CN108122654B - Grain boundary diffusion heavy rare earth neodymium iron boron magnetic material and preparation method thereof - Google Patents
Grain boundary diffusion heavy rare earth neodymium iron boron magnetic material and preparation method thereof Download PDFInfo
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- H01F1/057—Alloys characterised by their composition containing rare earth metals and magnetic transition metals, e.g. SmCo5 and IIIa elements, e.g. Nd2Fe14B
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Abstract
The invention relates to the field of permanent magnets, in particular to a grain boundary diffusion heavy rare earth neodymium iron boron magnetic material and a preparation method thereof, and the technical scheme of the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material is that the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material comprises a magnetic material body and a surface coating attached to the surface of the magnetic material body, wherein the magnetic material body comprises Pr: 4-6.2 wt%, Nd: 18-25 wt%, Dy: 0.8-1.5 wt%, B: 0.8 to 2.8 wt%, Cr: 2.2-4.2 wt%, Al: 0.1 to 0.4 wt%, Cu: 0.1 to 0.4 wt%, Zr: 0.1-0.4 wt% and the balance of Fe, wherein the surface coating comprises an inner heavy rare earth layer and an outer anticorrosive layer, so that the coercive force of the magnet is improved, the residual magnetic induction intensity and the magnetic energy product are not reduced, the comprehensive magnetic property is good, and the anticorrosive performance is good.
Description
Technical Field
The invention relates to the field of permanent magnets, in particular to a grain boundary diffusion heavy rare earth neodymium iron boron magnetic material and a preparation method thereof.
Background
The sintered NdFeB magnet is widely used due to its excellent magnetic properties such as high saturation magnetic induction, high coercive force, and high magnetic energy product, and particularly in the field of new energy vehicles, the demand for NdFeB magnets is rapidly increasing. However, because the operating temperature of a new energy automobile is generally about 200 ℃, the coercive force is required to be more than 30kOe or more than 33kOe, and the neodymium iron boron magnet is required to have high remanence (more than 12KGs) and magnetic energy product (more than 37 MGOe).
Heavy rare earth is added by an alloying method to form a high magnetocrystalline anisotropy (NdDy)2Fe14B hard magnetic phase, so that the coercive force of the magnet can be obviously improved, and the magnetic performance attenuation caused by high temperature can be reduced, but simultaneously, Dy atoms and Fe atoms can form anti-iron coupling to cause the reduction of residual magnetic induction strength and magnetic energy product, and the magnetic field intensity of the permanent magnet can be reduced under the limit environment at high temperature. Therefore, it is difficult to obtain high-performance Nd-Fe-B magnetic material by adding heavy rare earth by alloying method.
Disclosure of Invention
The invention aims to provide a grain boundary diffusion heavy rare earth neodymium iron boron magnetic material and a preparation method thereof.
The technical purpose of the invention is realized by the following technical scheme:
the utility model provides a grain boundary diffusion heavy rare earth neodymium iron boron magnetism material, includes magnetism material body and adheres to the surface coating on magnetism material body surface, magnetism material body includes Pr: 4-6.2 wt%, Nd: 18-25 wt%, Dy: 0.8-1.5 wt%, B: 0.8 to 2.8 wt%, Cr: 2.2-4.2 wt%, Al: 0.1 to 0.4 wt%, Cu: 0.1 to 0.4 wt%, Zr: 0.1-0.4 wt%, and the balance of Fe, wherein the surface coating comprises an inner heavy rare earth layer and an outer anti-corrosion layer.
Through adopting above-mentioned technical scheme, include when the magnetism material body: pr: 4-6.2 wt%, Nd: 18-25 wt%, Dy: 0.8-1.5 wt%, B: 0.8 to 2.8 wt%, Cr: 2.2-4.2 wt%, Al: 0.1 to 0.4 wt%, Cu: 0.1 to 0.4 wt%, Zr: 0.1-0.4 wt%, and the balance of Fe, the residual magnetism, coercive force and maximum magnetic energy product of the magnetic material body are high, so that the magnetic material has good magnetic comprehensive performance, the coercive force of the neodymium iron boron magnetic material can be improved through the heavy rare earth layer, and the corrosion resistance of the neodymium iron boron magnetic material can be improved through the anticorrosive layer.
Preferably, the heavy rare earth layer includes Cr: 7.3 wt%, B: 2.4 wt%, Dy: 4.25 wt%, V: 2.7 wt%, the remainder being Fe.
By adopting the technical scheme, when the heavy rare earth layer comprises Cr: 7.3 wt%, B: 2.4 wt%, Dy: 4.25 wt%, V: 2.7 wt%, and the balance of Fe, the coercive force of the neodymium iron boron magnetic material is improved by the arrangement of the heavy rare earth layer, the remanence and the maximum magnetic energy product are not obviously reduced, and the magnetic composite material has the best magnetic comprehensive performance.
Preferably, the corrosion protection layer comprises Nb: 2.82 wt%; ti: 23 wt%; mn: 1.65 wt%; mo: 1.13 wt%, the remainder being Fe.
By adopting the technical scheme, when the anticorrosive coating comprises Nb: 2.82 wt%; ti: 23 wt%; mn: 1.65 wt%; mo: 1.13 wt%, and the balance being Fe, the corrosion resistance of the neodymium iron boron magnetic material with the anticorrosive layer is obviously improved, and the coercive force, residual magnetism and maximum magnetic energy product of the neodymium iron boron magnetic material are not obviously reduced, so that the neodymium iron boron magnetic material has the best magnetic comprehensive performance.
A preparation method of a grain boundary diffusion heavy rare earth neodymium iron boron magnetic material comprises the following steps:
s1, preparing a magnetic material body, which comprises the following steps:
a1, mixing materials, namely mixing Pr, Nd, Dy, B, Cr, Al, Cu, Zr and Fe into a first mixed powder according to the proportion in the table 1, and mixing the first mixed powder for 30min by using a V-shaped mixer;
a2, smelting and casting, namely putting the mixed powder I into a vacuum induction smelting furnace, carrying out vacuum smelting at the temperature of 1450 ℃ of 1000-.
A3, hydrogen crushing, namely putting the cast sheet into a hydrogen crushing furnace for hydrogen crushing, and crushing the cast sheet into mixed particles B.
A4, grinding by an air flow mill, and grinding the mixed particles B into mixed fine powder C with the particle size of 10-15 mu m by the air flow mill.
A5, performing magnetic field orientation shaping, and putting the mixed fine powder C into a forming press die for orientation shaping to form a blank D
A6, powder metallurgy sintering, namely putting the blank D into a vacuum sintering furnace, and sintering for 4-5h under the condition of 1040-1090 ℃ in a nitrogen atmosphere to form a compact.
S2, preparing the heavy rare earth layer, wherein the method comprises the following specific steps:
b1, slicing, namely cutting the magnetic material body into slices of 5mm by 10mm by 4 mm;
b2, removing impurities, removing an oxide layer and oil stains on the magnetic material body sheet, cleaning by alcohol, electrostatic dust removal, ultrasonic cleaning and the like, and drying for later use;
b3, mixing materials, namely uniformly mixing Cr, B, Dy, V and Fe powder in proportion to form mixed powder II;
b4, evaporation, namely putting the mixed powder II into an evaporation furnace, heating, melting, evaporating, cooling, and uniformly attaching to the magnetic material body sheet to form a metal film;
b5, performing permeation treatment, namely performing permeation treatment on the evaporated sheet for 7 hours under a vacuum condition;
b6, heat treatment, quenching, and tempering after quenching;
s3, preparing an anticorrosive layer, which comprises the following specific steps:
c1, mixing materials, namely uniformly mixing Nb powder, Ti powder, Mn powder, Mo powder and Fe powder in proportion to form mixed powder III;
c2, ball-milling and agglomerating, grinding the mixed powder III by using a ball mill, grinding the mixed powder III for 20min by using a stainless steel ball with the ball-milling medium being 8mm in diameter under the condition that the rotating speed is 226r/min, and adding absolute ethyl alcohol serving as a binder to uniformly mix after grinding is finished to prepare an agglomerate;
c3, preparing a preset layer, uniformly coating the agglomerates on the surface of the shaft body to form the preset layer, enabling the thickness of the preset layer to be about 4mm, and drying the preset layer indoors in the shade for 12 hours;
c4, laser cladding, namely performing laser cladding on the preset layer, introducing argon gas as protective gas in advance, wherein the parameters adopted in the cladding process are as follows: laser output power is 1.6-2.5 kW, scanning speed is 4-8 mm/s, the diameter of a light spot is 5mm, argon flow is 6-8L/min, lap joint rate is 35-45 wt%, and after cladding, slow cooling is performed;
c5, heat treatment, and aging treatment is carried out on the neodymium iron boron magnetic material with the anticorrosive coating.
By adopting the technical scheme, the magnetic material body is prepared by S1; slicing through B1 in S2 to slice the magnetic material body, and making sufficient preparation for subsequent grain boundary diffusion; b2, removing impurities, namely removing oil stains and oxide layers on the surface of the magnetic material body to ensure the quality of the subsequent evaporation process; b3, mixing materials, and uniformly mixing the components according to the proportion to ensure that the components of the plating layer are uniform and stable; b4, vapor plating, B5, permeation treatment, B6 and heat treatment, wherein heavy rare earth metal is used as a substitute phase to enter a main phase, and a continuous region with high rare earth content is formed at the boundary of the main phase, so that the coercive force of the neodymium iron boron product is greatly improved, and the remanence almost has no influence. Meanwhile, after the grain boundary is permeated by the heavy rare earth, the grain boundary rare earth-rich phase is more continuous and clearer, and the isolation exchange coupling effect is more effective. The result is that the coercive force is greatly improved, the remanence is hardly reduced, the use amount of heavy rare earth is reduced, the production cost is well saved, Dy atoms are diffused into the surface region of the main phase crystal grains to partially replace Nd and Pr atoms in the surface region of the main phase crystal grains in the grain boundary diffusion treatment process to form (Nd, Pr and Dy) FeB intermetallic compounds, the magnetocrystalline anisotropy constant of the surface structure defect region of the crystal grains is improved, the main phase crystal grain epitaxial layer is magnetically hardened, and the intrinsic coercive force of the magnet is obviously improved. Dy elements are enriched in the rare earth-rich phase, and Nd and Pr atoms in the surface layer region of the main phase crystal grains which are displaced enter the grain boundary phase, so that the number of the rare earth-rich phase in the microstructure is increased, and the coercive force of the magnet is improved.
Meanwhile, Cr in the heavy rare earth layer improves the strength, hardness and wear resistance of the heavy rare earth layer, and improves the oxidation resistance and corrosion resistance of the heavy rare earth layer; the compactness and the hot rolling performance of the heavy rare earth layer are improved, and the strength of the heavy rare earth layer is improved; cr and B react chemically to generate a CrB reinforcing phase, so that the structural strength of the heavy rare earth layer is improved, Cr in the heavy rare earth layer reacts with B in the magnetic material body, and B in the heavy rare earth layer reacts with Cr in the magnetic material body to generate the CrB reinforcing phase, so that the structural strength of the medium rare earth layer is improved, and the bonding strength of the heavy rare earth layer and the magnetic material body is improved; v plays a role in refining structure grains, and improves the strength and toughness of the heavy rare earth layer.
Nb in the anticorrosive coating plays a role in refining, reducing the overheating sensitivity and the tempering brittleness of the anticorrosive coating, improving the strength of the anticorrosive coating, simultaneously improving the atmospheric corrosion resistance and the hydrogen, nitrogen and ammonia corrosion resistance of the anticorrosive coating at high temperature, and microscopically preventing intergranular corrosion; mn in the anticorrosive layer is a good deoxidizer and desulfurizer, prevents sulfur impurities mixed in the anticorrosive layer from causing thermal brittleness of the anticorrosive layer, improves hardenability of the anticorrosive layer, and further improves thermal processing performance of the anticorrosive layer; mo in the anticorrosive coating plays a role of crystal grains, improves the hardenability and the heat strength of the anticorrosive coating, increases the remanence and the coercive force, has the corrosion resistance to acid, hydrogen peroxide, sulfuric acid, nitrous acid, sulfate, acid dye and bleaching powder, and prevents the pitting corrosion tendency generated by the existence of chlorine ions; ti in the anticorrosive coating improves the density of the anticorrosive coating, reduces aging sensitivity and cold catalysis, refines crystal grains from the microcosmic view and avoids intergranular corrosion; meanwhile, Ti and B in the heavy rare earth layer have in-situ self-generated reaction under the laser condition, a TiB reinforcing phase is generated, whiskers are formed, the structural strength of the anticorrosive coating and the bonding strength of the heavy rare earth layer are greatly improved, and the surface strength of the neodymium iron boron magnetic material is further improved.
Preferably, in B2, the oxide layer and the oil stain on the sheet are cleaned by ultrasonic waves.
By adopting the technical scheme, the oxide layer, the oil stain and the oxide layer are cleaned by utilizing ultrasonic waves, when the sound wave pressure transmitted by ultrasonic vibration in the oil stain and the oxide layer reaches one atmospheric pressure, the sound wave pressure peak value of the ultrasonic waves can reach vacuum or negative pressure, but no negative pressure exists actually, so that great force is generated in the oil stain and the oxide layer, the oil stain and the oxide layer are pulled and cracked into cavities which are very close to vacuum, the cavities are cracked when the ultrasonic pressure is reversely maximized, the oil stain and the oxide layer are impacted by strong impact generated by cracking, the surface of the sheet is cleaned by the ultrasonic waves, the cleaning is more thorough, and after the sheet is cleaned by the ultrasonic waves, no residue is generated on the surface of the sheet due to the ultrasonic cleaning, and the cleaning effect is good.
Preferably, the specific steps in B4 are: before vapor deposition, adding carbon particles into the vapor deposition furnace, vacuumizing the vapor deposition furnace continuously, starting vapor deposition after vacuumizing for 1h, increasing the temperature of the vapor deposition furnace to 400-.
By adopting the technical scheme, the vacuum pumping is firstly carried out for 1h, and the vacuum pumping is continuously carried out, so that the interior of the evaporation furnace is in a high vacuum state, and the situation that the second mixed powder and the second mixed powder are mixed in the evaporation process is preventedThe oxygen in the evaporation furnace is oxidized to generate a large amount of oxide layers on the surface, but the oxygen in the evaporation furnace cannot be evacuated by vacuumizing. Along with the temperature rise to 400-550 ℃, a small amount of Fe on the two surfaces of the mixed powder reacts with oxygen to generate Fe3O4And a compact oxide film is formed to prevent oxygen from continuously permeating to react with deep Fe. The reducibility of the carbon particles is continuously enhanced along with the rise of the temperature, the carbon particles react with the oxygen remained in the evaporation furnace, and the content of the oxygen in the evaporation furnace is further reduced after the temperature is kept for 2 hours. Continuously raising the temperature to 2000-plus 2200 ℃, preserving the heat for 4h, melting and evaporating the mixed powder II, uniformly attaching the mixed powder II to the surface of the slice after cooling, and raising the temperature of Fe3O4Gradually melting and evaporating, and continuously reducing Fe after carbon particles reduce oxygen in the evaporation furnace3O4Thereby Fe3O4Reduced to Fe and evaporated to the surface of the flake along with the other powder in the second mixed powder.
Preferably, the specific steps in B6 are: and (3) putting the sheet into an induction coil, carrying out induction heating surface quenching on the sheet, wherein the induction current adopts 600-plus-800 kHz, and the power is cut off after the power is turned on for 3S-4S, so that the surface of the sheet reaches 850-plus-950 ℃, introducing cooling liquid into the induction coil to rapidly cool the induction coil, and simultaneously filling cooling water into a quenching water spraying sleeve and spraying water to the sheet, thereby rapidly cooling the surface of the sheet and finishing the surface quenching.
By adopting the technical scheme, the induction current with high density is generated on the surface of the sheet by utilizing the electromagnetic induction principle, the surface of the sheet is rapidly heated to an austenite state, when alternating current with certain frequency passes through the induction coil, an alternating magnetic field with the same frequency as the current change frequency is generated inside and outside the induction coil, under the action of the alternating magnetic field, the induction current with the same frequency and the opposite direction as the current frequency in the induction coil is generated in the sheet, and the induction current forms a closed loop along the surface of a workpiece to form an eddy current. The distribution of the eddy current in the thin sheet is exponentially attenuated from the surface to the core, so that the eddy current is mainly distributed on the surface of the thin sheet, and almost no current passes through the interior of the thin sheet, namely the skin effect. By utilizing the skin effect of the eddy current, the surface of the sheet is rapidly heated to 850-.
Because the induction heating has high temperature rise speed and extremely short heat preservation time, compared with the common quenching, the induction heating has large superheat degree, more austenite nucleation and difficult growth, fine cryptocrystal martensite is obtained on the surface of the sheet after the quenching, and the surface has better mechanical property compared with the common quenching. Meanwhile, because the heating speed is high, the problems of oxidation and decarburization on the surface of the slice are not generated, so that quenching under a vacuum condition is not needed, and the use is convenient; because the interior of the thin slice is not heated, the interior of the thin slice cannot deform due to quenching, and the shape and the size of the thin slice are kept stable; through induction heating quenching, consuming time is short, and is efficient, the mechanized and automatic realization of being convenient for, and then improves the production efficiency of neodymium iron boron magnetism material.
Preferably, when the quenching water spraying sleeve sprays water, the surface temperature of the sheet is reduced to 160-220 ℃, so that the tempering is carried out by utilizing the residual heat of the sheet.
By adopting the technical scheme, during tempering, the surface temperature of the sheet is reduced to 160-class 220 ℃ by controlling the pressure, the temperature and the spraying time of the cooling water in the induction coil without putting the sheet into the heat treatment furnace again, so that the tempering is performed by utilizing the self waste heat of the sheet, the operation is convenient, the heat treatment rate of the sheet is improved, and the production efficiency of the neodymium iron boron magnetic material is further improved. Because only the surface of the sheet is quenched and only the surface of the sheet needs to be tempered during tempering, the hardened layer is thin, so that austenite is conveniently converted into martensite, the surface of the sheet has almost no retained austenite, and the stability of the elastic limit size of the sheet is ensured.
Preferably, after the cladding in C4, an aluminum silicate heat insulating material is coated in the cladding area.
By adopting the technical scheme, the aluminum silicate heat-insulating material has the characteristics of high temperature resistance, good heat-insulating property and good earthquake resistance. The cooling speed of the cladding area can be further reduced by covering the aluminum silicate heat-insulating material, so that the crystallized crystal volume of the cladding area is larger and more uniform, and the structural strength of the solidified cladding area is improved.
In conclusion, the invention has the following beneficial effects:
the magnetic material body is prepared according to a certain proportion of components, so that the magnetic material body has higher magnetic performance, heavy rare earth is diffused through evaporation of crystal boundary, the coercive force of the neodymium iron boron magnetic material is improved, the remanence and the maximum magnetic energy product are kept not to be reduced, and the corrosion-resistant layer is prepared through laser cladding, so that the corrosion resistance of the neodymium iron boron magnetic material is improved. .
Drawings
FIG. 1 is a flow chart of a process for preparing a grain boundary diffusion heavy rare earth neodymium iron boron magnetic material;
FIG. 2 is a schematic view of the operation of a surface induction heating furnace
In the figure: 1. an induction coil; 2. quenching the water spraying sleeve; 3. and (4) water spray holes.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The utility model provides a grain boundary diffusion heavy rare earth neodymium iron boron magnetism material, includes magnetism material body and adheres to at magnetism material body and adheres to the surface coating on magnetism material body surface.
The magnetic material body includes: pr: 4-6.2 wt%, Nd: 18-25 wt%, Dy: 0.8-1.5 wt%, B: 0.8 to 2.8 wt%, Cr: 2.2-4.2 wt%, Al: 0.1 to 0.4 wt%, Cu: 0.1 to 0.4 wt%, Zr: 0.1-0.4 wt%, and the balance Fe.
With reference to figure 1 of the drawings,
s1, preparing a magnetic material body.
A1, mixing:
pre-purchasing raw materials required by the neodymium iron boron magnetic material, mixing Pr, Nd, Dy, B, Cr, Al, Cu, Zr and Fe into mixed powder I according to the proportion in the table 1, and mixing the mixed powder I for 30min by using a V-shaped mixer;
a2, smelting and casting:
and putting the mixed powder I into a vacuum induction smelting furnace, carrying out vacuum smelting at the temperature of 1450 ℃ of 1000-.
A3, hydrogen crushing:
and putting the cast sheet into a hydrogen crushing furnace for hydrogen crushing, so that the cast sheet is crushed into mixed particles B.
A4, grinding by an air flow mill;
and grinding the mixed particles B into mixed fine powder C with the particle size of 10-15 mu m by using a jet mill.
A5, magnetic field orientation shaping:
and (4) putting the mixed fine powder C into a forming press die for orientation and shaping to form a blank D.
A6, powder metallurgy sintering:
putting the blank D into a vacuum sintering furnace, and sintering for 4-5h at 1040-1090 ℃ in a nitrogen atmosphere to form a compact;
s2, preparing a heavy rare earth layer:
a magnetic material body was prepared in the same ratio as in example 3, and the preparation of the heavy rare earth layer was continued on the basis thereof.
B1, slicing, namely cutting the magnetic material body into slices of 5mm by 10mm by 4 mm;
b2, removing impurities, removing an oxide layer and oil stains on the magnetic material body sheet, cleaning by alcohol, electrostatic dust removal, ultrasonic cleaning and the like, and drying for later use;
b3, mixing materials, namely uniformly mixing Cr, B, Dy, V and Fe powder according to the proportion in the table 3 to form mixed powder II;
b4, evaporation, namely putting the mixed powder II into an evaporation furnace, heating, melting, evaporating, cooling, and uniformly attaching to the magnetic material body sheet to form a metal film;
before vapor deposition, adding carbon particles into the vapor deposition furnace, vacuumizing the vapor deposition furnace continuously, starting vapor deposition after vacuumizing for 1h, raising the temperature of the vapor deposition furnace to 400-.
B5, performing permeation treatment, namely performing permeation treatment on the evaporated sheet for 4 hours at 950 ℃ under a vacuum condition;
b6, heat treatment, surface quenching is carried out by using a surface induction heating furnace, and tempering is carried out at 160-220 ℃ after quenching.
The working principle diagram of the surface induction heating furnace is shown in the attached drawing 2, the surface induction heating furnace comprises an induction coil 1 and a quenching water spraying sleeve 2, a copper hollow coil is arranged inside the induction coil 1, and cooling liquid can be introduced into the induction coil 1 so as to timely cool the induction coil 1 after heating is finished and prevent overheating during quenching. The quenching water spraying sleeve 2 is internally provided with a water spraying cavity, the inner side of the quenching water spraying sleeve 2 is provided with a plurality of water spraying holes 3, when the heating is finished and the quenching is needed, cooling water is filled in the quenching water spraying sleeve 2 and is sprayed out from the water spraying holes 3 to quench the surface of the slice, and the quenching water spraying sleeve 2 can move in the actual use process, so that the surface of the slice is uniformly quenched.
When the induction quenching device is used, the thin slice is placed into the induction coil 1, induction heating surface quenching is carried out on the thin slice, the induction current adopts 600-plus-800 kHz, power is cut off after being electrified for 3S-4S, the surface of the thin slice reaches 850-plus-950 ℃, cooling liquid is introduced into the induction coil 1, and temperature is reduced in time. The quenching water-spraying sleeve 2 sprays water to the thin sheet, so that the surface of the thin sheet is rapidly cooled, and surface quenching is completed.
After quenching is finished, after the slice is cooled to room temperature, the slice is placed into a heat treatment furnace for tempering treatment for 1-2h at the temperature of 150-;
or the pressure, the temperature and the spraying time of cooling water in the quenching water spraying sleeve 2 can be controlled during quenching, so that the surface temperature of the slice is reduced to 220 ℃ along with 160-.
S3, preparing an anticorrosive layer;
mixing materials, namely preparing Nb powder, Ti powder, Mn powder, Mo powder and Fe powder in proportion to enable the mixed proportion to meet the component proportion in the table 5, and uniformly mixing to form mixed powder III;
c2, ball-milling and agglomerating, grinding the mixed powder III by using a ball mill, grinding the mixed powder III for 20min by using a stainless steel ball with the ball-milling medium being 8mm in diameter under the condition that the rotating speed is 226r/min, and adding absolute ethyl alcohol serving as a binder to uniformly mix after grinding is finished to prepare an agglomerate;
c3, preparing a preset layer, uniformly coating the agglomerates on the surface of the shaft body to form the preset layer, enabling the thickness of the preset layer to be about 4mm, and drying the preset layer indoors in the shade for 12 hours;
c4, laser cladding, namely performing laser cladding on the preset layer, introducing argon gas as protective gas in advance, wherein the parameters adopted in the cladding process are as follows: laser output power is 1.6-2.5 kW, scanning speed is 4-8 mm/s, the diameter of a light spot is 5mm, argon flow is 6-8L/min, the lap joint rate is 35-45 wt%, after cladding, an aluminum silicate heat-insulating material is used for covering a cladding area, and the cladding area is slowly cooled;
c5, heat treatment, and aging treatment is carried out on the neodymium iron boron magnetic material with the anticorrosive coating.
And (3) performance detection:
and (3) detecting the magnetic property of the neodymium iron boron magnetic material according to a GB/T3217 permanent magnet (hard magnet) material magnetic test method.
The neodymium iron boron magnetic material is subjected to a neutral salt spray test, and a sodium chloride aqueous solution with the concentration of 5 wt% is used for performing a spray salt spray test on the test material, wherein the test temperature is 35 ℃. Because the corrosion reaction of the neodymium iron boron magnetic material in neutral salt fog is mainly oxidation stripping, the weight loss rate is used as the detection basis of the corrosion resistance of the test material. The results are shown in Table 2
Table 1: chemical composition table of neodymium iron boron magnetic material
Table 2 magnetic property test and corrosion resistance test results of nd-fe-b magnetic material
As can be seen from the data in table 2, when the corrosion protection layer includes Nb: 2-3.6 wt%; ti: 18-27 wt%; mn: 1.2-1.8 wt%; mo: 0.8-1.3 wt%, the balance being Fe, when the heavy rare earth layer comprises Cr: 7.3 wt%, B: 2.4 wt%, Dy: 4.25 wt%, V: 2.7 wt%, and the balance being Fe, when the corrosion protection layer comprises Nb: 2.82 wt%; ti: 23 wt%; mn: 1.65 wt%; mo: 1.13 wt%, and the balance of Fe, wherein the remanence of the neodymium iron boron magnetic material is more than 12.2KGs, the coercive force is more than 34.2KOe, and the maximum magnetic energy product is more than 37.8MGOe, so that the neodymium iron boron magnetic material has good magnetic comprehensive performance and meets the use requirements of new energy automobiles. Meanwhile, compared with the comparative example 1 and the comparative example 2, the corrosion resistance of the neodymium iron boron magnetic material is obviously improved after the anticorrosive coating is added, and the magnetic performance of the neodymium iron boron magnetic material is not influenced.
The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.
Claims (8)
1. The utility model provides a grain boundary diffusion heavy rare earth neodymium iron boron magnetism material, includes magnetism material body and adheres to the surface coating on magnetism material body surface, its characterized in that, magnetism material body includes Pr: 4-6.2 wt%, Nd: 18-25 wt%, Dy: 0.8-1.5 wt%, B: 0.8 to 2.8 wt%, Cr: 2.2-4.2 wt%, Al: 0.1 to 0.4 wt%, Cu: 0.1 to 0.4 wt%, Zr: 0.1-0.4 wt%, and the balance of Fe, wherein the surface coating comprises an inner heavy rare earth layer and an outer anti-corrosion layer; the heavy rare earth layer comprises Cr: 7.3 wt%, B: 2.4 wt%, Dy: 4.25 wt%, V: 2.7 wt%, the remainder being Fe.
2. The grain boundary diffused heavy rare earth neodymium-iron-boron magnetic material as claimed in claim 1, wherein the corrosion-resistant layer comprises Nb: 2.82 wt%; ti: 23 wt%; mn: 1.65 wt%; mo: 1.13 wt%, the remainder being Fe.
3. The method for preparing the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material according to claim 2, characterized by comprising the following steps: s1, preparing a magnetic material body, which comprises the following steps:
a1, mixing materials, namely mixing Pr, Nd, Dy, B, Cr, Al, Cu, Zr and Fe into mixed powder I according to a proportion, and mixing the mixed powder I for 30min by using a V-shaped mixer;
a2, smelting and casting, namely putting the mixed powder I into a vacuum induction smelting furnace, carrying out vacuum smelting at the temperature of 1450 ℃ of 1000-;
a3, hydrogen crushing, namely putting the cast sheet into a hydrogen crushing furnace for hydrogen crushing to crush the cast sheet into mixed particles B;
a4, grinding by an air current mill, grinding the mixed particles B into mixed fine powder C with the particle size of 10-15 mu m by the air current mill;
a5, carrying out magnetic field orientation shaping, and putting the mixed fine powder C into a forming press die for orientation shaping to form a blank D;
a6, powder metallurgy sintering, namely putting the blank D into a vacuum sintering furnace, and sintering for 4-5h at 1040-1090 ℃ in a nitrogen atmosphere to form a compact;
s2, preparing the heavy rare earth layer, wherein the method comprises the following specific steps:
b1, slicing, namely cutting the magnetic material body into slices of 5mm by 10mm by 4 mm;
b2, removing impurities, removing an oxide layer and oil stains on the magnetic material body sheet, cleaning by alcohol, performing electrostatic dust collection and ultrasonic waves, and drying for later use;
b3, mixing materials, namely uniformly mixing Cr, B, Dy, V and Fe powder in proportion to form mixed powder II;
b4, evaporation, namely putting the mixed powder II into an evaporation furnace, heating, melting, evaporating, cooling, and uniformly attaching to the magnetic material body sheet to form a metal film;
b5, performing permeation treatment, namely performing permeation treatment on the evaporated sheet for 7 hours under a vacuum condition;
b6, heat treatment, quenching, and tempering after quenching;
s3, preparing an anticorrosive layer, which comprises the following specific steps:
c1, mixing materials, namely uniformly mixing Nb powder, Ti powder, Mn powder, Mo powder and Fe powder in proportion to form mixed powder III;
c2, ball-milling and agglomerating, grinding the mixed powder III by using a ball mill, grinding the mixed powder III for 20min by using a stainless steel ball with the ball-milling medium being 8mm in diameter under the condition that the rotating speed is 226r/min, and adding absolute ethyl alcohol serving as a binder to uniformly mix after grinding is finished to prepare an agglomerate;
c3, preparing a preset layer, uniformly coating the agglomerates on the surface of the heavy rare earth layer to form the preset layer, enabling the thickness of the preset layer to be about 4mm, and placing the preset layer indoors and drying in the shade for 12 hours;
c4, laser cladding, namely performing laser cladding on the preset layer, introducing argon gas as protective gas in advance, wherein the parameters adopted in the cladding process are as follows: laser output power is 1.6-2.5 kW, scanning speed is 4-8 mm/s, the diameter of a light spot is 5mm, argon flow is 6-8L/min, lap joint rate is 35-45 wt%, and after cladding, slow cooling is performed;
c5, heat treatment, and aging treatment is carried out on the neodymium iron boron magnetic material with the anticorrosive coating.
4. The method for preparing the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material according to claim 3, wherein ultrasonic waves are used for cleaning an oxide layer and oil stains on a sheet in B2.
5. The method for preparing the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material according to claim 3, wherein the specific steps in B4 are as follows: before vapor deposition, adding carbon particles into the vapor deposition furnace, vacuumizing the vapor deposition furnace continuously, starting vapor deposition after vacuumizing for 1h, increasing the temperature of the vapor deposition furnace to 400-.
6. The method for preparing the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material according to claim 3, wherein the specific steps in B6 are as follows: and (3) putting the sheet into an induction coil, carrying out induction heating surface quenching on the sheet, wherein the induction current adopts 600-plus-800 kHz, and the power is cut off after the power is turned on for 3S-4S, so that the surface of the sheet reaches 850-plus-950 ℃, introducing cooling liquid into the induction coil to rapidly cool the induction coil, and simultaneously filling cooling water into a quenching water spraying sleeve and spraying water to the sheet, thereby rapidly cooling the surface of the sheet and finishing the surface quenching.
7. The method for preparing the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material as claimed in claim 6, wherein the surface temperature of the thin sheet is reduced to 160-220 ℃ when the quenching water spraying sleeve sprays water, so that the tempering is performed by utilizing the self-residual heat of the thin sheet.
8. The method for preparing the grain boundary diffusion heavy rare earth neodymium iron boron magnetic material according to claim 3, wherein after cladding in C4, an aluminum silicate heat insulating material is covered in a cladding area.
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| CN108899190B (en) * | 2018-06-29 | 2020-12-22 | 烟台首钢磁性材料股份有限公司 | A kind of gradient NdFeB magnet and its making method |
| CN110335733B (en) * | 2019-06-05 | 2021-11-09 | 宁波合力磁材技术有限公司 | High-temperature-resistant neodymium-iron-boron magnet and preparation method thereof |
| CN113118441A (en) * | 2019-12-30 | 2021-07-16 | 吉凯恩粉末冶金(仪征)有限公司 | High-performance automobile part powder metallurgy part and preparation method thereof |
| CN112309661A (en) * | 2020-08-24 | 2021-02-02 | 宁波奥达磁业有限公司 | Neodymium-iron-boron magnet and preparation method thereof |
| CN113161093B (en) * | 2021-01-19 | 2024-05-31 | 宁波晟誉磁电科技有限公司 | Neodymium-iron-boron magnet and preparation method thereof |
| CN113257508B (en) * | 2021-05-13 | 2023-09-01 | 中钢天源股份有限公司 | Manufacturing method of neodymium iron boron |
| CN116749093B (en) * | 2023-08-11 | 2023-11-07 | 太原理工大学 | Preparation process of magnetic grinding tool and slender tube internal polishing device based on magnetic grinding tool |
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