Neodymium-iron-boron permanent magnet material and preparation method thereof
阅读说明：本技术 一种钕铁硼永磁材料及其制备方法 (Neodymium-iron-boron permanent magnet material and preparation method thereof ) 是由 赵吉明 徐林云 于 2020-11-20 设计创作，主要内容包括：本申请涉及磁性材料领域,具体公开了一种钕铁硼永磁材料及其制备方法。钕铁硼永磁材料包括按质量份数计的以下组分：钕90-100份、硼铁15-20份、铁170-180份、铈1.5-2份、铝1-2份、钆8-10份、锆0.5-0.7份、铜0.4-0.6份、钴2-4份；其制备方法为：先对所需的原料进行称重,再放入熔炼炉内进行高温熔炼,然后进行氢破碎成粗颗粒,使用气流磨将粗颗粒粉碎至粉末状,真空下将钕铁硼合金粉末压制成型得到压坯,再进行高温烧结,最后进行回火处理。本申请的钕铁硼永磁材料可用于使用温度大于150℃的环境,其具有改善钕铁硼永磁材料的耐温性能的同时磁性能几乎不变的优点。(The application relates to the field of magnetic materials, and particularly discloses a neodymium iron boron permanent magnet material and a preparation method thereof. The neodymium iron boron permanent magnet material comprises the following components in parts by weight: 90-100 parts of neodymium, 15-20 parts of ferroboron, 180 parts of iron 170-containing iron, 1.5-2 parts of cerium, 1-2 parts of aluminum, 8-10 parts of gadolinium, 0.5-0.7 part of zirconium, 0.4-0.6 part of copper and 2-4 parts of cobalt; the preparation method comprises the following steps: weighing required raw materials, putting the raw materials into a smelting furnace for high-temperature smelting, then carrying out hydrogen crushing to obtain coarse particles, crushing the coarse particles into powder by using an airflow mill, carrying out compression molding on neodymium iron boron alloy powder under vacuum to obtain a pressed blank, carrying out high-temperature sintering, and finally carrying out tempering treatment. The neodymium iron boron permanent magnet material can be used in an environment with the use temperature being larger than 150 ℃, and has the advantages that the temperature resistance of the neodymium iron boron permanent magnet material is improved, and meanwhile, the magnetic performance is almost unchanged.)
1. The neodymium iron boron permanent magnet material is characterized by comprising the following raw materials in parts by weight: 90-100 parts of neodymium; 15-20 parts of ferroboron; 180 portions of iron 170; 1.5-2 parts of cerium; 1-2 parts of aluminum; 8-10 parts of gadolinium; 0.5-0.7 part of zirconium; 0.4-0.6 part of copper; 2-4 parts of cobalt.
2. A nd-fe-b permanent magnetic material according to claim 1, characterized in that: the raw materials comprise the following components in parts by weight: 94.4-98 parts of neodymium; 16-17 parts of ferroboron; 173.1-178 parts of iron; 1.6-1.9 parts of cerium; 1.5-1.9 parts of aluminum; 8.5-9.5 parts of gadolinium; 0.55-0.65 part of zirconium; 0.45-0.55 part of copper; 2.5-3.5 parts of cobalt.
3. A nd-fe-b permanent magnetic material according to claim 1, characterized in that: the amount of cobalt accounts for 1.0 wt% of the total amount of the raw materials, and the amount of aluminum accounts for 0.5 wt% of the total amount of the raw materials.
4. A nd-fe-b permanent magnetic material according to claim 1, characterized in that: the amount of copper is 0.18 wt% of the total amount of the raw materials.
5. A nd-fe-b permanent magnetic material according to claim 1, characterized in that: the amount of cerium is 0.55 wt% of the total amount of the raw materials.
6. The method for preparing a neodymium-iron-boron permanent magnet material according to any one of claims 1 to 5, characterized by comprising the following preparation steps:
(1) weighing the required raw materials;
(2) putting the weighed raw materials into a smelting furnace for high-temperature smelting;
(3) carrying out hydrogen crushing on the raw materials smelted in the step (2) to obtain coarse particles;
(4) crushing the coarse particles in the step (3) into powder by using an airflow mill to obtain neodymium iron boron alloy powder;
(5) pressing and forming the neodymium iron boron alloy powder under the vacuum condition to obtain a pressed blank;
(6) sintering the pressed blank prepared in the step (5) at a high temperature;
(7) and (4) tempering the product obtained in the step (6) after high-temperature sintering.
7. The method for preparing the neodymium-iron-boron permanent magnet material according to claim 6, characterized by comprising the following steps: (4) 0.03-0.05 wt% of compound of dibutyl hydroxy toluene and tert-butyl hydroquinone is added.
8. The method for preparing the neodymium-iron-boron permanent magnet material according to claim 6, characterized by comprising the following steps: (5) 0.04-0.06 wt% of polyethylene oxide allyl ether and polyethylene oxide compound is added.
9. The method for preparing the neodymium-iron-boron permanent magnet material according to claim 6, characterized by comprising the following steps: (6) wherein the sintering temperature is 1020-1080 ℃, and the sintering time is 4.5-5.5 h.
10. The method for preparing the neodymium-iron-boron permanent magnet material according to claim 6, characterized by comprising the following steps: (7) the tempering process comprises the steps of firstly performing primary tempering at 860-900 ℃ and keeping for 2-4h, and then performing secondary tempering at 500-540 ℃ and keeping for 2-4 h.
Technical Field
The application relates to the field of magnetic materials, in particular to a neodymium iron boron permanent magnetic material and a preparation method thereof.
Background
Nd-Fe-B is prepared from Nd, Fe and B (Nd)2Fe14B) The formed tetragonal crystal has Curie temperature of 320-460 deg.c.
The neodymium iron boron can be divided into sintered neodymium iron boron and bonded neodymium iron boron. In recent years, in order to protect the environment and save resources, development of new energy vehicles such as electric vehicles has been a trend. In new energy vehicles, including driving motors, generators and the like, neodymium iron boron permanent magnet materials are required to be sintered. The sintered Nd-Fe-B permanent magnet has small volume and high performance, can well reduce the motor quality and improve the motor efficiency, is more suitable for the miniaturization and the lightweight of automobiles, and plays an indispensable role in the fields of information industry, wind power generation industry, medical equipment industry, magnetic suspension trains and the like. The sintered Nd-Fe-B permanent magnet material is one of important material bases for promoting the modern science and technology and social progress, and provides a material base for the development of novel industries.
For example, the invention with the publication number of CN1308344A discloses a heat-resistant Nd-Fe-B permanent magnet material and a preparation method thereof, and is characterized in that the general formula of the magnetic alloy molecular formula is (15-x-y) NdxDyyTb (79-z-u-v-w) FeuCovNbwGazB.
In view of the above-mentioned related arts, the inventors believe that when the environment temperature for applying the ndfeb is 180 ℃ or more, the sintered ndfeb is demagnetized when exceeding the usage temperature of the sintered ndfeb.
Disclosure of Invention
In order to improve the use temperature of the neodymium iron boron permanent magnet material, the application provides the neodymium iron boron permanent magnet material and the preparation method thereof.
In a first aspect, the present application provides a neodymium iron boron permanent magnetic material, which adopts the following technical scheme:
the neodymium iron boron permanent magnet material comprises the following raw materials in parts by weight: 90-100 parts of neodymium; 15-20 parts of ferroboron; 180 portions of iron 170; 1.5-2 parts of cerium; 1-2 parts of aluminum; 8-10 parts of gadolinium; 0.5-0.7 part of zirconium; 0.4-0.6 part of copper; 2-4 parts of cobalt.
By adopting the technical scheme, the content of the rare earth elements in the raw materials is higher, and the bending strength of the neodymium iron boron magnet can be increased and the mechanical property of the neodymium iron boron magnet can be improved due to the addition of the rare earth elements.
Meanwhile, the higher the content of the rare earth element is, the more uniform and continuous the distribution of the rare earth-rich phase is. The rare earth-rich phase is a plastic phase in the sintered neodymium-iron-boron magnet, the plasticity of the rare earth-rich phase is better than that of the main phase, and the toughness of the magnet can be improved by increasing the content of the rare earth-rich phase. Secondly, the grain size of the main phase of the magnet with high content of rare earth is smaller than that of the magnet with low content of rare earth. The grain size is reduced, and the coercive force of the neodymium iron boron magnet is increased, so that high coercive force is obtained.
The aluminum element and the cobalt element in the raw materials can improve the interface of the main body of the neodymium iron boron magnet, thereby improving the temperature resistance of the neodymium iron boron magnet. The aluminum atom has no atomic magnetic moment, and the aluminum atom can occupy 8j of the neodymium-iron-boron compound2Crystal site, 8j2The crystal position is located at the center of the iron atom hexagonal prism, more iron atoms are adjacent to each other, the crystal position forms an alpha-Fe layer in neodymium iron boron, and aluminum atoms occupy 8j2After the crystal position, the magnetic moment of iron atoms adjacent to aluminum atoms is reduced, the remanence is reduced, and the intrinsic coercive force of the magnet can be improved by adding the aluminum element.
The aluminum element has the effect of refining and sintering the grains of the neodymium-iron-boron, the aluminum element in the deep layer enters the neodymium-rich phase, the infiltration angle of the neodymium-rich phase and the neodymium-iron-boron solid phase is improved, the width of the neodymium-rich phase and the boron-rich grain boundary phase can be reduced, and the distribution of the grain boundary rare earth-rich phase is more uniform. The aluminum element improves the wettability between the neodymium-rich phase and the main phase of the neodymium iron boron, so that the neodymium-rich phase is more uniformly distributed along the boundary, and the intrinsic coercive force of the sintered neodymium iron boron is improved. The grain refinement and the improvement of the intrinsic coercive force ensure that the temperature resistance of the neodymium iron boron is also improved.
Cobalt has high Curie temperature and large atomic magnetic moment, and cobalt atoms can replace part of iron atoms to participate in exchange action and improve the Curie temperature, so that the temperature resistance of the neodymium iron boron magnet is improved to some extent.
Contain aluminium element and cobalt element simultaneously in the above-mentioned raw materials, both can form aluminium cobalt phase in the preparation process of neodymium iron boron magnetism body, have improved the microstructure of neodymium iron boron magnetism body, when refining the crystalline grain, increase the wettability of crystalline grain, improved curie temperature, show the temperature resistance who improves sintering neodymium iron boron, and the reduction of neodymium iron boron magnetism body magnetic energy product is almost not counted for neodymium iron boron has good magnetic properties when improving temperature resistance.
Preferably, the neodymium iron boron alloy is prepared from the following raw materials in parts by mass: the raw materials comprise the following components in parts by weight: 94.4-98 parts of neodymium; 16-17 parts of ferroboron; 173.1-178 parts of iron; 1.6-1.9 parts of cerium; 1.5-1.9 parts of aluminum; 8.5-9.5 parts of gadolinium; 0.55-0.65 part of zirconium; 0.45-0.55 part of copper; 2.5-3.5 parts of cobalt.
By adopting the technical scheme, the content of the rare earth in the raw materials is further improved, and the bending strength of the neodymium iron boron magnet can be further improved, so that the mechanical property of the neodymium iron boron magnet is improved.
Preferably, the amount of cobalt is 1.0 wt% of the total amount of the raw materials, and the amount of aluminum is 0.5 wt% of the total amount of the raw materials.
By adopting the technical scheme, the intrinsic coercivity is improved by adding the aluminum element, and the microstructure of the grain boundary is improved by adding the aluminum element. The addition of the aluminum element is more than 0.5 wt%, the intrinsic coercive force of the neodymium iron boron magnet is reduced, the irreversible loss of magnetic flux is improved, and the temperature resistance is further deteriorated. Within the range of 0.5 wt%, excellent temperature resistance can be obtained and good magnetic performance of the neodymium iron boron magnet can be ensured.
By adding the cobalt element, the temperature resistance of the magnet can be improved. The amount of cobalt added was in the range of 1.0 wt%, the magnetic flux loss rate decreased with increasing amount of cobalt added, and the magnetic flux loss rate was minimized to 0.04% at 1.0 wt% of cobalt added. If the addition amount of the cobalt element exceeds 1.0 wt%, excessive cobalt atoms may be substituted for iron atoms, and the magnetic properties of the neodymium iron boron magnet may be reduced. Meanwhile, the price of cobalt is much higher than that of iron, and the cost is increased by adding too much cobalt.
Preferably, the copper is used in an amount of 0.18 wt% based on the total amount of the raw materials.
By adopting the technical scheme, the addition of the copper element improves the microstructure and the intrinsic coercive force, so that the temperature resistance of the magnet is improved. The copper element can form an orthogonal NdCu phase and a tetragonal NdFeB phase at the grain boundary, so that the wettability of a liquid phase is improved, and the corrosion resistance is enhanced. In the neodymium iron boron magnet without copper elements, the crystal grains are larger in size and are looser.
The addition amount of the copper element is within 0.18 wt%, the remanence is hardly reduced along with the addition of the copper element, the intrinsic coercive force is obviously increased, and the maximum energy product of the magnet is improved. In the magnet added with 0.18 wt% of copper element, the crystal boundary structure is clear, the crystal grains are more uniform, the magnet has no loose phenomenon, and the sintering performance and the crystal boundary structure of the magnet are improved. When the amount of the copper element added exceeds 0.18 wt%, both remanence and intrinsic coercive force are lowered, and the addition of the copper element also easily causes the generation of α -Fe, so that the content of the copper element needs to be strictly controlled.
Preferably, the cerium is used in an amount of 0.55 wt% based on the total amount of the raw materials.
By adopting the technical scheme, on the premise of remarkably improving the temperature resistance and ensuring the magnetic property, a proper amount of cerium is added to replace part of expensive neodymium elements, so that the production cost can be reduced.
In a second aspect, the present application provides a method for preparing a neodymium iron boron permanent magnet material, which adopts the following technical scheme:
a preparation method of a neodymium iron boron permanent magnet material comprises the following preparation steps:
(1) weighing the required raw materials;
(2) putting the weighed raw materials into a smelting furnace for high-temperature smelting;
(3) carrying out hydrogen crushing on the raw materials smelted in the step (2) to obtain coarse particles;
(4) crushing the coarse particles in the step (3) into powder by using an airflow mill;
(5) pressing and forming the neodymium iron boron alloy powder under the vacuum condition to obtain a pressed blank;
(6) sintering the pressed blank prepared in the step (5) at a high temperature;
(7) and (4) tempering the product obtained in the step (6) after high-temperature sintering.
Preferably, 0.03-0.05 wt% of compound of dibutylhydroxytoluene and tert-butylhydroquinone is added in (4).
By adopting the technical scheme, the compound of the butylated hydroxytoluene and the tertiary butyl hydroquinone is a composite product of two antioxidants, and the oxygen content in the neodymium iron boron alloy can be reduced, so that the magnetic performance is improved. In the preparation process of the neodymium iron boron permanent magnet material, a trace amount of oxygen enters the sintered neodymium iron boron in each procedure. The oxygen entering will react with the rare earth and the more active material to generate the corresponding oxide, reducing the magnetic performance.
Especially, in the powder making stage in (4), the neodymium-rich phase in the raw material of the ndfeb permanent magnet material is very easily oxidized into neodymium oxide, and the generation of the neodymium oxide can affect the microstructure of the ndfeb magnet, so that the remanence and the intrinsic coercivity of the ndfeb magnet are reduced, and the higher the content of the neodymium oxide is, the larger the reduction range of the remanence and the intrinsic coercivity of the ndfeb magnet is.
Therefore, a proper amount of antioxidant is added in the step (4), so that the oxygen content in the neodymium iron boron alloy can be effectively reduced, and the content of neodymium iron boron in the sintered neodymium iron boron permanent magnet is reduced to the lowest.
Preferably, 0.04-0.06 wt% of polyethylene oxide allyl ether and polyethylene oxide compound is added in (5).
By adopting the technical scheme, the compound of the polyethylene oxide allyl ether and the polyethylene oxide is a compound of two lubricants, so that the flowability of the neodymium iron boron alloy powder can be improved, and the production of the high-quality neodymium iron boron permanent magnet is facilitated.
(5) The forming process is a forming process of the neodymium iron boron permanent magnet material, the forming process is mechanical stacking of all neodymium iron boron alloy powder particles, the relative density of a pressed blank is very low, and the internal space of the powder particles is large and the strength is low. During the sintering process, the neodymium iron boron permanent magnet powder particles will be cohered due to poor fluidity, and the magnetic performance of the sintered magnet is very low. Therefore, a proper amount of lubricant is added in the molding section, so that the friction coefficient among powder particles can be reduced, the fluidity of the neodymium iron boron alloy powder is improved, and the magnetic performance of the sintered neodymium iron boron is improved.
Preferably, in the step (6), the sintering temperature is 1020-1080 ℃, and the sintering time is 4.5-5.5 h.
By adopting the technical scheme, organic matters in the pressed compact, gas adsorbed on the surfaces of the particles and gas remained in the pores can be fully removed. The magnetic property of the neodymium iron boron magnet is not improved due to overhigh sintering temperature or overlong sintering time. Along with the increase of the sintering temperature, the liquid phase is increased, more small particles are dissolved and separated out in the liquid phase, more small particles are separated out on the surface of large particles, so that abnormal growth of crystal grains occurs, and the driving force for the growth of the crystal grains is large under the condition of overhigh temperature. As the sintering time increases, the duration of solid phase sintering increases, the diffusion between crystal grains increases, the interface between crystal grains gradually disappears, and a phenomenon occurs in which several crystal grains grow into one crystal grain.
Preferably, in the step (7), the first-stage tempering is carried out at 860-900 ℃ and kept for 2-4h, and the second-stage tempering is carried out at 500-540 ℃ and kept for 3-4 h.
By adopting the technical scheme and the secondary tempering process, the grain boundary can become clear, the main phase grains are well separated, and the intrinsic coercivity is greatly improved. Because the neodymium-rich phase has serious agglomeration phenomenon before tempering, and after secondary tempering, the neodymium-rich phase is uniformly distributed around the grain boundary of the main phase, and a lamellar grain boundary phase is separated out, thereby reducing the agglomeration phenomenon of the neodymium-rich phase on the grain boundary and at the intersection of the grain boundaries. Therefore, the secondary tempering can better isolate the main phase grains, remove the exchange coupling effect among the grains, and is beneficial to improving the coercive force, and the grain boundary of the main phase is very regular after the secondary tempering treatment, so that the diamagnetic domain is difficult to form.
In summary, the present application has the following beneficial effects:
1. the microstructure of the neodymium iron boron permanent magnet is improved due to the aluminum-cobalt phase formed by aluminum and cobalt, so that the reduction of the magnetic energy product is almost negligible while the temperature resistance of the sintered neodymium iron boron is obviously improved, and the neodymium iron boron has a good magnetic property effect while the temperature resistance is improved;
2. copper element accounting for 0.18 wt% of the total amount of the raw materials is preferably added in the application, and the addition of the copper element improves the microstructure of the neodymium iron boron magnet, so that the effects of improving the intrinsic coercive force and improving the temperature resistance of the magnet are obtained;
3. according to the method, a proper amount of antioxidant is added in the powder making working section, and a proper amount of lubricant is added in the forming working section, so that the effects of reducing the oxygen content of the neodymium iron boron alloy and improving the magnetic performance of the sintered neodymium iron boron are achieved.
Drawings
FIG. 1 is a scanning electron micrograph of the green body obtained in example 1 after primary tempering;
FIG. 2 is a scanning electron micrograph of the green body of example 1 after secondary tempering.
Detailed Description
The present application will be described in further detail with reference to the following drawings and examples.
Example 1
A preparation method of a neodymium iron boron permanent magnet material comprises the following preparation steps:
(1) weighing required raw materials, including 94.4kg of neodymium, 16kg of ferroboron (6.25% of boron and 93.75% of iron), 173.1kg of iron, 1.9kg of cerium, 1.5kg of aluminum, 9kg of gadolinium, 0.6kg of zirconium, 0.5kg of copper and 3kg of cobalt;
(2) putting the weighed raw materials into a vacuum smelting furnace for high-temperature smelting;
(3) carrying out hydrogen crushing on the raw materials smelted in the step (2) to obtain coarse particles;
(4) adding 0.03-0.05 wt% of antioxidant into the jet mill, and crushing the coarse particles in (3) into fine powder with the average particle size of 3.5 um;
(5) under the vacuum condition, 0.04-0.06 wt% of lubricant is added into a vacuum furnace, the neodymium iron boron powder is prepared into a green compact by adopting a mould pressing mode, orientation treatment is carried out by utilizing a 1280kA/m magnetic field in the mould pressing forming process, and then the green body is further compacted by adopting a cold isostatic pressing method;
(6) keeping the blank prepared by isostatic cool pressing in the step (5) at the temperature of 1020-1080 ℃ for 4.5-5.5h, and keeping the vacuum condition of 10 < -2 > -10 < -3 > Pa in the sintering process;
(7) and (4) performing secondary tempering treatment on the product obtained after the high-temperature sintering in the step (6), cooling the furnace to 100 ℃ after sintering, then heating the furnace to 860-800 ℃ and keeping the temperature for 2-4h, then cooling the furnace to 500-540 ℃ and keeping the temperature for 2-4h, and finally air-cooling to room temperature.
Wherein the antioxidant is a compound of dibutyl hydroxy toluene and tert-butyl hydroquinone, and the mass ratio of the dibutyl hydroxy toluene to the tert-butyl hydroquinone is 1: 1. meanwhile, the lubricant is a compound of polyethylene oxide allyl ether and polyethylene oxide, and the mass ratio of the polyethylene oxide allyl ether to the polyethylene oxide is 1: 3.
referring to fig. 1 and 2, fig. 1 shows a primary tempered SEM microstructure of example 1 of the present application, and fig. 2 shows a secondary tempered SEM microstructure of example 1 of the present application. Comparing fig. 1 and fig. 2, it can be seen that after the secondary tempering, the neodymium-rich phase is uniformly distributed around the grain boundary of the main phase, and the agglomeration phenomenon on the grain boundary and at the intersection of the grain boundaries is reduced.
Examples 2 to 5
The preparation method of the neodymium iron boron permanent magnetic materials of the embodiments 2 to 5 is the same as that of the embodiment 1, except that the method is as shown in the following table 1:
table 1 raw material composition and amount of nd-fe-b permanent magnet material in examples 1-5
Performance test
1. Respectively taking out the finished neodymium iron boron magnet blocks in the embodiments 1 to 5, and after natural cooling, carrying out a coercivity test on the finished neodymium iron boron magnet blocks by using American MicroSense high precision;
2. testing the residual magnetism and intrinsic coercivity of the finished neodymium iron boron magnetic block by using an MATS-2010 permanent magnet measuring device;
3. testing the bending strength of the finished product neodymium iron boron magnetic block by using a bending strength testing machine;
the test results are shown in table 2 below:
table 2 examples 1-5 performance test results
Combining examples 1-5 and table 2, it can be seen that the higher the ratio of the rare earth content in the neodymium iron boron raw material is, the greater the bending strength of the finished neodymium iron boron magnetic block is.
Performance test
Three groups of finished neodymium iron boron products in the embodiments 1 to 5 are respectively heated to different temperatures, and after natural cooling, the tests are carried out by adopting the same method as the test, as shown in table 3:
TABLE 3 magnetic Properties of examples 1-5 at different test temperatures
It can be seen by combining examples 1-5 and table 3 that the finished ndfeb iron block can be applied to an environment with a use environment greater than 150 ℃, the magnetic performance of the ndfeb magnetic block at 180 ℃ is almost reduced, and the magnetic performance of the ndfeb magnetic block at 190 ℃ is slightly reduced, but the use performance is not affected.
Comparative examples 1 to 4
Comparative examples 1 to 4 were designed, wherein comparative examples 1 to 4 differed from example 1 only in the difference in Al and Co contents as shown in table 4:
TABLE 4 raw material composition and dosage of Nd-Fe-B permanent-magnet materials of comparative examples 1-4
Comparative example 1
Comparative example 2
Comparative example 3
Comparative example 4
Iron/kg
173.3
172.7
174.0
172.0
Ferroboron/kg
16
16
16
16
Nd/kg
94.0
94.0
94.0
94.0
Cerium/kg
1.6
1.6
1.6
1.6
Copper/kg
0.45
0.45
0.45
0.45
Gadolinium/kg
8.5
8.5
8.5
8.5
Zirconium/kg
0.55
0.55
0.55
0.55
Aluminum/kg
1.2
1.8
1.5
1.5
Cobalt/kg
3.0
3.0
2.0
4.0
The ndfeb films of comparative examples 1 to 4 were first heated to 180 ℃, then cooled to room temperature, and comparative examples 1 to 4 were tested using the same test method as in example 1, with the test results shown in table 5 below:
TABLE 5 magnetic Property test results of comparative examples 1 to 4
Test items
Br(kGs)
Hcj(kOe)
(BH)max
Comparative example 1
12.65
21.8
41.42
Comparative example 2
11.78
19.5
41.89
Comparative example 3
12.98
22.5
41.82
Comparative example 4
12.42
20.5
39.73
As can be seen from the combination of examples 1 to 5 and comparative examples 1 to 4 and Table 4, the addition of aluminum element can improve the intrinsic coercive force within a certain range; when the amount of the aluminum element added exceeds 0.5 wt%, the intrinsic coercive force is lowered. When the amount of Co added exceeds 1 wt%, the magnetic properties thereof are also deteriorated.
Examples 6 to 10
The ndfeb permanent magnet materials of examples 6-10 were prepared the same as in example 1, except as shown in table 6:
table 6 raw material composition and amount of nd-fe-b permanent magnet material in examples 6-10
Example 6
Example 7
Example 8
Example 9
Example 10
Iron/kg
173.1
173.1
173.1
173.1
173.1
Ferroboron/kg
16
16
16
16
16
Nd/kg
94.4
94.4
94.4
94.4
94.4
Cerium/kg
1.6
1.6
1.6
1.6
1.6
Copper/kg
0.45
0.45
0.45
0.45
0.45
Gadolinium/kg
8.5
8.5
8.5
8.5
8.5
Zirconium/kg
0.55
0.55
0.55
0.55
0.55
Aluminum/kg
1.5
1.5
1.5
1.5
1.5
Cobalt/kg
2.5
2.5
2.5
2.5
2.5
Antioxidant/kg
0.09
0.12
0.15
0.12
0.12
Lubricant/kg
0.12
0.12
0.12
0.15
0.18
The finished neodymium-iron-boron magnet of the embodiment 6-10 is tested by the same testing method as the embodiment 1, and the residual magnetism and the intrinsic coercive force of the neodymium-iron-boron magnet can be improved by adding a proper amount of antioxidant and lubricant, and can be reduced by adding excessive or small amount of antioxidant and lubricant.
Comparative examples 5 to 8
Comparative examples 5 to 8 were designed, wherein comparative examples 5 to 8 differed from example 1 only in the difference between the primary tempering and the secondary tempering temperatures as shown in table 4:
TABLE 7 temperature ranges for first and second temper
Procedure for the preparation of the
Comparative example 5
Comparative example 6
Comparative example 7
Comparative example 8
First temper/. degree.C
860-900
860-900
820-860
900-940
Secondary tempering deg.C
460-500
540-580
500-540
500-540
The ndfeb of comparative examples 5 to 8 were first cooled to room temperature and the results of the tests of comparative examples 5 to 8 were tested using the same test method as in example 1, and are shown in table 8 below:
TABLE 8 magnetic Property test results of comparative examples 5 to 8
Test items
Br(kGs)
Hcj(kOe)
(BH)max
Comparative example 5
12.49
21.5
40.36
Comparative example 6
11.49
19.3
41.49
Comparative example 7
12.62
22.4
41.49
Comparative example 8
12.82
20.1
40.63
It can be seen from the combination of example 1 and comparative examples 5-8 and table 8 that the magnetic performance is reduced when the sintering temperature is too high or too low, which is not good for improving the magnetic performance of the ndfeb magnet.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.
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