CN109133900A - High dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density and preparation method thereof - Google Patents

High dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density and preparation method thereof Download PDF

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Publication number
CN109133900A
CN109133900A CN201811264778.8A CN201811264778A CN109133900A CN 109133900 A CN109133900 A CN 109133900A CN 201811264778 A CN201811264778 A CN 201811264778A CN 109133900 A CN109133900 A CN 109133900A
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dry
pressing formed
flux density
magnetic
permanent
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姚锐
刘超
郑自儒
陈晓宇
邓雅之
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Hunan Aerospace Magnet and Magneto Co Ltd
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Hunan Aerospace Magnet and Magneto Co Ltd
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    • 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
    • H01F1/032—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 hard-magnetic materials
    • H01F1/10—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 hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure
    • H01F1/11—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 hard-magnetic materials non-metallic substances, e.g. ferrites, e.g. [(Ba,Sr)O(Fe2O3)6] ferrites with hexagonal structure in the form of particles
    • 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
    • H01F41/0253—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 for manufacturing permanent magnets
    • 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
    • H01F41/0253—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 for manufacturing permanent magnets
    • H01F41/0266—Moulding; Pressing
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    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
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Abstract

High dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density and preparation method thereof, the magnet is made of following methods: (1) in permanent ferrite prefiring material plus water, after wet ball grinding, adding cellulose ethers additive, stir, obtain mixed slurry；(2) in magnetic field, wet process compression moulding is carried out, is dried, is crushed, the premagnetization material block with orientation is obtained；(3) lubrication binder, co-grinding is added, sieving obtains anisotropy powder；(4) dry-pressing formed in magnetic field, it is sintered, grinding,.For the surface magnetic flux density of the dry-pressing formed permanent magnetic ferrite magnet of the present invention up to 1920 Gs or more, magnetic property is substantially better than permanent magnetic ferrite magnet obtained by existing dry-forming technique；The method of the present invention premagnetization effect maximizes, and dry method compacting magnetic field strength is low, is not necessarily to heating, and simple process, low energy consumption, at low cost, is suitable for industrialized production.

Description

High dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density and preparation method thereof
Technical field
The present invention relates to a kind of permanent magnetic ferrite magnets and preparation method thereof, and in particular to a kind of high surface magnetic flux density is dry Molded permanent magnetic ferrite magnet and preparation method thereof.
Background technique
With the quickening of global industry and home intelligence, automated process, the market demand of all kinds of motors persistently increases It is long, and size to motor and efficiency require to be increasingly stringenter, and motor is promoted to accelerate to miniaturization, planarization, energy-saving development. Dry-pressing formed permanent magnetic ferrite magnet is because cost is relatively low, magnetic property and chemical stability are excellent, it is complex-shaped small to can get for it The advantages that size anisotropy device, is widely used in the micro- special magneto of all kinds of low and middle-ends, and the market demand surges, prospect It is wide.
For the application range for widening dry-pressing formed strontium ferrite magnet, increase its application in high-end micro- special magneto Ratio must further increase the magnetic property of such magnet, it is especially desirable to improve its surface magnetic flux density.The prior art is in magnet Increase precompressed premagnetization process, i.e., life needed for permanent magnet ferrite powder being pressed into final products under magnetic field in manufacturing process Before base, by one or many pressing under magnetic fields, but resulting green body is frequently not green compact shape required for final products, But the mostly parallel three-dimensional shape in the upper and lower end faces such as cube, cuboid, cylindrical body.The starting point of precompressed premagnetization process Be: powder can improve the magnetic domain orientation consistency of green body after one or many premagnetizations during final pressing under magnetic field, Magnetic property to obtain.
Dry-pressing formed magnet product magnetic property, especially surface magnetic flux density are improved, key is precompressed premagnetization Magnetic field orientating effect maximize, this needs to solve the problems, such as following two: (1) must reduce magnetic powder as much as possible when precompressed premagnetization Frictional resistance of the particle under magnetic field when rotational alignment；(2) the resulting green body of precompressed premagnetization must just may be used after break process Green compact needed for being pressed into final products under magnetic field, shattering process can be orientated the magnetic domain of precompressed premagnetization and damage, palpus Its extent of the destruction is reduced as much as possible, i.e., as far as possible remains the magnetic domain orientation effect of precompressed premagnetization.
The prior art useful precompressed premagnetization process as one of the means enhanced product performance.
CN101599333A discloses a kind of manufacturing method of anisotropic multi-pole magnetic ring through dry-press forming, still, this method Drying and processing is carried out to the magnetic powder of wet pulverizing before precompressed premagnetization, although then joined a certain amount of adhesive And lubricant, but it is limited for the lubricant effect of dry powder, since the intergranular friction resistance of dry powder is larger, cause The difficulty of powder granule rotational alignment under magnetic field is big during precompressed premagnetization, and premagnetization effect is poor, it is difficult to prepare surface Magnetic flux density is greater than the premium quality product of 1900Gs, fails to handle above-mentioned (1) a problem well.
CN105622082A discloses a kind of preparation method of permanent-magnet ferrite anisotropic dry press-powder material, and this method is to wet Slurry after method ball milling carries out precompressed premagnetization, and the aqueous medium during premagnetization between magnetic powder particle plays good lubrication Effect, significantly reduces intergranular friction power, and premagnetization effect is more excellent, and still, the operating procedure after premagnetization is first Broken re-dry, is crushed premagnetization green body under saturation state, first is that, broken difficulty is increased, production effect is reduced Rate, second is that, it is easily destroyed premagnetization bring magnetic domain orientation effect, fails to handle above-mentioned (2) a problem well, it is difficult to prepare Premium quality product out.
CN108147803A discloses a kind of preparation method of dry-press process strontium ferrite magnet, is equally to wet ball grinding Slurry afterwards carries out precompressed premagnetization, and takes premagnetization green body the operating procedure first dried and be crushed afterwards, although in certain journey The orientation effect of premagnetization is had cured on degree, but its effect is extremely limited, equally fail to handle well that above-mentioned (2) are a to ask Topic, therefore when dry method suppresses final products green compact, stronger forming magnetic field need to be applied, and need to additionally be heated up to 40~200 DEG C, with It enhances product performance, this undoubtedly increases production cost and efficiency, weakens the competitiveness of product in market.
Summary of the invention
The technical problem to be solved by the present invention is to overcome drawbacks described above of the existing technology, provide a kind of premagnetization Effect maximizes, and dry method compacting magnetic field strength is low, is not necessarily to heating, and simple process, low energy consumption, at low cost, is suitable for industrial metaplasia Produce, the high dry-pressing formed permanent magnetic ferrite magnet of high surface magnetic flux density of gained permanent magnetic ferrite magnet surface magnetic flux density and its Preparation method.
The technical solution adopted by the present invention to solve the technical problems is as follows: the high dry-pressing formed permanent magnet of surface magnetic flux density Ferrite magnet is made of following methods:
(1) add water in permanent ferrite prefiring material, after carrying out wet ball grinding, add cellulose ethers additive, stir, obtain Mixed slurry；
(2) by mixed slurry obtained by step (1) in magnetic field, wet process compression moulding is carried out, is dried, is crushed, is obtained with orientation Premagnetization material block；
(3) in the magnetization material block obtained by the step (2) with orientation, be added lubrication binder, co-grinding, sieving, obtain it is each to Anisotropic powder；
(4) dry-pressing formed by anisotropy powder obtained by step (3) in magnetic field, it is sintered, grinding obtains high surface magnetic flux density Dry-pressing formed permanent magnetic ferrite magnet.
Preferably, in step (1), the permanent ferrite prefiring material is Strontium ferrite powder, characteristic molecular formula are as follows: ABxO19；Wherein, A Sr, or there are also one or more of Ca, Ba or La etc.；B is Fe, or there are also in Co, Al or Ti etc. One or more, the valence state of Co element are+divalent；X is 10~12.
Preferably, in step (1), after permanent ferrite prefiring material is mixed with magnetic property reinforcing agent, it is wet to add water progress Method ball milling.
Preferably, the additive amount of the magnetic property reinforcing agent is 0~15%(more preferable 5 of permanent ferrite prefiring material quality ~12%).
Preferably, the magnetic property reinforcing agent is CaCO3、Al2O3、H3BO3Or SiO2One or more of Deng.More preferably Ground, CaCO in the magnetic property reinforcing agent3、Al2O3、H3BO3And SiO2Mass ratio be 1:0~1:0~1:0~1；It is further excellent Choosing, the magnetic property reinforcing agent are CaCO3、Al2O3And H3BO3Mass ratio be 1:0.4~0.8:0.4~0.8 mixture, or CaCO3And SiO2Mass ratio be 1:0.4~0.8 mixture.
Preferably, in step (1), the mass ratio of the permanent ferrite prefiring material and water is 1:0.5~5.0.If water Dosage is excessive, then slurry is too dilute, it is difficult to form, must increase the slurry sedimentation time, to reduce production efficiency；If the dosage mistake of water Few, then slurry is too dry, and domain particles rotate under magnetic field when being unfavorable for step (2) molding.
Preferably, in step (1), 0.95 μm of powder mean particle sizes < of the wet ball grinding into slurry.It, will if granularity is excessive Green body can be made to form coarse more magnetic domain crystal grain after sintering, product magnetic property is caused to decline to a great extent.
The method of the present invention step (1) adds cellulose ethers additive after wet ball grinding, can effectively avoid ball milling mistake The mechanical shock of journey generates destruction to the structure of matter of cellulose ethers additive；Meanwhile cellulose ethers additive dissolves in Water, being added in slurry slightly stirring can be uniformly mixed with slurry.
Preferably, in step (1), the dosage of the cellulose ethers additive is permanent ferrite prefiring material quality 0.01~0.80%.Cellulose ethers additive has special molecular structure, water-soluble, and slightly stirring can be with after addition Slurry is uniformly mixed；When the slurry of addition cellulose ethers additive carries out Wet-pressing molding, i.e. precompressed premagnetization under magnetic field, material A large amount of aqueous mediums present in slurry play good lubricating action, and suitable cellulose ethers additive will not only interfere to turn To process, magnetic-particle can also can turn to well under magnetic field, guarantee in premagnetization green compact there is good magnetic domain to take To consistency；The cellulose ethers additive for containing a small amount of disperse in premagnetization green compact, by shape in subsequent drying process At firm reticular structure, the magnetic powder particle package after capable of being well orientated premagnetization is protected, thus after being greatly reduced The destruction that continuous shattering process is orientated magnetic domain, can preferably remain the effect of premagnetization, to reduce final The resistance of powder particles rotational alignment under magnetic field when dry-pressing formed improves the intracorporal magnetic domain degree of orientation of product base, produces being promoted Production cost and energy consumption are reduced while moral character energy.
Preferably, in step (1), the cellulose ethers additive is methylcellulose, ethyl cellulose, hydroxyalkyl fibre One or more of dimension element, carboxymethyl cellulose or their derivative etc..Sodium carboxymethylcellulose is carboxymethyl cellulose A kind of common derivative.
Preferably, in step (1), the revolving speed of the stirring is 30~29000 r/min, and the time is 0.5~800 min (more preferable 1~500 min).
Preferably, in step (2), the intensity in the magnetic field be 3500~12000Oe(be more preferably 4000~ 10000Oe).If magnetic field strength is too small, it is difficult to reach the satisfied green compact degree of orientation, deteriorates properties of product；If magnetic field strength It is excessive, then require high, field coil to generate heat molding equipment serious, so that high production cost, low efficiency.
Preferably, in step (2), the pressure of the wet process compression moulding is that 10~30 MPa(are more preferably 12~25 MPa), compression moulding to green compact density >=2.8 g/cm3.If pressure is too small, green strength is low, easily-deformable；If pressure mistake Greatly, then easily green compact is caused to crack.Preferred 30~40 mm of diameter of the shape of the wet process compression moulding, the circle of 10~20mm of thickness Cylindricality.
Preferably, in step (2), the temperature of the drying is 80~120 DEG C, and the time is 4~12 h.If drying temperature mistake The low or time is too short, then gained material block moisture content is excessively high, is unfavorable for subsequent dispersion and is sufficiently mixed with lubrication binder； If drying temperature is excessively high or overlong time, expects that block moisture content is too low, be unfavorable for subsequent forming.
Preferably, in step (3), it is described lubrication binder additive amount be permanent ferrite prefiring material quality 0.1~ 3.0%(is more preferably 0.2~2.5%).Lubrication binder mainly plays lubrication and bonding.If lubricating the dosage mistake of binder It is few, then it is difficult to have the function that lubrication and bonding, is unfavorable for subsequent forming；If the dosage for lubricating binder is excessive, easily cause Product air holes increase, density and magnetic property decline, or even cause product cracking and other issues.
Preferably, in step (3), partial size≤80 mesh of the lubrication binder.
Preferably, in step (3), the lubrication binder is polyethylene glycol, polyvinyl alcohol, camphor, stearic amide, oil One or more of the double stearic amides of sour amide, vinyl, Metallic stearates or fatty acid series wax etc..The stearic acid The preferred calcium stearate of metal salt.It is highly preferred that the mass ratio that the lubrication binder is calcium stearate and polyethylene glycol be 1:1~ 3 mixture or stearic amide and the mass ratio of oleamide are the mixture of 1:0.5~1.5.
Preferably, in step (3), mesh number≤40 mesh of the sieving.If powder size is excessively thick when molding, green body and production Easily there is the problems such as stomata, crackle in product.
Preferably, in step (4), the intensity in the magnetic field is that 3500~9500 Oe(are more preferably 4000~9000 Oe).If magnetic field strength is too small, it is difficult to reach the satisfied green compact degree of orientation, deteriorates properties of product；If magnetic field strength is excessive, Then high, field coil is required to generate heat molding equipment serious, so that high production cost, low efficiency.It must be noted that step (1) the cellulose ethers additive added in, so that the premagnetization orientation effect in step (2) wet process compression moulding is protected substantially Stay, thus each magnetic domain being used in inside dry-pressing formed powder particles be substantially oriented unanimously, this greatly reduces Rotary resistance of the powder particle under magnetic field, therefore it is not necessarily to very strong magnetic field herein, magnetic domain inside the green compact of final products can be made Be orientated it is almost the same, reach improve product magnetic property, especially surface magnetic flux density effect, meanwhile, production cost can be reduced With energy consumption.
Preferably, in step (4), the dry-pressing formed temperature be room temperature, pressure be 10~30 MPa, it is dry-pressing formed extremely The density of green compact >=2.8 g/cm3.The room temperature is 15~35 DEG C.Due to the addition of cellulose ethers additive, so that dry-pressing Rotary resistance of the molding powder particles under magnetic field is little, without additionally heat can under weaker magnetic field rotational alignment. If dry-pressing formed pressure is too small, green strength is low, easily-deformable；If dry-pressing formed pressure is excessive, easily green compact is caused to crack.
Preferably, in step (4), the sintering, which refers to, is warming up to 1000~1300 DEG C with the rate of 2~5 DEG C/min, burns 1~3h of knot.
The method of the present invention has the beneficial effect that:
(1) the present inventor, which is put forward for the first time, is added cellulose ethers additive after permanent ferrite prefiring material carries out wet ball grinding, To improve the surface magnetic flux density of magnet, the surface magnetic flux density of the dry-pressing formed permanent magnetic ferrite magnet of the present invention is up to 1920 Gs or more, magnetic property are substantially better than permanent magnetic ferrite magnet obtained by existing dry-forming technique；
(2) the method for the present invention can maximize the magnetic domain orientation effect of precompressed premagnetization process, reach and promote product magnetic property, especially It is the purpose of surface magnetic flux density；Meanwhile the method for the present invention significantly reduces the magnetic field strength of dry method compacting, and forming process It can carry out at room temperature, without additional heating, production cost and energy consumption be effectively reduced, is suitable for industrialized production.
Detailed description of the invention
Fig. 1 is that the surface magnetic flux of the 2 high dry-pressing formed strontium ferrite magnet of surface magnetic flux density of gained of the embodiment of the present invention is close Spend distribution map；
Fig. 2 is the surface magnetic flux density distribution map of the 1 dry-pressing formed strontium ferrite magnet of gained of comparative example of the present invention；
Fig. 3 is the surface magnetic flux density distribution map of the 2 dry-pressing formed strontium ferrite magnet of gained of comparative example of the present invention.
Specific embodiment
Below with reference to embodiment and attached drawing, the invention will be further described.
Strontium ferrite powder used in the embodiment of the present invention and comparative example be commercial product (La, Sr) (Fe, Co)12O19(valence state of Co element is+divalent)；Chemical reagent used in the embodiment of the present invention passes through unless otherwise specified Routine business approach obtains.
Embodiment 1
(1) 200 kg water are added in 65 kg Strontium ferrite powders, carry out powder mean particle sizes of the wet ball grinding into slurry After 0.80 μm, 0.5 kg methylcellulose is added, at 29000 r/min, 1 min is stirred, obtains mixed slurry；
(2) by mixed slurry obtained by step (1) in 7000 magnetic fields Oe, under 25 MPa, wet process compression moulding is carried out to green compact Density be 3.0 g/cm3Cylinder (30 mm of diameter, 15 mm of thickness), at 120 DEG C, dry 5 h, be crushed, must have The premagnetization material block of orientation；
(3) it in the magnetization material block with orientation obtained by step (2), is added 1.3 kg camphors (100 mesh), co-grinding, crosses 60 Mesh obtains anisotropy powder；
(4) dry-pressing formed to raw at 20 DEG C, 12 MPa by anisotropy powder obtained by step (3) in 5000 magnetic fields Oe The density of base is 3.1 g/cm3Cylinder (30 mm of diameter, 15 mm of thickness), then be placed in electric kiln, with the speed of 5 DEG C/min Rate is warming up to 1250 DEG C, is sintered 1h, and grinding obtains the dry-pressing formed strontium ferrite magnet of high surface magnetic flux density.
Through detecting, the surface magnetic flux of the high dry-pressing formed strontium ferrite magnet of surface magnetic flux density obtained by the embodiment of the present invention is close Degree peak value is 1840 Gs or more, and magnetic property is excellent.
Embodiment 2
(1) by 65kg Strontium ferrite powder and 3.25 kg CaCO3、1.95 kg Al2O3With 1.95 kg H3BO3After mixing, 35kg water is added, it is fine to add 0.16kg carboxymethyl after powder mean particle sizes of the progress wet ball grinding into slurry are 0.85 μm Plain sodium is tieed up, at 90r/min, 10min is stirred, obtains mixed slurry；
(2) by mixed slurry obtained by step (1) in the magnetic field 4000Oe, under 16MPa, wet process compression moulding is carried out to green compact Density is 2.8g/cm3Cylinder (diameter 40mm, thickness 20mm), at 100 DEG C, dry 10h, be crushed, obtain with orientation Premagnetization material block；
(3) in the magnetization material block with orientation obtained by step (2), 0.2 kg calcium stearate (325 mesh) is added and 0.4 kg is poly- Ethylene glycol (325 mesh), co-grinding cross 40 meshes, obtain anisotropy powder；
(4) dry-pressing formed to green compact at 25 DEG C, 25MPa by anisotropy powder obtained by step (3) in the magnetic field 8000Oe Density be 2.8g/cm3Cylinder (diameter 40mm, thickness 20mm), then be placed in electric kiln, with the rate liter of 3 DEG C/min Temperature is sintered 2h to 1200 DEG C, and grinding obtains the dry-pressing formed strontium ferrite magnet of high surface magnetic flux density.
As shown in Figure 1, the surface magnetic of the high dry-pressing formed strontium ferrite magnet of surface magnetic flux density obtained by the embodiment of the present invention Flux density peak value is 1900Gs or more, and magnetic property is excellent.
Embodiment 3
(1) by 65 kg Strontium ferrite powders and 3.00kg CaCO3With 1.85kg SiO2After mixing, 65 kg water are added, into After powder mean particle sizes of the row wet ball grinding into slurry are 0.75 μm, 0.13kg ethyl cellulose and 0.13kg hydroxyl are added Alkylcellulose stirs 480 min, obtains mixed slurry at 1000 r/min；
(2) by mixed slurry obtained by step (1) in 10000 magnetic fields Oe, under 12 MPa, wet process compression moulding is carried out to life The density of base is 2.8 g/cm3Cylinder (40 mm of diameter, 10 mm of thickness), at 80 DEG C, dry 12 h, be crushed, must have There is the premagnetization material block of orientation；
(3) in the magnetization material block with orientation obtained by step (2), 0.16 kg stearic amide (200 mesh) and 0.16kg is added Oleamide (200 mesh), co-grinding cross 80 meshes, obtain anisotropy powder；
(4) dry-pressing formed to raw at 30 DEG C, 30 MPa by anisotropy powder obtained by step (3) in 9000 magnetic fields Oe The density of base is 3.2 g/cm3Circular ring shape (overall diameter 50mm, interior diameter 30mm, thickness 20mm), then be placed in electric kiln, with The rate of 2 DEG C/min is warming up to 1145 DEG C, is sintered 3 h, and grinding obtains the dry-pressing formed strontium ferrite magnet of high surface magnetic flux density.
Through detecting, the surface magnetic flux of the high dry-pressing formed strontium ferrite magnet of surface magnetic flux density obtained by the embodiment of the present invention is close Degree peak value is 1920 Gs or more, and magnetic property is excellent.
Comparative example 1
The difference of this comparative example and embodiment 2 is only that: (1) by 65kg Strontium ferrite powder and 3.25 kg CaCO3、1.95 kg Al2O3With 1.95 kg H3BO3After mixing, 35kg water is added, carrying out powder mean particle sizes of the wet ball grinding into slurry is After 0.85 μm, mixed slurry is obtained；Remaining same embodiment 2.
As shown in Figure 2, the surface magnetic flux density peak value of dry-pressing formed strontium ferrite magnet obtained by comparative example of the present invention is 1500~1600Gs, magnetic property are general.
Comparative example 2(refers to the step of embodiment 1 CN 101599333A)
(1) by 65kg Strontium ferrite powder and 3.25 kg CaCO3、1.95 kg Al2O3With 1.95 kg H3BO3After mixing, 35kg water is added and obtains mixed slurry after powder mean particle sizes of the progress wet ball grinding into slurry are 0.85 μm；
(2) by mixed slurry obtained by step (1) at 100 DEG C, 10h is dried, is crushed, obtains material block；
(3) in the material block obtained by step (2), 0.2 kg calcium stearate (325 mesh) and 0.4 kg polyethylene glycol (325 mesh) is added, Co-grinding crosses 40 meshes, adds 100 kg of water, in the magnetic field 4000Oe, under 16MPa, carries out wet process compression moulding to green compact Density be 2.8g/cm3Cylinder (diameter 40mm, thickness 20mm) after, at 100 DEG C, dry 10h, crush, obtain each to different Property powder；
(4) dry-pressing formed to green compact at 25 DEG C, 25MPa by anisotropy powder obtained by step (3) in the magnetic field 8000Oe Density be 2.8g/cm3Cylinder (diameter 40mm, thickness 20mm), then be placed in electric kiln, with the rate liter of 3 DEG C/min Temperature is sintered 2h to 1200 DEG C, and grinding obtains dry-pressing formed strontium ferrite magnet.
From the figure 3, it may be seen that the surface magnetic flux density peak value of dry-pressing formed strontium ferrite magnet obtained by comparative example of the present invention is 1500~1600Gs, magnetic property are general.
In conclusion cellulose ethers additive and the mutually auxiliary phase of the method for the present invention technical solution that the method for the present invention is added At realization is better than the technical effect of existing additive and dry process for forming, and technical process is simple, and production cost is low, production effect Rate is high.

Claims (8)

1. a kind of dry-pressing formed permanent magnetic ferrite magnet of high surface magnetic flux density, which is characterized in that be made of following methods:
(1) add water in permanent ferrite prefiring material, after carrying out wet ball grinding, add cellulose ethers additive, stir, obtain Mixed slurry；
(2) by mixed slurry obtained by step (1) in magnetic field, wet process compression moulding is carried out, is dried, is crushed, is obtained with orientation Premagnetization material block；
(3) in the magnetization material block obtained by the step (2) with orientation, be added lubrication binder, co-grinding, sieving, obtain it is each to Anisotropic powder；
(4) dry-pressing formed by anisotropy powder obtained by step (3) in magnetic field, it is sintered, grinding obtains high surface magnetic flux density Dry-pressing formed permanent magnetic ferrite magnet.
2. the dry-pressing formed permanent magnetic ferrite magnet of high surface magnetic flux density according to claim 1, it is characterised in that: step (1) in, the permanent ferrite prefiring material is Strontium ferrite powder, characteristic molecular formula are as follows: ABxO19；Wherein, A Sr, or There are also one or more of Ca, Ba or La；B is Fe, or there are also one or more of Co, Al or Ti, the valence states of Co element For+divalent；X is 10~12.
3. the dry-pressing formed permanent magnetic ferrite magnet of high surface magnetic flux density according to claim 1 or claim 2, it is characterised in that: step Suddenly in (1), after permanent ferrite prefiring material is mixed with magnetic property reinforcing agent, carry out wet ball grinding is added water；The magnetic property The additive amount of reinforcing agent is the 0~15% of permanent ferrite prefiring material quality；The magnetic property reinforcing agent is CaCO3、Al2O3、 H3BO3Or SiO2One or more of.
4. the high dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density, feature described according to claim 1~one of 3 exist In: in step (1), the mass ratio of the permanent ferrite prefiring material and water is 1:0.5~5.0；Wet ball grinding is into slurry 0.95 μm of powder mean particle sizes <.
5. the high dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density, feature described according to claim 1~one of 4 exist In: in step (1), the dosage of the cellulose ethers additive is the 0.01~0.80% of permanent ferrite prefiring material quality；Institute State cellulose ethers additives be methylcellulose, ethyl cellulose, hydroxy alkyl cellulose, carboxymethyl cellulose or they spread out One or more of biology；The revolving speed of the stirring is 30~29000 r/min, and the time is 0.5~800 min.
6. the high dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density, feature described according to claim 1~one of 5 exist In: in step (2), the intensity in the magnetic field is 3500~12000Oe；The pressure of the wet process compression moulding is 10~30 MPa, density >=2.8 g/cm of compression moulding to green compact3；The temperature of the drying is 80~120 DEG C, and the time is 4~12 h.
7. the high dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density, feature described according to claim 1~one of 6 exist In: in step (3), the additive amount of the lubrication binder is the 0.1~3.0% of permanent ferrite prefiring material quality；The lubrication The partial size of binder≤80 mesh；The lubrication binder is polyethylene glycol, polyvinyl alcohol, camphor, stearic amide, oleic acid acyl One or more of the double stearic amides of amine, vinyl, Metallic stearates or fatty acid series wax；The mesh number of the sieving≤ 40 mesh.
8. the high dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density, feature described according to claim 1~one of 7 exist In: in step (4), the intensity in the magnetic field is 3500~9500 Oe；The dry-pressing formed temperature is room temperature, pressure 10 ~30 MPa, the dry-pressing formed density to green compact >=2.8 g/cm3；The sintering refers to be warming up to the rate of 2~5 DEG C/min 1000~1300 DEG C, it is sintered 1~3h.
CN201811264778.8A 2018-10-29 2018-10-29 High dry-pressing formed permanent magnetic ferrite magnet of surface magnetic flux density and preparation method thereof Pending CN109133900A (en)

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