Classifications

• • 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
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
  • F16K31/00—Actuating devices; Operating means; Releasing devices
  • F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
  • F16K31/06—Actuating devices; Operating means; Releasing devices electric; magnetic using a magnet, e.g. diaphragm valves, cutting off by means of a liquid
• • 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
  • 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
  • H01F1/33—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 mixtures of metallic and non-metallic particles; metallic particles having oxide skin

Definitions

• the invention relates to a sintered soft magnetic composite material, in particular for use in solenoid valves, and a method for producing such a composite material according to the type of the independent claims.
• Known fast-switching magnetic injection valves are made from soft magnetic materials such as FeCr or FeCo alloys or from powder composite materials with the highest possible specific electrical resistance.
• the sintered soft magnetic composite material according to the invention and the method for its production have the advantage over the prior art that specific electrical resistances of more than 2 ⁇ m can be achieved. Furthermore, the composite material according to the invention is very temperature-resistant and at the same time also fuel-resistant. In addition, it can be machined at least to a limited extent.
• the composite material according to the invention further achieves a saturation polarization of approximately 1.6 Tesla, which is comparable to known materials made of iron powder and organic binder.
• a large number of known soft or hard magnetic ferrite powders are also suitable for the second, ferrimagnetic starting component.
• the use of oxidic powders such as Fe 2 0 3 is particularly advantageous.
• known strontium or barium hard ferrites or known soft ferrites such as MnZn or NiZn.
• the average grain size the powder particles of the ferromagnetic starting component is significantly larger than the average grain size of the powder particles of the ferrite powder.
• silicon or silicon dioxide can advantageously be used to increase the specific electrical resistance and the permeability of the composite material.
• Aluminum or aluminum oxide is suitable, for example, for increasing the specific electrical resistance.
• the pressing aid which is more preferably added to the starting mixture, facilitates the compression and shaping of the starting mixture in a die. It is advantageous that this pressing aid is completely removed or evaporated again during debinding, so that it has no direct influence on the achievable material characteristics of the sintered soft magnetic composite material obtained.
• the invention is explained in more detail with reference to the drawing and in the description below.
• the figure shows a basic sketch of an initial mixture.
• a sintered soft magnetic composite material by combining a powdery, ferromagnetic first starting component 11 with a ferrite powder as the ferritic second starting component 12, the ferrite powder being present at least largely as a grain boundary phase in the composite material after sintering.
• the first starting component 11 pure iron powder or a powder alloyed with 0.1 to 1% by weight phosphorus (phosphated iron powder) is specified as the main constituent.
• This powder has a grain size distribution of 60 ⁇ m to 200 ⁇ m.
• a ferrite powder in the form of a powder with a very fine grain size is then added to this ferromagnetic starting component 11 as the second starting component 12.
• a suitable ferrite powder is, for example, a powdery soft ferrite such as MnZn or NiZn ferrite, a powdery hard ferrite such as strontium ferrite (6Fe 2 0 3 : SrO) or barium ferrite (6Fe 2 0 3 : BaO), or iron oxide powder
• the average particle size of the powder particles of the second starting component 12 is preferably less than 20 ⁇ m.
• the respective weight ratios between the ferromagnetic first output component 11 and the added second output component 12 result in the individual case from the required magnetic properties of the composite material to be produced and the desired specific electrical resistance.
• the proportion of the ferromagnetic starting component 11 as the main constituent is between 88 and 98% by weight and the proportion of the second starting component 12 is between 2 and 12% by weight.
• further additives can be added to achieve or fine-tune the magnetic or electrical properties of the composite material to be produced.
• silicon and / or aluminum and their oxides are particularly suitable, both of which are added as powders with a preferred grain size of less than 50 ⁇ m.
• Micro wax is also expediently added to the starting mixture as a pressing aid.
• the achievable specific electrical resistance of the sintered composite material finally obtained is determined primarily by the amount of the ferrite powder added.
• composition of the starting mixture can be varied within the following limits:
• the materials mentioned in the starting mixture are then first mixed with one another, the mixing time depending on the composition being between 30 minutes and 240 minutes.
• the starting mixture is then shaped and compressed by uniaxial pressing in a die, so that a green body is formed.
• the pressure during uniaxial pressing is preferably 500 MPa to 750 MPa.
• the green bodies obtained are first debindered in a nitrogen atmosphere at a temperature between 450 ° C. and 500 ° C. over a period of 30 minutes to 45 minutes before sintering.
• the micro wax added as a pressing aid is removed again by essentially evaporating it.
• This debinding is followed by a two-stage sintering process.
• the first stage of the sintering process at a temperature between 500 ° C. and 700 ° C. for a period of 30 minutes to 12 hours in a gas atmosphere with the composition 50% by volume to 100% by volume nitrogen and 0% by volume to 50 vol. % Oxygen sintered.
• the gas atmosphere preferably contains 5 vol. % to 30 vol.% oxygen.
• This first stage of the sintering process is followed by a second stage at temperatures between 900 ° C and 1150 ° C.
• This second sintering stage extends over a period of 5 minutes to 2 hours, with the heating rate between 10 to 40 K / min and the cooling rate between 5 to 40 K / min is selected.
• the sintering is carried out in a gas atmosphere which initially consists of 50 vol. % up to 100 vol.% embroidery Fabric and 0 vol. % to 50 vol.% oxygen.
• the gas atmosphere preferably contains 5 vol.
• % up to 30 vol. % Oxygen At the beginning of the second stage of the sintering process.
• the oxygen content of the gas atmosphere is then gradually or continuously reduced.
• the oxygen content can be reduced to up to 0% by volume, ie the gas atmosphere at the end of the second sintering stage can consist only of nitrogen. In this case, too, another inert gas can be used instead of nitrogen.
• a thermal aftertreatment of the soft magnetic composite material is then carried out, if necessary, which extends over a period of 30 minutes to 3 hours.
• the sintered body is subjected to a gas atmosphere at temperatures of 600 ° C to 800 ° C, 50% by volume to 100% by volume.
• % of nitrogen and 0 vol. % up to 50 vol. % consists of oxygen.
• the gas atmosphere preferably has an oxygen content of 10 to 30% by volume during the thermal aftertreatment.
• This thermal aftertreatment serves to improve the physical properties of the sintered composite body obtained and, depending on the qualitative requirements for the composite material and the starting components used, can therefore also be omitted in order to save costs.
• the debinding of the compressed starting mixture and the sintering of the compressed, debindered starting mixture to form the composite material can take place in succession in one work step. After completion of the sintering, the soft magnetic composite material obtained can then, if necessary, be reworked mechanically.
• the composite material finally obtained has a typical saturation polarization of approximately 1 Tesla to 1.6 Tesla, in particular more than 1.5 Tesla, with a specific electrical resistance of more than 2 ⁇ m. It is also fully fuel and temperature resistant for use in solenoid valves under typical conditions.
• a further exemplary embodiment of the invention provides, in a slight modification of the above exemplary embodiment, to first mix the first ferromagnetic starting component 11 and the second starting component 12 in the form of a ferrite powder, optionally with the addition of silicon, aluminum or their oxides, and this mixture then first, ie to undergo heat treatment before pressing or compacting.
• This heat treatment is carried out at 400 ° C to 700 ° C for 15 min to 45 min under a gas atmosphere of the composition 50 vol.% To 100 vol. % Nitrogen and 0 vol. % to 50 vol.% oxygen.
• the gas atmosphere preferably has a proportion of 10% by volume to 30% by volume of oxygen.
• Another inert gas is also suitable instead of nitrogen.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Dispersion Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Mechanical Engineering (AREA)
• Soft Magnetic Materials (AREA)
• Powder Metallurgy (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7932501

Family Applications (1)

Country Status (6)

Families Citing this family (13)

Family Cites Families (16)

• 1999
  • 1999-12-14 DE DE19960095A patent/DE19960095A1/de not_active Ceased
• 2000
  • 2000-10-26 JP JP2001545321A patent/JP2003517195A/ja active Pending
  • 2000-10-26 WO PCT/DE2000/003801 patent/WO2001045116A1/de not_active Application Discontinuation
  • 2000-10-26 KR KR1020017010238A patent/KR20020005586A/ko not_active Application Discontinuation
  • 2000-10-26 EP EP00987036A patent/EP1166290A1/de not_active Withdrawn
  • 2000-10-26 US US09/913,776 patent/US6726740B1/en not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events