A kind of method preparing rare earth permanent-magnetic material
Technical field
The present invention relates to magnetic material correlative technology field, refer in particular to a kind of method preparing rare earth permanent-magnetic material.
Background technology
Since the neodymium iron boron magnetic body appearance eighties in last century, because its excellent magnetic property is rapidly in electronics, communication, friendship
The fields such as logical transport, automatization, medical treatment and new forms of energy obtain and are widely applied.Up to the present, Nd-Fe-B permanent magnet material is comprehensive
Close the most excellent permanent magnet material of magnetic property, be described as " magnetic king ", to device miniaturization, integrated and high efficiency, there is important meaning
Justice.
Divide by preparation method, neodymium iron boron magnetic body is broadly divided into sintering, bonding, hot pressing/heat distortion magnet, wherein to sinter neodymium
Ferrum boron consumption is maximum.The preparation technology of Sintered NdFeB magnet mainly obtains Nd Fe B alloys using strip casting, then will
Alloy grinds the single crystal grain obtaining 3-5 μm, monocrystalline magnetic powder particle is put into oriented moulding in magnetic field and obtains green compact, green compact are existed
1040-1100 DEG C of temperature sintering obtains sintered NdFeB blank, and blank finally gives sintered NdFeB through over mechanical processing again and produces
Product.Aborning, in addition to small part larger product can be obtained by monolithic molding, other most of sintered NdFeBs
Product is required for machining, and compound material utilization rate is about 66%, and material is sharp for some thin slices and special-shaped product
With rate less than 50%.The particularly special-shaped thin wall product such as magnet ring or magnetic shoe, because magnetic powder poor fluidity causes green density uneven
Even, the deformation that the shrinkage ratio difference in sintering process causes product is even ftractureed, thus affecting yield rate and the material of product
Material utilization rate.In addition, during the preparation radiation particular orientation product such as ring, due to being limited by core sataration it is impossible to obtain magnetic field strong
Spend very high (more than 1t) radially oriented magnetic field, thus limiting the development of radiation magnetic loop.
The preparation technology of hot pressing/thermal deformation neodymium iron boron magnetic body is that granularity is about 200 μm of nanocrystalline fast quenching neodymium-iron-boron
Powder obtains isotropic magnet in 500-600 DEG C of hot pressing densification, and then at 850-950 DEG C, thermal deformation obtains anisotropy again
Neodymium iron boron magnetic body.In general, the HCJ of hot pressing/heat distortion magnet is more slightly higher than sintered NdFeB, this is because
The temperature that hot pressing/thermal deformation adopts is lower than sintering temperature, and the time is short, so crystal grain is more tiny.And hot pressing/heat distortion magnet can
To realize dead size or to connect near-net-shape, can also effectively suppress the strain cracking of magnet simultaneously, so material use
Rate is higher.The major defect of hot pressing/heat distortion magnet is high cost.Nanocrystalline rapidly quenched magnetic powder price first used by hot pressing is relatively
High;Thermal deformation technique production efficiency is very low simultaneously, so production cost is high.
Agglutinate neodymium-iron-boron magnet is also using the preparation of nanocrystalline rapidly quenched magnetic powder, will by adding a certain proportion of bonding agent
The magnet that magnetic powder is bonded to.The stock utilization of Agglutinate neodymium-iron-boron magnet is very high, close to 100%, and can realize abnormity product
The preparation of product.The disadvantage of Agglutinate neodymium-iron-boron is that magnetic property is low, and Agglutinate neodymium-iron-boron magnet magnetic energy product is mostly in 60-90kjm-3.
In sum, the advantage of Sintered NdFeB magnet is that magnetic powder is cheap, simple production process, efficiency high, low cost;Lack
Point is that stock utilization is low, yielding cracking.The advantage of hot pressing/heat distortion magnet is that magnet crystal grain is tiny, and stock utilization is high;
Shortcoming is that magnetic powder (the special quenched powder of hot pressing/thermal deformation) price is high, and thermal deformation efficiency is low, high cost.Agglutinate neodymium-iron-boron magnet
Advantage is that stock utilization is high, it is possible to achieve the production of special-shaped magnet;Major defect is that magnetic property is low, Agglutinate neodymium-iron-boron magnet magnetic
Energy product is mostly in 60-90kjm-3.
Content of the invention
The present invention is above-mentioned in order to overcome the shortcomings of to exist in prior art, there is provided one kind can improve stock utilization
And realize the method preparing rare earth permanent-magnetic material of sustainable development.
To achieve these goals, the present invention employs the following technical solutions:
A kind of method preparing rare earth permanent-magnetic material, comprises the steps:
(1) magnetic powder prepares: chooses sintered NdFeB blank, waste and old neodymium iron boron magnetic body or the neodymium after over cleaning and drying
Ferrum boron leftover pieces, are broken into more than 10 μm of neodymium iron boron powder;
(2) oriented moulding: neodymium iron boron powder is applied with the alignment magnetic field of 0.2-1.5t, makes neodymium iron boron green compact;
(3) pressure sintering: neodymium iron boron green compact are placed in the cavity of pressure sintering mould, pressure sintering mould is in
Airtight space, under vacuum or inert gas shielding, is warming up to 450~900 DEG C, and pressurize 1~200mpa, pressurize 10 seconds~10
Minute carries out pressure sintering, and then cooling is taken out;
(4) heat treatment: the magnet after pressure sintering is inserted and in vacuum drying oven, carries out double tempering heat treatment, using 850~
950 DEG C are incubated 1~8 hour, then are incubated 0.5~6 hour using 350~650 DEG C, prepared neodymium iron boron magnetic body.
In the present invention, choose sintered NdFeB blank, waste and old neodymium iron boron magnetic body or the neodymium ferrum after over cleaning and drying
Boron leftover pieces carry out powder processed, can improve stock utilization, can also realize waste and old neodymium iron boron magnetic body efficient circulation simultaneously and utilize,
Thus realizing the sustainable development of Rare-earth Permanent Magnet Industry.Obtained neodymium iron boron powder diameter is apparently higher than traditional sintering neodymium ferrum
Boron magnetic powder, so magnetic powder good fluidity;Required alignment magnetic field is low, it is possible to achieve the batch of the particular orientation magnet such as radiation ring
Steady production;Pressure sintering is carried out by pressure sintering mould so that magnet overall dimensions close to final finished size, material
Utilization rate is high.
Preferably, in step (1), choose sintered NdFeB blank, waste and old neodymium iron boron magnetic body or through over cleaning and
The neodymium iron boron powder that neodymium iron boron leftover pieces after drying are broken into more than 10 μm is polycrystal powder.Using polycrystalline bulky grain magnetic powder system
, so that magnetic powder good fluidity, production efficiency height, the little cracking of deformation of products is few for standby magnet.
Preferably, in step (1), the average particle size range of prepared neodymium iron boron powder controls at 50-300 μm.It is in
More preferably, production efficiency is higher for neodymium iron boron powder flowbility in this particle size range, and the less cracking of deformation of products is less.
Preferably, in step (1), after prepared neodymium iron boron powder, adding rich rare earth alloy powder, rich rare earth closes
Bronze end constituent be: one or more of Rare Earth Elements of Praseodymium, neodymium, dysprosium, terbium, other non-rare earths be aluminum, copper,
One or more of gallium, ferrum, and the mass percent sum of Rare Earth Elements of Praseodymium, neodymium, dysprosium, terbium is more than 50%;Rich rare earth alloy
The adding proportion of powder is the 0-30% of Nd Fe B alloys powder, and described rich rare earth alloy powder average particle size range controls
0.3-10μm.The temperature of pressure sintering so can be reduced, contribute to inhibiting grain growth and extend the use of pressure sintering mould
Life-span, improve production efficiency;Rich rare earth alloy powder is added by crystal boundary simultaneously and improves grain boundary structure, improve magnet consistency,
Thus improving hast weightlessness and the yield rate of magnet.
Preferably, in step (3), pressure sintering mould is in an airtight space, in vacuum or noble gases
Under protection, it is warming up to 650~850 DEG C, pressurize 3~100mpa, pressurize carries out pressure sintering in 10 seconds~10 minutes, then cooling takes
Go out.
Preferably, in step (4), double tempering heat treatment: it is incubated 2~6 hours using 880 DEG C, then using 450~
620 DEG C are incubated 2~4 hours.
The invention has the beneficial effects as follows:
1st, magnetic powder good fluidity, production efficiency is high, and the little cracking of deformation of products is few;
2nd, alignment magnetic field is low, it is possible to achieve the batch steady production of the particular orientation magnet such as radiation ring;
3rd, pressure sintering is carried out using pressure sintering mould, magnet overall dimensions are close to the size of final finished, material profit
High, the low cost with rate, magnetic property is high.
Specific embodiment
With reference to specific embodiment, the present invention will be further described.
Embodiment 1:
1st, composition is nd26.25pr8.75fe64b1The sintered NdFeB blank Mechanical Crushing of (weight/mass percentage composition) becomes average
Particle diameter is 200 μm of granule;
2nd, the magnetic field of 1t, green compact size r8.1 × r3.6 × 10, green compact weight 29.97g are applied;
3rd, green compact are placed in the cavity of pressure sintering mould, pressure sintering mould is in an airtight space, first takes out
Empty to 8 × 10-3Pa, then applying argon gas are to 8 × 104Pa, then heats to 850 DEG C, and the thickness direction along sintered NdFeB green compact adds
Pressure 200mpa, pressurize cools down after 6 minutes and takes out;
4th, the magnet after pressure sintering is inserted in vacuum drying oven and carries out heat treatment, be respectively adopted 900 DEG C insulation 4 hours and
4 hours technique of 500 DEG C of insulations carries out heat treatment to hot pressing blank, and prepared specification is the magnet of r8.1 × r3.6 × 5.3, material profit
With rate 100%, no arrisdefect cracking, yield rate 100%.
Embodiment 2:
Composition is nd26.25pr8.75fe64b1The sintered NdFeB blank Mechanical Crushing of (weight/mass percentage composition) becomes average grain
Footpath is 50 μm of granule.Add 5%nd in polycrystalline neodymium iron boron particles70cu30(weight/mass percentage composition) richness rare earth alloy powder,
The mean diameter of wherein neodymium copper alloy powder is 3 μm.Temperature during pressure sintering is 700 DEG C, other techniques and embodiment 1 phase
With.
Embodiment 3:
The leftover pieces of sintered NdFeB are broken into 300 μm of polycrystalline particle through over cleaning with after drying, then add 5%
nd70cu30(weight/mass percentage composition) richness rare earth alloy powder, the mean diameter of neodymium copper alloy powder is 3 μm.Using 0.5t radiation
Magnetic field orientating is obtained the annular green compact of φ 30 × φ 24 × 20.Temperature during pressure sintering is 650 degrees Celsius, other techniques and reality
Apply example 1 identical.
Comparative example 1:
Using with batch magnetic powder oriented moulding, green compact specification 43.56 × 39.6 × 29.82, by conventional sintering work with embodiment 1
Skill is in 1068 DEG C of sintering densifications, technique heat treatment same as Example 1.
Sintering blank specification 33 × 30 × 2, wire cutting become the black-film of r8.1 × r3.6 × 5.5 and carry out inside and outside arc mill plus
Work, finally gives the magnet of r8.1 × r3.6 × 5.3, stock utilization 76%, and 0.3 yuan of machining expense/only, the course of processing
In have arrisdefect, yield rate 98%.
Embodiment 1, embodiment 2 are shown in Table 1 with the preparation technology of comparative example 1 and product attribute contrast.Embodiment 1 basically reaches
Dead size molding, can be in order to avoid processing for the not high product of tolerance, and stock utilization is close to 100%, but the product of embodiment 1
Product hast weightlessness is bigger.Embodiment 2 is added rich rare earth alloy powder by crystal boundary and is improved grain boundary structure, improve magnet consistency from
And improve hast weightlessness and the yield rate of magnet.Comparative example 1 adopts traditional method to prepare, and product needed adds through wire cutting mill
The operations such as work, greatly reduce stock utilization, increased processing cost simultaneously.
The preparation technology of table 1 embodiment 1, embodiment 2 and comparative example 1 and product attribute
|
Densification temperature |
Stock utilization |
Hast is weightless |
Machining is taken |
Yield rate |
Embodiment 1 |
850℃ |
~100% |
2mg/cm2 |
0 |
99% |
Embodiment 2 |
700℃ |
~100% |
0.5mg/cm2 |
0 |
~100% |
Comparative example 1 |
1068℃ |
76% |
1mg/cm2 |
0.3 yuan/only |
97% |
Neodymium iron boron magnetic body items magnetic property index using different process preparation is shown in Table 2.Embodiment 3 can realize high-performance
The preparation of thin-walled magnet ring product.Compared with thin-walled magnet ring similar on market, embodiment 3 has obvious price advantage.And implement
In example 3, magnetic powder particle is larger, good fluidity, and the alignment magnetic field of needs is low, is conducive to producing in batches.
The neodymium iron boron magnetic body items magnetic property index of table 2 different process preparation
From above-mentioned Tables 1 and 2, embodiment 1, the comparison of embodiment 2, embodiment 3 and comparative example 1 understand, with traditional handicraft
Contrast, the present invention using polycrystalline bulky grain magnetic powder prepare magnet particularly particular orientation magnet when, it is high to have a stock utilization, becomes
This low, advantage such as magnetic property height.