The product of a kind of anisotropy rare earth permanent magnet powder preparation technique and equipment and preparation
Technical field
The present invention relates to a kind of preparation technology and device and product of anisotropy rare earth permanent magnet powder, be specifically related in the magnetic preparation process, apply magnetic field and improve associated magnetic performances such as degree of anisotropy.
Technical background
Bonding NdFeB magnet has excellent magnetism energy, mechanical performance, good machinability, have very big application and development prospect, market demand phenomenal growth has been widely used in automobile, computer peripheral equipment, electronics, office automation and other electronic devices at present.Bonded rare earth permanent magnetic is mainly used in the stator or the rotor magnet of various micromachines in information industry, information products require micromachine export higher power when reducing volume, so require magnet to have higher magnetic property, littler, accurate dimensions more.Consider above factor, on the basis of selecting unique rare-earth iron-based permanent magnetism NdFeB that reaches practicability for use, anisotropy permanent magnetism is an inevitable developing direction of bonded permanent magnet.The anisotropic magnetic powder, preparation method thereof is exactly the method by HDDR except the forge hot casting, and this method is the NdFeB virgin alloy to be heated to 750~950 ℃ inhale H-H reaction in hydrogen, makes principal phase Nd
2Fe
14Disproportionation takes place and decomposes in B, makes the dehydrogenation program of disproportionation phase releasing hydrogen gas generation reverse transformation after this, obtains the tiny anisotropic magnetic powder of crystal grain.
The parameter of investigating anisotropic magnet powder mainly contains coercivity iHc, remanent magnetism Br and degree of anisotropy etc.Wherein iHc is relevant with the magnetic grain size, and the more little degree of anisotropy of crystal grain is just big more; Remanent magnetism Br depends primarily on degree of anisotropy, and crystal orientation is consistent more, and promptly degree of anisotropy is high more, and remanent magnetism Br is just big more, and end reaction is that magnetic energy product (BH) m is just big more.
Degree of anisotropy can be represented with DOA (Degree Of Alignment), be formulated as:
DOA=(Br
//-Br
⊥)Br
//
In the formula: Br
//Expression is parallel to the remanent magnetism that the magnetic field orientating direction obtains
Br
⊥The remanent magnetism that expression obtains perpendicular to the magnetic field orientating direction
Isotropic magnetic DOA=0, Qu Xiang sample DOA=1 fully, DOA is big more, and anisotropy of material is strong more, is impossible but in fact reach 1.Aspect the preparation method of anisotropic magnet powder, like to know that there has been patent application in companies such as making steel.Mitsubishi has found that at first the HDDR method of NdFeB produces anisotropic magnet powder, its in 88106845.4 and 92113705.2 SEPARATE APPLICATION microstructure patent and technology patent; And like to know that the system steel has further developed HDDR technology, proposing RFeB in 01140696.8 patent is hydride (RFeBHx) and the R1 element (monomer of one or more compositions among Tb, Dy, Nd, the Pr, alloy, compound or by its spread powder of forming) mix, the anisotropic magnet powder that counterdiffusion obtains high-coercive force is carried out in heat treatment; In 96103173.5,, propose to carry out opposite reaction and produce the heat that absorbs when identical heat balance rare earth magnet powders is inhaled the heat of hydrogen generation and dehydrogenation with a kind of compensative material at the uppity problem of temperature in the HDDR technology.99123355.7 effect and the multistep hydrogen treatment process of middle proposition Nb and Ga propose in 20048001073.7 and 200510070024.5 to increase after the stage in disproportionation and organize stabilization process, and prepare (R with this technology
1-xLa
x)
12-14Fe
BalB
9-10It is the high-temperature stability anisotropic powder; 200410085531.1 propose the technology that anisotropy NdFeB magnetic and SmFeN powder are mixed and made into the magnetic of high magnetic characteristics.
Prepare aspect the equipment at anisotropic magnet powder, like to know that the system steel applied for that in 96103173.5 a kind of anisotropic magnet powder prepares equipment, synchronously carry out the heat that absorbs when opposite reaction produces the heat that produces when identical heat comes balanced because described rare earth magnet powders suction hydrogen and dehydrogenation with a kind of compensative material.98125398.9 middle adding thermal compensation device and a bearing part, bearing part moves up and down reaction raw materials and enhances productivity.Domestic patent 200710061622.5 has also proposed a kind of externally heating type rotating vacuum furnace, has guaranteed reaction uniformity and accuracy control over temperature.
Above-mentioned domestic and international patent or relevant anisotropic magnetic powder preparation technique patent, or relevant magnet prepares related magnetic preparation technology in the patent, or the preparation facilities of magnetic, the preparation technology that all to have related to relevant rare earth R-T-B to some extent be anisotropic magnet powder.But all do not relate to and in preparation process, apply magnetic field and improve the anisotropy of magnetic and the crystalline form situation for preparing magnetic by this kind method.
In the multiple processing procedure of different magnetic materials, all observe the phenomenon that high-intensity magnetic field is induced texture structure, aspect preparing at anisotropic magnet powder, the present magnetic anisotropy for preparing by traditional process is all below 0.6, and the magnetic particle capability loss is more.
Summary of the invention
The object of the present invention is to provide a kind of preparation method who prepares the high anisotropy magnetic, implement the device of this method and the anisotropic magnet powder for preparing according to this device.
Can know by theory of magnetism, magnetic field is by making the material magnetization, change thermodynamics and kinetics condition in the material processed process, even directly influence the behaviors such as migration, coupling, complexing of atom in the material, molecule or ion, can produce influence profound, essence to tissue, micro-structural and the performance of material.Concerning magnetic material, because magnetocrystalline anisotropy, apply magnetic field and can in material, produce the grain-oriented magnetocrystalline anisotropy energy of dependence, thereby for crystal boundary migration provides additional driving force, in Fe base alloy, because<001〉direction magnetic conductivity maximum, so its magnetocrystalline anisotropy energy is minimum, be that the free energy that magnetic field causes increases minimum, thereby promote the grain growth of<001〉crystal orientation parallel magnetic field direction, therefore can needed texture orientation.
Apparatus of the present invention and method make hydrogenization method prepare anisotropic magnet powder an induced by magnetic field in certain embodiments, because when the crystal of composition material had obvious magnetic anisotropy, crystal was with the magnetized energy difference of different crystallographic axis parallel magnetic fields.The difference of this magnetic energy is the driving force that crystal is orientated in magnetic field, therefore can use the texturing of induced by magnetic field material structure.Behind the NdFeB material process high temperature hydrogenation process, the disproportionation tissue can act on magnetic energy minimum crystal orientation preferential growth in lower edge in magnetic field, thereby makes the tissue that finally prepares have better magnetic anisotropy.
The technology that application apparatus of the present invention are carried out anisotropic magnet powder comprises following several steps:
(1) at first contain the rare-earth element R that comprises Sc and Y, and iron, elements such as boron are the alloy of main component, are 10~90kPa in the pressure size, temperature range is that 650~900 ℃ of high temperature that carried out 30 minutes to 3 hours are inhaled the hydrogen processing procedure;
(2) to product through obtaining after the high temperature hydrogen treatment operation, be that 0.1~10kPa and treatment temperature T2 are under 750~950 ℃ the condition at the permanent magnetic field, the hydrogen dividing potential drop P2 that keep applying 0.05-10kOe, carry out dehydrogenation operation under the magnetic field that 0.1~3h handles;
(3) discharge with the hydrogen in the environment with through hydrogen residual in the product that obtains after the dehydrogenation operation processing under the magnetic field, and the vacuum of carrying out is forced the dehydrogenation operation;
(4) the pressure refrigerating work procedure that environment and product are carried out.
This kind anisotropy rare earth permanent magnet powder preparation technique, the permanent magnetic field magnitude range that applies in step (2) is preferably 0.1-3kOe, and the duration is 0.1~2.5h.
This kind anisotropy rare earth permanent magnet powder preparation technique, the hydrogen dividing potential drop P2 scope that is kept in step (2) is 2-6kPa.
This kind rare earth aeolotropic rare earth permanent magnet powder preparation technique before above-mentioned high temperature hydrogen treatment operation, comprises that also with R-Fe-B be the low temperature hydrogenation treatment process that alloy carried out 30 minutes to 3 hours under 50-500 ℃ of temperature.
Force to get rid of the hydrogen in the reaction environment, carry out carrying out water-cooled or air-cooled after vacuum forces dehydrogenation to be handled, obtain the Magnaglo of high anisotropy degree, the chemical expression of described high anisotropy rare earth permanent magnet powder be (R '
1-xNd
x)
zM
yFe
100-z-y-δB
δ, wherein, the content of each composition in the formula is in atm%, and R ' is one or more in all rare earth elements that comprises Sc and Y except that Nd, x=0~1; M is one or more in the following metallic element: Zr, Hf, Mn, Ti, Si, V, Co, Ni, Cr, Mo, Al, Nb, Ga, In, Cu and Zn, y=0~2, z=11.5~14, δ=6~12.
R ' is preferably one or both in all rare earth elements that comprises Sc and Y except that Nd, R ' more preferably in the rare earth element of Pr, Dy, Gd, Ho, Ce and La one or both.M be preferably in Zr, Hf, Mn, Ti, Si, V, Co, Ni, Cr, Mo, Al, Nb, Ga, In, Cu and the Zn metallic element a kind of, two or three.
M is one or more in the following metallic element: Zr, Hf, Mn, Ti, Si, V, Co, Ni, Cr, Mo, Al, Nb, Ga, In, Cu and Zn, M be preferably in Zr, Hf, Mn, Ti, Si, V, Co, Ni, Cr, Mo, Al, Nb, Ga, In, Cu and the Zn metallic element a kind of, two or three.
The virgin alloy that is prepared anisotropic magnet powder is polycrystalline ingot casting or the rapid hardening thin slice that contains column crystal, virgin alloy for have (R '
1-xNd
x)
zM
yFe
100-z-y-δB
δThe content of each composition in the formula is in atm%; the 0.3mm of ratio of components~0.9mm rapid hardening thin slice or common ingot casting; with alloy through 900 ℃~1170 ℃; the Ar gas shiled heat treatment of 5~25h or do not handle is eliminated in the thick band alloy a spot of α-Fe and is made the abundant alligatoring to 50 of main phase grain broad ways~250 μ m.
Equipment provided by the invention is mainly by the magnetic field orientating heating system, flow control system, and vacuum system three parts are formed; Heating and magnetic field orientating system are provided with high temperature resistant quartz ampoule (1) in body of heater (2), in the body of heater (2) and be provided with heating control apparatus (6) and thermocouple (5), outer wall at body of heater (2) is surrounded by water collar (4), around solenoid (3), solenoid power supply (7) connects solenoid (3) by magnetic field sensor (19) in water collar (4) outer peripheral; Water collar (4) connects water-cooling system by circulating water pipe (8); High temperature resistant quartz ampoule (1) is an enclosed construction, and its entrance point is provided with air inlet that is connected with air inlet pipe and the vacuum orifice that is connected with vacuum-pumping tube.
Flow control system is connected in series pressure maintaining valve (9), Pressure gauge (13), flow stabilizing valve (10), flowmeter (12) and switch valve (11) respectively by source of the gas and taps into tracheae afterwards and form.
Vacuum system is the import that is connected mechanical pump (18) by the outlet of diffusion pump (17), the outlet serial connection of mechanical pump (18) switching valve (14) of bleeding, and switch valve (15), vacuum meter (16), and be connected with vacuum-pumping tube.
The permanent magnetic field intensity that the solenoid of this apparatus characteristic (3) is produced is regulated by solenoid power supply (7) in the 0.05-10kOe scope.
The environment facies of preparation anisotropic magnet powder of the present invention to the traditional preparation process environmental advantages are:
1. has a magnetic field orientating device in the preparation facilities provided by the invention
Anisotropic magnet powder preparation facilities principal focal point concentrates on change temperature and pressure situation and obtains excellent anisotropic magnetic generally speaking, this method is induced crystal structure and forming core by applying magnetic field, the influence of the unmanageable temperature and pressure condition that weakened to magnetic particle capability.
2. preparation facilities provided by the invention has a flow control system
Preparation facilities provided by the invention has a flow control system, can be used by the trace of the flowmeter in the flow control system, flow stabilizing valve and vacuum system and the switching valve of bleeding in a large number, can accurately control reaction condition by experimental needs.
Description of drawings
Carry out multistep hydrogen Processing of Preparation anisotropic magnet powder schematic diagram under the situation of Fig. 1 magnetic field.
The high temperature resistant quartz ampoule of being numbered among the figure: 1-, 2-heating furnace body, 3-solenoid, 4-water collar, 5-thermocouple, 6-heating control apparatus, 7-solenoid power supply, 8-circulating water pipe, 9-pressure maintaining valve, 10-flow stabilizing valve, 11-switch valve, 12-flowmeter, 13-Pressure gauge, 14-trace bleed in a large number switching valve, 15-switch valve, 16-vacuum meter, 17-diffusion pump, 18-mechanical pump, 19-magnetic field sensor.
Fig. 2 is the schematic diagram that carries out magnetic field multistep hydrogen Processing of Preparation anisotropic magnet powder, and wherein abscissa is the processing time, and ordinate is for handling hydrogen pressure and temperature.Time, temperature and hydrogen pressure scope that black matrix is partly handled for magnetic field, dotted line is cut apart magnetic field dehydrogenation and two stages of high temperature hydrogenation, and bullet is the end point of each stage of reaction.
The specific embodiment
With example rare-earth magnetic of the present invention and preparation method thereof is further described below, will helps to understand better the characteristics and the advantage of middle rare earth magnetic of the present invention.Protection domain of the present invention is not limited by the following examples, and protection scope of the present invention is determined by claims.
(1) implements alloy
Choose rare earth alloy (R '
1-xNd
x)
zM
yFe
100-z-y-δB
δ(atm%) alloy cast ingot or rapid hardening thin slice, rare earth element mainly is made up of Nd, in all Sc, Y and lanthanide, Nd
2Fe
14B each side magnetic property is the highest, but the adding of other rare earth elements is to Nd
4Fe
14The B coercivity, aspect performances such as temperature stability have the improvement effect, add other rare earth elements on the basis of this patent rare earth Nd and carry out certain modification, wherein optimum element is Pr, Gd, Ho, Dy etc., wherein the adding of Gd, Ho has certain effect to improving temperature stability, and the adding of Dy can improve the coercivity of magnetic.
In addition, NdFeB is to be iron as main component in the alloy, and when all as 100atm%, ideal is to contain the R of 10~14atm% and the B of 6~12atm%, if Nd content is lower than 10atm%, α-Fe will separate out mutually, causes magnetic property to descend; If Nd content surpasses 14atm%, R
2Fe
14B will reduce mutually, equally also cause magnetic property to descend.On the other hand, if the content of B is lower than 6atm%, R
2Fe
17To separate out mutually, and cause magnetic property to descend, B content surpasses 12atm%, R
2Fe
14B reduces mutually, equally also causes magnetic property to descend.B content is higher than 10atm%, can suppress separating out of a-Fe.
The adding of transition element M is mainly the partial properties of improving magnetic, is the effective element that improves remanent magnetism as Nb, and Ga has very important effect to the coercivity that improves magnetic, and wherein the content of Ga is preferably 0.01%~2at%, and optimum content is 0.1~0.6at%.If Ga contains quantity not sufficient 0.01%, the effect of modification will be can not get; On the other hand, the content of Ga surpasses 2at%, causes the minimizing of iHc conversely.The content of Nb is preferably 0.01%~1at%, and optimum content is 0.1~0.4at%, if Nb contain quantity not sufficient 0.01%, the effect of modification will be can not get, Nb content surpasses 1atm%, cause the passivation of high temperature disproportionated reaction, and compound interpolation Ga and Nb can improve magnetic coercivity and degree of anisotropy.
Generally speaking, among Zr, Hf, Mn, Ti, Si, V, Co, Ni, Cr, Mo, Al, Nb, Ga, In, Cu, the Zn one or more, performances such as the anisotropy that improves magnetic and coercivity are played an important role, content preferably is controlled within the 2atm% scope, content is crossed the major general and is made DeGrain, content too much will the rare earth dephasign, causes magnetic property to descend.
Quartz ampoule 1 is put in the coarse crushing after annealing of above-mentioned alloy, seals quartz ampoule 1, as shown in Figure 1.Mainly acting as of annealing reduces dephasign content in the alloy, homogenising tissue etc., and the crystal grain of growing up simultaneously has certain booster action to the HDDR process.
(2) preparation technology
Begin to open vacuum system after checking gas circuit connection situation, as shown in Figure 1, open trace bleed in a large number switching valve 14, switch valve 15 successively, vacuumize, treat to close vacuum system after vacuum that vacuum meter 16 is surveyed reaches setting value with diffusion pump 17 and mechanical pump 18; Open air-channel system, open pressure maintaining valve 9, flow stabilizing valve 10, switch valve 11 successively, charge into hydrogen, wherein, flowmeter 12 can be surveyed the flow of the hydrogen that enters quartz ampoule 1, and Pressure gauge 13 can be surveyed the pressure that charges into hydrogen.Carry out the processing of multistep hydrogen according to the technology that configures and carry out the preparation of anisotropic magnetic powder, wherein, control the pressure of the hydrogen of quartz ampoules 1 by pressure maintaining valve 9, flow stabilizing valve 10, switch valve 11; By the temperature in the heating control apparatus 6 control quartz ampoules 1; By magnetic field sensor 19 and electromagnet control device 7 control solenoids 3, with the intensity in the magnetic field in the control quartz ampoule 1; Water collar 4 connects water-cooling system by circulating water pipe 8, so that 2 coolings of control body of heater.
At first at 90~150kPa, the low temperature that carried out below 50-500 ℃ 30 minutes to 3 hours is inhaled hydrogen; Then at 10~90kPa, the high temperature that carried out 30 minutes to 3 hours under 650~900 ℃ of conditions is inhaled the hydrogen process; Under 0.05-10kOe magnetic field, carry out dehydrogenation processing under the magnetic field in 750~950 ℃ of scopes, rapid cooling obtains high magnetic anisotropy, high performance magnetic after vacuum is forced dehydrogenation then.
The effect that low temperature is inhaled hydrogen is mainly the hydrogen diffusion admittance of opening the high temperature disproportionation stage, makes the high temperature disproportionation more even.But concerning the RFeB alloy, it is not necessary operation that low temperature is inhaled hydrogen, and a small amount of raw material of handling also can carry out this operation simultaneously at hot stage, concerning the raw material of a large amount of processing, can carry out this low temperature hydrogenation process and carry out steady production.
High temperature is inhaled the hydrogen process at 10~90kPa, 650~900 ℃, carry out under 30 minutes to the 3 hours conditions, wherein hydrogen pressure is arranged on 10~90kPa scope, too high hydrogen pressure makes reaction speed too fast, is unfavorable for reacting evenly carrying out, when hydrogen pressure is lower than 10kPa, reaction does not reach thermodynamic power and learns condition, thereby makes reaction carry out difficulty.Temperature is in 650~900 ℃ of scopes, and temperature is below 650 ℃ the time, and reaction can not be carried out, and when surpassing 900 ℃, is difficult to separate out Fe from supersaturation Fe
2B, reaction speed is too fast simultaneously, is difficult to form tissues needed and structure, causes magnetic remanent magnetism to reduce.The time range of 30min~3h guarantees to react evenly carries out fully.
The magnetic field dehydrogenation again chemical combination the processing stage at 0.05~10kOe, carry out in 750~950 ℃ of scopes.Magnetic field greater than 10kOe is not only not obvious to improving the magnetic anisotropy, and is difficult to reach on equipment.Because dehydrogenation chemical combination processing again is the endothermic reaction, need carry out under certain temperature range, temperature is lower than 750kPa makes the material dehydrogenation incomplete, also has the not disproportionation phase of complete reaction in the product, temperature is higher than 950 ℃ makes tiny grain growth behind the chemical combination again, reduces the magnetic coercivity.
Vacuum forces to adopt water-cooled or air-cooled after the dehydrogenation, makes material remain on the tiny crystal grain state of high temperature, avoids in cooling procedure crystal grain to grow up.
(3) equipment state
The device of using under the magnetic field of the present invention the preparation rare-earth magnetic as shown in Figure 1, high temperature resistant quartz ampoule 1 diameter is 5~20mm, length is 20~80mm, seals up quartz ampoule 1 after the alloy that needs to handle of packing into, stays outlet and links to each other with vacuum system with flow control system.Heating furnace body 2 is in quartz ampoule 1 outside, and thermocouple 5 and links to each other with external heated control device 6 between heating furnace body 2 and quartz ampoule 1.Quartz ampoule 1, heating furnace body 2 are nested from inside to outside with outside electromagnet axis coinciding, and heating furnace body 2 and solenoid 3 are separated by heat-preservation cotton and water collar 4.The magnetic field that solenoid 3 produces is along quartz ampoule 1 axial direction, and magnetic field intensity can dynamically be controlled in the 0.05-10kOe scope by solenoid power supply 7.
Vacuum system adopts mechanical pump 17 and diffusion pump 18 to carry out compound vacuumizing, and flow control system adopts the flowmeter 12 of 0-80ml/min.The high vacuum of vacuum system reaches 2.5 * 10
-3Pa is by can slowly filling hydrogen and keep the atmosphere that flows with being used of flowmeter 12 in reaction quartz ampoule 1.
Describe this patent by the following examples in detail.
Embodiment
(1) raw-material preparation
Be grouped into the one-tenth shown in the table 1; batch scale content of starting materials element or raw alloy; prepare and carry out induction melting or rapid hardening behind the material and get rid of band and obtain alloy; the annealing in process of carrying out uniform temperature and time then under the protection of argon gas makes alloy structure even, obtains particle diameter after the coarse crushing and is to carry out hydrogen in the corase meal access arrangement of 5-25mm and cause reaction treatment.In table 1, composition consists of atomic percent.
(2) preparation of anisotropic magnetic powder
After annealing and fragmentation, carry out the processing that hydrogen causes course of reaction according to the alloy of the composition proportion shown in the table 1.
Alloy is that the high temperature of handling under P1 and the treatment temperature T1 condition is inhaled the hydrogen operation keeping the hydrogen dividing potential drop;
Inhale the suction hydrogen product that obtains after the hydrogen operation is handled through high temperature, keep applying certain permanent magnetic field, the hydrogen dividing potential drop is under P2 and the treatment temperature T2 condition, dehydrogenation operation under the magnetic field of handling.
Discharge with the hydrogen in the environment with through hydrogen residual in the product that obtains after the dehydrogenation operation processing under the magnetic field, and the vacuum of carrying out is forced the dehydrogenation operation.
The pressure refrigerating work procedure that environment and product are carried out at last.
The condition that is responded is as shown in table 2
So just prepare and have good anisotropic Magnaglo.
Gained magnetic powder particle size accounts for 90% of total amount between 25 μ m~1000 μ m.The magnetic crystalline form is mainly uniform column crystal, and column crystal volume ratio accounts for 90%, and grain size all below 300 μ m, is analyzed magnetic and magnet performance and seen Table 2.
Magnetic is estimated
By embodiment 1#-12# as can be seen, the raising that every magnetic property and the degree of anisotropy by magnetic after the magnetic-field heat treatment all had a lot of degree, wherein degree of anisotropy is all more than 0.75.