Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
  • C22C33/0207—Using a mixture of prealloyed powders or a master alloy
  • C22C33/0228—Using a mixture of prealloyed powders or a master alloy comprising other non-metallic compounds or more than 5% of graphite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/16—Metallic particles coated with a non-metal
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
  • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
  • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
  • H01F1/12—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials
  • H01F1/14—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys
  • H01F1/20—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder
  • H01F1/22—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together
  • H01F1/24—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of soft-magnetic materials metals or alloys in the form of particles, e.g. powder pressed, sintered, or bound together the particles being insulated
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
  • Y10T428/2982—Particulate matter [e.g., sphere, flake, etc.]
  • Y10T428/2991—Coated
  • Y10T428/2993—Silicic or refractory material containing [e.g., tungsten oxide, glass, cement, etc.]

Definitions

• the invention relates to a metal powder composite material with high electrical resistivity and a starting material and a method for producing such a composite material.
• Metal powder composite materials with high electrical resistivity find technical application, for example as high-resistance steels and as soft magnetic components in high-speed solenoid valves.
• special metal powder-plastic composites have been developed. They are produced by techniques of powder metallurgy by pressing metal powder particles which are coated with electrically insulating plastic. The pressed metal powder particles are glued together over the plastic.
• These metal powder-plastic composites have a very high electrical resistance compared to pure iron. However, they show reductions in strength, permeability, magnetic saturation and temperature and fuel resistance over the classic sintered materials.
• the metal powders are mixed with small amounts of release agent or lubricant before being pressed. This addition results in a higher density of the molded articles because it promotes slippage of the metal powder particles during compaction, reduces mold release forces, and increases the life of the press tool by lubricating the ram and die.
• the release agents or lubricants are usually added in amounts between 0.1 and 1.5 wt .-% of the metal powders.
• the shaping by axial pressing is usually followed by a heat treatment.
• the added processing agents pyrolyze at temperatures between 150 and 500 ° C far below the sintering temperature of the metal powder (sintering temperature of iron 1120 ° C to 1280 ° C).
• metal soaps in the powder dressing leave metal oxides.
• the sintered, axially pressed soft magnetic metal powder would have a substantially (about a factor of 100) higher electrical resistance in order to achieve a good switching dynamics.
• oxides in composites consisting mainly of metal powder have some of the negative effects on properties such as mechanical and possibly magnetic properties, the inventors have found that multiple oxides which form at least one common phase give composites very good mechanical, thermal and chemical resistance convey.
• the starting material according to the invention for the production of a metal powder composite material having a high electrical resistivity can be composed without problems in such a way that the composite material produced therefrom not only has a high resistance but also a satisfactory compression density. If the amount of release agent required for a high resistance in the composite material is too large to simultaneously obtain an optimum compression density, oxidic fine powder may be added to the at least one release agent in at least one of the at least one release agent can form a common phase. You do not have to accept any deterioration in the properties of the composite material.
• the process according to the invention is therefore particularly advantageous because the oxides formed by pyrolysis of the release agents used in powder metallurgy can be used to produce the common phase.
• the inventive high-resistance composite materials can be used in the embodiment as soft magnetic composites also due to their high magnetic saturation and high permeability, especially for solenoid valves with good switching dynamics.
• the metal powder consists essentially of iron materials, such as those of iron, iron silicon, iron cobalt and iron nickel or mixtures of the materials mentioned, with iron being particularly preferred. "consisting essentially of " in this context means that other substances can only be present in amounts such that the soft magnetic properties do not deteriorate appreciably.
• the glass serves as the at least one common phase, such as silicate or boron-containing glass, or a defined compound from the group of mixed oxides with spinel structure, the metal phosphates and the metal silicates.
• At least one metal soap and / or at least one material from the group of mono-, di- or triesters of phosphoric acid, boric acid and silicic acid with long-chain alcohols and / or polydimethyldisiloxane is (are) contained in the starting material as release agent.
• At least one metal oxide and / or silicic acid is preferably used as the fine powder.
• the particle diameter (primary particle diameter) of the fine powder is ⁇ about 100 nm.
• a satisfactory compression density in the molded body combined with a sufficiently high electrical resistance in the metal powder composite material can be achieved in an advantageous manner when based on the weight of the metal powder, the proportion of release agent is between about 0.1 and about 1.5 wt .-% or the sum of the proportions of release agent and fine powder between about 0.2 and about 3 wt .-%.
• the ratio of the added amounts of release agent or fine powder, optionally taking into account the amounts of mitreagierendem metal from the metal powder surfaces, with respect to the at least one to be formed in the reaction of the oxides defined compound is approximately stoichiometric.
• the soft magnetic composite materials with high specific resistance consist of pressed powdered metal powder, which are provided with a coating mainly of defined chemical compounds which adhere well to the bare or surface-modified, for example phosphated metal particles and depending on the application in addition a high electrical resistance, temperature and Provide fuel resistance and / or protect the metal from corrosion.
• the coating prevents electrical connection between the metal particles.
• the defined chemical compounds are derived from mixed oxides with spinel structure, such as mixed oxides from the group Al2MgO4 (spinel), Al2ZnO4 (zinc spinel), Al2MnO4 (manganese spinel), Al2FeO4 (iron spinel), Fe2MgO4 (magnoferrite), Fe304 (magnetite), Fe2Zn04 (Franklinite), Fe2MnO4 (Jakobsite), Fe2Ni04 (Trevirite), Cr2Fe04 (Chromite) and Cr2MgO4 (Magnochromite), metal phosphates such as zinc and iron phosphate, silicate glasses, boron-containing glasses and metal silicates such as CoSiO3.
• mixed oxides from the group Al2MgO4 (spinel), Al2ZnO4 (zinc spinel), Al2MnO4 (manganese spinel), Al2FeO4 (iron spinel), Fe2Mg
• novel soft magnetic composites thus contain no thermosets or thermosets as insulation and binder as the metal-plastic composites. Nevertheless, in comparison to these, they also have a high electrical resistivity, comparable or better mechanical strength, better temperature and fuel resistance, comparable magnetic saturation and comparable permeability.
• the soft magnetic composite materials according to the invention are therefore suitable for use in fast-switching magnetic valves, in particular those used in automotive engineering.
• metal powders are mixed with combinations of novel or known release agents or lubricants or coated with these combinations (see above).
• the release agents are also used in the invention to provide a composite material to generate a high electrical resistance.
• the optimum proportion of release agent based on the amount of metal powder is ⁇ about 1% by weight. Release agent levels of> about 2% by weight are therefore generally not useful.
• the release agents oxide fine powder primary particle diameter preferably ⁇ about 100 nm
• Separating agents react, instead of increasing the proportion of release agent significantly above the optimum in terms of press density.
• the amount ratio of the release agent or the release agent and fine powder depends on the composition of the desired by the reaction of the pyrolysis and optionally the fine powder common phase. If these are mixed oxides with spinel structure, metal phosphates or metal silicates, the release agent or the release agent / fine powder combinations should be composed so that a stoichiometric conversion takes place in said compounds.
• the components of the defined compounds may also originate from the surface of the metal powder.
• the correct composition of the release agent or release agent / fine powder combination must be determined by simple tests. If a common phase in the form of glasses forms in the reaction instead of defined compounds, then larger tolerances can be permitted in the composition of the release agent or release agent / fine powder combinations.
• Examples of the said release agents are metal soaps, such as the stearates of calcium, magnesium, aluminum, zinc, cobalt, iron, nickel, copper, molybdenum and manganese, or esters of higher alcohols of phosphoric, boronic or silicic acid.
• Examples of the fine powders mentioned are oxides such as Fe 2 O 3 and silicic acid.
• the mixture of metal powder, release agent and optionally Fine powder is pressed axially into shaped bodies. Subsequently, the moldings are heated in a non-reducing atmosphere, for example in a nitrogen or argon atmosphere, to a temperature which is well below the sintering temperature of the metal powder, ie preferably below about 800 ° C. and more preferably between about 150 and about 550 ° C., so that the release agents pyrolyze. Below about 150 ° C., at most incomplete pyrolysis and the reactions proceed very slowly. At temperatures below 550 ° C., it is impossible for the metal particles to sinter together and thereby form electrical current paths. The pyrolysis residues react at the temperatures used either together and / or with the added fine powders and optionally with the surface of the metal particles to said defined chemical compounds.
• a non-reducing atmosphere for example in a nitrogen or argon atmosphere
• a mixture of iron powder and zinc stearate and a mono-, di-triester of phosphoric acid with long-chain alcohols, such as a mixture of phosphoric acid monostearyl ester and phosphoric acid distearyl ester having a melting point of 70 ° C, as a release agent was pressed into a molded article, wherein the proportion of the release agent based on the weight of the iron powder was about 1.7% by weight and the atomic ratio Zn: P was about 3: 2.
• the shaped body was heated in a non-reducing atmosphere, for example in nitrogen, to a maximum temperature of about 550 ° C., whereby the separating agents pyrolyzed to ZnO or P 2 O 5 and the resulting oxides reacted with one another to give zinc phosphate.
• zinc phosphate has a high electrical resistivity, adheres well to metals and specifically protects iron from corrosion.
• the resulting composite material was suitable as a soft magnetic material for high-speed electrical valves.
• a mixture of iron powder and cobalt stearate and reactive group-modified polydimethylsiloxane as a release agent was pressed into a molded article, wherein the proportion of the release agent based on the weight of the iron powder was about 1.6 wt .-% and the atomic ratio Co: Si was about 1 ,
• the molding was further treated as described in Example 1.
• the resulting from the release agents pyrolysis CoO and SiO 2 thereby reacted to form CoSiO3.
• the cobalt silicate had good adhesion to the iron powder, was well electrically insulating and well protected against corrosion.
• a mixture of iron powder, cobalt stearate as a release agent, to which a stoichiometric amount of fumed silica (primary particle diameter ⁇ about 100 nm) was added was pressed into a molded article, wherein the proportion of the release agent based on the weight of the iron powder at about 1.3 wt .-% was.
• the molding was further treated as described in Example 1. The resulting from the release agent pyrolysis CoO reacted with the SiO 2 of the silica to CoSiO3.
• a mixture of iron powder and as a release agent zinc stearate and iron stearate was pressed into a molded article, wherein the proportion of the release agent based on the weight of the iron powder was about 1.4 wt .-% and the atomic ratio Zn: Fe was about 1: 2.
• the molding was further treated as described in Example 1.
• the resulting from the release agents pyrolysis ZnO and Fe203 reacted with each other to the spinel Fe2Zn04 (Franklinite).
• Spinels have - as stated - a good adhesion to iron powder, they are electrically good insulating and they protect iron excellent against corrosion.
• the molding was further treated as described in Example 1.
• the pyrolysis product ZnO formed from the release agent reacted with the Fe 2 O 3 to form the spinel Fe 2 ZnO 4.
• the molding was further treated as described in Example 1.
• the resulting pyrolysis products NiO and Fe2O3 reacted with each other to form the spinel Fe2Ni04.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Dispersion Chemistry (AREA)
• Power Engineering (AREA)
• Soft Magnetic Materials (AREA)
• Powder Metallurgy (AREA)
• Parts Printed On Printed Circuit Boards (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)

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• 2001
  • 2001-03-03 DE DE10110341A patent/DE10110341A1/de not_active Ceased
  • 2001-03-03 DE DE20122873U patent/DE20122873U1/de not_active Expired - Lifetime
  • 2001-12-21 EP EP01130567A patent/EP1236808B1/fr not_active Expired - Lifetime
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• 2002
  • 2002-02-28 US US10/086,760 patent/US6756118B2/en not_active Expired - Lifetime

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