CN101958171B - Method for preparing corrosion-resistant sintered neodymium iron boron (NdFeB) magnet - Google Patents
Method for preparing corrosion-resistant sintered neodymium iron boron (NdFeB) magnet Download PDFInfo
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Abstract
The invention discloses a method for preparing a corrosion-resistant sintered neodymium iron boron (NdFeB) magnet. In the method, an intergranular phase optimized design is used as a starting point on the basis of preparation technology of a double-alloy method, the high-cobalt content rare earth cobalt-based alloy which does not contain iron and boron is selected as an auxiliary alloy, and the melting point of the auxiliary alloy is ensured to be lower than 1,050 DEG C through component control so as to meet the liquid-phase sintering effect. By measuring the weightlessness condition of the material placed in an environment of the temperature of 120 DEG C, two atmosphere and 100 percent of humidity for 96 hours, results show that the weightlessness of the prepared sintered NdFeB magnet is only less than 1/3 of that of the sintered NdFeB magnet prepared by a single-alloy method and a conventional double-alloy method, and the sintered NdFeB magnet has excellent corrosion resistance. The method for preparing the corrosion-resistant sintered NdFeB magnet can be widely applied in the field of production of high-performance sintered NdFeB magnets.
Description
Technical field
The present invention relates to a kind of preparation method's of Sintered NdFeB magnet, particularly a kind of corrosion-resistant Sintered NdFeB magnet preparation method.
Background technology
Through the Sintered NdFeB magnet of powder metallurgical technique preparation, have the excellent magnetic ability, be widely used in various fields such as electronics, automobile, computer, electric power, machinery, the energy, environmental protection, national defence, medicine equipment.The sintered NdFeB series permanent magnetic material mainly by principal phase (near Nd
2Fe
14The B phase) constitute mutually with rich rare earth (annotate: other has boron-rich phase, when the atomic percent of boron in the sintered NdFeB less than 6.5% the time, this phase can be ignored).Rich rare earth generally is distributed in the crystal boundary place mutually, has constituted the crystal boundary phase.Rich rare earth mainly is made up of the intermetallic compound of rare-earth-iron mutually, and its rare earth atom percentage composition often is higher than 75%.Rich rare earth plays the degaussing exchange-coupling interaction in magnet, help coercitive raising, because its fusing point is lower than principal phase, also helps the densification of magnet sintering simultaneously.But because the decay resistance of rich rare earth phase is relatively poor, also make the decay resistance of Sintered NdFeB magnet reduce greatly, limited its application in adverse circumstances.The main mechanism of sintered neodymium iron boron material corrosion comprises oxide etch and electrochemical corrosion.The oxidation of sintered NdFeB at first from crystal boundary (being rich rare earth phase) beginning, forms grain boundary corrosion; And because material density is not high, and oxidation product is more loose, can chain reaction in case form after the oxidation, accelerated oxidation.To this Chinese patent ZL200610038444.X propose to utilize non magnetic rare earth based block metal glass as crystal boundary with anti-oxidant, and obtain the lifting of decay resistance preferably.Yet electrochemical corrosion is to sintered NdFeB decay resistance also important influence usually.Because the corrosion potential of crystal boundary phase is lower, and volume fraction is little, so the local corrosion primary cell of the big negative electrode form of primary anode has brought crystal boundary to compare big corrosion electric current density, has quickened intercrystalline corrosion and destruction.To electrochemical corrosion, number of patent application CN200510050000.3 and number of patent application CN200910098783.0 disclose " middle mutually nano-silicon nitride raising neodymium iron boron working temperature and the corrosion resistance method of adding of crystal boundary " and " nanometer Zn crystal boundary modified high-corrosion resistance Sintered NdFeB magnet and preparation method thereof " two patent applications respectively.They are the basis with the pairing gold process; Change the microstructure of crystal boundary phase through corrosion resistant nano-si 3 n 4 ceramics particle of interpolation and nanometer Zn particle in the rich rare earth intermetallic compound that constitutes the crystal boundary phase; Reach the effect that reduces corrosion electric current density, improved decay resistance.Though this method can improve the corrosion resisting property of material, it is quite limited that it improves effect, is difficult to use; And the chemistry that this technical method does not change rich rare earth phase intermetallic compound constitutes, and the decay resistance of material still receives the influence of crystal boundary potential difference mutually and between the principal phase, does not fundamentally solve the corrosion proof problem of material.And prepare in the technology of sintered NdFeB at the single alloyage powder metallurgy of tradition, to this point, often usually improve the corrosion resisting property of material through compound other yuan of interpolation.Typically two patent ZL87106209.7 and the ZL91103569.9 like Sumitomo Special Metal Co., Ltd discloses " production method with rare-earth permanent magnet of excellent corrosion resistance " and " rare-earth permanent magnet with excellent corrosion resistance " respectively, points out that the interpolation of Co, Al element in single alloy technique can effectively improve the corrosion resisting property of rare-earth permanent magnet.Yet the rare-earth permanent magnet combination property of material prescription that relates in these two patents and production method correspondence is lower, does not solve the relevant issues of the corrosion resistance of performance Nd Fe B sintered magnet.
Pairing gold method is a kind of advanced method of preparation performance Nd Fe B sintered magnet.Its process route is the composition that designs main and auxiliary alloy respectively corresponding to principal phase and crystal boundary mutually; Control the microstructure of Sintered NdFeB magnet through the ratio of controlling main and auxiliary alloy.Through pairing gold method can the optimal design Sintered NdFeB magnet crystal boundary, effectively improve its comprehensive magnetic property and decay resistance.In the typical pairing gold process, the composition of auxilliary alloy carries out the composition design on the basis mutually at the rich rare earth of the sintered NdFeB of single alloy technique preparation, still contains multiple elements such as the Fe that is prone to cause oxide etch and electrochemical corrosion, B.
Summary of the invention
The technical problem that the present invention solved is to provide a kind of preparation method of corrosion-resistant Sintered NdFeB magnet, it with the rare earth cobalt-base alloys of high cobalt content as the auxilliary alloy in the pairing gold process, thereby improve the corrosion resistance of Sintered NdFeB magnet.
The technical solution that realizes the object of the invention is: a kind of preparation method of corrosion-resistant Sintered NdFeB magnet may further comprise the steps:
Step 1, choose master alloying, master alloying is Nd Fe B alloys ingot casting or the neodymium iron boron rapid hardening thin slice processed with rapid hardening thin slice technology;
Step 2, the auxilliary alloy of preparation, the atomic percent of auxilliary alloy is R1
100-x-y-zCo
xM
yR2
z, wherein 25≤x≤60,0≤y≤10,0≤z≤10.R1 is a kind of among Nd or the Pr or the mixing of the two, and R2 is a kind of among Dy, the Tb or the mixing of the two, and M is one or both and the above mixing among Al, Ga, Cu, Ti, Nb, Zr, the Hf;
Step 3, the auxilliary alloy of melting obtain auxilliary alloy cast ingot;
Step 4, main and auxiliary alloy is carried out the hydrogen fragmentation respectively, and to the master alloying dehydrogenation after the fragmentation;
Step 5, the major-minor alloy after the hydrogen break process is mixed, and add lubricant, oxidation inhibitor, gasoline;
Step 6, utilize airflow milling to grind in the powder that mixes, and in the air-flow process of lapping, add the activity that oxygen reduces particle surface, the granularity after the grinding is 1-10 μ m; The concentration that adds oxygen is 40-60ppm;
Step 7, the powder after will grinding place in the batch mixer and mix, and place magnetic field vertical orientated, and die mould becomes blank;
Step 8, the blank that die mould is good place the vacuum sintering, adopt double tempering heat treatment afterwards, obtain corrosion-resistant Sintered NdFeB magnet.
The present invention compared with prior art; Its remarkable advantage: the present invention is on pairing gold preparation technology's basis; Be designed to starting point mutually to optimize crystal boundary, with iron content not, boracic and rare earth cobalt-base alloys with high cobalt content be not as the auxilliary alloy in the pairing gold process.Rare earth cobalt-base alloys with high cobalt content mainly is made up of rare earth-cobalt intermetallic compound, under the situation of high cobalt content, shows stronger electrochemical corrosion resistant ability.The Sintered NdFeB magnet that obtains according to the present invention, its decay resistance have carried out the acceleration experiment with measuring in environmental laboratory, measure magnet is placed 96h in the environment of 121 ± 2 ℃, 2 atmospheric pressure and 100% humidity weightless situation.Its result shows the magnet that the present invention obtains, and compares weightlessness with the Sintered NdFeB magnet that single alloy method and conventional pairing gold process prepare and significantly reduces, and weightlessness is merely prepared by other and obtains below 1/3 of magnet weightlessness.Sintered NdFeB magnet constructed in accordance, its decay resistance can satisfy the harsh requirement of applications such as high-power wind-driven generator.
Below in conjunction with accompanying drawing the present invention is described in further detail.
Description of drawings
Accompanying drawing is preparation method's flow chart of a kind of corrosion-resistant Sintered NdFeB magnet of the present invention.
Embodiment
In conjunction with accompanying drawing, the preparation method of a kind of corrosion-resistant Sintered NdFeB magnet of the present invention may further comprise the steps:
Step 1, choose master alloying, master alloying is the Nd Fe B alloys ingot casting processed of casting technique or the neodymium iron boron rapid hardening thin slice of processing with rapid hardening thin slice technology, and its composition atomic ratio approaches Nd: Fe: B=2: 14: 1, concrete composition was adjusted according to performance requirement; Carrying out the 10-20h homogenization of composition for alloy cast ingot at 1050-1150 ℃ handles.
Step 2, the auxilliary alloy of preparation, the atomic percent of auxilliary alloy is R1
100-x-y-zCo
xM
yR2
z, 25≤x≤60,0≤y≤10,0≤z≤10 wherein, R1 is a kind of among Nd or the Pr or the mixing of the two, and R2 is a kind of among Dy, the Tb or the mixing of the two, and M is one or both and the above mixing among Al, Ga, Cu, Ti, Nb, Zr, the Hf.
Step 3, under inert gas shielding, by the auxilliary alloy of intermediate frequency furnace or arc melting, and obtain auxilliary alloy cast ingot.
Step 4, main and auxiliary alloy is carried out the hydrogen fragmentation respectively, and to the master alloying dehydrogenation after the fragmentation; Temperature during to the master alloying dehydrogenation after the fragmentation is 500-550 ℃, and dehydrogenation time is 2-4h.
Step 5, the major-minor alloy after the hydrogen break process is mixed, and add lubricant, oxidation inhibitor, gasoline; Auxilliary alloy powder weight accounted for the 3%-15% of both total weights when major-minor alloy was mixed, and lubricant accounts for the 0.05%-0.1% of alloy powder total weight, and oxidation inhibitor accounts for alloy powder total weight 0-3%, and gasoline accounts for the 0-1% of alloy powder total weight.
Step 6, utilize airflow milling to grind in the powder that mixes, and in the air-flow process of lapping, add the activity that oxygen reduces particle surface; When utilizing airflow milling to grind in the powder that mixes, the granularity after the grinding is 1-10 μ m; The concentration that adds oxygen is 40-60ppm.
Step 7, the powder after will grinding place in the batch mixer and mix, and place magnetic field vertical orientated, are pressed into blank afterwards; Mixing time is 30-90min, and alignment magnetic field is 1.5-2T.
Step 8, the blank that suppresses is placed the vacuum sintering, adopt double tempering heat treatment afterwards, obtain corrosion-resistant Sintered NdFeB magnet.When the blank that suppresses was carried out sintering, the temperature of sintering was 1050-1100 ℃, and sintering time is 3-6h; Double tempering heat treatment is specially: 850-950 ℃ the insulation 2-4h after gas quench to room temperature, be warming up to again 450-550 ℃ the insulation 2-4h after gas quench to room temperature.
Below in conjunction with embodiment the present invention is done further detailed description:
Embodiment 1
A kind of preparation method of corrosion-resistant Sintered NdFeB magnet may further comprise the steps:
Step 1, to choose master alloying be alloy cast ingot, and the master alloying atomic percent consists of Nd:11.0%, Dy:1.0%, Tb:0.5%; Nb:0.1%, Al:0.2%, Cu:0.1%, Ga:0.1%; Fe:81.0%, B:6.0%, master alloying ingot casting carry out the 20h homogenizing at 1100 ℃ to be handled.
Step 2, the auxilliary alloy of preparation, the atomic percent of auxilliary alloy consists of Nd:40.0%, Co:60.0%.
Step 3, the auxilliary alloy of employing induction melting method melting obtain auxilliary alloy cast ingot.
Step 4, with the broken powder process of hydrogen respectively of major-minor alloy.For the master alloying after the fragmentation at 550 ℃ of dehydrogenase 13 h.
Step 5, the major-minor alloy after the hydrogen break process is mixed, auxilliary alloy powder weight accounts for 5% of both total weights, adds the lubricant that accounts for alloy powder weight ratio 0.05% simultaneously.
Step 6, utilize airflow milling to be ground to 2-4 μ m in the powder that mixes, the oxygen that adds 50ppm in the air-flow process of lapping reduces the activity of particle surface.
Step 7, with the magnetic after the fragmentation place in the three-dimensional blender machine mix 60min after, vertical orientated compression moulding in the alignment magnetic field of 1.7T.
Step 8, the die mould base is placed under the vacuum atmosphere behind 1070 ℃ of sintering 4h, adopt double tempering heat treatment, gas is quenched to room temperature behind 900 ℃ of insulation 3h, be warming up to 500 ℃ of insulation 3h again after gas quench to room temperature, obtain corrosion-resistant Sintered NdFeB magnet.
As with the contrast of above-mentioned prepared sample, with major-minor alloy by weight 95: 5 pairing composition, prepare comparative sample with single alloy technique, its atomic percent consists of Nd:12.02%; Dy:0.97%, Tb:0.48%, Co:2.11%; Nb:0.10%, Al:0.19%, Cu:0.10%; Ga:0.10%, Fe:78.14%, B:5.79%; Fragmentation under identical process conditions, batch mixing, orientation die mould, with identical heating rate sintering and tempering, gas is quenched to room temperature in the high vacuum heat-treatment furnace; Design the auxilliary alloy formula of rich rare earth, Fu Tie, boracic with conventional pairing gold process, the composition atomic percent of its auxilliary alloy is Nd:30%, Fe:24%; Co:35%, B:6%, Al:1%; Cu:4%, according to main and auxiliary weight alloy than 95: 5 batch mixings, fragmentation under identical process conditions, batch mixing, orientation die mould; With identical heating rate sintering and tempering, gas is quenched to room temperature in the high vacuum heat-treatment furnace.Two comparative sample are placed in the environment of 121 ℃, 2 atmospheric pressure and 100% humidity measure its weightless situation behind the 96h, the result shows that the weightlessness that single alloyage prepares sample is 3.5mg/cm
2The sample weightlessness for preparing according to conventional pairing gold process is 2.1mg/cm
2And be 0.5mg/cm according to the weightlessness of the corrosion-resistant sintered NdFeB sample of process of the present invention preparation
2
Embodiment 2
A kind of preparation method of corrosion-resistant Sintered NdFeB magnet may further comprise the steps:
Step 1, to choose master alloying be the rapid hardening thin slice, and the master alloying atomic percent consists of Nd:7.2%, Pr:0.5%, Dy:2.2%, Tb:0.9%, Co:1.5%, Nb:0.3%, Al:0.3%, Fe:80.8%, B:6.3%.
Step 2, the auxilliary alloy of preparation, auxilliary alloy atom percentage consists of Nd:30%, Pr:25%, Dy:1%, Co:40%, Cu:2%, Ga:2%.
Step 3, the auxilliary alloy of employing induction melting method melting obtain auxilliary alloy cast ingot.
Step 4, with the broken powder process of hydrogen respectively of major-minor alloy, the master alloying after the fragmentation is at 500 ℃ of dehydrogenase 34 h.
Step 5, the major-minor alloy after the hydrogen break process is mixed, auxilliary alloy powder weight accounts for 7% of both total weights, adds accounting for the lubricant of weight ratio 0.1% simultaneously, and accounts for the oxidation inhibitor of alloy powder total weight 3% and 1% gasoline.
Step 6, utilize airflow milling to be ground to 3-6 μ m in the powder that mixes, the oxygen that adds 40ppm in the air-flow process of lapping reduces the activity of particle surface.
Step 7, with the magnetic after the fragmentation place in the three-dimensional blender machine mix 90min after, place the vertical orientated die mould of alignment magnetic field of 2T.
Step 8, the die mould base is placed under the vacuum atmosphere behind 1100 ℃ of sintering 4h, adopt double tempering heat treatment, gas is quenched to room temperature behind 950 ℃ of insulation 3h, be warming up to 550 ℃ of insulation 3h again after gas quench to room temperature, obtain corrosion-resistant Sintered NdFeB magnet.
As with the contrast of above-mentioned prepared sample, with major-minor alloy by weight 93: 7 pairing composition, prepare atomic percent with single alloy technique and consist of Nd:8.70%, Pr:0.60%; Dy:2.16%, Tb:0.86%, Co:3.88%; Nb:0.29%, Al:0.29%, Cu:0.12%; Ga:0.12%, B:6.00%, the comparative sample of Fe:76.98%; Batch mixing, fragmentation, orientation die mould under identical process conditions, with identical heating rate sintering and tempering, gas is quenched to normal temperature at last in the high vacuum heat-treatment furnace; Design the auxilliary alloy formula of rich rare earth, Fu Tie, boracic with conventional pairing gold process, the composition atomic percent of its auxilliary alloy is Nd:30%, Fe:24%; Co:35%, B:6%, Al:1%; Cu:4%, according to main and auxiliary weight alloy than 93: 7 batch mixings, fragmentation under identical process conditions, batch mixing, orientation die mould; With identical heating rate sintering and tempering, gas is quenched to room temperature in the high vacuum heat-treatment furnace.Two comparative sample are placed in the environment of 121 ℃, 2 atmospheric pressure and 100% humidity measure its weightless situation behind the 96h, the result shows that the weightlessness that single alloyage prepares sample is 2.2mg/cm
2The sample weightlessness for preparing according to conventional pairing gold process is 1.5mg/cm
2And be 0.3mg/cm according to the weightlessness of the corrosion-resistant sintered NdFeB sample of process of the present invention preparation
2
Embodiment 3
A kind of preparation method of corrosion-resistant Sintered NdFeB magnet may further comprise the steps:
Step 1, to choose master alloying be alloy cast ingot, and the master alloying atomic percent consists of Nd:7.2%, Pr:0.5%, Dy:2.0%; Tb:0.5%, Co:2.0%, Nb:0.3%, Al:0.5%; Cu:0.4%, Nb:0.4%, Ga:0.5%; Fe:80.0%, B:6.0%, the master alloying ingot casting is handled 1050 ℃ of homogenizing of carrying out 10h.
Step 2, the auxilliary alloy of preparation, auxilliary alloy atom percentage consists of Nd:40%, Pr:15%, Dy:5%, Tb:5%, Co:25%, Al:4%, Cu:2%, Nb:1%, Ga:3%.
Step 3, the auxilliary alloy of employing electric arc melting method melting obtain auxilliary alloy cast ingot.
Step 4, with the broken powder process of hydrogen respectively of major-minor alloy, the master alloying after the fragmentation is at 550 ℃ of dehydrogenase 34 h.
Step 5, the major-minor alloy after the hydrogen break process is mixed, auxilliary alloy powder weight accounts for 3% of both total weights, adds the lubricant that accounts for weight ratio 0.05% simultaneously.
Step 6, utilize airflow milling to be ground to 2-6 μ m in the powder that mixes, the oxygen that adds 60ppm in the air-flow process of lapping reduces the activity of particle surface.
Step 7, with the magnetic after the fragmentation place in the three-dimensional blender machine mix 90min after, place the vertical orientated die mould of alignment magnetic field of 1.5T.
Step 8, the die mould base is placed under the vacuum atmosphere behind 1050 ℃ of sintering 6h, adopt double tempering heat treatment, gas is quenched to room temperature behind 850 ℃ of insulation 2h, be warming up to 450 ℃ of insulation 2h again after gas quench to room temperature, obtain corrosion-resistant Sintered NdFeB magnet.
As with the contrast of above-mentioned prepared sample, with major-minor alloy by weight 97: 3 pairing composition, prepare atomic percent with single alloy technique and consist of Nd:7.74%, Pr:0.74%; Dy:2.05%, Tb:0.58%, Co:2.38%; Nb:0.43%, Al:0.56%, Cu:0.43%; Ga:0.54%, B:5.90%, the comparative sample of Fe:78.6%; Batch mixing, fragmentation, orientation die mould under identical process conditions, with identical heating rate sintering and tempering, gas is quenched to normal temperature at last in the high vacuum heat-treatment furnace; Design the auxilliary alloy formula of rich rare earth, Fu Tie, boracic with conventional pairing gold process, the composition atomic percent of its auxilliary alloy is Nd:30%, Fe:24%; Co:35%, B:6%, Al:1%; Cu:4%, according to main and auxiliary weight alloy than 97: 3 batch mixings, fragmentation under identical process conditions, batch mixing, orientation die mould; With identical heating rate sintering and tempering, gas is quenched to room temperature in the high vacuum heat-treatment furnace.Two comparative sample are placed in the environment of 121 ℃, 2 atmospheric pressure and 100% humidity measure its weightless situation behind the 96h, the result shows that the weightlessness that single alloyage prepares sample is 2.5mg/cm
2The sample weightlessness for preparing according to conventional pairing gold process is 2.3mg/cm
2And be 0.7mg/cm according to the weightlessness of the corrosion-resistant sintered NdFeB sample of process of the present invention preparation
2
Embodiment 4
A kind of preparation method of corrosion-resistant Sintered NdFeB magnet may further comprise the steps:
Step 1, to choose master alloying be the rapid hardening thin slice, and the master alloying atomic percent consists of Nd:12.5%, Nb:0.1%, Al:1.0%, Cu:1.0%, Fe:79.4%, B:6.0%.
Step 2, the auxilliary alloy of preparation, auxilliary alloy atom percentage consists of Nd:30.0%, Dy:6%, Co:59%, Al:1%, Cu:4%.
Step 3, the auxilliary alloy of employing electric arc melting method melting obtain auxilliary alloy cast ingot.
Step 4, with the broken powder process of hydrogen respectively of major-minor alloy.For the master alloying after the fragmentation at 550 ℃ of dehydrogenase 12 h.
Step 5, the major-minor alloy after the hydrogen break process is mixed, auxilliary alloy powder weight accounts for both total weights 10%, adds lubricant, 1% oxidation inhibitor and 1% the gasoline that accounts for weight ratio 0.05% simultaneously.
Step 6, utilize airflow milling to be ground to 3-6 μ m in the powder that mixes, the oxygen that adds 60ppm in the air-flow process of lapping reduces the activity of particle surface.
Step 7, with the magnetic after the fragmentation place in the three-dimensional blender machine mix 30min after, place the alignment magnetic field of 2T to be orientated die mould.
Step 8, the die mould base is placed under the vacuum atmosphere behind 1090 ℃ of sintering 3h, adopt double tempering heat treatment, gas is quenched to room temperature behind 900 ℃ of insulation 3h, be warming up to 500 ℃ of insulation 3h again after gas quench to room temperature, obtain corrosion-resistant Sintered NdFeB magnet.
As with the contrast of above-mentioned prepared sample, with major-minor alloy by weight 90: 10 pairing composition, prepare atomic percent with single alloy technique and consist of Nd:13.77%, Dy:0.44%; Fe:73.63%, Co:4.29%, B:5.56%; Al:1.00%, Cu:1.22%, Nb:0.09%; Batch mixing, fragmentation, orientation die mould under identical process conditions, with identical heating rate sintering and tempering, gas is quenched to normal temperature at last in the high vacuum heat-treatment furnace; Design the auxilliary alloy formula of rich rare earth, Fu Tie, boracic with conventional pairing gold process, the composition atomic percent of its auxilliary alloy is Nd:20%, Dy:10%; Fe:24%, Co:35%, B:6%; Al:1%, Cu:4%, according to main and auxiliary weight alloy than 90: 10 batch mixings; Fragmentation under identical process conditions, batch mixing, orientation die mould, with identical heating rate sintering and tempering, gas is quenched to room temperature in the high vacuum heat-treatment furnace.Two comparative sample are placed in the environment of 121 ℃, 2 atmospheric pressure and 100% humidity measure its weightless situation behind the 96h, the result shows that the weightlessness that single alloyage prepares sample is 5.5mg/cm
2The sample weightlessness for preparing according to conventional pairing gold process is 2.5mg/cm
2And be 0.75mg/cm according to the weightlessness of the corrosion-resistant sintered NdFeB sample of process of the present invention preparation
2
Embodiment 5
A kind of preparation method of corrosion-resistant Sintered NdFeB magnet may further comprise the steps:
Step 1, to choose master alloying be alloy cast ingot, and the master alloying atomic percent consists of Nd:10.0%, Dy:1.2%, Al:2.5%, Cu:0.3%, Ga:0.5%, Fe:79.0%, B:6.5%.The master alloying ingot casting carries out the 15h homogenizing at 1050 ℃ to be handled.
Step 2, the auxilliary alloy of preparation, auxilliary alloy atom percentage consists of Nd:25%, Pr:17%, Dy:2%, Tb:2%, Co:50%, Ti:1%, Hf:1%, Zr:1%, Nb:1%.
Step 3, the auxilliary alloy of employing induction melting method melting obtain auxilliary alloy cast ingot.
Step 4, with the broken powder process of hydrogen respectively of major-minor alloy.For the master alloying after the fragmentation at 550 ℃ of dehydrogenase 34 h.
Step 5, the major-minor alloy after the hydrogen break process is mixed, auxilliary alloy powder weight accounts for both total weights 15%, adds the lubricant that accounts for weight ratio 0.05% simultaneously.
Step 6, utilize airflow milling to be ground to 3-6 μ m in the powder that mixes, the oxygen that adds 50ppm in the air-flow process of lapping reduces the activity of particle surface.
Step 7, with the magnetic after the fragmentation place in the three-dimensional blender machine mix 90min after, place the alignment magnetic field of 1.7T to be orientated die mould.
Step 8, the die mould base is placed under the vacuum atmosphere behind 1090 ℃ of sintering 6h, adopt double tempering heat treatment, gas is quenched to room temperature behind 950 ℃ of insulation 4h, be warming up to 550 ℃ of insulation 4h again after gas quench to room temperature, obtain corrosion-resistant Sintered NdFeB magnet.
As with the contrast of above-mentioned prepared sample, with major-minor alloy by weight 85: 15 pairing composition, prepare atomic percent with single alloy technique and consist of Nd:11.49%, Pr:1.69%; Dy:1.28%, Tb:0.20%, Fe:71.16%, Co:4.96%; B:5.85%, Al:2.25%, Cu:0.27%, Nb:0.10%; Ga:0.45%, Ti:0.10%, Zr:0.10%, Hf:0.10%; Batch mixing, fragmentation, orientation die mould under identical process conditions, with identical heating rate sintering and tempering, gas is quenched to normal temperature at last in the high vacuum heat-treatment furnace; Design the auxilliary alloy formula of rich rare earth, Fu Tie, boracic with conventional pairing gold process, the composition atomic percent of its auxilliary alloy is Nd:20%, Dy:10%; Fe:24%, Co:35%, B:6%; Al:1%, Cu:4%, according to main and auxiliary weight alloy than 85: 15 batch mixings; Fragmentation under identical process conditions, batch mixing, orientation die mould, with identical heating rate sintering and tempering, gas is quenched to room temperature in the high vacuum heat-treatment furnace.Two comparative sample are placed in the environment of 121 ℃, 2 atmospheric pressure and 100% humidity measure its weightless situation behind the 96h, the result shows that the weightlessness that single alloyage prepares sample is 1.8mg/cm
2The sample weightlessness for preparing according to conventional pairing gold process is 1.5mg/cm
2And be 0.35mg/cm according to the weightlessness of the corrosion-resistant sintered NdFeB sample of process of the present invention preparation
2
Sample according to the foregoing description preparation compares with the test that single alloyage of prior art and conventional pairing gold legal system are equipped with sample, and weightlessness significantly reduces, and therefore, the Sintered NdFeB magnet that makes according to the present invention has possessed more superior decay resistance.
Claims (5)
1. the preparation method of a corrosion-resistant Sintered NdFeB magnet is characterized in that, may further comprise the steps:
Step 1, choose master alloying, master alloying is Nd Fe B alloys ingot casting or the neodymium iron boron rapid hardening thin slice processed with rapid hardening thin slice technology;
Step 2, the auxilliary alloy of preparation, the atomic percent of auxilliary alloy is R1
100-x-y-zCo
xM
yR2
z, 25≤x≤60,0≤y≤10,0≤z≤10 wherein, R1 is a kind of among Nd or the Pr or the mixing of the two, and R2 is a kind of among Dy, the Tb or the mixing of the two, and M is one or both and the above mixing among Al, Ga, Cu, Ti, Nb, Zr, the Hf;
Step 3, the auxilliary alloy of melting obtain auxilliary alloy cast ingot;
Step 4, main and auxiliary alloy is carried out the hydrogen fragmentation respectively, and to the master alloying dehydrogenation after the fragmentation;
Step 5, the major-minor alloy after the hydrogen break process is mixed, and add lubricant, oxidation inhibitor, gasoline;
Step 6, utilize airflow milling to grind in the powder that mixes, and in the air-flow process of lapping, add the activity that oxygen reduces particle surface, the granularity after the grinding is 1-10 μ m; The concentration that adds oxygen is 40-60ppm;
Step 7, the powder after will grinding place in the batch mixer and mix, and place magnetic field vertical orientated, and die mould becomes blank;
Step 8, the blank that die mould is good place the vacuum sintering, adopt double tempering heat treatment afterwards, obtain corrosion-resistant Sintered NdFeB magnet.
2. the preparation method of corrosion-resistant Sintered NdFeB magnet according to claim 1 is characterized in that, the temperature during master alloying dehydrogenation after the step 4 pair fragmentation is 500-550 ℃, and dehydrogenation time is 2-4h.
3. the preparation method of corrosion-resistant Sintered NdFeB magnet according to claim 1; It is characterized in that; Auxilliary alloy powder weight accounted for the 3%-15% of both total weights when step 5 pair major-minor alloy mixed; Lubricant accounts for the 0.05%-0.1% of alloy powder total weight, and oxidation inhibitor accounts for alloy powder total weight 0-3%, and gasoline accounts for the 0-1% of alloy powder total weight.
4. the preparation method of corrosion-resistant Sintered NdFeB magnet according to claim 1 is characterized in that, mixing time is 30-90min in the step 7, and alignment magnetic field is 1.5-2T.
5. the preparation method of corrosion-resistant Sintered NdFeB magnet according to claim 1 is characterized in that, when step 8 was carried out sintering with the blank that suppresses, the temperature of sintering was 1050-1100 ℃, and sintering time is 3-6h; Double tempering heat treatment is specially: 850-950 ℃ the insulation 2-4h after gas quench to room temperature, be warming up to again 450-550 ℃ the insulation 2-4h after gas quench to room temperature.
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| 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 |
| CN113517125B (en) * | 2021-07-12 | 2023-05-05 | 安徽大地熊新材料股份有限公司 | High-stability sintered NdFeB magnet and preparation method thereof |
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