CN104575903A - Neodymium iron boron magnet added with Dy powder and preparation method thereof - Google Patents
Neodymium iron boron magnet added with Dy powder and preparation method thereof Download PDFInfo
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Abstract
The invention specifically relates to a neodymium iron boron magnet added with Dy powder and a preparation method thereof, belonging to the technical field of magnetic materials. The composition and mass percentage of the neodymium iron boron magnet are as follows: 28.70-29.0 percent of PrNd, 2.90-3.10 percent of Gd, 0.94-0.97 percent of B, 0.68-0.75 percent of Al, 0.20-0.23 percent of Cu, 0.10-0.30 percent of Dy and 2.0-3.0 percent of Ho, and the remaining is Fe. The invention further provides a method for preparing the neodymium iron boron magnet, comprising the following steps of: firstly compounding; then smelting, casting in a manner of scale to obtain the melt-spinning sheets; and then hydrogen-smashing, airflow-grinding, spark plasma sintering and second temper heat treating to obtain neodymium iron boron magnet end products. The neodymium iron boron magnet disclosed by the invention has relatively high coercive force, residual magnetism and magnetic energy product simultaneously, good corrosion resistance and good mechanical property.
Description
Technical field
The present invention relates to a kind of neodymium iron boron magnetic body, be specifically related to a kind ofly add neodymium iron boron magnetic body of Dy powder and preparation method thereof, belong to technical field of magnetic materials.
Background technology
Neodymium iron boron magnetic body is as rare earth permanent-magnetic material of new generation, and having the features such as high remanent magnetism, high-coercive force and high energy product, is the permanent magnetic material that in the world today, comprehensive magnetic can be the strongest.Along with the development of electronic information, automobile and machinery manufacturing industry, neodymium iron boron magnetic body also obtains fast development, particularly now the environmental consciousness of people is more and more stronger, and the demand of Nd-Fe-B permanent magnet for the high combination property that can be used for the energy-conservation field of Environment Protection such as electric automobile, wind-powered electricity generation constantly increases.
Neodymium iron boron magnetic body can be divided into Sintered NdFeB magnet and Agglutinate neodymium-iron-boron magnet, and Sintered NdFeB magnet is the best permanent magnetic material of current magnetic property, is most widely used.But for sintered Nd-Fe-B permanent magnet, the defects such as it also exists, and decay resistance is poor, mechanical property is good not.At present, the research for the combination property improving Sintered NdFeB magnet also gets more and more, but while improving these performances, often to the remanent magnetism of neodymium iron boron magnetic body and the negative effect of magnetic energy product also larger.
The preparation method of heavy rare earth hydride nano-particle doped sintered NdFeB permanent magnet is disclosed in Chinese invention patent application file (publication number: CN101521069A), its technical process is first adopt rapid hardening thin slice technique and the quick-fried legal system of hydrogen for NdFeB powder, prepare hydrogenation terbium or hydrogenation dysprosium nanometer powder with physics gas deposition technique again, carry out after then both being mixed suppressing, sinter and heat treatment obtains magnet.Prepare compared with NdFeB magnet prepares sintered NdFeB magnet with conventional art by the method, improve coercive force to a certain extent, and reduce the usage ratio of heavy rare earth terbium or dysprosium.But the carryover effect preparing NdFeB magnet by the method is that coercive force raising is not obvious, and remanent magnetism and magnetic energy product reduce obviously.And this application file does not embody to some extent for the aspect such as corrosion resistance and mechanical property improving sintered NdFeB magnet.
Summary of the invention
The object of the invention is for the deficiencies in the prior art, provide one to have higher coercivity, remanent magnetism and magnetic energy product simultaneously, and corrosion-resistant R-Fe-B magnet.
Object of the present invention realizes by following technical proposal: a kind of neodymium iron boron magnetic body adding Dy powder, its constituent and mass percent are: PrNd:28.70%-29.00%, Gd:2.90%-3.10%, B:0.94%-0.97%, Al:0.68%-0.75%, Cu:0.20%-0.23%, Dy:0.10%-0.30%, Ho:2.0%-3.0%, and surplus is Fe.
Compared to prior art, the present invention, by adding Dy powder, reduces the consumption of Ho on the one hand, relaxes the sintering range of magnet, suppresses the growth of crystal grain on the other hand, improves coercive force and the temperature stability of NdFeB magnet; And the adding of Al, Cu and rare-earth Gd, the effect played in magnet by them, not only effectively can improve the coercive force of NdFeB magnet, and can improve the corrosion resistance of NdFeB magnet.
In neodymium iron boron magnetic body, improve the magnetic properties such as the coercive force of magnet usually through interpolation rare earth element as Gd, Dy, Ho, Tb etc.Rare earth Gd, Dy, Ho is added in neodymium iron boron magnetic body of the present invention, because they are heavy rare earth, the saturated pole intensity of the compound that they are formed in NdFeB magnet is lower, but there is high anisotropy field, and there is temperature compensation function, therefore can obtain the NdFeB magnet with high-coercive force and high-temperature stability.In neodymium iron boron magnetic body, the coercive force of Gd by suppressing the generation of harmful phase α-Fe to carry out magnet, but too much Gd can enter principal phase, reduces the coercive force of magnet on the contrary, therefore in the present invention controls Gd at 2.90%-3.10%.And Ho add the degree of orientation that can improve magnet, rich neodymium is compared and is evenly distributed in main phase grain border, thus improve the coercive force of magnet, and the fall of remanent magnetism is little, but the consumption of Ho is too much, then can seriously reduce the magnetic properties such as the remanent magnetism of magnet.Therefore, the present invention adds appropriate Dy, the consumption of Ho can be reduced on the one hand, effectively prevent the harmful effect that Ho too much causes, on the other hand Dy can produce with the element such as Cu and act synergistically, not only can improving the coercive force of NdFeB magnet, by changing the structural constituent of the rich neodymium phase of crystal boundary, thus the resistance to Hydrogen Energy power of NdFeB magnet can be improved again.
In neodymium iron boron magnetic body of the present invention, with PrNd alloy, B and Fe for primary raw material, in order to obtain the NdFeB magnet of more high combination property, compositely add Al and Cu, their energy are most of or enter Grain-Boundary Phase completely, make Grain-Boundary Phase have better magnetic decoupling effect, effectively improve the coercive force of NdFeB magnet, and improve the decay resistance of NdFeB magnet, also can improve the mechanical property such as bending strength, toughness of NdFeB magnet simultaneously.Al has special wettability on the one hand, good wetting action is played on the border of crystal grain, Al can form the new rich neodymium phase containing Al on the border of crystal grain on the other hand, the border of crystal grain is made to become more clear, thus effectively reduce the demagnetizing effect of intercrystalline exchange coupling, not only substantially increase the coercive force of magnet, and reduce the remanent magnetism of NdFeB magnet and the negative effect of magnetic energy product.And Cu not only can enter principal phase, respectively improve its coercive force to different field property by the single shaft improving NdFeB magnet, but also can the specific area of crystal grain be increased crystal grain thinning, thus make rich neodymium Entropy density deviation more even, be more conducive to improving its coercive force.In addition, difference due to the chemical composition of each phase of magnet can cause its electrochemical potentials different, these can contact with each other in the environment of higher temperature and humidity thus composition corrodes micro cell and accelerated corrosion between phase, Al and Cu adds, and effectively can prevent the generation of this corrosion phenomenon.But the addition of Al and Cu is too much, and can reduce the magnetic property of NdFeB magnet on the contrary, the addition of Al and Cu controls at 0.75%-0.85% and 0.19%-0.22% by the present invention respectively.
In neodymium iron boron magnetic body of the present invention, with PrNd alloy, B and Fe for primary raw material, add Dy powder, and compositely add heavy rare earth Gd, Ho and there is Al and Cu of decay resistance improving magnet, by they synergies in NdFeB magnet, obtain coercive force, remanent magnetism and magnetic energy product all higher, the NdFeB magnet that good corrosion resistance, mechanical property are good.
Further, as preferably, component and the mass percent of the neodymium iron boron magnetic body of described interpolation Dy powder are: PrNd:28.90%, Gd:3.00%, B:0.95%, Al:0.70%, Cu:0.21%, Dy:0.20%, Ho:2.5%, surplus is Fe.
The present invention also provides a kind of method preparing the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, and described preparation method comprises the steps:
S1, batching and melting: the constituent of adding the neodymium iron boron magnetic body of Dy powder according to described and mass percent are prepared burden, and then send into vacuum rapid hardening smelting furnace, are evacuated down to 10
-3pa-10
-2pa, stops vacuumizing and being filled with after argon gas reaches 0.042-0.048MPa and carries out melting, carry out after furnace charge melts completely scale casting obtain thickness be 0.20-0.40mm get rid of strap;
S2, Dy powder preparation: adopting inert gas vaporize-condensation law to prepare also collection cut size is the Dy powder of 20-40nm;
Broken and the airflow milling process of S3, hydrogen: the above-mentioned strap that gets rid of is obtained through hydrogen break process the flour that average grain diameter is 10.0 μm-12.0 μm, then adds above-mentioned Dy powder and antioxidant and carries out airflow milling and obtain the fine powder that average grain diameter is 3.0 μm-4.0 μm;
S4, compacting and sintering: in above-mentioned fine powder, add lubricant, by the pulsed magnetic field of 3.5T-4.5T, the pressure orientation of 195-210MPa compressing under the protective atmosphere of nitrogen, then obtain neodymium iron boron magnetic body blank through discharge plasma sintering process;
S5, tempering heat treatment: above-mentioned neodymium iron boron magnetic body blank is carried out second annealing heat treatment and obtains neodymium iron boron magnetic body finished product; Wherein the temperature of first order tempering heat treatment is 880-920 DEG C, and temperature retention time is 3.2-3.5h, and the temperature of second level tempering heat treatment is 540-610 DEG C, and temperature retention time is 3.8-4.2h.
In the preparation method of the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, the holmium ferroalloy that the gadolinium-iron alloy that the praseodymium neodymium alloy of to be Pr content the be 20%-25% of the furnace charge described in step S1, Gd content are 65%-70%, Ho content are 65%-70%, B content are the ferro-boron of 10%-20%, industrial aluminium ingot, ingot iron and cathode copper.
In the preparation method of the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, the chill roll rotating speed in the scale casting cycle described in step S1 is 2.58m/s-2.70m/s.In traditional water-cooled copper mold casting ingot process, because cooling rate can not suppress peritectic reaction comparatively slowly, make in ingot casting, to there is more α-Fe phase, thus cause the ratio of principal phase to reduce, rich neodymium Entropy density deviation is uneven, is unfavorable for the generation of the bad phenomenon such as the raising of the magnetic property of NdFeB magnet.Therefore, in order to effectively prevent the generation of above-mentioned bad phenomenon, having abandoned traditional handicraft in the preparation method of neodymium iron boron magnetic body of the present invention and having adopted rapid casting casting ingot process to obtain getting rid of strap.And in rapid casting casting ingot process, the chill roll rotating speed in scale casting cycle for final magnet magnetic property particularly remanent magnetism have a great impact.If the rotating speed of chill roll is too low, get rid of composition generation segregation in strap crystalline structure, after part α-Fe separates out mutually, unnecessary rich neodymium phase and other non-magnetic phase can be formed, cause volume shared by principal phase to reduce, thus reduce remanent magnetism; If the rotating speed of chill roll is too high, then can form a large amount of polycrystalline particle after obtained powder, thus reduce remanent magnetism.Therefore, in order to obtain the NdFeB magnet of high magnetic characteristics, the chill roll rotating speed in scale casting cycle controls in suitable scope by the present invention.In addition, after furnace charge is put into vacuum rapid hardening smelting furnace, want first power transmission to carry out preheating before carrying out melting, to get rid of the adsorbed gas, organic substance etc. of furnace charge, thus make finally to obtain high-quality NdFeB magnet.
In the preparation method of the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, in inert gas vaporize-condensation law described in step S2, generation atmosphere is inert gas, wherein inert gas can be argon gas, helium or both gaseous mixtures, and gas pressure intensity is 90-95MPa, voltage is 16-18V, electric current is 190-210A.Inert gas vaporize-condensation law refers in the atmosphere of inert gas, using tungsten electrode and copper coin as anode and cathode, energising makes the gas discharge between anode and cathode and produces high temperature, after gas between the two poles of the earth is ionized to plasma, as for the metal on anode just rapidly by high-temperature plasma heating, melting and then flash to metallic vapour, last condensation is also deposited as nanometer powder.Prepare at employing inert gas vaporize-condensation law and collect in the process of Dy powder, gas pressure intensity, voltage and size of current all have impact for the particle diameter of final powder and productive rate.Gas pressure intensity increases, the corresponding increase of productive rate, but the average grain diameter of obtained nanometer powder is also larger; Same, suitable increase voltage to reduce the nanometer powder particle diameter that current strength can make to prepare less, but crossing conference reduces productive rate, therefore in the present invention all controls inert gas pressure, voltage and current strength in suitable scope.
In the preparation method of the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, in the hydrogen break process described in step S3, the heating-up temperature of dehydrogenation reaction is 420-550 DEG C, and heating time is 180-210min.Compared with Mechanical Crushing flouring technology, hydrogen decrepitation can keep the integrality of crystal grain by the ratio reducing transgranular fracture in pulverizing process, and can suppress the abnormal growth of crystal grain in sintering process, thus effectively improves the combination property of magnet.For hydrogen decrepitation, its cardinal principle is rich neodymium phase and Nd
2fe
14b phase successively inhales hydrogen, causes volumetric expansion, and due to the difference of both expansion rates, cause producing internal stress at crystal grain intersection, along crystal boundary, alloy is then preferential occurs that crackle is broken for single crystal grain through External Force Acting.Hydrogen break process in the preparation method of neodymium iron boron magnetic body of the present invention comprises inhales hydrogen and dehydrogenation two processes, namely first to proceed in reaction vessel and pass into hydrogen and make it inhale hydrogen by getting rid of strap to 0.20-0.22MPa (pressure is the pressure under normal temperature state), until the stove heating of after no longer inhaling hydrogen, reactor being put into 420-550 DEG C is carried out dehydrogenation reaction and vacuumizes, stop after keeping 180-210min heating and being filled with argon gas, circulating water is adopted to reactor, cooling water temperature is 60-80 DEG C, obtains flour after being cooled to room temperature.
In the preparation method of the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, in step S3 after hydrogen break process, add the Dy nanometer powder of 0.10%-0.30% and the antioxidant of 0.038%-0.042% in flour after, carry out airflow milling again.Dy can better be mixed with obtained flour by the form of nanometer powder, what the effect of Dy in NdFeB magnet was played is more abundant, the growth of effective suppression crystal grain, relaxes the sintering range of magnet, improves the coercive force etc. of final obtained NdFeB magnet.And adding of antioxidant, make the NdFeB magnet obtained have better non-oxidizability.Wherein, described antioxidant be triethanolamine borate, N-dodecyl bi-quaternary ammonium salt, tristerin one or more.
In the preparation method of the neodymium iron boron magnetic body of above-mentioned interpolation Dy powder, in order to reduce the friction between powder particle, preventing powder particle from reuniting thus improving the mobility of powder, after airflow milling, adding lubricant carry out orientation compacting again.But the addition of lubricant can not be too much, otherwise causing being difficult to deviate to reduce on the contrary magnet remanent magnetism and magnetic energy product completely when sintering, therefore in the present invention, the addition of lubricant being controlled at 0.025%-0.030%.Wherein, described lubricant is one or more in fat alcohol polyethylene ether, olein and lauryl sodium sulfate.
In orientation and after pressing process, the present invention adopts discharge plasma sintering process to obtain neodymium iron boron magnetic body blank, wherein sintering atmosphere is vacuum degree is 0.01Pa-0.02Pa or argon gas atmosphere, sintering pressure is 32-48MPa, sintering temperature is 680-820 DEG C, heating rate is 150-200 DEG C/min, and temperature retention time is 5-10min.Discharge plasma sintering process is the pressure sintering method utilizing DC pulse resistance sintering; it can carry out in vacuum or protective atmosphere; have that programming rate is fast, sintering time is short, sintering temperature is low, uniform crystal particles, be conducive to controlling the fine structure of sintered body, and simple to operate, safe and reliable, energy savings, low cost and other advantages.In the preparation method of neodymium iron boron magnetic body of the present invention, sintering temperature, sintering pressure, heating rate and the temperature retention time quality to obtained NdFeB magnet has material impact, and the unreasonable of these parameters arranges the quality that all can reduce final NdFeB magnet.Programming rate is too fast, sintering temperature is too high, makes grain growth speed fast and causes crystal grain abnormal large, reducing the performance of magnet, otherwise then do not reach the quality requirement of magnet; Sintering pressure increases in right amount effectively can suppress growing up and reducing sintering temperature of crystal grain, but sintering pressure is excessive, can make on the contrary to reduce density and these beneficial effects; Temperature retention time is long, crystal grain can be made during this period of time sharply to grow up, reduce magnetic property, temperature retention time is too short, and the density of magnet can be caused to reduce, and therefore sintering temperature, sintering pressure, heating rate and temperature retention time all control in suitable scope by the present invention.In addition, in the preparation method of neodymium iron boron magnetic body of the present invention, after sintering second annealing heat treatment and surface treatment are carried out to magnet, make final neodymium iron boron magnetic body have better combination property.Wherein, surface treatment is the common surface treatment process in this area.
Compared with prior art, the present invention has following beneficial effect:
1) the present invention adds the neodymium iron boron magnetic body of Dy powder, on the basis being primary raw material with PrNd alloy, B and Fe, compositely add rare earth Gd, Dy, Ho and Al, Cu, by their synergies in NdFeB magnet and reasonable disposition, the NdFeB magnet obtained has higher coercive force, remanent magnetism and magnetic energy product simultaneously, and good corrosion resistance, mechanical property are good.
2) the present invention adds preparation method's simple possible of the neodymium iron boron magnetic body of Dy powder, by the reasonable set of each technological parameter, and the good combination property of the NdFeB magnet obtained.
Embodiment
Be below specific embodiments of the invention, technical scheme of the present invention is further described, but the present invention is not limited to these embodiments.
Table 1: embodiment 1-3 is for the preparation of the constituent of neodymium iron boron magnetic body and the mass percent of adding Dy powder
Embodiment 1
Batching and melting: prepare burden according to the constituent of neodymium iron boron magnetic body described in table 1 embodiment 1 and mass percent, then send into vacuum rapid hardening smelting furnace and power transmission carries out preheating, is evacuated down to 10
-3pa, stops vacuumizing and being filled with after high-purity argon gas (content>=99.99%) reaches 0.042MPa and carries out melting, and after furnace charge melts completely, that carries out scale casting with the chill roll rotating speed of 2.58m/s to obtain average thickness be 0.20mm gets rid of strap; Wherein the praseodymium neodymium alloy of furnace charge to be Pr content be 20%-25%, the Gd content gadolinium-iron alloy that is 65%-70%, the Ho content holmium ferroalloy that is 65%-70%, B content are the ferro-boron of 10%-20%, industrial aluminium ingot, ingot iron and cathode copper.
Dy powder preparation: adopting inert gas vaporize-condensation law to prepare also collection cut size is the Dy powder of 20-40nm; Generation atmosphere wherein in inert gas vaporize-condensation law is argon gas atmosphere, and gas pressure intensity is 90MPa, voltage is 16V, electric current is 190A.
Hydrogen fragmentation and airflow milling process: the above-mentioned strap that gets rid of is obtained through hydrogen break process the flour that average grain diameter is 10.0 μm, then add above-mentioned Dy powder and 0.038% triethanolamine borate carry out airflow milling and obtain the fine powder that average grain diameter is 3.0 μm, and stir 2.0h with mixer;
Wherein, hydrogen break process comprises inhales hydrogen and dehydrogenation two processes, namely first to proceed in reaction vessel and pass into high-purity hydrogen (content >=99.99%) and make it inhale hydrogen by getting rid of strap to 0.20MPa (pressure is the pressure under normal temperature state), until the stove heating of after no longer inhaling hydrogen, reactor being put into 420 DEG C is carried out dehydrogenation reaction and vacuumizes, stop after keeping 180min heating and being filled with argon gas, circulating water is adopted to reactor, cooling water temperature is 60 DEG C, obtains flour after being cooled to room temperature.
Compacting and sintering: in the above-mentioned fine powder be stirred, add the fat alcohol polyethylene ether of 0.025%, by the pulsed magnetic field of 3.5T, the pressure orientation of 195MPa compressing under the protective atmosphere of nitrogen, then obtain neodymium iron boron magnetic body blank through discharge plasma sintering process; Wherein, the sintering atmosphere in discharge plasma sintering process is vacuum degree is 0.01Pa atmosphere, and sintering pressure is 32MPa, and sintering temperature is 680 DEG C, and heating rate is 150 DEG C/min, and temperature retention time is 5min.
Tempering heat treatment: above-mentioned neodymium iron boron magnetic body blank is carried out second annealing heat treatment and surface treatment obtains neodymium iron boron magnetic body finished product; Wherein the temperature of first order tempering heat treatment is 880 DEG C, and temperature retention time is 3.2h, and the temperature of second level tempering heat treatment is 540 DEG C, and temperature retention time is 3.8h.
Embodiment 2
Batching and melting: prepare burden according to the constituent of neodymium iron boron magnetic body described in table 1 embodiment 2 and mass percent, then send into vacuum rapid hardening smelting furnace and power transmission carries out preheating, is evacuated down to 5 × 10
-3pa, stops vacuumizing and being filled with after high-purity argon gas (content>=99.99%) reaches 0.045MPa and carries out melting, and after furnace charge melts completely, that carries out scale casting with the chill roll rotating speed of 2.62m/s to obtain average thickness be 0.30mm gets rid of strap; Wherein the praseodymium neodymium alloy of furnace charge to be Pr content be 20%-25%, the Gd content gadolinium-iron alloy that is 65%-70%, the Ho content holmium ferroalloy that is 65%-70%, B content are the ferro-boron of 10%-20%, industrial aluminium ingot, ingot iron and cathode copper.
Dy powder preparation: adopting inert gas vaporize-condensation law to prepare also collection cut size is the Dy powder of 20-40nm; Generation atmosphere wherein in inert gas vaporize-condensation law is the gaseous mixture of argon gas and helium, and wherein the ratio of argon gas and helium is 6:4, and gas pressure intensity is 93MPa, voltage is 17V, electric current is 200A.
Hydrogen fragmentation and airflow milling process: the above-mentioned strap that gets rid of is obtained through hydrogen break process the flour that average grain diameter is 11.0 μm, then add above-mentioned Dy powder and the triethanolamine borate of 0.020% and the tristerin of 0.020% to carry out airflow milling and obtain the fine powder that average grain diameter is 4.0 μm, and stir 2.5h with mixer;
Wherein, hydrogen break process comprises inhales hydrogen and dehydrogenation two processes, namely first to proceed in reaction vessel and pass into high-purity hydrogen (content >=99.99%) and make it inhale hydrogen by getting rid of strap to 0.21MPa (pressure is the pressure under normal temperature state), until the stove heating of after no longer inhaling hydrogen, reactor being put into 480 DEG C is carried out dehydrogenation reaction and vacuumizes, stop after keeping 200min heating and being filled with argon gas, circulating water is adopted to reactor, cooling water temperature is 70 DEG C, obtains flour after being cooled to room temperature.
Compacting and sintering: in the above-mentioned fine powder be stirred, add 0.028% olein, by the pulsed magnetic field of 4.0T, the pressure orientation of 200MPa compressing under the protective atmosphere of nitrogen, then obtain neodymium iron boron magnetic body blank through discharge plasma sintering process; Wherein, the sintering atmosphere in discharge plasma sintering process is vacuum degree is argon gas atmosphere, and sintering pressure is 40MPa, and sintering temperature is 720 DEG C, and heating rate is 180 DEG C/min, and temperature retention time is 8min.
Tempering heat treatment: above-mentioned neodymium iron boron magnetic body blank is carried out second annealing heat treatment and surface treatment obtains neodymium iron boron magnetic body finished product; Wherein the temperature of first order tempering heat treatment is 900 DEG C, and temperature retention time is 3.5h, and the temperature of second level tempering heat treatment is 580 DEG C, and temperature retention time is 4.0h.
Embodiment 3
Batching and melting: prepare burden according to the constituent of neodymium iron boron magnetic body described in table 1 embodiment 3 and mass percent, then send into vacuum rapid hardening smelting furnace and power transmission carries out preheating, is evacuated down to 10
-2pa, stops vacuumizing and being filled with after high-purity argon gas (content>=99.99%) reaches 0.048MPa and carries out melting, and after furnace charge melts completely, that carries out scale casting with the chill roll rotating speed of 2.70m/s to obtain average thickness be 0.40mm gets rid of strap; Wherein the praseodymium neodymium alloy of furnace charge to be Pr content be 20%-25%, the Gd content gadolinium-iron alloy that is 65%-70%, the Ho content holmium ferroalloy that is 65%-70%, B content are the ferro-boron of 10%-20%, industrial aluminium ingot, ingot iron and cathode copper.
Dy powder preparation: adopting inert gas vaporize-condensation law to prepare also collection cut size is the Dy powder of 20-40nm; Generation atmosphere wherein in inert gas vaporize-condensation law is helium atmosphere, and gas pressure intensity is 95MPa, voltage is 18V, electric current is 210A.
Hydrogen fragmentation and airflow milling process: the above-mentioned strap that gets rid of is obtained through hydrogen break process the flour that average grain diameter is 12.0 μm, then add above-mentioned Dy powder and 0.040% three N-dodecyl bi-quaternary ammonium salts carry out airflow milling and obtain the fine powder that average grain diameter is 4.0 μm, and stir 3.0h with mixer;
Wherein, hydrogen break process comprises inhales hydrogen and dehydrogenation two processes, namely first to proceed in reaction vessel and pass into high-purity hydrogen (content >=99.99%) and make it inhale hydrogen by getting rid of strap to 0.22MPa (pressure is the pressure under normal temperature state), until the stove heating of after no longer inhaling hydrogen, reactor being put into 550 DEG C is carried out dehydrogenation reaction and vacuumizes, stop after keeping 210min heating and being filled with argon gas, circulating water is adopted to reactor, cooling water temperature is 80 DEG C, obtains flour after being cooled to room temperature.
Compacting and sintering: in the above-mentioned fine powder be stirred, add the olein of 0.015% and the lauryl sodium sulfate of 0.015%, by the pulsed magnetic field of 4.5T, the pressure orientation of 210MPa compressing under the protective atmosphere of nitrogen, then obtain neodymium iron boron magnetic body blank through discharge plasma sintering process; Wherein, the sintering atmosphere in discharge plasma sintering process is argon gas atmosphere, and sintering pressure is 48MPa, and sintering temperature is 800 DEG C, and heating rate is 200 DEG C/min, and temperature retention time is 10min.
Tempering heat treatment: above-mentioned neodymium iron boron magnetic body blank is carried out second annealing heat treatment and surface treatment obtains neodymium iron boron magnetic body finished product; Wherein the temperature of first order tempering heat treatment is 920 DEG C, and temperature retention time is 3.4h, and the temperature of second level tempering heat treatment is 610 DEG C, and temperature retention time is 4.2h.
Neodymium iron boron magnetic body obtained in embodiment 1-3 is carried out performance test, and with do not add Dy powder, the performance of the neodymium iron boron magnetic body that other conditions are identical and obtained with embodiment 1-3 compares, and result is as shown in table 2.
The neodymium iron boron magnetic body that table 2: embodiment of the present invention 1-3 obtains and the performance comparison result of neodymium iron boron magnetic body of not adding Dy powder
Comparative example 1-3 for not add Dy powder, the neodymium iron boron magnetic body that other conditions are identical and obtained with embodiment 1-3.
In sum, the neodymium iron boron magnetic body that the present invention adds Dy powder adopts rational chemical composition, by adding of Dy powder and Al, Cu etc., synergy is produced between each composition, the neodymium iron boron magnetic body obtained is not compared with adding the neodymium iron boron magnetic body of Dy powder, and its coercive force significantly improves, and then magnetic property is more stable for demagnetization curve rectangular degree height, remanent magnetism and magnetic energy product decline not obvious, and the good combination properties such as corrosion resistance.
Specific embodiment described herein is only to the explanation for example of the present invention's spirit.Those skilled in the art can make various amendment or supplement or adopt similar mode to substitute to described specific embodiment, but can't depart from spirit of the present invention or surmount the scope that appended claims defines.
Claims (10)
1. one kind is added the neodymium iron boron magnetic body of Dy powder, it is characterized in that, the constituent of described neodymium iron boron magnetic body and mass percent are: PrNd:28.70%-29.00%, Gd:2.90%-3.10%, B:0.94%-0.97%, Al:0.68%-0.75%, Cu:0.20%-0.23%, Dy:0.10%-0.30%, Ho:2.0%-3.0%, and surplus is Fe.
2. the neodymium iron boron magnetic body of interpolation Dy powder according to claim 1, it is characterized in that, the component of described neodymium iron boron magnetic body and mass percent are: PrNd:28.90%, Gd:3.00%, B:0.95%, Al:0.70%, Cu:0.21%, Dy:0.20%, Ho:2.5%, and surplus is Fe.
3. prepare a method of adding the neodymium iron boron magnetic body of Dy powder as claimed in claim 1, it is characterized in that, described preparation method comprises the steps:
S1, batching and melting: prepare burden according to the constituent of neodymium iron boron magnetic body described in claim 1 and mass percent, then send into vacuum rapid hardening smelting furnace, be evacuated down to 10
-3pa-10
-2pa, stops vacuumizing and being filled with after argon gas reaches 0.042-0.048MPa and carries out melting, carry out after furnace charge melts completely scale casting obtain thickness be 0.20-0.40mm get rid of strap;
S2, Dy powder preparation: adopting inert gas vaporize-condensation law to prepare also collection cut size is the Dy powder of 20-40nm;
Broken and the airflow milling process of S3, hydrogen: the above-mentioned strap that gets rid of is obtained through hydrogen break process the flour that average grain diameter is 10.0 μm-12.0 μm, then adds above-mentioned Dy powder and antioxidant and carries out airflow milling and obtain the fine powder that average grain diameter is 3.0 μm-4.0 μm;
S4, compacting and sintering: in above-mentioned fine powder, add lubricant, by the pulsed magnetic field of 3.5T-4.5T, the pressure orientation of 195-210MPa compressing under the protective atmosphere of nitrogen, then obtain neodymium iron boron magnetic body blank through discharge plasma sintering process;
S5, tempering heat treatment: above-mentioned neodymium iron boron magnetic body blank is carried out second annealing heat treatment and obtains neodymium iron boron magnetic body finished product; Wherein the temperature of first order tempering heat treatment is 880-920 DEG C, and temperature retention time is 3.2-3.5h, and the temperature of second level tempering heat treatment is 540-610 DEG C, and temperature retention time is 3.8-4.2h.
4. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, it is characterized in that, the holmium ferroalloy that the gadolinium-iron alloy that the praseodymium neodymium alloy of to be Pr content the be 20%-25% of the furnace charge described in step S1, Gd content are 65%-70%, Ho content are 65%-70%, B content are the ferro-boron of 10%-20%, industrial aluminium ingot, ingot iron and cathode copper.
5. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, is characterized in that, the chill roll rotating speed in the process of the scale casting described in step S1 is 2.58m/s-2.70m/s.
6. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, it is characterized in that, in inert gas vaporize-condensation law described in step S2, generation atmosphere is inert gas, wherein inert gas can be argon gas, helium or both gaseous mixtures, and gas pressure intensity is 90-95MPa, voltage is 16-18V, electric current is 190-210A.
7. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, it is characterized in that, in the hydrogen break process described in step S3, the heating-up temperature of dehydrogenation reaction is 420-550 DEG C, and heating time is 180-210min.
8. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, it is characterized in that, the addition of the antioxidant described in step S3 is 0.038%-0.042%.
9. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, it is characterized in that, the addition of the lubricant described in step S4 is 0.025%-0.030%.
10. the preparation method of the neodymium iron boron magnetic body of interpolation Dy powder according to claim 3, it is characterized in that, in discharge plasma sintering process described in step S4, sintering atmosphere is vacuum degree is 0.01Pa-0.02Pa or argon gas atmosphere, sintering pressure is 32-48MPa, sintering temperature is 680-820 DEG C, heating rate is 150-200 DEG C/min, and temperature retention time is 5-10min.
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| CN105244162A (en) * | 2015-11-12 | 2016-01-13 | 北京科技大学 | Method for preparing high-coercivity neodymium-iron-boron magnet with low dysprosium usage amount |
| CN108597708A (en) * | 2018-04-12 | 2018-09-28 | 江苏柯普斯磁业有限公司 | A kind of high performance sintered neodymium-iron-boron and manufacturing method |
| WO2019056643A1 (en) * | 2017-09-20 | 2019-03-28 | 江民德 | Method for producing neodymium-iron-boron composite magnetic material |
| CN112435820A (en) * | 2020-11-18 | 2021-03-02 | 宁波金鸡强磁股份有限公司 | High-performance sintered neodymium-iron-boron magnet and preparation method thereof |
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| CN113223798A (en) * | 2021-04-28 | 2021-08-06 | 慈溪市兴发磁业科技有限公司 | Neodymium iron boron magnetic material and preparation method thereof |
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| CN114242437A (en) * | 2021-11-15 | 2022-03-25 | 天津三环乐喜新材料有限公司 | Preparation method of high-performance sintered Re-Fe-B system |
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