CN100356487C - Method for increasing sintering Nd-Fe-B coercive force by adding nano-oxide in crystal boundary phase - Google Patents

Method for increasing sintering Nd-Fe-B coercive force by adding nano-oxide in crystal boundary phase Download PDF

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CN100356487C
CN100356487C CN 200510049962 CN200510049962A CN100356487C CN 100356487 C CN100356487 C CN 100356487C CN 200510049962 CN200510049962 CN 200510049962 CN 200510049962 A CN200510049962 A CN 200510049962A CN 100356487 C CN100356487 C CN 100356487C
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CN1688000A (en
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严密
于濂清
罗伟
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Zhejiang University ZJU
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Abstract

The present invention discloses a method for improving sintered Nd-Fe-B coercive force by adding nano-oxides in a crystal boundary phase. The present invention comprises the following steps: 1) manufacturing main-phase alloys into Nd-Fe-B ingot casting alloys by adopting a casting technique or into Nd-Fe-B rapid solidifying sheets by adopting a rapid solidifying sheet technique, and manufacturing crystal boundary phase alloys into ingot casting alloys by adopting the casting technique, or into rapid solidifying sheets by adopting the rapid solidifying sheet technique or into rapid quenching belts by adopting a rapid quenching technique; 2) respectively milling the main-phase alloys and the crystal boundary phase alloys; 3) adding nano-oxides to crystal boundary phase alloy powder; 4) molding the main phase alloys and the crystal boundary phase alloy powder, which are mixed, by pressing; 5) manufacturing a sintered magnet in a high vacuum sintering furnace. The coercive force of the sintered Nd-Fe-B manufactured by the present invention is higher than the coercive force of a magnet manufactured by a dual-alloy technique without adding the nano-oxides and a magnet manufactured in a single alloy method. The present invention can be used for large-scale batch production and can be used for preparing sintered Nd-Fe-B with high coercive force.

Description

A kind of preparation method of Sintered NdFeB magnet
Technical field
The present invention relates to a kind of preparation method of Sintered NdFeB magnet.
Background technology
Nd-Fe-B rare earth permanent magnetic material is that people such as 1983 SUMITOMO CHEMICAL particulate metal Sagawa of company are at first produced.Rare-earth Nd-Fe-B permanent magnet is the strongest permanent magnet of contemporary magnetic, it not only has excellent specific properties such as high energy product, high performance-price ratio, and be processed into various sizes easily, Aeronautics and Astronautics, short-wave communication tedhnology, electronics, electroacoustic, electromechanics, computing technique, automatic technology, auto industry, petrochemical industry, magnetic separation technique, instrument and meter, magnetic medical skill now have been widely used in and other need be specially adapted to develop the various regeneration products of high-performance, miniaturization, lightness with in the device and equipment of permanent-magnetic field.The rare-earth Nd-Fe-B series permanent magnetic material is current and most important permanent magnetic material in significant period of time from now on, and the new beginning in rare earth permanent magnet field has been opened up in its appearance.
The basic mechanical design feature index of Nd-Fe-B material is remanent magnetism B r, coercive force H c(HCJ H CjWith magnetic strength coercive force H Cb), magnetic energy product (BH) MaxWith Curie temperature T cThe researcher of permanent magnetic material and the producer's main task are exactly the potentiality of excavated material to greatest extent, improve the B of permanent magnetic material r, H c, (BH) MaxAnd T cB rLimiting value be, J s, (BH) MaxLimiting value be 1/4J s 2, and J sDepend on the magnetic atom number of forming this material and the size of atomic magnetic moment.H CjLimiting value be magnetocrystalline anisotropy field H A, it depends on the magnetocrystalline anisotropy constant K of material 1And K 2
Nd 2Fe 14The anisotropy field of B compound, promptly coercitive theoretical boundary is 80kOe, however the actual coercive force of sintered Nd-Fe-B alloy only is the 1/3-1/30 of its theoretical value, thereby the coercive force of raising Sintered NdFeB magnet is also had great potentialities and can be dug.A large amount of experimental results show: the Sintered NdFeB magnet microstructural undesirable be the main cause that causes coercive force lower than its theoretical value, coercive force is a structure sensitive parameter.Everybody generally admits, and the microstructure model with high-coercive force sintered neodymium iron boron material should be: the uniform crystal boundary of thickness is wrapped in Nd mutually 2Fe 14B crystal grain, Nd 2Fe 14B crystal grain is tiny, be evenly distributed, and the grain shape rule is spherical in shape, Nd 2Fe 14B grain orientation height unanimity, Nd 2Fe 14The chemical composition of B crystal grain is consistent with even structure.Element adds and substitutes is to improve coercitive common method, discovers that elements such as Dy, Al, Nb, Ga, Tb, W, Mo can improve the coercive force and the temperature stability thereof of alloy, but magnet remanent magnetism and magnetic energy product are all had adverse effect.
Adopting two alloyages is that principal phase and crystal-boundary phase alloy are smelted respectively, and the main-phase alloy composition is near Nd 2Fe 14B is just dividing ratio, crystal-boundary phase alloy is rich rare earth (R=Nd, Pr, Dy, Tb etc.), and contain one or more the element of Co, Al, Cu, Ga, B, Ti etc., two kinds of alloys are broken respectively, proportioning according to a certain percentage, pass through magnetic field orientating compression moulding then, be prepared into Sintered NdFeB magnet through the oversintering tempering process at last.
Utilizing two alloyages also is to improve the coercitive effective way of magnet, and it had both reduced crystal boundary separating out in principal phase, can reduce it again in the reunion that crystal boundary hands over the corner to locate, and makes principal phase more reasonable with crystal boundary composition mutually, and the content of rare earth of principal phase can be more near Nd simultaneously 2Fe 14B is just dividing ratio, also can obtain higher H CjThis is because principal phase is Nd 2Fe 14During B, there is not unnecessary neodymium metal to be present in the alloy, so be difficult for oxidation, though crystal boundary has the very high neodymium of content mutually, but the amorphous alloy with the fast quenching technology obtains does not exist crystal grain and grain boundary, so also be difficult for oxidation, therefore two alloyages can guarantee to also have when very low neodymium content enough crystal boundary phase and rich boron borderline phase to exist, and guarantee that alloy has high H Cj
The present invention adopts two alloyages, by the interpolation of nano-oxide, with nano-oxide be dispersed in crystal boundary mutually in, to modified grain boundary phase to improve the coercive force of sintered NdFeB.In the invention, main-phase alloy and crystal-boundary phase alloy are prepared respectively, adopt the airflow milling flouring technology, by add nano-oxide particles in crystal boundary mutually in, and add lubricant, antioxidant, the non magnetic crystal boundary phase through the nano-oxide modification is dispersed in principal phase Nd 2Fe 14The B crystal grain boundary improves microstructure, effectively cuts off the exchange-coupling interaction between the hard magnetic phase, thereby improves the magnet coercive force.Adopt two alloyage technologies to add nano-oxide and can effectively improve the crystal boundary phase morphology, make the crystal boundary after the modification be uniformly distributed in around the main phase grain mutually, play an important role at aspects such as magnet densification and degaussing exchange-coupling interactions simultaneously, thereby promote coercive force to improve.
Summary of the invention
The preparation method who the purpose of this invention is to provide a kind of Sintered NdFeB magnet.
Its step is:
1) main-phase alloy adopts casting technique to make the neodymium iron boron alloy of ingot or make neodymium iron boron rapid hardening thin slice with rapid hardening thin slice technology, and crystal-boundary phase alloy adopts casting technique to make alloy of ingot or rapid hardening thin slice technology makes the rapid hardening thin slice or rapid quenching technique is made rapid tempering belt;
2) adopt the quick-fried method of hydrogen or by alloy of ingot, rapid hardening thin slice or the rapid tempering belt fragmentation of disintegrating machine with alloy of ingot or the rapid hardening thin slice and the crystal-boundary phase alloy of main-phase alloy, broken back is by the airflow milling abrasive material, making average particulate diameter respectively is 2-10 μ m powder;
3) in the crystal-boundary phase alloy powder, add account for its weight 2-20%, through the nano-oxide of dispersion treatment, in above-mentioned crystal-boundary phase alloy powder and nano-oxide, add the antioxidant of 1-10% weight again, evenly mixed in batch mixer, nano-oxide is SiO 2, ZrO 2, CuO, Fe 2O 3, Al 2O 3, Y 2O 3, TiO 2In one or more, average particulate diameter is 2-40nm;
4) will mix with the main-phase alloy powder through the crystal-boundary phase alloy powder that nano-oxide mixes, the crystal-boundary phase alloy powder weight accounts for the 1-20% of total weight, adds the gasoline of 0.5-5% weight again, is uniformly mixed into mixed-powder in batch mixer;
5) mixed-powder compression moulding blank in the magnetic field of 1.2-2.0T;
6) parison spare is put into high vacuum sintering furnace,, pass through 500-650 ℃ of tempering heat treatment 2-4h again, make sintered magnet at 1050-1125 ℃ of sintering 2-4h.
Magnet coercive force that the present invention makes does not add nano-oxide than adopting the pairing gold process and makes magnet coercive force height, more makes magnet coercive force height than single alloyage, and principal phase and crystal boundary powder mutually are difficult for oxidation, and technical process is suitable for mass production.By two alloyages and add nano-oxide, can prepare the sintered NdFeB of high-coercive force.
Embodiment
Concrete steps of the present invention are as follows:
1) adopt the pairing gold process that main-phase alloy and crystal-boundary phase alloy are made respectively.Main-phase alloy adopts casting technique to make the neodymium iron boron alloy of ingot, or makes neodymium iron boron rapid hardening thin slice with rapid hardening thin slice technology, and its composition is Nd aFe 100-a-b-cB bM c(at%), 11≤a≤16,5.4≤b≤6.6,0≤c≤6 wherein, M be in Dy, Tb, Nb, Co, Ga, Zr, Al, the Cu element one or more.Crystal-boundary phase alloy adopts casting technique to make alloy of ingot or rapid hardening thin slice technology makes the rapid hardening thin slice or rapid quenching technique is made rapid tempering belt, and its composition is by molecular formula Nd dFe 100-d-e-fB eR f(at%) preparation, wherein R be in Dy, Tb, Nb, Co, Ga, Zr, C, Al, Cu, the Si element one or more, 13.5≤d≤30,4≤e≤7,0≤f≤15 wherein.
2) with main-phase alloy and crystal-boundary phase alloy powder process respectively.Undertaken slightly breaking by jaw crusher earlier, broken in being undertaken by middle disintegrating machine then.Perhaps adopt the quick-fried method of hydrogen directly broken, at room temperature saturated suction hydrogen is made the quick-fried powder of hydrogen at 400-600 ℃ of dehydrogenase 12-10h then.Broken back main-phase alloy and crystal-boundary phase alloy are by the airflow milling abrasive material, and making average particulate diameter is 2-10 μ m powder.
3) in the crystal-boundary phase alloy powder, add account for its weight 2-20%, through the nano-oxide of dispersion treatment, and the antioxidant of 1-10%, evenly mixed in batch mixer, wherein antioxidant is a kind of in polyethylene oxide alkyl ethers or poly(ethylene oxide) mono fatty acid ester or the poly(ethylene oxide) allyl ether.
4) will mix with the main-phase alloy powder through the crystal-boundary phase alloy powder that nano-oxide mixes, the crystal-boundary phase alloy powder weight accounts for the 1-20% of total weight, adds the gasoline of 0.5-5% simultaneously, is uniformly mixed into mixed-powder in batch mixer.Wherein nano-oxide is SiO 2, ZrO 2, CuO, Fe 2O 3, Al 2O 3, Y 2O 3, TiO 2In one or more, average particulate diameter is 2-40nm.
4) mixed-powder is compressed to parison spare in the magnetic field orientating moulding press, and moulding alignment magnetic field 1.2-2.0T increases the degree of orientation that magnetic can be improved in magnetic field.And the compression moulding of parison spare is finished in the glove box of sealing fully, makes the magnetic air-isolation, has avoided on the one hand the danger of catching fire because of magnet oxidation heating, has reduced the oxygen content of final magnet on the other hand again.
5) parison spare is put into high vacuum sintering furnace, 1050-1125 ℃ of sintering 2-4h passes through 500-650 ℃ of tempering heat treatment 2-4h again, makes sintered magnet.
Casting technique of the present invention is made alloy of ingot, is the alloy liquid after the melting to be cast in the water cooled mo(u)ld of 3-10mm thickness the Nd of alloy of ingot 2Fe 14The B crystal is grown in the sheet mode, the about 30-50 μ of the brilliant thickness of sheet m, and the about 500-1500 μ of width m, length depends on ingot casting cooling direction ingot mould size, its cooling rate is slow.
Rapid hardening thin slice technology is made the rapid hardening thin slice, it is the surface of the alloy liquid after the melting being watered the cooling running roller, about running roller rotational line speed 1-2m/s, the strip of near quick setting is sent in the cooling bath, obtain the about 0.3mm of thickness, the about 5-25 μ of the brilliant thickness of sheet m in the wide tens millimeters thin slice, crystal, its cooling rate about 2.5 * 10 3K/s.
Rapid quenching technique is made rapid tempering belt, is the red copper wheel surface that the alloy liquid after the melting is watered high speed rotating, and about rotational line speed 18m/s, the thickness that makes strip is 30-80 μ m, width 1-30mm, cooling rate about 10 5K/s.
The quick-fried method technology of hydrogen is with the rustless steel container of packing into of the NdFeB alloy with unsalted surface, after vacuumizing, charge into high-purity hydrogen, reach about an atmospheric pressure, will hear behind the process 20-30min that the cracker of alloy and the temperature of container raise, this is to form hydride behind the absorption hydrogen and explosion vacuumizes dehydrogenase 12-10h at 400-600 ℃ then.The airflow milling flouring technology is to utilize air-flow that powder particle is accelerated to supersonic speed to make it head-on collision mutually and fragmentation.
The particular content of above technology is seen Zhou Shouzeng, Dong Qingfei " superpower permanet magnetic body---rare-earth system permanent magnetic material " Beijing, metallurgical industry publishing house, 2004.2 second editions, p159-164, p498-504, p326-332, p508-511, p169-172 respectively.
Embodiment 1:
1) main-phase alloy and crystal-boundary phase alloy are prepared respectively.Main-phase alloy adopts rapid hardening thin slice technology, and copper roller linear resonance surface velocity is 1.2m/s, and composition is Nd 13.12Fe 80.31B 5.73(Dy 0.32Al 0.24Nb 0.28) (at%), crystal-boundary phase alloy adopts 20m/s fast quenching speed to be prepared into rapid tempering belt, composition is Nd 17.2Fe 75.04B 6.38Dy 0.64Ga 0.2Cu 0.54(at%).
2) with main-phase alloy and crystal-boundary phase alloy powder process respectively.Undertaken slightly breaking by jaw crusher, broken in being undertaken by middle disintegrating machine, under nitrogen protection, make the powder that average particulate diameter is 3 μ m then by airflow milling.
3) in the crystal-boundary phase alloy powder, add account for its weight 10%, through the nanometer Al of dispersion treatment 2O 3Powder (average particulate diameter is 30nm), and 3% antioxidant polyethylene oxide alkyl ethers, evenly mixed in batch mixer.
4) will be through nanometer Al 2O 3The crystal-boundary phase alloy powder that mixes mixes with the main-phase alloy powder, makes its weight account for 8% of total weight, adds 1% gasoline simultaneously, is uniformly mixed into mixed-powder in batch mixer.
5) mixed powder is compressed to parison spare by the magnetic field orientating moulding press, moulding alignment magnetic field 1.6T finishes in the glove box of sealing fully, makes the magnetic air-isolation.
6) parison spare is put into the high vacuum sintering furnace sintering, 1080 ℃ of sintering 3h, and 600 ℃ of tempering heat treatment 3h make sintered magnet again.
7) adopt the pairing gold process, add crystal-boundary phase alloy as stated above and account for total weight 8% composition mixed-powder, but do not add nanometer Al 2O 3, adopt identical magnetic field orientating die mould and sintering, tempering process to be prepared into magnet.
8) in addition, with the single alloy Nd of rapid hardening thin slice prepared 13.42Fe 79.87B 5.82(Dy 0.35Al 0.22Nb 0.26Ga 0.02Cu 0.04) (at%), promptly crystal-boundary phase alloy and main-phase alloy are by weight the composition of being formed at 8: 92, copper roller linear resonance surface velocity is 1.2m/s.Make the powder that average particulate diameter is 3 μ m by jaw crusher, middle disintegrating machine and airflow milling respectively.Add 1% gasoline, evenly mix after 0.24% the antioxidant polyethylene oxide alkyl ethers, in identical magnetic field orientating die mould and sintering, tempering process, be prepared into magnet.
Adopt the magnetic property of characteristic of magnetization automatic measuring instrument AMF measurement magnet, performance such as table one.
Table one, the magnet performance that adopts different process to prepare
Preparation technology B r(kGs) H cj(kOe) (BH) max(MGOe)
Single alloy technique 13.52 11.3 42.13
The pairing gold process does not add nanometer Al 2O 3 13.50 12.08 42.56
The pairing gold process adds nanometer Al 2O 3 13.49 14.21 43.22
Therefrom as can be seen, adopt the pairing gold process to add nanometer Al 2O 3Make the sintered NdFeB coercive force and do not add nano-oxide and make magnet coercive force height, more make magnet coercive force height, therefore add nanometer Al by the pairing gold process than single alloyage than adopting the pairing gold process 2O 3Can prepare the sintered NdFeB of high-coercive force.
Embodiment 2:
1) main-phase alloy and crystal-boundary phase alloy are prepared respectively.Main-phase alloy adopts rapid hardening thin slice technology, and copper roller linear resonance surface velocity is 2.0m/s, and composition is Nd 14.2Fe 78.13B 5.81(Tb 0.21Al 0.24Co 1.12Nb 0.28) (at%), crystal-boundary phase alloy adopts 18m/s fast quenching speed to be prepared into rapid tempering belt, composition is Nd 16.7Fe 76.27B 6.31(Dy 0.84Ga 0.2Cu 0.32) (at%).
2) with main-phase alloy and crystal-boundary phase alloy powder process respectively.Directly broken by the quick-fried method of hydrogen, at room temperature saturated suction hydrogen is made the quick-fried powder of hydrogen at 500 ℃ of dehydrogenation 8h then, makes the powder that average particulate diameter is 3.3 μ m by airflow milling then under nitrogen protection.
3) in the crystal-boundary phase alloy powder, add account for its weight 10%, through the nanometer SiO of dispersion treatment 2Powder (average particulate diameter is 10nm), and 4% antioxidant poly(ethylene oxide) mono fatty acid ester, evenly mixed in batch mixer.
4) will be through nanometer SiO 2The crystal-boundary phase alloy powder that mixes mixes with the main-phase alloy powder, makes its weight account for 5% of total weight, adds 1.2% gasoline simultaneously, is uniformly mixed into mixed-powder in batch mixer.
5) mixed powder is compressed to parison spare by the magnetic field orientating moulding press, moulding alignment magnetic field 1.6T finishes in the glove box of sealing fully, makes the magnetic air-isolation.
6) parison spare is put into the high vacuum sintering furnace sintering, 1070 ℃ of sintering 3h, and 510 ℃ of tempering heat treatment 2.5h make sintered magnet again.
7) adopt the pairing gold process, add crystal-boundary phase alloy as stated above and account for total weight 5% composition mixed-powder, but do not add nanometer SiO 2, adopt identical magnetic field orientating die mould and sintering, tempering process to be prepared into magnet.
8) in addition, with the single alloy Nd of rapid hardening thin slice prepared 14.48Fe 77.77B 5.89(Tb 0.2Dy 0.04Al 0.25Co 1.07Nb 0.27Ga 0.01Cu 0.02) (at%), promptly crystal-boundary phase alloy and main-phase alloy are by weight the composition of being formed at 5: 95, copper roller linear resonance surface velocity is 2.0m/s.Make the powder that average particulate diameter is 3.3 μ m by jaw crusher, middle disintegrating machine and airflow milling respectively.Add 1.2% gasoline, evenly mix behind 0.2% the antioxidant poly(ethylene oxide) mono fatty acid ester, in identical magnetic field orientating die mould and sintering, tempering process, be prepared into magnet.
Adopt the magnetic property of characteristic of magnetization automatic measuring instrument AMF measurement magnet, performance such as table two.
Table two, the magnet performance that adopts different process to prepare
Preparation technology B r(kGs) H cj(kOe) (BH) max(MGOe)
Single alloy technique 12.15 15.81 35.51
The pairing gold process does not add nanometer SiO 2 12.05 16.58 37.36
The pairing gold process adds nanometer SiO 2 12.02 17.02 38.43
Therefrom as can be seen, adopt the pairing gold process to add nanometer SiO 2Make the sintered NdFeB coercive force and do not add nano-oxide and make magnet coercive force height, also make magnet coercive force height, therefore add nanometer SiO by the pairing gold process than single alloyage than adopting the pairing gold process 2Can prepare the sintered NdFeB of high-coercive force.
Embodiment 3:
1) main-phase alloy and crystal-boundary phase alloy are prepared respectively.Main-phase alloy adopts rapid hardening thin slice technology, and copper roller linear resonance surface velocity is 2.2m/s, and composition is Nd 11.06Fe 82.25B 5.9Dy 0.79(at%), adopt the fast quenching technology, with crystal-boundary phase alloy Nd 27.83Fe 56.2B 6.68Dy 2.47Co 6.82(at%) be prepared into rapid tempering belt, fast quenching speed 18m/s.
2) with main-phase alloy and crystal-boundary phase alloy powder process respectively.Undertaken slightly breaking by jaw crusher, broken in being undertaken by middle disintegrating machine, under nitrogen protection, make the powder that average particulate diameter is 4.0 μ m then by airflow milling.
3) in the crystal-boundary phase alloy powder, add the nanometer SiO that accounts for its weight 5% through dispersion treatment 2Powder (average particulate diameter is 10nm), 5% nanometer ZrO 2Powder (average particulate diameter is 20nm), and 1% antioxidant polyethylene oxide alkyl ethers, evenly mixed in batch mixer.
4) will be through nanometer SiO 2, ZrO 2The crystal-boundary phase alloy powder that powder mixes mixes with the main-phase alloy powder, makes its weight account for 18% of alloy total weight, adds 2% gasoline simultaneously, is uniformly mixed into mixed-powder in batch mixer.
5) mixed powder is compressed to parison spare by the magnetic field orientating moulding press, moulding alignment magnetic field 1.6T finishes in the glove box of sealing fully, makes the magnetic air-isolation.
6) parison spare is put into the high vacuum sintering furnace sintering, 1065 ℃ of sintering 4.5h, and 560 ℃ of tempering heat treatment 3h make sintered magnet again.
Adopt the magnetic property of characteristic of magnetization automatic measuring instrument AMF measurement magnet, performance such as table three.
Table three adopts the pairing gold process to add nanometer SiO 2, ZrO 2The magnet performance of preparation
Preparation technology B r(kGs) H cj(koe) (BH) max(MGOe)
The pairing gold process adds nanometer SiO 2、ZrO 2 12.20 16.53 37.18
Embodiment 4:
1) main-phase alloy and crystal-boundary phase alloy are prepared respectively.Main-phase alloy adopts rapid hardening thin slice technology, and copper roller linear resonance surface velocity is 1.5m/s, and composition is Nd 12.59Fe 81.32B 5.7Dy 0.4(at%), crystal-boundary phase alloy adopts 18m/s fast quenching speed to be prepared into rapid tempering belt, and composition is Nd 23.74Fe 64.78B 6.89(Dy 0.92Co 1.27Cu 0.35Nb 0.4Al 1.66) (at%).
2) with main-phase alloy and crystal-boundary phase alloy powder process respectively.Directly broken by the quick-fried method of hydrogen, at room temperature saturated suction hydrogen is made the quick-fried powder of hydrogen at 500 ℃ of dehydrogenation 8h then, makes the powder that average particulate diameter is 3.5 μ m by airflow milling then under nitrogen protection.
3) in the crystal-boundary phase alloy powder, add the nanometer SiO that accounts for its weight 5% through dispersion treatment 2Powder (average particulate diameter is 1Onm), 3% nanometer Al 2O 3Powder (average particulate diameter is 30nm), and 1% antioxidant poly(ethylene oxide) allyl ether, evenly mixed in batch mixer.
4) will be through nanometer SiO 2, Al 2O 3The crystal-boundary phase alloy powder that mixes mixes with the main-phase alloy powder, makes its weight account for 20% of total weight, adds 2% gasoline simultaneously, is uniformly mixed into mixed-powder in batch mixer.
4) mixed powder is compressed to parison spare by the magnetic field orientating moulding press, moulding alignment magnetic field 1.8T finishes in the glove box of sealing fully, makes the magnetic air-isolation.
5) parison spare is put into the high vacuum sintering furnace sintering, 1100 ℃ of sintering 3h, and 560 ℃ of tempering heat treatment 3h make sintered magnet again.
Adopt the magnetic property of characteristic of magnetization automatic measuring instrument AMF measurement magnet, performance such as table five.
Table five adopts the pairing gold process to add nanometer SiO 2, Al 2O 3The magnet performance of preparation
Preparation technology B r(kGs) H cj(kOe) (BH) max(MGOe)
The pairing gold process adds nanometer SiO 2、Al 2O 3 13.2 14.69 42.38

Claims (4)

1. the preparation method of a Sintered NdFeB magnet is characterized in that its step is:
1) main-phase alloy adopts casting technique to make the neodymium iron boron alloy of ingot or make neodymium iron boron rapid hardening thin slice with rapid hardening thin slice technology, and crystal-boundary phase alloy adopts casting technique to make alloy of ingot or rapid hardening thin slice technology makes the rapid hardening thin slice or rapid quenching technique is made rapid tempering belt;
2) adopt the quick-fried method of hydrogen or by alloy of ingot, rapid hardening thin slice or the rapid tempering belt fragmentation of disintegrating machine with alloy of ingot or the rapid hardening thin slice and the crystal-boundary phase alloy of main-phase alloy, broken back is by the airflow milling abrasive material, making average particulate diameter respectively is 2-10 μ m powder;
3) in the crystal-boundary phase alloy powder, add account for its weight 2-20%, through the nano-oxide of dispersion treatment, in above-mentioned crystal-boundary phase alloy powder and nano-oxide, add the antioxidant of 1-10% weight again, evenly mixed in batch mixer, nano-oxide is SiO 2, ZrO 2, CuO, Fe 2O 3, Al 2O 3, Y 2O 3, TiO 2In one or more, average particulate diameter is 2-40nm;
4) will mix with the main-phase alloy powder through the crystal-boundary phase alloy powder that nano-oxide mixes, the crystal-boundary phase alloy powder weight accounts for the 1-20% of total weight, adds the gasoline of 0.5-5% weight again, is uniformly mixed into mixed-powder in batch mixer;
5) mixed-powder compression moulding blank in the magnetic field of 1.2-2.0T;
6) parison spare is put into high vacuum sintering furnace,, pass through 500-650 ℃ of tempering heat treatment 2-4h again, make sintered magnet at 1050-1125 ℃ of sintering 2-4h.
2. the preparation method of a kind of Sintered NdFeB magnet according to claim 1 is characterized in that its composition of said main-phase alloy counts Nd with atomic percent aFe 100-a-b-cB bM c, 11≤a≤16,5.4≤b≤6.6,0≤c≤6 wherein, M be in Dy, Tb, Nb, Co, Ga, Zr, Al, the Cu element one or more.
3. the preparation method of a kind of Sintered NdFeB magnet according to claim 1 is characterized in that its composition of said crystal-boundary phase alloy counts Nd with atomic percent dFe 100-d-e-fB eR f, 13.5≤d≤30,4≤e≤7,0≤f≤15 wherein, R be in Dy, Tb, Nb, Co, Ga, Zr, C, Al, Cu, the Si element one or more.
4. the preparation method of a kind of Sintered NdFeB magnet according to claim 1 is characterized in that said antioxidant is a kind of in polyethylene oxide alkyl ethers or poly(ethylene oxide) mono fatty acid ester or the poly(ethylene oxide) allyl ether.
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