnetic materials, such as pure iron or pure nickel, the pyrolysis takes place under protective gas. In order to obtain composite bodies with a low proportion of pores, the pyrolysis must occur. de Volume loss should be low, which is guaranteed by the connections used.
  • silicon-hydrogen compounds silicon hydrides
  • Silicon hydrides with multiple Si atoms can be melted and thus also serve as lubricants for the coated magnetic powders. Depending on the hydride used, they decompose into Si and H 2 at higher temperatures. When the temperature increases further, the Si alloys in a surface layer, for example with pure iron powder. The Fe-Si alloy layer has a higher electrical resistance and a lower melting point than pure iron. The iron powder particles coated with Fe-Si sinter together to form composites with a higher electrical resistance than pure iron. An alternative to this is the deposition of high-purity silicon on iron powder particles by thermal decomposition of SiH 4 . The method is common in semiconductor manufacturing for the build-up of silicon layers and in the tempering of glasses. Low molecular weight silicon hydrides are self-igniting, so that all process steps take place under protective gas.
  • a silicon carbide ceramic according to the invention is produced, for example, by pyrolysis of polydialkylsilanes. In connection with powders from the range of ferrous metals, the elimination of carbon-containing compounds leads to carburization during pyrolysis. The carbon content is then extracted from the metal again by means of annealing treatments in a hydrogen-containing atmosphere.
  • Precursor compounds for BN ceramics as coating material are pyrolyzed under an ammonia atmosphere.
  • RCP Cubbon RAPRA Review Report No. 76, Polymeric Precursors for Ceramic Materials, Vol. 7, No. 4, 1994.
  • Borazol (B3N3Hg) which has proven to be particularly suitable for soft magnetic composites with a ceramic coating cleaving off under reduced pressure already at 90 ° CH 2 and passes into an analog to polyphenylene polymer.
  • the elimination of H 2 continues until the hexagonal modification of BN is reached at approx. 750 ° C.
  • the pyrolysis takes place only under protective gas, for example argon or nitrogen, and not in an ammonia atmosphere.
  • the resulting slight weight loss of 5.1% results in low shrinkage and thus a small pore volume in the combination of BN and the magnetic powder.
  • Polyazalane has proven to be a suitable starting material for coating magnetic powders with an aluminum nitride ceramic. These were synthesized by thermal condensation of diisobutyl aluminum hydride with unsaturated nitriles, which leads to curable liquid polyazalanes. This was used to coat the magnetic powders.
  • the polyazalanes serve simultaneously as a thermosetting lubricant and binder which, after subsequent pyrolysis, crosslinks to a non-melting solid at 200 ° C. and, in the next process step, completely pyrolyzes to AlN under an inert atmosphere.
  • Carbosilanes and polysilazanes have proven to be a suitable starting material for coating magnetic powders with a silicon nitride ceramic.
  • Silicon nitride Si3N 4 is formed by pyrolysis of these compounds in an ammonia atmosphere. The pyrolysis under protective gas produced a coating with silicon carbonitrides of the formula SiN x C v .
  • Glasses, enamels and glazes represent combinations of metal and non-metal oxides of different compositions.
  • One embodiment for the production of glass-like coatings of soft magnetic powders is the use of silanes with several silanol groups, which are added form water from water with elimination of alcohol.
  • the product NH 2100 manufactured by Hüls is a not yet fully cross-linked, soluble and meltable poly condensate of trimethoxymethylsilane (CH 3 Si (OCH 3 ) 3 ) ⁇ and is an excellent precursor material for a glass-like coating of magnetic powders.
  • the electrical resistance drops to 5 ⁇ m (pure iron has 0.1 ⁇ m), while the bending strength increases to 80 N / mm 2 .
  • the iron-iron sintered bridges and the strength increase, while the specific electrical resistance continues to decrease.
  • the corresponding glasses or enamels are formed by adding further compounds which can be converted into glass-forming oxides. Their composition is selected with a view to good adhesion to the magnetic powder.
  • An addition of aluminum stearate serves both as a lubricant Demolding from the press tool and after its thermal decomposition to A1 2 0 3 as a glass former.
  • phosphated iron powder (AB 100.32, Höganäs) is wetted in a kneader with a solution of 2.4 g of methylpolysiloxane prepolymer (NH 2100, Nünchritz chemical plant) in acetone. After adding a solution of 46.3 g sodium trimethylsilanolate in acetone, a gel coat forms around the iron particles. After the acetone has been evaporated in a kneader, 5 g of aluminum tristearate are added and this is melted at 140 ° C. while kneading. The aluminum tristearate often acts as a slip and mold release agent during the subsequent axial pressing of the composite.
  • the methylpolysiloxane prepolymer When the compacts are heated to 200 ° C under protective gas, the methylpolysiloxane prepolymer initially hardens. With further increase in temperature to 800 ° C to pyrolyze and melt all products used about 40 grams of a glass having the approximate com- position 27 g Si0 2, 12.8 g of Na 2 0 and 0.3 g A1 2 0 3.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Manufacturing & Machinery (AREA)
  • Soft Magnetic Materials (AREA)
  • Powder Metallurgy (AREA)

Abstract

A soft magnetic, deformable composite material consists of a powder whose grains are coated with non-magnetic thermoplastic compounds, molecular ceramic precursors or intermetallic compounds, such that the magnetic properties of the soft magnetic composite material can be adjusted. Also disclosed is a process for producing such a coated, soft magnetic, deformable composite material which can then be moulded into shaped parts.

Description

Weichmagnetischer, formbarer Verbundwerkstoff und Verfahren zu dessen HerstellungSoft magnetic, mouldable composite material and process for its production
Stand der TechnikState of the art
Die Erfindung betrifft einen weichmagnetischen, formbaren Verbundwerkstoff, der weichmagnetische Eigenschaften aufweisende Pulver enthält, die eine nichtmagnetische Beschichtung aufweisen nach den unabhängigen Ansprüchen 1, 5, 13 und 16, sowie ein Verfahren zu dessen Herstellung nach den unabhängigen Ansprüchen 19 und 23.The invention relates to a soft-magnetic, mouldable composite material which contains powders which have soft-magnetic properties and have a non-magnetic coating according to independent claims 1, 5, 13 and 16, and to a method for producing the same according to independent claims 19 and 23.
Weichmagnetischen Werkstoffe werden zur Herstellung von tem- peratur-, korrosions- und lösungsmittelbeständigen magneti- sehen Bauteilen im Elektroniksektor und insbesondere in der Elektromechanik benötigt. Dabei bedürfen diese weichmagnetischen Bauteile gewisser Eigenschaften: sie sollen eine hohe Permeabilität (Umax' ' e:Lne hohe magnetische Sättigung (Bs) , eine geringe Koerzitivfeidstärke (Hc) und einen hohen spezi- fischen elektrischen Widerstand (pSpez' aufweisen. Die Kombination dieser magnetischen Eigenschaften mit einem hohen spezifischen elektrischen Widerstand ergibt eine hohe Schaltdynamik, das heißt, die magnetische Sättigung und die Entmagnetisierung eines derartigen Bauteiles erfolgen inner- halb kurzer Zeit. Bislang werden beispielweise Weicheisenbleche zu Lamellenpaketen verklebt, um als Anker von Elektromotoren zu dienen. Die Lagenisolation wirkt jedoch nur in einer Richtung. Aus dem EP 0 540 504 Bl ist bekannt, weichmagne ische Pulvern mit einem Kunststoffbinder aufzubereiten und damit durch ein Spritzgußverfahren entsprechende Bauteile herzustellen. Um die für das Spritzgießen notwendige Fließfähigkeit zu gewährleisten, sind die Pulveranteile in spritzgießfähigen Verbundwerkstoffen auf maximal 65 Vol.-% begrenzt. Demgegenüber erfolgt beispielsweise bei axialem Verpressen die Verdichtung von rieselfähigen Pulvern nahezu ohne Materialfluß. Die Füllgrade dieser Verbundwerkstoffe liegen typischerweise bei 90-98 Vol.-%. Die durch axiales Verpressen von Pulvern geformten Bauteile zeichnen sich im Vergleich zu spritzgegossenen deshalb durch wesentlich höhere Permeabilitäten und höhere magnetische Feldstärken im Sättigungsbereich aus. Axiales Verpressen von Pulvern aus Reineisen oder Eisen- Nickel mit Duroplastharzen, beispielweise Epoxiden oder Phe- nolharzen hat jedoch den Nachteil, daß die bislang verwendeten thermoplastischen und duroplastischen Bindemittel bei erhöhter Temperatur in organischen Lösungsmitteln, beispielsweise Kraftstoffen für Verbrennungsmotoren, löslich sind, beziehungsweise stark aufquellen. Die entsprechenden Verbundbauteile ändern unter diesen Bedingungen ihre Abmessungen, verlieren ihre Festigkeit und versagen gänzlich. Es war bislang nicht möglich, entsprechende Verbundwerkstoffe mit hoher Temperatur- und Medienbeständigkeit, beispielsweise in organischen Lösungsmitteln, insbesondere Kraftstoffen für Verbrennungsmotoren, herzustellen. Ein weiteres Problem stellten bislang diejenigen Einsatzbedingungen dieser Bauteile dar, unter denen sowohl Thermoplaste als auch Duroplaste kein geeignetes Bindemittel mehr darstellen, da sie sich sonst vollständig zersetzen würden. In dem Artikel von H. P. Baldus und M. Jansen in: "Angewandte Chemie 1997, 109, Seite 338-394", werden moderne Hochleistungskeramiken beschrieben, die aus molekularen Vorläufern durch Pyrolyse gebildet werden und teilweise eben- falls magnetische Eigenschaften aufweisen. Diese Keramiken sind äußerst temperatur- und lösungsmittelstabil.Soft magnetic materials are required for the manufacture of temperature, corrosion and solvent resistant magnetic components in the electronics sector and especially in electromechanics. These soft magnetic components require certain properties: they should have a high permeability (Umax '' e: Lne high magnetic saturation (B s ), a low coercive field strength (H c ) and a high specific electrical resistance (p S p e z ' The combination of these magnetic properties with a high specific electrical resistance results in high switching dynamics, ie the magnetic saturation and demagnetization of such a component take place within a short time. So far, for example, soft iron sheets have been glued to form lamellar packets in order to serve as an anchor for electric motors. However, the layer insulation only works in one direction. It is known from EP 0 540 504 B1 to prepare soft magnetic powders with a plastic binder and thus to produce corresponding components by means of an injection molding process. In order to ensure the flowability required for injection molding, the powder content in injection-molded composite materials is limited to a maximum of 65% by volume. In contrast, for example, in the case of axial pressing, free-flowing powders are compacted with almost no material flow. The fill levels of these composite materials are typically 90-98% by volume. Compared to injection molded parts, the components formed by the axial pressing of powders are characterized by significantly higher permeabilities and higher magnetic field strengths in the saturation range. Axial pressing of pure iron or iron-nickel powders with thermosetting resins, for example epoxies or phenol resins, has the disadvantage, however, that the thermoplastic and thermosetting binders used hitherto are soluble in organic solvents, for example fuels for internal combustion engines, or swell strongly . Under these conditions, the corresponding composite components change their dimensions, lose their strength and fail completely. Until now, it has not been possible to produce corresponding composite materials with high temperature and media resistance, for example in organic solvents, in particular fuels for internal combustion engines. A further problem has so far been the operating conditions of these components under which both thermoplastics and thermosets are no longer a suitable binder, since they would otherwise decompose completely. In the article by HP Baldus and M. Jansen in: "Angewandte Chemie 1997, 109, pages 338-394", modern high-performance ceramics are described which are formed from molecular precursors by pyrolysis and in some cases also have magnetic properties. These ceramics are extremely temperature and solvent stable.
Vorteile der ErfindungAdvantages of the invention
Durch die Beschichtung von weichmagnetischen Pulverkörnern mit einer nichtmagnetischen thermoplastischen Verbindung ist es möglich, in vorteilhafter Weise den Anteil des Weichmagnetpulvers im Verbundwerkstoff zu erhöhen, und durch die Verwendung von stabilen thermoplastischen Verbindungen eine gute Temperatur- und Lösemittelbeständigkeit des daraus hergestellten Formteiles zu erzielen.By coating soft magnetic powder grains with a non-magnetic thermoplastic compound, it is possible to increase the proportion of soft magnetic powder in the composite material in an advantageous manner and to achieve good temperature and solvent resistance of the molded part produced therefrom by using stable thermoplastic compounds.
Es ist ebenso besonders vorteilhaft, ein weichmagne ische Eigenschaf en aufweisendes Pulver mit einer siliziumhaltigen Verbindung zu beschichten, die bei Pyrolyse in eine silizi- umhaltige Keramik übergeht, wodurch die Koerzitivfeidstärke erhöht wird und die Temperaturstabilität eines aus diesem Verbundwerkstoff hergestellten Formteils entscheidend erhöht wird.It is also particularly advantageous to coat a powder which has soft magnetic properties with a silicon-containing compound which, upon pyrolysis, changes into a silicon-containing ceramic, which increases the coercive force and increases the temperature stability of a molded part produced from this composite material.
Beschichten des Weichmagnetpulvers mit Verbindungen des Bors, beziehungsweise des Aluminiums, die bei Pyrolyse in entsprechende Keramiken übergehen ist eine weitere bevorzugte Möglichkeit, die Lösemittelbeständigkeit und die Tempera- turbeständigkeit des weichmagnetischen Verbundwerkstoffes und der daraus hergestellten Formteile zu erhöhen.Coating the soft magnetic powder with compounds of boron or aluminum, which merge into corresponding ceramics during pyrolysis, is a further preferred possibility of increasing the solvent resistance and the temperature resistance of the soft magnetic composite material and the molded parts produced therefrom.
In einem vorteilhaf es Verfahren zur Herstellung eines weichmagnetischen Verbundwerkstoffes, wird eine thermopla- stische Verbindung aus einer Lösung auf die Pulverkörner aufgebracht. Dabei werden die Pulverkörner in die Polymerlösung eingebracht und das Lösungsmittel unter staändiger Bewegung des Pulvers bei erhöhter Temperatur oder im Vakuum abgezogen. Dadurch erhalten die Pulverkörner auf einfache Weise einen dünnen Polymerüberzug („coating"), so daß komplizierte Verfahrensprozesse entfallen.In an advantageous method for producing a soft magnetic composite material, a thermoplastic connection is made from a solution onto the powder grains upset. The powder grains are introduced into the polymer solution and the solvent is drawn off with constant movement of the powder at elevated temperature or in vacuo. As a result, the powder grains are given a thin polymer coating in a simple manner, so that complicated process processes are eliminated.
Bei einer Beschichtung mit einem Material aus einer Vorläuferkeramik, auch „Precursorkeramik" genannt, welches entwe- der Silicium, Aluminium oder Bor als Hauptbestandteile enthält, wird die Temperatur nach einer Formgebung des Materials vorteilhafterweise so gewählt, daß sich das Beschich- tungsmaterial in ein keramisches, metallisches oder sogar intermetallisches Endprodukt umwandelt, wobei eine hohe Ma- gnetisierung und eine Temperatur- und Lösemittelbeständigkeit erzielt wird.In the case of a coating with a material made from a precursor ceramic, also called “precursor ceramic”, which contains either silicon, aluminum or boron as the main constituents, the temperature after shaping the material is advantageously chosen such that the coating material turns into a ceramic , metallic or even intermetallic end product, whereby a high magnetization and a temperature and solvent resistance is achieved.
Weitere vorteilhafte Ausgestaltungen und Weiterbildungen der Erfindung sind in den Unteransprüchen aufgeführt.Further advantageous refinements and developments of the invention are listed in the subclaims.
In besonders bevorzugter Weise werden als Beschichtungsmate- rial Siliziumverbindungen ausgewählt aus der Gruppe bestehend aus binären Wasserstoffverbindungen des Siliziums, Po- lydialkylsilanen, Carbosilanen, Polysilazanen, Alkoxyalkyl- silanen, Alkylpolysiloxanen, Alkylsilanolen und Verbindungen von Alkylsilanolen mit Elementen der ersten Hauptgruppe verwendet. Damit ist gewährleistet, daß eine breite Verbindungsklasse von molekularen Vorläuferverbindungen des Siliziums eingesetzt werden kann, welches bei Pyrolyse zu ver- schiedenen Keramiken, sowohl auf Silizium-Sauerstoffbasis, beziehungsweise ebenso auf Silizium-Stickstoff oder Silizium-Stickstoff-Sauerstoff-Basis zur Verfügung gestellt werden können und je nach erwünschtem Anforderungsprofil optimiert sind. Entsprechend den Anwendungen des herzustellenden Bau- teiles kann so die entsprechende Keramik, die auch einen Einfluß auf die magnetische Feldstärke und die Schaltzeit der weichmagnetischen Verbindungen hat, gewählt werden. Ebenso ist es dadurch möglich, den Temperaturbereich für die Anwendung entsprechend zu wählen.Silicon compounds selected from the group consisting of binary hydrogen compounds of silicon, polydialkylsilanes, carbosilanes, polysilazanes, alkoxyalkylsilanes, alkylpolysiloxanes, alkylsilanols and compounds of alkylsilanols with elements of the first main group are particularly preferably used as the coating material. This ensures that a wide class of molecular precursors of silicon can be used, which are made available for pyrolysis to various ceramics, both on a silicon-oxygen basis and also on a silicon-nitrogen or silicon-nitrogen-oxygen basis can and are optimized according to the desired requirement profile. Depending on the application of the component to be manufactured, the corresponding ceramic can be used Influence on the magnetic field strength and the switching time of the soft magnetic connections can be selected. It is also possible to select the temperature range for the application accordingly.
In ebenso bevorzugter Weise können zum Beschichten des Weichmagnetpulvers Borverbindungen ausgewählt aus der Gruppe bestehend aus Borazol, Pyridin- oder sonstige π-Donor- Boranaddukte, beispielsweise Boran-Phosphan, Boran- Phosphinit, Boran-Schwefel oder Boran-Stickstoff-Addukte, Borsilazane und Polyborazane eingesetzt werden, so daß in einfacher Weise nach der Thermolyse verschiedene Borhaltige Keramiken in einfacher Weise zur Verfügung gestellt werden könnenIn a likewise preferred manner, boron compounds selected from the group consisting of borazole, pyridine or other π-donor-borane adducts, for example borane-phosphine, borane-phosphinite, borane-sulfur or borane-nitrogen adducts, borosilazanes and polyborazanes, can be used to coat the soft magnetic powder are used so that various boron-containing ceramics can be made available in a simple manner after the thermolysis
Ebenso ist es bevorzugt möglich, ein Polyazalan als Alumini- umvorläuferverbindung zu verwenden, welches in Kleinstmengen von 0,2-2 Gew.%, bezogen auf die Gesamteinwaage, eingesetzt werden kann. Damit werden Aluminium-Stickstoff-Keramiken als Beschichtung für das weichmagnetische Pulver erzeugt, wobei der Gewichtsanteil des weichmagnetischen Pulvers besonders hoch ist.It is also preferably possible to use a polyazalan as the aluminum precursor compound, which can be used in very small quantities of 0.2-2% by weight, based on the total weight. Aluminum-nitrogen ceramics are thus produced as a coating for the soft magnetic powder, the proportion by weight of the soft magnetic powder being particularly high.
Ausführungsbeispieleembodiments
Im folgenden werden nachstehende Abkürzungen verwendet :The following abbreviations are used:
PPA: Polyphthalamid NMP: N-MethylpyrrolidonPPA: polyphthalamide NMP: N-methylpyrrolidone
1. Kraftstoffbeständige Thermoplaste mit hoher Wärmeformbeständigkeit .1. Fuel-resistant thermoplastics with high heat resistance.
Thermoplaste mit hoher Wärmeformbeständigkeit weisen im Ver- gleich zu niedrigschmelzenden Thermoplasten einen wesentlich geringeren kalten Fluß auf. Bei Verpressen eines Gemisches aus Magnetpulver mit geringen Anteilen an Thermoplastpulvern entsteht somit nur bei duktilen Thermoplastpulvern eine ausreichende Isolationsschicht um die Magnetteilchen. Darüber- hinaus sind hochschmelzende Thermoplaste nicht als Pulver mit der notwendigen geringen Korngröße von < 5 Mikrometer im Handel erhältlich. Beide Schwierigkeiten werden durch die Erfindung dadurch umgegangen, daß das Magnetpulver vor dem axialen Verpressen mit einer Polymerlösung ummantelt wird. Falls die Löslichkeit des Polymers nur bei höherer Temperatur gegeben ist, muß das Lösen des Polymers und das Beschichten des Magnetpulvers zur Vermeidung einer thermooxi- dativen Schädigung des Thermoplastmaterials unter Schutzgas stattfinden.Thermoplastics with a high heat resistance have one essential advantage compared to low-melting thermoplastics less cold flow. When a mixture of magnetic powder with small proportions of thermoplastic powders is pressed, a sufficient insulation layer is created around the magnetic particles only with ductile thermoplastic powders. In addition, high-melting thermoplastics are not commercially available as powders with the necessary small grain size of <5 micrometers. Both difficulties are avoided by the invention in that the magnetic powder is coated with a polymer solution before the axial pressing. If the solubility of the polymer is only given at a higher temperature, the dissolving of the polymer and the coating of the magnetic powder must take place under protective gas in order to avoid thermooxidative damage to the thermoplastic material.
Ausführungsbeispiel 1 :Example 1:
17,5 g eines handelsüblichen Granulates aus unverstärktem PPA (Amodel 1000 GR der Firma Amoco) wird grob aufgemahlen und in einem Sigma-Kneter mit 2500g ABM 100.3217.5 g of a commercial granulate made of unreinforced PPA (Amodel 1000 GR from Amoco) is roughly ground and in a Sigma kneader with 2500 g ABM 100.32
(oberflächenphosphatiertes Reineisenpulver der Firma Hö- ganäs) trockengemischt. Nach Zusatz von NMP wird so lange Stickstoff durch die Knetkammer geleitet, bis der Sauerstoff verdrängt ist. Anschließend wird der Stickstoffström abge- stellt und die Kammer auf 200°C (Siedepunkt NMP: 204 °C) aufgeheizt. Nach einer Knetdauer von ca. 1 h, welche abhängig von der Größe des Thermoplastmaterials ist, hat sich das PPA in NMP vollständig gelöst. Daraufhin wird das Lösungsmittel durch erneutes Durchleiten von Schutzgas durch die Knetkammer abgezogen und in einem Kühler wieder kondensiert, der Kneter abgekühlt und das mit PPA beschichtete Magnetpulver entnommen. Letzte Lösungsmittelreste lassen sich durch Vakuumtrocknen entfernen. An das kalte Verpressen des gecoateten Magnetpulvers schließt sich eine Wärmebehandlung des Preßlings unter Schutzgas über den Schmelzpunkt des Polymers hinaus (PPA, 320 °C) an. Die erhaltenen Proben weisen eine Festigkeit von ca. 80 N/mm2 und einen spezifischen elektrischen Widerstand von mindestens 400 μOhm*m auf. Eine bessere Entformbarkeit der verpreßten Bauteile aus der Formpresse erreicht man durch eine Oberflächenbehandlung des beschichteten Pulvers mit einem Gleitmittel. Das Gleitmittel wird in einen wesent- lieh geringeren Anteil als die Thermoplastbeschichtung zugegeben, um die Dichte der verpreßten Teile möglichst wenig zu verringern und es sollte derart flüchtig sein, daß es sich vor dem Aufschmelzen des Polymers bei der anschließenden Wärmebehandlung verflüchtigt und mit dem Polymer nicht che- misch reagiert. Beispiele für geeignete Gleitmittel sind beispielsweise Stanzöle, wie sie beim Stanzen von Blechen eingesetzt werden, oder Rapsölmethylester und Stearinsäurea- mid in Zusätzen von etwa 0.2% bezogen auf das Gewicht des Magnetpulvers .(surface-phosphated pure iron powder from Höganas) dry mixed. After adding NMP, nitrogen is passed through the kneading chamber until the oxygen is displaced. The nitrogen flow is then switched off and the chamber is heated to 200 ° C (boiling point NMP: 204 ° C). After a kneading time of approx. 1 h, which depends on the size of the thermoplastic material, the PPA has completely dissolved in NMP. The solvent is then drawn off by passing protective gas through the kneading chamber again and condensed again in a cooler, the kneader is cooled and the magnetic powder coated with PPA is removed. Last solvent residues can be removed by vacuum drying. The cold pressing of the coated magnetic powder is followed by a heat treatment of the compact under protective gas above the melting point of the polymer (PPA, 320 ° C). The samples obtained have a strength of approx. 80 N / mm 2 and a specific electrical resistance of at least 400 μOhm * m. A better demoldability of the pressed components from the molding press is achieved by surface treatment of the coated powder with a lubricant. The lubricant is added in a substantially smaller proportion than the thermoplastic coating in order to reduce the density of the pressed parts as little as possible and it should be so volatile that it volatilizes before the polymer melts during the subsequent heat treatment and does not with the polymer reacts chemically. Examples of suitable lubricants are, for example, punching oils, such as those used for punching sheet metal, or rapeseed oil methyl ester and stearic acid amide in additions of about 0.2%, based on the weight of the magnetic powder.
2. Verpressen von trockenen Gemischen aus Magnetpulver und anorganischen Pulvern2. Compressing dry mixtures of magnetic powder and inorganic powder
Die zum Beschichten der weichmagnetischen Pulver eingesetz- ten anorganischen, beziehungsweise Silizium-, bor und aluminiumorganischen Verbindungen mit vorwiegend polymeren Charakter weisen gute Gleit-, beziehungsweise Schmiereigenschaften auf. Nach der Aushärtung stellen sie somit ein duroplastisches Bindemittel dar, welches durch anschließende thermische Zersetzung (Pyrolyse) in eine Keramik oder in Legierungszusätze für Eisenmetalle umgewandelt wird. In Verbindung mit oxidationsempfindlichen magnetischen Materialien, wie beispielsweise Reineisen oder Reinnickel, erfolgt die Pyrolyse unter Schutzgas. Um Verbundkörper mit geringem Porenanteil zu erhalten, muß der bei der Pyrolyse auftreten- de Volumenschwund gering sein, was durch die eingesetzten Verbindungen gewährleistet ist. Ein Beispiel stellen Silizi- um-Wasserstoffverbindungen (Siliziumhydride) dar. Siliziumhydride mit mehren Si-Atomen sind schmelzbar und dienen so- mit zugleich als Gleitmittel für die beschichteten magnetischen Pulver. Sie zerfallen bei höheren Temperaturen je nach eingesetztem Hydrid in Si und H2. Bei weiterer Temperaturerhöhung legiert das Si in einer Oberflächenschicht, beispielsweise mit Reineisenpulver . Die Fe-Si-Legierungsschicht weist einen höheren elektrischen Widerstand und einen niedrigen Schmelzpunkt auf als Reineisen. Die mit Fe-Si beschichteten Eisenpulverteilchen sintern zu Verbundkörpern mit einem im Vergleich zu Reineisen höheren elektrischen Widerstand zusammen. Eine Alternative dazu ist die Abscheidung von Reinstsilizium auf Eisenpulverteilchen durch thermische Zersetzung von SiH4 . Das Verfahren ist bei der Halbleiterfertigung zum Aufbau von Siliziumschichten und beim Vergüten von Gläsern üblich. Niedermolekulare Siliziumhydride sind selbstentzündlich, so daß alle Verfahrensschritte unter Schutzgas erfolgen.The inorganic, or silicon, boron and organoaluminum compounds used for coating the soft magnetic powders with a predominantly polymeric character have good sliding or lubricating properties. After hardening, they thus represent a thermosetting binder, which is converted into a ceramic or into alloy additives for ferrous metals by subsequent thermal decomposition (pyrolysis). In connection with oxidation-sensitive magnetic materials, such as pure iron or pure nickel, the pyrolysis takes place under protective gas. In order to obtain composite bodies with a low proportion of pores, the pyrolysis must occur. de Volume loss should be low, which is guaranteed by the connections used. One example is silicon-hydrogen compounds (silicon hydrides). Silicon hydrides with multiple Si atoms can be melted and thus also serve as lubricants for the coated magnetic powders. Depending on the hydride used, they decompose into Si and H 2 at higher temperatures. When the temperature increases further, the Si alloys in a surface layer, for example with pure iron powder. The Fe-Si alloy layer has a higher electrical resistance and a lower melting point than pure iron. The iron powder particles coated with Fe-Si sinter together to form composites with a higher electrical resistance than pure iron. An alternative to this is the deposition of high-purity silicon on iron powder particles by thermal decomposition of SiH 4 . The method is common in semiconductor manufacturing for the build-up of silicon layers and in the tempering of glasses. Low molecular weight silicon hydrides are self-igniting, so that all process steps take place under protective gas.
Eine erfindungsgemäße Siliciumcarbidkeramik wird beispielsweise durch Pyrolyse von Polydialkylsilanen hergestellt. In Verbindung mit Pulvern aus der Reihe der Eisenmetalle führt die Abspaltung von kohlenstoffhaltigen Verbindungen bei der Pyrolyse zu Aufkohlen. Durch Glühbehandlungen in wasser- stoffhaltiger Atmosphäre wird anschließend dem Metall der Kohlenstoffanteil wieder entzogen.A silicon carbide ceramic according to the invention is produced, for example, by pyrolysis of polydialkylsilanes. In connection with powders from the range of ferrous metals, the elimination of carbon-containing compounds leads to carburization during pyrolysis. The carbon content is then extracted from the metal again by means of annealing treatments in a hydrogen-containing atmosphere.
Vorläuferverbindungen für BN-Keramiken als Beschichtungsma- terial werden unter Ammoniakatmosphäre pyrolysiert. (R.C.P. Cubbon, RAPRA Review Report Nr. 76, Polymeric Precursors for Ceramic Materials, Vol. 7, No. 4, 1994). Als besonders geeignet für weichmagnetische Verbundwerkstoffe mit einer ke- ramischen Beschichtung erwies sich Borazol (B3N3Hg) , welches unter vermindertem Druck bereits bei 90 °C H2 abspaltet und in ein zu Polyphenylen analoges Polymer übergeht. Bei höheren Temperaturen schreitet die Abspaltung von H2 fort, bis bei ca. 750 °C die Stufe der hexagonalen Modifikation von BN erreicht ist. In diesem besonderen Falle erfolgt die Pyrolyse lediglich unter Schutzgas, beispielsweise Argon oder Stickstoff, und nicht in Ammoniakatmosphäre. Der dabei auftretende geringe Gewichtsverlust von 5,1 % hat eine geringe Schwindung und damit ein geringes Porenvolumen im Verbund aus BN und dem Magnetpulver zur Folge.Precursor compounds for BN ceramics as coating material are pyrolyzed under an ammonia atmosphere. (RCP Cubbon, RAPRA Review Report No. 76, Polymeric Precursors for Ceramic Materials, Vol. 7, No. 4, 1994). Borazol (B3N3Hg), which has proven to be particularly suitable for soft magnetic composites with a ceramic coating cleaving off under reduced pressure already at 90 ° CH 2 and passes into an analog to polyphenylene polymer. At higher temperatures, the elimination of H 2 continues until the hexagonal modification of BN is reached at approx. 750 ° C. In this particular case, the pyrolysis takes place only under protective gas, for example argon or nitrogen, and not in an ammonia atmosphere. The resulting slight weight loss of 5.1% results in low shrinkage and thus a small pore volume in the combination of BN and the magnetic powder.
Als geeigneter Ausgangstoff für die Beschichtung von Magnet- pulvern mit einer Aluminiumnitrid-Keramik erwiesen sich Po- lyazalane. Diese wurden durch thermische Kondensation von Diisobutylaluminiumhydrid mit ungesättigten Nitrilen synthetisiert, was zu aushärtbarem flüssigen Polyazalanen führt. Damit wurden die magnetischen Pulver beschichtet. Die Polya- zalane dienen dabei gleichzeitig als duroplastisches Gleit und Bindemittel, welches nach sich anschließender Pyrolyse bei 200 °C zu einem nichtschmelzenden Feststoff vernetzt und in nächsten Verfahrensschritt vollständig unter inerter Atmosphäre zu AlN pyrolysiert.Polyazalane has proven to be a suitable starting material for coating magnetic powders with an aluminum nitride ceramic. These were synthesized by thermal condensation of diisobutyl aluminum hydride with unsaturated nitriles, which leads to curable liquid polyazalanes. This was used to coat the magnetic powders. The polyazalanes serve simultaneously as a thermosetting lubricant and binder which, after subsequent pyrolysis, crosslinks to a non-melting solid at 200 ° C. and, in the next process step, completely pyrolyzes to AlN under an inert atmosphere.
Als geeigneter Ausgangstoff für die Beschichtung von Magnet- pulvern mit einer Siliziumnitrid-Keramik erwiesen sich Car- bosilane und Polysilazane . Siliziumnitrid Si3N4 entsteht dabei durch Pyrolyse dieser Verbindungen in Ammoniakatmosphäre. Die Pyrolyse unter Schutzgas erbrachte eine Beschichtung mit Siliziumcarbonitriden der Formel SiNxCv.Carbosilanes and polysilazanes have proven to be a suitable starting material for coating magnetic powders with a silicon nitride ceramic. Silicon nitride Si3N 4 is formed by pyrolysis of these compounds in an ammonia atmosphere. The pyrolysis under protective gas produced a coating with silicon carbonitrides of the formula SiN x C v .
Gläser, Emails und Lasuren stellen Kombinationen von Metall- und Nichtmetalloxiden unterschiedlicher Zusammensetzung dar. Ein Ausführungsbeispiel zur Herstellung von glasartigen Beschichtungen von weichmagnetischen Pulvern ist die Verwen- düng von Silanen mit mehreren Silanolgruppen, die bei Zugabe von Wasser unter Abspaltung von Alkohol Polymere bilden. Das von der Fa. Hüls hergestellten Produkt NH 2100 ist ein noch nicht vollständig vernetztes, lösliches und schmelzbares Po- lykondensat des Trimethoxymethylsilan (CH3Si (OCH3) 3)χ und stellt ein ausgezeichnetes Vorläufermaterial für eine glasartige Beschichtung magnetischer Pulver dar. NH 2100 läßt sich unter Abspaltung von Wasser und Alkohol weiter kondensieren und geht bei einer anschließenden Pyrolyse mit einer keramischen Ausbeute von ca. 90 Gew.-% in ein Glas der Zusammensetzung SiOxCy (x = 1,9-2,1, y = 0,6-3,0) über.Glasses, enamels and glazes represent combinations of metal and non-metal oxides of different compositions. One embodiment for the production of glass-like coatings of soft magnetic powders is the use of silanes with several silanol groups, which are added form water from water with elimination of alcohol. The product NH 2100 manufactured by Hüls is a not yet fully cross-linked, soluble and meltable poly condensate of trimethoxymethylsilane (CH 3 Si (OCH 3 ) 3 ) χ and is an excellent precursor material for a glass-like coating of magnetic powders. NH 2100 can be further condensed with the elimination of water and alcohol and, during a subsequent pyrolysis, goes into a glass of the composition SiO x Cy (x = 1.9-2.1, y =) with a ceramic yield of approximately 90% by weight 0.6-3.0) above.
Ausführungsbeispiel 2 :Example 2:
99,9 Gew.-% Weicheisenpulver ABM 100,32 (oberflächen- phosphatiert, Fa. Höganäs) werden mit 0,6 Gew.-% NH 2100 ge- coatet, welches in einer Lösung in Aceton erfolgt. Bei Raumtemperatur wird diese Mischung unter 6 to/cm2 zu Probestäben verpreßt und das Harz bei 220 °C vernetzt. Die derart hergestellte Probe weist eine Festigkeit von 26 N/mm2 und einen spezifischen elektrischen Widerstand von 20000 μOhm auf. Das Polymer wird anschließend bei 700 °C unter Schutzgas pyroly- siert und geht in ein kohlenstoffhaltiges Glas SiOxCy über. Zusätzlich bilden sich erste Sinterhälse zwischen den Ξisen- teilchen. Dadurch sinkt der elektrische Widerstand auf 5 μΩm (Reineisen weist 0,1 μΩm auf), während die Biegefestigkeit auf 80 N/mm2 ansteigt. Bei weiterer Temperaturerhöhung nehmen die Eisen-Eisen-Sinterbrücken und die Festigkeit zu, während der spezifische elektrische Widerstand weiter abnimmt .99.9% by weight of soft iron powder ABM 100.32 (surface-phosphated, from Höganäs) are coated with 0.6% by weight of NH 2100, which is carried out in a solution in acetone. At room temperature, this mixture is pressed under 6 to / cm2 to test rods and the resin is crosslinked at 220 ° C. The sample produced in this way has a strength of 26 N / mm 2 and a specific electrical resistance of 20,000 μOhm. The polymer is then pyrolyzed under protective gas at 700 ° C and passes into a carbon-containing glass SiO x Cy. In addition, the first sinter necks form between the iron particles. As a result, the electrical resistance drops to 5 μΩm (pure iron has 0.1 μΩm), while the bending strength increases to 80 N / mm 2 . As the temperature increases further, the iron-iron sintered bridges and the strength increase, while the specific electrical resistance continues to decrease.
Durch Zusatz weiterer Verbindungen, welche sich in glasbildende Oxide überführen lassen, entstehen die entsprechenden Gläser oder Emails. Ihre Zusammensetzung wird im Hinblick auf eine gute Haftung am Magnetpulver ausgewählt. So dient ein Zusatz von Aluminiumstearat sowohl als Gleitmittel zur Entformung aus dem Preßwerkzeug als auch nach seiner thermischen Zersetzung zu A1203 als Glasbildner.The corresponding glasses or enamels are formed by adding further compounds which can be converted into glass-forming oxides. Their composition is selected with a view to good adhesion to the magnetic powder. An addition of aluminum stearate serves both as a lubricant Demolding from the press tool and after its thermal decomposition to A1 2 0 3 as a glass former.
Ausführungsbeispiel 3 :Example 3:
946,5 g phosphatiertes Eisenpulver (AB 100.32, Fa. Höganäs) wird im Kneter mit einer Lösung von 2,4 g Methylpolysiloxan- Präpolymer (NH 2100, Chemiewerk Nünchritz) in Aceton benetzt. Nach Zugabe einer Lösung von 46,3 g Natrium- Trimethylsilanolat in Aceton bildet sich ein Gelmantel um die Eisenpartikel. Nach dem Verdampfen des Acetons im Kneter wird 5 g Aluminiumtristearat zugesetzt und dieses unter Kneten bei 140 °C aufgeschmolzen. Das Aluminiumtristearat wirkt beim anschließenden axialen Verpressen des Verbundwerks of- fes als Gleit- und Formtrennmittel. Beim Erhitzen der Preßlinge unter Schutzgas auf 200 °C härtet das Methylpolysilox- an-Präpolymer zunächst aus. Bei weiterer Temperaturerhöhung auf 800°C pyrolysieren alle eingesetzten Produkte und schmelzen zu ca. 40 g eines Glases mit der ungefähren Zusam- mensetzung 27 g Si02, 12,8 g Na20 und 0,3 g A1203 auf. 946.5 g of phosphated iron powder (AB 100.32, Höganäs) is wetted in a kneader with a solution of 2.4 g of methylpolysiloxane prepolymer (NH 2100, Nünchritz chemical plant) in acetone. After adding a solution of 46.3 g sodium trimethylsilanolate in acetone, a gel coat forms around the iron particles. After the acetone has been evaporated in a kneader, 5 g of aluminum tristearate are added and this is melted at 140 ° C. while kneading. The aluminum tristearate often acts as a slip and mold release agent during the subsequent axial pressing of the composite. When the compacts are heated to 200 ° C under protective gas, the methylpolysiloxane prepolymer initially hardens. With further increase in temperature to 800 ° C to pyrolyze and melt all products used about 40 grams of a glass having the approximate com- position 27 g Si0 2, 12.8 g of Na 2 0 and 0.3 g A1 2 0 3.

Claims

Ansprüche Expectations
1. Weichmagnetischer, formbarer Verbundwerkstoff, bestehend aus einem weichmagne ische Eigenschaften aufweisenden Pulver und einer thermoplastischen Verbindung, dadurch gekennzeich- net, daß die Körner des Pulvers mit der nichtmagnetischen thermoplastischen Verbindung beschichtet sind.1. Soft magnetic, mouldable composite material, consisting of a powder having soft magnetic properties and a thermoplastic compound, characterized in that the grains of the powder are coated with the non-magnetic thermoplastic compound.
2. Verbundwerkstoff nach Anspruch 1, dadurch gekennzeichnet, daß die thermoplastische Verbindung gegenüber organischen aliphatischen Lösungsmitteln beständig ist.2. Composite material according to claim 1, characterized in that the thermoplastic compound is resistant to organic aliphatic solvents.
3. Verbundwerkstoff nach Anspruch 1 und 2, dadurch gekennzeichnet, daß die thermoplastische Verbindung eine Temperaturbeständigkeit bis 300 °C aufweist.3. Composite material according to claim 1 and 2, characterized in that the thermoplastic compound has a temperature resistance up to 300 ° C.
4. Verbundwerkstoff nach Anspruch 1 bis 3, dadurch gekennzeichnet, daß der Anteil der thermoplastischen Verbindung 0,2 bis 1 Gew.-%, vorzugsweise 0,3 bis 0,8 Gew.-%, bezogen auf die Gesamteinwaage, beträgt.4. Composite material according to claim 1 to 3, characterized in that the proportion of the thermoplastic compound is 0.2 to 1 wt .-%, preferably 0.3 to 0.8 wt .-%, based on the total weight.
5. Weichmagnetischer, formbarer Verbundwerkstoff, bestehend aus einem weichmagnetische Eigenschaften aufweisenden Pulver und mindestens einer Silizium enthaltenden Verbindung, dadurch gekennzeichnet, daß die Körner des Pulvers mit der Si- liziumverbindung beschichtet sind. 5. Soft magnetic, mouldable composite material, consisting of a powder having soft magnetic properties and at least one silicon-containing compound, characterized in that the grains of the powder are coated with the silicon compound.
6. Verbundwerkstoff nach Anspruch 5, dadurch gekennzeichnet, daß die Siliziumverbindung ausgewählt ist aus der Gruppe bestehend aus: Wasserstoffverbindungen des Siliziums, Poly- dialkylsilanen, Carbosilanen, Polysilazanen, Alkoxyalkylsi- lanen, Alkylpolysiloxanen, Alkylsilanolen und Verbindungen von Alkylsilanolen mit Elementen der ersten Hauptgruppe.6. Composite material according to claim 5, characterized in that the silicon compound is selected from the group consisting of: hydrogen compounds of silicon, poly-dialkylsilanes, carbosilanes, polysilazanes, alkoxyalkylsilanes, alkylpolysiloxanes, alkylsilanols and compounds of alkylsilanols with elements of the first main group.
7. Verbundwerkstoff nach Anspruch 6, dadurch gekennzeichnet, daß der Anteil der Siliziumverbindung 0,2 bis 6 Gew.-%, insbesondere 0,3 bis 1 Gew.-%, bezogen auf die Gesamteinwaage, beträgt .7. Composite material according to claim 6, characterized in that the proportion of the silicon compound is 0.2 to 6 wt .-%, in particular 0.3 to 1 wt .-%, based on the total weight.
8.Verbundwerkstoff nach Anspruch 5, dadurch gekennzeichnet, daß mindestens zwei Siliziumverbindungen ausgewählt aus der Gruppe, bestehend aus: Wasserstoffverbindungen des Siliziums, Chlorverbindungen des Siliziums, Silizium enthaltene Carbodiimide) , Polydialkylsilanen, Carbosilanen, Polysilazanen, Silazanen, Alkoxyalkylsilanen, Alkylpolysiloxanen, Al- kylsilanolen und Verbindungen von Alkylsilanolen mit Elementen der ersten Hauptgruppe in der Beschichtung enthalten sind.8.Composite material according to claim 5, characterized in that at least two silicon compounds selected from the group consisting of: hydrogen compounds of silicon, chlorine compounds of silicon, silicon-containing carbodiimides), polydialkylsilanes, carbosilanes, polysilazanes, silazanes, alkoxyalkylsilanes, alkylpolysiloxanes, alkylsilanols and compounds of alkylsilanols with elements of the first main group are contained in the coating.
9. Verbundwerkstoff nach Anspruch 8, dadurch gekennzeichnet, daß der Anteil der Siliziumverbindungen 0,2 bis 6 Gew.-%, insbesondere 0,3 bis 5 Gew.-%, bezogen auf die Gesamteinwaage, beträgt.9. Composite material according to claim 8, characterized in that the proportion of silicon compounds is 0.2 to 6 wt .-%, in particular 0.3 to 5 wt .-%, based on the total weight.
10. Verbundwerkstoff nach Anspruch 9, dadurch gekennzeich- net, daß das Gewichtsverhältnis der zwei Siliziumverbindungen zueinander 1 : 10 bis 1 : 25, insbesondere 1 : 15 bis10. Composite material according to claim 9, characterized in that the weight ratio of the two silicon compounds to one another 1:10 to 1:25, in particular 1:15 to
1 : 21, beträgt. 1:21.
11. Verbundwerkstoff nach Anspruch 6 oder 8, dadurch gekennzeichnet, daß zusätzlich mindestens eine organometallische oder organische Aluminiumverbindung enthalten ist.11. A composite material according to claim 6 or 8, characterized in that it additionally contains at least one organometallic or organic aluminum compound.
12. Verbundwerkstoff nach Anspruch 11, dadurch gekennzeichnet, daß der Anteil der Aluminiumverbindung 0,2 bis 2 Gew.-%, insbesondere 0,2 bis 0,9 Gew.-% beträgt.12. Composite material according to claim 11, characterized in that the proportion of the aluminum compound is 0.2 to 2 wt .-%, in particular 0.2 to 0.9 wt .-%.
13. Weichmagnetischer, rformbarer Verbundwerkstoff, beste- hend aus einem weichmagnetische Eigenschaften aufweisenden Pulver und mindestens einer Aluminium enthaltenen Verbindung, dadurch gekennzeichnet, daß die Körner des Pulvers mit der Aluminiumverbindung/ beschichtet sind.13. Soft magnetic, mouldable composite material consisting of a powder having soft magnetic properties and at least one compound containing aluminum, characterized in that the grains of the powder are coated with the aluminum compound / .
14. Verbundwerkstoff nach Anspruch 13, dadurch gekennzeichnet, daß die Aluminiumverbindung ein Polyazalan ist.14. The composite material according to claim 13, characterized in that the aluminum compound is a polyazalan.
15. Verbundwerkstoff nach Anspruch 14, dadurch gekennzeichnet, daß der Anteil an Polyazalan 0,2 bis 2 Gew.-%, bezogen auf die Gesamteinwaage, beträgt.15. Composite material according to claim 14, characterized in that the proportion of polyazalan is 0.2 to 2 wt .-%, based on the total weight.
16. Weichmagnetischer, formbarer Verbundwerkstoff, bestehend aus einem weichmagnetische Eigenschaften aufweisenden Pulver und mindestens einer Bor enthaltenen Verbindung, dadurch ge- kennzeichnet, daß die Körner des Pulvers mit der Borverbindung beschichtet sind.16. Soft magnetic, mouldable composite material, consisting of a powder having soft magnetic properties and at least one compound containing boron, characterized in that the grains of the powder are coated with the boron compound.
17. Verbundwerkstoff nach Anspruch 16, dadurch gekennzeichnet, daß die Borverbindung ausgewählt ist aus der Gruppe be- stehend aus Borazol, π-Donor-Boranaddukt , Borasilazan, Poly- borasilazane.17. Composite material according to claim 16, characterized in that the boron compound is selected from the group consisting of borazole, π-donor-borane adduct, borasilazane, polyborasilazanes.
18. Verbundwerkstoff nach Anspruch 16 und 17, dadurch gekennzeichnet, daß der Anteil an der Borverbindung 0,2 bis 2 Gew.-% , bezogen auf die Gesamteinwaage beträgt. 18. Composite material according to claim 16 and 17, characterized in that the proportion of the boron compound is 0.2 to 2 wt .-%, based on the total weight.
19. Verfahren zur Herstellung eines weichmagnetischen Verbundwerkstoffes nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die thermoplastische Verbindung aus ei- ner Lösung auf die Pulverkörner aufgebracht wird.19. A method for producing a soft magnetic composite material according to one of claims 1 to 4, characterized in that the thermoplastic compound is applied to the powder grains from a solution.
20. Verfahren nach Anspruch 19, dadurch gekennzeichnet, daß der beschichtete Verbundwerkstoff kalt formgepreßt wird.20. The method according to claim 19, characterized in that the coated composite material is cold pressed.
21. Verfahren nach Anspruch 20, dadurch gekennzeichnet, daß der Formpreßling thermisch behandelt wird.21. The method according to claim 20, characterized in that the molding is thermally treated.
22. Verfahren nach Anspruch 21, dadurch gekennzeichnet, daß die Temperatur über dem Schmelzpunkt der thermoplastischen Verbindung liegt.22. The method according to claim 21, characterized in that the temperature is above the melting point of the thermoplastic compound.
23. Verfahren zur Herstellung eines weichmagnetischen Verbundwerkstoffes nach einem der Ansprüche 5 bis 18, dadurch gekennzeichnet, daß nach einem Formpreßschritt der Formpreß- ling einer thermischen Behandlung unterworfen wird.23. A method for producing a soft magnetic composite material according to one of claims 5 to 18, characterized in that, after a compression molding step, the compression molding is subjected to a thermal treatment.
24. Verfahren nach Anspruch 23, dadurch gekennzeichnet, daß die Temperatur nach dem Formpreßschritt so gewählt wird, daß sich das Beschichtungsmaterial in ein keramisches oder me- tallisches oder intermetallisches Endprodukt umwandelt.24. The method according to claim 23, characterized in that the temperature after the compression step is selected so that the coating material is converted into a ceramic or metallic or intermetallic end product.
25. Verfahren zur Herstellung eines weichmagnetischen Verbundwerkstoffes nach einem der Ansprüche 11 und 12, dadurch gekennzeichnet, daß der Verbundwerkstoff vor der thermischen Behandlung einer ersten thermischen Behandlung unterworfen wird.25. A method for producing a soft magnetic composite material according to one of claims 11 and 12, characterized in that the composite material is subjected to a first thermal treatment before the thermal treatment.
26. Verfahren nach Anspruch 25, dadurch gekennzeichnet, daß die Temperatur der ersten thermischen Behandlung 100 bis 200 °C , insbesondere 120 bis 180 °C beträgt. 26. The method according to claim 25, characterized in that the temperature of the first thermal treatment is 100 to 200 ° C, in particular 120 to 180 ° C.
EP98948761A 1997-08-14 1998-08-11 Soft magnetic, deformable composite material and process for producing the same Expired - Lifetime EP0931322B1 (en)

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DE19735271A1 (en) 1999-02-25
EP1061534A2 (en) 2000-12-20
WO1999009565A1 (en) 1999-02-25
DE19735271C2 (en) 2000-05-04
EP0931322B1 (en) 2003-05-21
US6537389B1 (en) 2003-03-25
DE59808444D1 (en) 2003-06-26
JP2001504283A (en) 2001-03-27

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