Samarium-iron-nitrogen magnetic powder and preparation method thereof
阅读说明：本技术 一种钐铁氮磁粉及其制备方法 (Samarium-iron-nitrogen magnetic powder and preparation method thereof ) 是由 孙永阳 李军华 韩相华 于 2019-11-27 设计创作，主要内容包括：本发明涉及一种钐铁氮磁粉及其制备方法,所述磁粉以质量分数表示的名义成分为：Re-zSm-(24-z)Fe-(76-y)M-yN-x,其中Re包括除Sm以外的稀土中的任意一种或至少两种的组合,M包括3d和/或4d过渡族元素在内的任意一种或至少两种的组合,0<x≤5,0≤y≤5,0≤z≤5。所述制备方法包括如下步骤：按照名义成分进行配料,得到熔炼原料；将得到的熔炼原料进行熔炼,然后依次进行浇铸和冷却,得到速凝薄带；将得到的速凝薄带进行热处理,得到热处理带；将得到的热处理带依次进行氢爆破碎和气流粉碎,得到成粉；将得到的成粉进行氮化处理,得到所述的磁粉。通过对制备过程中,物料的细度及氢爆破碎的配置,实现了高效渗氮。(The invention relates to samarium-iron-nitrogen magnetic powder and a preparation method thereof, wherein the magnetic powder comprises the following nominal components in percentage by mass: re z Sm 24‑z Fe 76‑y M y N x Wherein Re comprises any one or a combination of at least two of rare earths other than Sm, M comprises any one or a combination of at least two of transition group elements of 3d and/or 4d, 0<x is less than or equal to 5, y is less than or equal to 5 and is less than or equal to 0, and z is less than or equal to 5 and is more than or equal to 0. The preparation method comprises the following steps: mixing the materials according to nominal components to obtain a smelting raw material; smelting the obtained smelting raw materials, and then sequentially casting and cooling to obtain a rapid-hardening thin strip; carrying out heat treatment on the obtained quick-setting thin strip to obtain a heat-treated strip; sequentially carrying out hydrogen explosion crushing and airflow crushing on the obtained heat treatment zone to obtain powder; and nitriding the obtained powder to obtain the magnetic powder. The high-efficiency infiltration is realized by the fineness of the materials and the configuration of hydrogen explosion and crushing in the preparation processAnd (3) nitrogen.)
1. A method for preparing samarium iron nitrogen magnetic powder is characterized in that the magnetic powder comprises the following nominal components by mass fraction: rezSm24-zFe76-yMyNxWhere Re includes any one or a combination of at least two of the rare earths other than Sm, and M includes a 3d and/or 4d transition group element inAny one or a combination of at least two of them, 0<x≤5，0≤y≤5，0≤z≤5；
The preparation method comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material;
(2) smelting the smelting raw material obtained in the step (1), and then sequentially casting and cooling to obtain a rapid hardening thin strip;
(3) carrying out heat treatment on the quick-setting thin strip obtained in the step (2) to obtain a heat-treated strip;
(4) sequentially carrying out hydrogen explosion crushing and airflow crushing on the heat treatment zone obtained in the step (3) to obtain powder;
(5) and (4) nitriding the formed powder obtained in the step (4) to obtain the magnetic powder.
2. The method of manufacturing according to claim 1, wherein the magnetic powder has a nominal composition of mass fractions of: x is more than or equal to 2 and less than or equal to 4, y is more than or equal to 0.1 and less than or equal to 2, and z is more than or equal to 0.1 and less than or equal to 2.
3. The production method according to claim 1 or 2, wherein each of Re and Sm in the smelting raw material in the step (1) is 5 to 50% by mass more than that in the nominal composition.
4. The preparation method of any one of claims 1 to 3, wherein the smelting in the step (2) comprises the operations of vacuumizing, preheating and filling inert atmosphere protection in sequence;
preferably, the casting temperature in the step (2) is 1450-;
preferably, the rotation speed of the copper roller in the casting in the step (2) is 0.1-5m/s, preferably 2-3 m/s;
preferably, the cooling in step (2) is carried out by air blast cooling under inert atmosphere;
preferably, the thickness of the quick-setting thin strip in the step (2) is 0.1-0.3 mm.
5. The production method according to any one of claims 1 to 4, wherein the heat treatment in the step (3) is a homogenization treatment using a vacuum sintering furnace;
preferably, the temperature of the heat treatment in the step (3) is 900-1100 ℃;
preferably, the time of the heat treatment in the step (3) is 10-1200 min.
6. The production method according to any one of claims 1 to 5, wherein the pressure of hydrogen gas in the hydrogen decrepitation in the step (4) is 0.01 to 0.5 MPa;
preferably, the time for absorbing hydrogen in the hydrogen explosion in the step (4) is 10-1200 min.
7. The production method according to any one of claims 1 to 6, wherein the jet milling in the step (4) is carried out under an inert atmosphere;
preferably, the rotating speed in the airflow pulverization in the step (4) is 1-6000r/min, preferably 2000-5000 r/min;
preferably, the particle size of the powder formed in step (4) is 1.5-15 μm, preferably 2-3 μm.
8. The production method according to any one of claims 1 to 7, wherein the nitriding treatment of step (5) is nitriding in an atmosphere containing a nitrogen element;
preferably, the pressure of the nitrogen-containing atmosphere in the step (5) is 0.01-1 MPa;
preferably, the partial pressure of nitrogen element in the nitrogen element-containing atmosphere in the step (5) is 0.01-1 MPa;
preferably, the nitriding temperature in the nitriding treatment in the step (5) is 450-530 ℃;
preferably, the nitriding time in the nitriding treatment in the step (5) is 10-1200 min.
9. The method of any one of claims 1 to 8, wherein the method comprises the steps of:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass ratio of Re and Sm in the smelting raw materials is 5-50% more than that in the nominal components;
(2) sequentially carrying out operations of vacuumizing, preheating and filling inert atmosphere for protection on the smelting raw materials obtained in the step (1), then casting at 1450-1600 ℃ and at the rotating speed of a copper roller of 0.1-5m/s, and then cooling in the inert atmosphere to obtain a rapid-hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the quick-setting thin strip obtained in the step (2) at the temperature of 900-1100 ℃ by using a vacuum sintering furnace for 10-1200min to obtain a heat treatment strip;
(4) carrying out hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 10-1200min under the hydrogen pressure of 0.01-0.5MPa, and then carrying out jet milling under the inert atmosphere at the rotating speed of 1-6000r/min to obtain powder of 1.5-15 mu m;
(5) nitriding the powder obtained in the step (4) in an atmosphere containing nitrogen for 10-1200min to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 0.01-1 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.01-1 MPa; the nitriding temperature in the nitriding treatment is 450-530 ℃.
10. A samarium iron nitride magnetic powder produced by the method of manufacture of any of claims 1 to 9, the powder having the nominal composition, expressed in mass fractions, of: rezSm24-zFe76-yMyNxWherein Re comprises any one or a combination of at least two of the rare earths other than Sm, and M comprises any one or a combination of at least two of the transition group elements of 3d and/or 4 d; 0<x is less than or equal to 5, y is less than or equal to 5 and is less than or equal to 0, and z is less than or equal to 5 and is more than or equal to 0; the nitrogen content of the magnetic powder is 2.6%, the remanence is more than or equal to 7810Gs, and the coercive force is more than or equal to 7230 Oe.
Technical Field
The invention relates to the technical field of magnetic materials, in particular to iron-nitrogen magnetic powder and a preparation method thereof.
Background
At present, in recent years, with the rapid development of miniaturization and light weight of automobile industry and electronic and electric appliances, higher environmental use temperature and magnetic property requirements are put on the permanent magnet, Sm2Fe17NxSm is a permanent magnet material which is a rare earth permanent magnet material and has good temperature stability and excellent magnetic property, the potential application value of Sm draws attention again2Fe17NxThe system is a permanent magnetic material and also meets new research and development heat tide. Preparation of Sm by prior art2Fe17NxThe rare earth permanent magnetic material mainly comprises a smelting method, a mechanical alloying method, a rapid quenching method and a reduction diffusion method.
CN102737801A discloses a method for preparing Sm-Fe-N anisotropic magnetic powder by rapid quenching, which controls the cooling speed of the melt and the thickness of the rapid-hardening cast sheet by controlling the rotation speed of a copper roller, the jet gas pressure of the melt, the size of a nozzle, the temperature of the melt and the components of the melt in the rapid solidification process to obtain a rapid-hardening thin strip Sm with a main phase in fine columnar crystal arrangement2Fe17. Further, CN105129860A discloses a method for preparing rare earth permanent magnet Sm2Fe17The process of the NX powder greatly improves the process controllability of the preparation of the Sm2Fe17 alloy and obtains high-purity Sm2Fe17Alloying and finally improving Sm2Fe17The magnetic property and the performance stability of the Nx powder, and the preparation process is suitable for industrial scale batch production and application. But the nitriding period is long, the nitriding efficiency is low, the nitriding is not uniform, and the industrial production is hindered.
To Sm2Fe17The alloy is nitrided, and the introduction of nitrogen not only increases the magnetic performance of the samarium-iron alloy, but also improves the Curie temperature, the corrosion resistance, the oxidation resistance and other performances. However, the current development of samarium iron nitrogen is solid nitriding after the samarium iron alloy is pulverized. The influencing factors of the solid nitriding include pressure, temperature and powder granularity. Pressure has some effect on nitriding samarium-iron alloys in the solid state but increasing the pressure nitriding rate remains low. The nitriding effect is also affected by the particle size of samarium-iron alloy powder, but the nitriding effect and the magnetic property of the final product are easily affected by the oxidation of particles caused by too small particles. The nitriding time of the prior samarium-iron alloy is too long and the nitriding effect is poor due to the reasons, so that the samarium-iron-nitrogen is difficult to realize industrial production.
Disclosure of Invention
In view of the problems in the prior art, the invention aims to provide samarium iron nitrogen magnetic powder and a preparation method thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a method for preparing samarium-iron-nitrogen magnetic powder, wherein the magnetic powder comprises the following nominal components in percentage by mass: rezSm24-zFe76-yMyNxWherein Re comprises any one or a combination of at least two of rare earths other than Sm, M comprises any one or a combination of at least two of transition group elements of 3d and/or 4d, 0<x≤5，0≤y≤5，0≤z≤5；
The preparation method comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material;
(2) smelting the smelting raw material obtained in the step (1), and then sequentially casting and cooling to obtain a rapid hardening thin strip;
(3) carrying out heat treatment on the quick-setting thin strip obtained in the step (2) to obtain a heat-treated strip;
(4) sequentially carrying out hydrogen explosion crushing and airflow crushing on the heat treatment zone obtained in the step (3) to obtain powder;
(5) and (4) nitriding the formed powder obtained in the step (4) to obtain the magnetic powder.
According to the invention, the samarium-iron-nitrogen magnetic powder with higher remanence and coercive force can be prepared by the method provided by the invention. Furthermore, the high-efficiency nitriding is realized through the fineness of materials and the hydrogen explosion crushing treatment in the preparation process of the samarium-iron-nitrogen magnetic powder, and meanwhile, the adjustment of the nitriding process and the control of the nitriding result are realized through the reasonable configuration of the atmosphere in the nitriding process. The nitrogen content in the magnetic powder can be adjusted through atmosphere adjustment according to performance requirements, so that the performance can be adjusted, and expected performance can be achieved.
Re in the present invention may be one or a combination of at least two of Pr, Nd, La, Ce, Gd, or Ho, and examples thereof include a combination of Pr and Nd, a combination of Nd and La, a combination of La and Ge, a combination of Ge and Gd, and a combination of Ho and Pr, but not limited to the combinations listed, and other combinations not listed in the range are also applicable.
In the present invention, M may be one or a combination of at least two of Co, Ni, Mn, Nb, Ga, Zr, C r, etc., and may be, for example, a combination of Co and Ni, a combination of Ni and Mn, a combination of Mn and Nb, a combination of Nb and Ga, a combination of Ga and Zr, or a combination of Cr and Co, but is not limited to the combinations listed, and other combinations not listed in the range are also applicable.
In the present invention, x may be 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4, 4.5 or 5, but is not limited to the listed values, and other values not listed in the range are also applicable.
In the present invention, the value of y may be 0, 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4, 4.5 or 5, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.
In the present invention, z may be 0, 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4, 4.5 or 5, but is not limited to the listed values, and other values not listed in the range may be applied.
As a preferable technical scheme of the invention, the magnetic powder comprises the following nominal components in percentage by mass: x is more than or equal to 2 and less than or equal to 4, y is more than or equal to 0.1 and less than or equal to 2, and z is more than or equal to 0.1 and less than or equal to 2.
In a preferred embodiment of the present invention, the amount of Re and Sm in the smelting raw materials in step (1) is 5 to 50% more by mass than the amount of Re and Sm in the nominal components, and may be, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50% by mass, but is not limited to the values listed, and other values not listed within this range are also applicable.
As a preferable technical scheme of the invention, the smelting in the step (2) comprises the operations of vacuumizing, preheating and filling inert atmosphere for protection in sequence.
Preferably, the casting temperature in step (2) is 1450-.
Preferably, the speed of rotation of the copper roll in the casting in step (2) is 0.1 to 5m/s, and may be, for example, 0.1m/s, 0.2m/s, 0.4m/s, 0.6m/s, 0.8m/s, 1.0m/s, 2m/s, 3m/s, 4m/s or 5m/s, etc., but is not limited to the values listed, and other values not listed in this range are equally applicable, preferably 2 to 3 m/s.
Preferably, the cooling in step (2) is carried out by air-blast cooling under an inert atmosphere.
Preferably, the thickness of the rapid-hardening thin strip in the step (2) is 0.1-0.3mm, for example, 0.1mm, 0.12mm, 0.14mm, 0.16mm, 0.18mm, 0.2mm, 0.22mm, 0.24mm, 0.26mm, 0.28mm, or 0.3mm, but not limited to the listed values, and other values not listed in the range are also applicable.
In a preferred embodiment of the present invention, the heat treatment in step (3) is performed by homogenizing in a vacuum sintering furnace.
Preferably, the temperature of the heat treatment in step (3) is 900-.
Preferably, the time of the heat treatment in the step (3) is 10-1200 min.
As a preferable technical scheme of the invention, the pressure of the hydrogen in the hydrogen explosion and fragmentation in the step (4) is 0.01-0.5 MPa.
Preferably, the hydrogen absorption time in the hydrogen explosion in the step (4) is 10-1200min, such as 10min, 20min, 40min, 60min, 80min, 100min, 200min, 300min, 400min, 500min, 600min, 700min, 800min, 900min, 1000min, 1100min or 1200min, etc., but not limited to the listed values, and other values not listed in the range are also applicable.
In a preferred embodiment of the present invention, the jet milling in step (4) is performed under an inert atmosphere, for example, the inert atmosphere includes an inert gas such as nitrogen or argon, but is not limited to the above-mentioned gases, and other gases not listed in this range are also applicable.
Preferably, the rotational speed in the jet milling in step (4) is 1-6000r/min, such as 1r/min, 10r/min, 100r/min, 200r/min, 400r/min, 800r/min, 1000r/min, 2000r/min, 3000r/min, 4000r/min, 5000r/min, or 6000r/min, but not limited to the listed values, and other values not listed in the range are equally applicable, preferably 2000-.
Preferably, the particle size of the powder formed in step (4) is 1.5-15 μm, and may be, for example, 1.5 μm, 3 μm, 4.5 μm, 6 μm, 7.5 μm, 9 μm, 10.5 μm, 12 μm, 13.5 μm or 15 μm, but is not limited to the values listed, and other values not listed in this range are equally applicable, preferably 2-3 μm.
In a preferred embodiment of the present invention, the nitriding treatment in the step (5) is performed in an atmosphere containing a nitrogen element. For example, the nitrogen-containing compound may be nitrogen, a mixed gas of nitrogen and hydrogen, ammonia, a mixed gas of ammonia and hydrogen, or a mixed gas of nitrogen, hydrogen and ammonia, and the like, and may also include other substances that generate nitrogen elements when heated.
Preferably, the pressure of the nitrogen-containing atmosphere in the step (5) is 0.01 to 1MPa, and for example, it may be 0.01MPa, 0.02MPa, 0.03MPa, 0.04MPa, 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa or 1MPa, but is not limited to the listed values, and other values not listed in the range are also applicable.
Preferably, the partial pressure of nitrogen in the nitrogen-containing atmosphere in step (5) is 0.01 to 1MPa, and may be, for example, 0.01MPa, 0.02MPa, 0.03MPa, 0.04MPa, 0.05MPa, 0.06MPa, 0.07MPa, 0.08MPa, 0.09MPa, or 1MPa, but is not limited to the values listed, and other values not listed in this range are also applicable.
Preferably, the nitriding temperature in the nitriding treatment in the step (5) is 450-530 ℃, for example, 450 ℃, 460 ℃, 470 ℃, 480 ℃, 490 ℃, 500 ℃, 510 ℃, 520 ℃ or 530 ℃ and the like, but is not limited to the listed values, and other values not listed in the range are also applicable.
Preferably, the nitriding time in the nitriding treatment in the step (5) is 10-1200min, for example, 10min, 20min, 40min, 60min, 80min, 100min, 200min, 300min, 400min, 500min, 600min, 700min, 800min, 900min, 1000min, 1100min or 1200min, etc., but is not limited to the listed values, and other values not listed in the range are also applicable.
As a preferred technical scheme of the invention, the method comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass ratio of Re and Sm in the smelting raw materials is 5-50% more than that in the nominal components;
(2) sequentially carrying out operations of vacuumizing, preheating and filling inert atmosphere for protection on the smelting raw materials obtained in the step (1), then casting at 1450-1600 ℃ and at the rotating speed of a copper roller of 0.1-5m/s, and then cooling in the inert atmosphere to obtain a rapid-hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the quick-setting thin strip obtained in the step (2) at the temperature of 900-1100 ℃ by using a vacuum sintering furnace for 10-1200min to obtain a heat treatment strip;
(4) carrying out hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 10-1200min under the hydrogen pressure of 0.01-0.5MPa, and then carrying out jet milling under the inert atmosphere at the rotating speed of 1-6000r/min to obtain powder of 1.5-15 mu m;
(5) nitriding the powder obtained in the step (4) in an atmosphere containing nitrogen for 10-1200min to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 0.01-1 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.01-1 MPa; the nitriding temperature in the nitriding treatment is 450-530 ℃.
In a second aspect, the invention provides samarium-iron-nitrogen magnet prepared by the preparation method of the first aspectPowder having a nominal composition, expressed in mass fraction, of: rezSm24-zFe76-yMyNxWherein Re comprises any one or a combination of at least two of the rare earths other than Sm, and M comprises any one or a combination of at least two of the transition group elements of 3d and/or 4 d; 0<x is less than or equal to 5, y is less than or equal to 5 and is less than or equal to 0, and z is less than or equal to 5 and is more than or equal to 0; the nitrogen content of the magnetic powder is 2.6%, the remanence is more than or equal to 7810Gs, and the coercive force is more than or equal to 7230 Oe.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) the invention realizes reasonable control of granularity during nitriding by introducing hydrogen explosion crushing, and realizes high efficiency of nitriding.
(2) According to the invention, the nitriding atmosphere is reasonably configured and the hydrogen explosion is introduced, so that the nitriding is controllable in the nitriding process.
(3) The nitrogen content of the samarium-iron-nitrogen magnetic powder prepared by the invention can reach more than 3.5 percent at most, the remanence can reach more than 8210Gs at most, and the coercive force can reach more than 10860Oe at most.
Drawings
FIG. 1 is Sm after heat treatment in example 12Fe17XRD diffraction patterns of the alloys;
FIG. 2 shows Sm after nitriding in example 12Fe17NxXRD diffraction pattern of the alloy.
The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:
example 1
Nominal composition in mass fraction in the samarium iron nitrogen magnetic powder prepared in this exampleComprises the following steps: NdSm23Fe75.5Co0.5Nx。
The method for preparing the samarium iron nitrogen magnetic powder comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass of each of Nd and Sm in the smelting raw material is 10% more than that in the nominal composition;
(2) sequentially vacuumizing, preheating and filling inert atmosphere for protection of the smelting raw materials obtained in the step (1), then casting at 1480 ℃ and at the copper roller rotating speed of 1m/s, and then cooling in the inert atmosphere to obtain a rapid hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the quick-setting thin strip obtained in the step (2) at 980 ℃ for 480min by using a vacuum sintering furnace to obtain Sm mainly2Fe17The heat-treated tape of (1); the XRD test was performed on the thin strip after the heat treatment, and the test result is shown in fig. 1.
(4) Carrying out hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 60min under the hydrogen pressure of 0.5MPa, and then carrying out airflow crushing under the inert atmosphere at the rotating speed of 2000r/min to obtain powder of 2.8 mu m;
(5) nitriding the formed powder obtained in the step (4) in a mixed atmosphere of nitrogen and hydrogen for 600min to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 1 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.3 MPa; the nitriding temperature in the nitriding treatment is 450 ℃. Sm is obtained2Fe17NxThe phase composition of the magnetic powder and the nitrided magnetic powder is tested by XRD, and the test result is shown in figure 2.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
Example 2
The samarium iron nitrogen magnetic powder prepared in this example had nominal compositions expressed in mass fraction: sm24Fe76Nx。
The method for preparing the samarium iron nitrogen magnetic powder comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass of Sm in the smelting raw material is 30% more than that in the nominal composition;
(2) sequentially carrying out vacuumizing, preheating and Ar atmosphere protection on the smelting raw materials obtained in the step (1), then casting at 1520 ℃ and at the rotating speed of a copper roller of 3m/s, and then cooling in an inert atmosphere to obtain a rapid hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the quick-setting thin strip obtained in the step (2) at 1050 ℃ for 480min by using a vacuum sintering furnace to obtain the main Sm2Fe17The heat-treated tape of (1); the heat treated thin strip was subjected to XRD test.
(4) Carrying out hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 120min under the hydrogen pressure of 0.3MPa, and then carrying out jet milling at the rotating speed of 5000r/min in an inert atmosphere to obtain powder of 2.3 mu m;
(5) nitriding the formed powder obtained in the step (4) in a mixed atmosphere of nitrogen and ammonia for 480min to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 1 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.6 MPa; the nitriding temperature in the nitriding treatment is 490 ℃. Sm is obtained2Fe17NxThe phase composition of the nitrided magnetic powder is tested by XRD.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
Example 3
The samarium iron nitrogen magnetic powder prepared in this example had nominal compositions expressed in mass fraction: sm23.5Ce0.5Fe75MnNx。
The method for preparing the samarium iron nitrogen magnetic powder comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass of each of Ce and Sm in the smelting raw material is 10% more than that in the nominal composition;
(2) sequentially carrying out vacuumizing, preheating and Ar atmosphere protection on the smelting raw materials obtained in the step (1), then casting at 1500 ℃ and the rotating speed of a copper roller of 2m/s, and then cooling in an inert atmosphere to obtain a rapid hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the rapid hardening thin strip obtained in the step (2) at 910 ℃ for 720min by using a vacuum sintering furnace to obtain the main Sm2Fe17The heat-treated tape of (1); the heat treated thin strip was subjected to XRD test.
(4) Performing hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 120min under the hydrogen pressure of 0.5MPa, and then performing jet milling at the rotating speed of 2500r/min in an inert atmosphere to obtain powder of 2.6 mu m;
(5) nitriding the formed powder obtained in the step (4) for 360min in a mixed atmosphere of ammonia gas and hydrogen gas to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 1 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.5 MPa; the nitriding temperature in the nitriding treatment is 510 ℃. Sm is obtained2Fe17NxThe phase composition of the nitrided magnetic powder is tested by XRD.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
Example 4
The samarium iron nitrogen magnetic powder prepared in this example had nominal compositions expressed in mass fraction: sm24Fe76Nx。
The method for preparing the samarium iron nitrogen magnetic powder comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass of Sm in the smelting raw material is 50% more than that in the nominal composition;
(2) sequentially carrying out vacuumizing, preheating and Ar atmosphere protection on the smelting raw materials obtained in the step (1), then casting at 1500 ℃ and at the rotating speed of a copper roller of 3m/s, and then cooling in an inert atmosphere to obtain a rapid hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the rapid hardening thin strip obtained in the step (2) at 1000 ℃ for 480min by using a vacuum sintering furnace to obtain Sm2Fe17The heat-treated tape of (1); the heat treated thin strip was subjected to XRD test.
(4) Carrying out hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 120min under the hydrogen pressure of 0.5MPa, and then carrying out jet milling at the rotating speed of 6000r/min in an inert atmosphere to obtain powder of 2.2 mu m;
(5) nitriding the formed powder obtained in the step (4) for 360min in a nitrogen atmosphere to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 0.6 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.6 MPa; the nitriding temperature in the nitriding treatment is 510 ℃. Sm is obtained2Fe17NxThe phase composition of the nitrided magnetic powder is tested by XRD.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
Example 5
The samarium iron nitrogen magnetic powder prepared in this example had nominal compositions expressed in mass fraction: sm24Fe76Nx。
The method for preparing the samarium iron nitrogen magnetic powder comprises the following steps:
(1) mixing the materials according to nominal components to obtain a smelting raw material; wherein the mass of Sm in the smelting raw material is 40% more than that in the nominal composition;
(2) sequentially carrying out vacuumizing, preheating and Ar atmosphere protection on the smelting raw materials obtained in the step (1), then casting at 1500 ℃ and at the rotating speed of a copper roller of 3m/s, and then cooling in an inert atmosphere to obtain a rapid hardening thin strip with the thickness of 0.1-0.3 mm;
(3) homogenizing the rapid hardening thin strip obtained in the step (2) at 1000 ℃ for 480min by using a vacuum sintering furnace to obtain Sm2Fe17The heat-treated tape of (1); the heat treated thin strip was subjected to XRD test.
(4) Carrying out hydrogen explosion crushing on the heat treatment belt obtained in the step (3) for 120min under the hydrogen pressure of 0.5MPa, and then carrying out jet milling at the rotating speed of 6000r/min in an inert atmosphere to obtain powder of 2.2 mu m;
(5) nitriding the formed powder obtained in the step (4) for 360min in a mixed atmosphere of nitrogen, ammonia and hydrogen to obtain the magnetic powder; wherein the pressure of the nitrogen-containing atmosphere is 0.8 MPa; the partial pressure of nitrogen in the nitrogen-containing atmosphere is 0.7 MPa; the nitriding temperature in the nitriding treatment is 510 ℃. Sm is obtained2Fe17NxThe phase composition of the nitrided magnetic powder is tested by XRD.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
Comparative example 1
The only difference from example 2 is that the hydrogen decrepitation in step (4) was not carried out.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
Comparative example 2
The only difference from example 2 is that the jet milling in step (4) was not performed.
Wherein, nitrogen content test is carried out on the nitrided magnetic powder by adopting an ONH analyzer; meanwhile, 8g of magnetic powder is taken and added with 3.5 percent of epoxy resin binder, pressed into a small cylinder, and subjected to magnetic property test with reference to GB/T13560-2017 and GB/T18880-2012; the measured nitrogen content, remanence and coercivity are detailed in table 1.
TABLE 1 Nitrogen content, remanence and coercive force in the examples and comparative examples
It can be seen from the results of the above examples and comparative examples that the method provided by the present invention can prepare samarium-iron-nitrogen magnetic powder with high nitrogen content, and simultaneously realize high-efficiency nitriding through organic coupling among the steps in the preparation process. Furthermore, it can be seen that the samarium iron nitrogen magnetic powder provided by the invention cannot achieve the performance when hydrogen explosion crushing or jet milling crushing is removed in the preparation process.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.