阅读说明：本技术 一种间隙稀土永磁合金材料及其制备方法 (Interstitial rare earth permanent magnet alloy material and preparation method thereof ) 是由 孙永阳 李玉平 蒋云涛 张云逸 徐君 于 2021-08-24 设计创作，主要内容包括：本发明提供一种间隙稀土永磁合金材料及其制备方法,所述间隙稀土永磁合金材料的化学式为A-(δ)Fe-(γ)D-(ε)N-(Ψ),所述A包括Sc、Y或镧系元素中的任意一种或至少两种的组合,所述A必须包括Sm和/或Nd,所述D包括IVB、VB、VIB、VIIB、VIIIB、IB或II2B族元素中的任意一种或至少两种的组合,1.5≤δ≤2.5,15≤γ≤19,0＜ε/γ≤20,1≤Ψ/δ≤2。所述制备方法所用原材料成本低、还原扩散工艺简单可控、无需预还原、合金相纯度高,制备的粉料无需后期细粉碎粒度细且分布均匀,磁性能优异。(The invention provides a gap rare earth permanent magnet alloy material and a preparation method thereof, wherein the chemical formula of the gap rare earth permanent magnet alloy material is A δ Fe γ D ε N Ψ The A comprises any one or the combination of at least two of Sc, Y or lanthanide elements, the A must comprise Sm and/or Nd, the D comprises any one or the combination of at least two of elements in groups IVB, VB, VIB, VIIB, VIIIB, IB or II2B, 1.5 is larger than or equal to delta and smaller than or equal to 2.5, 15 is larger than or equal to gamma and smaller than or equal to 19, 0 is larger than epsilon/gamma and smaller than or equal to 20, and 1 is larger than or equal to psi/delta and smaller than or equal to 2. The preparation method has the advantages of low cost of raw materials, simple and controllable reduction and diffusion process, no need of pre-reduction, high purity of alloy phase, no need of fine grinding of prepared powder in later period, fine and uniform granularity, and high magnetismThe performance is excellent.)

1. The gap rare earth permanent magnet alloy material is characterized in that the chemical formula of the gap rare earth permanent magnet alloy material is A_δFe_γD_εN_ΨWherein A comprises any one or at least two of Sc, Y or lanthanoidThe combination, the A necessarily comprises Sm and/or Nd, the D comprises any one or combination of at least two of elements in groups IVB, VB, VIB, VIIB, VIIIB, IB or II2B, 1.5 is more than or equal to delta and less than or equal to 2.5, 15 is more than or equal to gamma and less than or equal to 19, 0 is more than epsilon/gamma and less than or equal to 20, and 1 is more than or equal to psi/delta and less than or equal to 2.

2. The method for preparing the gap rare earth permanent magnet alloy material as claimed in claim 1, wherein the method comprises the following steps:

(1) mixing the oxide powder A, the oxide powder D and the iron oxide powder, then carrying out first heat treatment, and mixing the mixed powder after heat treatment with a reducing agent, a separant and a disintegrator to obtain a mixed raw material;

(2) carrying out reduction diffusion sintering on the mixed raw material obtained in the step (1), and carrying out nitriding reaction after the reduction diffusion sintering is finished to obtain a block product;

(3) and (3) carrying out second heat treatment on the block product obtained in the step (2), then carrying out collapsing cleaning, and drying to obtain the powder of the gap rare earth permanent magnet alloy material.

3. The method according to claim 2, wherein the oxide powder A, the oxide powder D and the iron oxide powder in step (1) each independently have a particle diameter D50 of 1 to 3 μm;

preferably, the mixing of step (1) is carried out in a sand mill or a ball mill;

preferably, the mass ratio of the mixed medium material to the balls to the water is 1: 12-17: 1-2;

preferably, the mixing time is 1-20 h, preferably 2-10 h.

4. The production method according to claim 2 or 3, wherein the heat treatment of step (1) includes a first temperature rise, a first temperature hold, a second temperature rise, a second temperature hold, a third temperature rise, and a third temperature hold;

preferably, the temperature range of the first temperature rise is 20-150 ℃;

preferably, the first temperature rise time is 2-50 min;

preferably, the first heat preservation time is 1-60 min;

preferably, the temperature range of the second temperature rise is 150-300 ℃;

preferably, the time of the second temperature rise is 2-50 min;

preferably, the second heat preservation time is 1-120 min;

preferably, the temperature range of the third temperature rise is 300-700 ℃;

preferably, the third temperature rise time is 50-150 min;

preferably, the third heat preservation time is 1-120 min.

5. The preparation method according to claim 2 to 4, wherein the reducing agent in the step (1) comprises activated carbon and calcium particles;

preferably, the particle size D50 of the activated carbon is less than or equal to 1 μm;

preferably, the particle size D50 of the calcium particles is less than or equal to 5 mm;

preferably, the adding amount of the activated carbon is 1.0-1.3 times of the reaction equivalent;

preferably, the addition amount of the calcium particles is 1.1-1.5 times of the reaction equivalent;

preferably, the release agent and the collapsing agent are calcium oxide;

preferably, the particle size D50 of the calcium oxide is less than or equal to 1 μm;

preferably, the amount of the calcium oxide is 0.5-10% of the total mass of the mixed powder and the reducing agent.

6. The preparation method according to claim 2 to 5, wherein the reduction diffusion sintering in the step (2) is performed under vacuum;

preferably, the reduction diffusion sintering is performed under a protective atmosphere;

preferably, the reduction diffusion sintering comprises a first temperature rise, a first heat preservation, a second temperature rise, a second heat preservation, a third temperature rise, a third heat preservation, a fourth temperature rise and a fourth heat preservation;

preferably, the temperature range of the first temperature rise is 20-120 ℃;

preferably, the first temperature rise time is 10-80 min;

preferably, the first heat preservation time is 1-60 min;

preferably, the temperature range of the second temperature rise is 120-400 ℃;

preferably, the time of the second temperature rise is 20-60 min;

preferably, the second heat preservation time is 1-150 min;

preferably, the temperature range of the third temperature rise is 400-800 ℃;

preferably, the third temperature rise time is 10-90 min;

preferably, the third heat preservation time is 1-200 min;

preferably, the temperature range of the fourth temperature rise is 800-1050 ℃;

preferably, the fourth temperature rise time is 5-50 min;

preferably, the fourth heat preservation time is 1-300 min;

preferably, the vacuumizing is stopped and oxygen is filled when the second temperature rise is finished;

preferably, the charging amount of the oxygen is 0.01 to 0.05 atmosphere.

7. The preparation method according to the claim 2-6, characterized in that before the nitriding reaction in the step (2), the vacuum degree is pumped to be less than or equal to 0.01 Pa;

preferably, nitrogen-containing gas is filled after the vacuumizing;

preferably, the nitrogen-containing gas comprises a mixed gas of any one or a combination of at least two of nitrous oxide, nitrogen, nitric oxide, nitrogen dioxide, nitrous oxide, dinitrogen tetroxide, dinitrogen pentoxide or ammonia gas and hydrogen;

preferably, the reaction temperature of the nitriding reaction in the step (2) is 350-580 ℃;

preferably, the nitriding reaction in the step (2) comprises a first temperature rise, a first heat preservation, a second temperature rise, a second heat preservation, a third temperature rise and a third heat preservation;

preferably, the temperature range of the first temperature rise is 20-120 ℃;

preferably, the first temperature rise time is 10-80 min;

preferably, the first heat preservation time is 1-60 min;

preferably, the temperature range of the second temperature rise is 120-300 ℃;

preferably, the time of the second temperature rise is 10-60 min;

preferably, the second heat preservation time is 1-120 min;

preferably, the temperature range of the third temperature rise is 300-reaction temperature;

preferably, the third temperature rise time is 10-90 min;

preferably, the third heat preservation time is 1-600 min.

8. The preparation method according to claim 2 to 7, wherein the second heat treatment in step (3) comprises laying sodium borohydride on the upper and lower surfaces of the bulk product and carrying out a heating reaction;

preferably, the adding amount of the sodium borohydride is 0.5-5% of the mass of the block product;

preferably, the temperature of the second heat treatment is 200-450 ℃;

preferably, the vacuum degree of the second heat treatment is less than or equal to 0.1 Pa;

preferably, the temperature rise rate of the second heat treatment is less than 10 ℃/min;

preferably, the time of the second heat treatment is 10-300 min.

9. The preparation method according to claim 2 to 8, wherein the collapsing and cleaning in the step (3) comprises putting the product after the second heat treatment into water, and cleaning the product after the product is collapsed into powder by using acetic acid and clear water until the calcium content in the supernatant is less than 500 ppm;

preferably, the drying of step (3) is vacuum drying;

preferably, the vacuum degree of the vacuum drying in the step (3) is less than or equal to 100 Pa;

preferably, the temperature of the vacuum drying in the step (3) is 90-200 ℃.

10. The method according to claim 2 to 9, comprising the steps of:

(1) performing ball milling mixing on the oxide powder A, the oxide powder D and the iron oxide powder for 1-20 h, performing first heat treatment, and mixing the mixed powder after heat treatment with activated carbon, calcium particles and calcium oxide to obtain a mixed raw material, wherein the addition amount of the activated carbon is 1.0-1.3 times of the reaction equivalent, the addition amount of the calcium particles is 1.1-1.5 times of the reaction equivalent, and the use amount of the calcium oxide is 0.5-10% of the total mass of the mixed powder and the reducing agent;

the heat treatment comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-150 ℃, the time is 2-50 min, and the time of the first heat preservation is 1-60 min; the temperature range of the second temperature rise is 150-300 ℃, the time is 2-50 min, and the time of the second heat preservation is 1-120 min; the temperature range of the third temperature rise is 300-700 ℃, the time is 50-150 min, and the time of the third heat preservation is 1-120 min;

(2) carrying out reduction diffusion sintering on the mixed raw material obtained in the step (1), wherein the reduction diffusion sintering is carried out under the condition of vacuumizing, vacuumizing is carried out until the vacuum degree is less than or equal to 0.01Pa after the reduction diffusion sintering is finished, and nitrogen-containing gas is filled into the mixed raw material for nitriding reaction to obtain a block product;

the reduction diffusion sintering comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise, third heat preservation, fourth temperature rise and fourth heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 10-80 min, and the time of the first heat preservation is 1-60 min; the temperature range of the second temperature rise is 120-400 ℃, the time is 20-60 min, and the time of the second heat preservation is 1-150 min; stopping vacuumizing and filling oxygen when the second temperature rise is finished, wherein the filling amount of the oxygen is 0.01-0.05 atmospheric pressure; the temperature range of the third temperature rise is 400-800 ℃, the time is 10-90 min, and the time of the third heat preservation is 1-200 min; the temperature range of the fourth temperature rise is 800-1050 ℃, the time is 5-50 min, and the time of the fourth heat preservation is 1-300 min;

the nitriding reaction comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 10-80 min, and the time of the first heat preservation is 1-60 min; the temperature range of the second temperature rise is 120-300 ℃, the time is 10-60 min, and the time of the second heat preservation is 1-120 min; the temperature range of the third temperature rise is 300-reaction temperature, the time is 10-90 min, the time of the third heat preservation is 1-600 min, and the reaction temperature of the nitriding reaction is 350-580 ℃;

(3) performing second heat treatment on the block product obtained in the step (2), and then performing collapsing cleaning, wherein the vacuum degree is less than or equal to 100Pa, and the powder of the gap rare earth permanent magnet alloy material is obtained after vacuum drying at the temperature of 90-200 ℃;

the second heat treatment comprises the steps of laying sodium borohydride on the upper surface and the lower surface of the block product and performing a heating reaction, wherein the adding amount of the sodium borohydride is 0.5-5% of the mass of the block product, the temperature of the second heat treatment is 200-450 ℃, the vacuum degree is less than or equal to 0.1Pa, the heating rate is less than 10 ℃/min, and the time is 10-300 min;

and the collapse cleaning comprises the steps of putting the product after the second heat treatment into water, and cleaning the product by using acetic acid and clear water until the calcium content in the supernatant is less than 500ppm after the product is collapsed into powder.

Technical Field

The invention belongs to the technical field of rare earth alloy powder materials, and relates to a gap rare earth permanent magnet alloy material and a preparation method thereof.

Background

In 1990, Coey of Ireland and Yang Yingchang of Beijing university report that nitrogen atoms are introduced into a rare earth iron alloy, because the atomic distance between iron atoms in the rare earth iron binary alloy is close, the ferromagnetic moment is greatly influenced by adjacent atoms, the magnetic performance of the binary alloy is low, through the introduction of interstitial atoms, the distance between the iron atoms is increased due to crystal expansion, the mutual exchange effect between the iron atoms is enhanced, and the magnetic moment of the iron atoms is increased, so that the magnetic performance of the rare earth iron alloy is obviously improved, the saturation magnetization intensity and the Curie temperature are obviously improved, particularly the magnetocrystalline anisotropy of the rare earth iron alloy is specifically changed, and strong easy magnetization axis anisotropy is presented.

At present, with the miniaturization, high-performance and energy-saving development of information products and the historical trend of green economy and low-carbon economy, the development of rare earth permanent magnet materials is greatly promoted. The rare earth permanent magnet material is mainly neodymium iron boron at present, and the high-performance neodymium iron boron contains rare heavy metals such as Dy and Tb, so that the whole heavy metal content is high, and the high-performance neodymium iron boron is high in production cost and high in price. In addition, the Curie temperature of the neodymium iron boron is only about 580K, the corrosion resistance effect is poor, and electroplating processes with high pollution and the like are short plates made of neodymium iron boron materials.

The Curie temperature of the gap rare earth alloy material such as samarium-iron-nitrogen reaches about 740K, the gap rare earth alloy material is obviously higher than that of neodymium-iron-boron, the anisotropy field HA reaches about 16T, the Curie temperature is more than twice that of neodymium-iron-boron, Js and theoretical magnetic energy product are both close to that of neodymium-iron-boron, the gap rare earth alloy material HAs excellent corrosion resistance, the cost of raw materials is low, and the gap rare earth alloy material HAs the advantages that samarium-iron-nitrogen is expected to become a future new-generation rare earth permanent magnet and HAs wide application prospect.

At present, the methods for preparing the interstitial rare earth alloy material mainly comprise a smelting method, a rapid quenching method, a mechanical alloying method, a reduction diffusion method and the like. At present, the main industrialization is a smelting method, a rapid quenching method, a reduction diffusion method and the like. The smelting method and the rapid quenching method are both to smelt metals to form alloy, and because of different melting points between different metals, the saturated vapor pressure is different, the content of the two is difficult to control accurately, and the difficulty of the process and the equipment is great. The mechanical alloying method is to utilize ball milling to enable different metal powders to react to form metal alloy, and the method has low efficiency and large energy consumption, and is easy to oxidize and is generally applied only in a laboratory stage. The reduction diffusion method is a production method which is a mainstream at home and abroad at present, and compared with other methods, the reduction diffusion method has low production cost and easy realization of process conditions by using metal oxides as raw materials.

CN1286602C discloses a method for manufacturing samarium-iron-nitrogen alloy magnetic powder, which comprises the steps of mixing iron salt and samarium salt, precipitating by using a precipitator to form samarium-iron hydroxide, calcining the hydroxide to form metal oxide, pre-reducing the obtained metal oxide by using reducing gas, adding a metal reducing agent to perform reduction diffusion to form samarium-iron alloy, and then performing nitridation to form samarium-iron-nitrogen alloy powder. When the method is used for preparing the samarium-iron hydroxide, the ratio of the samarium-iron is unstable due to the inconsistency of two precipitation conditions, so that the final components of the shirt iron-nitrogen alloy magnetic powder are affected, and further the performance stability is affected. In addition, the method has complex process flow and great difficulty in process control.

CN105355354A discloses a preparation method of shirt iron nitrogen-based anisotropic rare earth permanent magnet powder, which is to use a rapid hardening ingot casting method to obtain shirt iron nitrogen magnetic powder by carrying out heat treatment, primary crushing, nitriding, ball milling and other procedures on an ingot casting sheet containing a main phase of a samarium-iron alloy structure and another auxiliary phase with crystal boundary. The method improves the problem that alpha-Fe impurity phase is difficult to control due to samarium volatilization in the smelting method to a certain extent, but most of the magnetic powder prepared by the method is flaky, so that the flowability is poor when the magnetic powder is compounded with an organic polymer material at the later stage, and the performance, the strength and the like of the magnet are influenced.

CN108648907A discloses a method for preparing anisotropic samarium iron nitrogen, which is to adopt iron powder and samarium oxide raw materials to firstly carry out mechanical grinding, then add metal calcium to carry out reduction diffusion to obtain samarium iron alloy, and carry out nitriding to obtain samarium iron nitrogen magnetic powder. The method uses metal iron powder and samarium oxide to carry out mechanical mixing, the granularity of the general thinner carbonyl iron powder is about 3 microns, the granularity of the samarium oxide powder is below 1 micron, the mixing effect of the two substances with different physical properties is not good during ball milling, the flaking of the iron powder after ball milling is not matched with the appearance of the samarium oxide, the layering of slurry after ball milling is very obvious, the later drying and the mixing of metal calcium are not facilitated, and the effect of reduction diffusion is not ideal.

CN108994311A discloses a preparation method for preparing anisotropic samarium iron nitrogen, which is to dissolve samarium ionic compound and ferrous ionic compound in hydrochloric acid, then carry out spray granulation, and carry out nitriding treatment on the granulated microspheres after reduction diffusion reaction with metal calcium particles to obtain the anisotropic samarium iron nitrogen. The patent does not describe the way of spray granulation, and the chloride used in spray granulation is easy to corrode equipment, and the magnetic powder after nitriding is difficult to clean with water, so that the subsequent granulation is greatly influenced.

Disclosure of Invention

In order to solve the technical problems, the invention provides a gap rare earth permanent magnet alloy material and a preparation method thereof, the preparation method has the advantages of low cost of raw materials, simple and controllable reduction and diffusion process, no need of pre-reduction, high alloy phase purity, no need of fine grinding in the later period of the prepared powder, fine and uniform granularity distribution and excellent magnetic performance.

In order to achieve the technical effects, the invention adopts the following technical scheme;

the invention aims to provide a gap rare earth permanent magnet alloy material which is characterized in that the chemical formula of the gap rare earth permanent magnet alloy material is A_δFe_γD_εN_ΨThe A comprises any one or the combination of at least two of Sc, Y or lanthanide elements, the A must comprise Sm and/or Nd, the D comprises any one or the combination of at least two of elements in groups IVB, VB, VIB, VIIB, VIIIB, IB or II2B, 1.5 is larger than or equal to delta and smaller than or equal to 2.5, 15 is larger than or equal to gamma and smaller than or equal to 19, 0 is larger than epsilon/gamma and smaller than or equal to 20, and 1 is larger than or equal to psi/delta and smaller than or equal to 2.

Where δ may be 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3 or 2.4, γ may be 15.5, 16, 16.5, 17, 17.5, 18 or 18.5, ε/γ may be 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 or 19, etc., Ψ/δ may be 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, etc., but is not limited to the recited values, and other values within each of the recited values are equally applicable.

The second purpose of the invention is to provide a preparation method of the gap rare earth permanent magnet alloy material, which comprises the following steps:

(1) mixing the oxide powder A, the oxide powder D and the iron oxide powder, then carrying out first heat treatment, and mixing the mixed powder after heat treatment with a reducing agent, a separant and a disintegrator to obtain a mixed raw material;

(2) carrying out reduction diffusion sintering on the mixed raw material obtained in the step (1), and carrying out nitriding reaction after the reduction diffusion sintering is finished to obtain a block product;

(3) and (3) carrying out second heat treatment on the block product obtained in the step (2), then carrying out collapsing cleaning, and drying to obtain the powder of the gap rare earth permanent magnet alloy material.

In a preferred embodiment of the present invention, the particle size D50 of the oxide powder A, the oxide powder D and the iron oxide powder in step (1) is 1 to 3 μm, such as 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm or 2.8 μm, but is not limited to the above-mentioned values, and other values not shown in the above-mentioned numerical range are also applicable.

In the present invention, the purity of the oxide powder A, the purity of the oxide powder D, and the purity of the iron oxide powder D are not less than 99.5% independently.

Preferably, the mixing of step (1) is carried out in a sand mill or a ball mill.

Preferably, the mass ratio of the material, the ball and the water in the mixing is 1: 12-17: 1-2, such as 1:13:1.2, 1:14:1.5, 1:15:1.6 or 1:16:1.8, but not limited to the enumerated values, and other non-enumerated values in the numerical range are also applicable.

Preferably, the mixing time is 1 to 20 hours, such as 2 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours or 18 hours, but not limited to the recited values, and other values not recited in the range of the values are also applicable, preferably 2 to 10 hours.

In the invention, the mixed powder is dried after mixing, the drying is spray drying, and the spray drying equipment can be pressure spray drying, centrifugal spray drying or airflow spray drying and the like.

As a preferable embodiment of the present invention, the heat treatment in the step (1) includes a first temperature rise, a first heat preservation, a second temperature rise, a second heat preservation, a third temperature rise, and a third heat preservation.

Preferably, the temperature range of the first temperature rise is 20 to 150 ℃, such as 30 ℃, 50 ℃, 60 ℃, 80 ℃, 90 ℃, 100 ℃, 120 ℃ or 140 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first temperature rise time is 2-50 min, such as 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min or 45min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first heat preservation time is 1-60 min, such as 5min, 10min, 20min, 30min, 40min or 50min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature range of the second temperature rise is 150 to 300 ℃, such as 160 ℃, 180 ℃, 200 ℃, 220 ℃, 250 ℃ or 280 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the time of the second temperature rise is 2-50 min, such as 5min, 10min, 15min, 20min, 25min, 30min, 35min, 40min or 45min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the second heat preservation time is 1-120 min, such as 20min, 30min, 50min, 80min, 100min or 110min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature range of the third temperature rise is 300 to 700 ℃, such as 350 ℃, 400 ℃, 450 ℃, 500 ℃, 550 ℃, 600 ℃ or 650 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the time of the third temperature rise is 50-150 min, such as 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min or 140min, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

Preferably, the third temperature is maintained for 1-120 min, such as 20min, 30min, 50min, 80min, 100min or 110min, but not limited to the recited values, and other values not recited in the range of values are also applicable.

In the invention, the first heat treatment is to carry out mutual solid phase diffusion on the powder of several oxides at high temperature to promote mutual fusion, thus being beneficial to complete reduction diffusion reaction. The heat treatment equipment can be a bell jar furnace or a pushed slab kiln, and equipment capable of performing inert gas shielding is only needed. The first heat treatment can be naturally cooled along with the furnace or the air cooling of the furnace can be opened.

As a preferable technical scheme of the invention, the reducing agent in the step (1) comprises activated carbon and calcium particles.

Preferably, the particle size D50 of the activated carbon is not more than 1 μm, such as 0.1 μm, 0.2 μm, 0.5 μm or 0.8 μm, but is not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, the calcium particles have a particle size D50 ≦ 5mm, such as 0.1 μm, 0.2 μm, 0.5 μm, 0.8 μm, 1 μm, 2 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 500 μm, 1mm, 2mm, or 4mm, but not limited to the recited values, and other values not recited in this range of values are equally applicable.

The active carbon has strong adsorbability and high reaction activity, is an excellent reducing agent, avoids the pre-reduction of iron oxide by using hydrogen by using the active carbon as the reducing agent, reduces the risk of generating high-risk gas, has very low cost and effectively reduces the using amount of metal calcium. The particle size of the activated carbon is too coarse to be fully mixed with reactants for contact, which is not favorable for subsequent diffusion reaction. The carbon source of the activated carbon is preferably bamboo charcoal, charcoal and coconut shell carbon.

In the invention, excessive calcium is added to cause waste and increase the economic cost.

Preferably, the amount of the activated carbon added is 1.0 to 1.3 times of the reaction equivalent, such as 1.05 times, 1.1 times, 1.15 times, 1.2 times, or 1.25 times, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

In the invention, the addition of too little carbon powder can cause the amount of iron oxide pre-reduced into simple substance iron to be small and the usage amount of metallic calcium to be large. Too much carbon powder is not beneficial to the reduction and diffusion reaction.

Preferably, the amount of the calcium particles added is 1.1 to 1.5 times, such as 1.15 times, 1.2 times, 1.25 times, 1.3 times, 1.35 times, 1.4 times, or 1.45 times the reaction equivalent, but is not limited to the recited values, and other values not recited in the numerical range are also applicable.

Preferably, the release agent and the collapsing agent are calcium oxide.

Preferably, the calcium oxide has a particle size D50 ≦ 1 μm, such as 0.1 μm, 0.2 μm, 0.5 μm, or 0.8 μm, but not limited to the recited values, and other values not recited in this range are also applicable.

Preferably, the calcium oxide is used in an amount of 0.5 to 10% by mass of the sum of the mixed powder and the reducing agent, such as 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, or 9%, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

As a preferable technical scheme of the invention, the reduction diffusion sintering in the step (2) is carried out under the condition of vacuumizing.

Preferably, the reductive diffusion sintering is performed under a protective atmosphere.

Preferably, the reduction diffusion sintering includes a first temperature rise, a first heat preservation, a second temperature rise, a second heat preservation, a third temperature rise, a third heat preservation, a fourth temperature rise, and a fourth heat preservation.

Preferably, the temperature range of the first temperature rise is 20 to 120 ℃, such as 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ or 110 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first temperature rise time is 10-80 min, such as 20min, 30min, 40min, 50min, 60min or 70min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first heat preservation time is 1-60 min, such as 5min, 10min, 20min, 30min, 40min or 50min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature range of the second temperature rise is 120 to 400 ℃, such as 150 ℃, 200 ℃, 250 ℃, 300 ℃ or 350 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the time of the second temperature rise is 20-60 min, such as 25min, 30min, 35min, 40min, 45min, 50min or 55min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the second heat preservation time is 1-150 min, such as 5min, 10min, 20min, 50min, 80min, 100min, 120min or 140min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature range of the third temperature rise is 400 to 800 ℃, such as 450 ℃, 500 ℃, 550 ℃, 600 ℃, 650 ℃, 700 ℃ or 750 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the time of the third temperature rise is 10-90 min, such as 20min, 30min, 40min, 50min, 60min, 70min or 80min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the third temperature is maintained for 1-200 min, such as 10min, 20min, 50min, 80min, 100min, 120min, 150min or 180min, but not limited to the recited values, and other values not recited in the range of values are also applicable.

Preferably, the temperature range of the fourth temperature rise is 800 to 1050 ℃, such as 850 ℃, 900 ℃, 950 ℃ or 1000 ℃, but is not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

Preferably, the fourth temperature rise time is 5-50 min, such as 10min, 15min, 20min, 25min, 30min, 35min, 40min or 45min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the fourth heat preservation time is 1-300 min, such as 10min, 50min, 100min, 150min, 200min or 250min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the vacuumizing is stopped and the oxygen is filled when the second temperature rise is finished.

Preferably, the oxygen is introduced at a level of from 0.01 to 0.05 atmospheres, such as 0.02 atmospheres, 0.03 atmospheres, or 0.04 atmospheres, but not limited to the recited values, and other values not recited within the range are equally applicable.

In the present invention, it is preferable to keep the vacuum pump for evacuation until the temperature is raised to 400 ℃ to remove the gas adsorbed between the powders. Preferably, when the temperature is raised to 400 ℃, the evacuation is stopped, and oxygen gas of 0.01 to 0.05 atm is charged. The charged oxygen reacts with carbon at high temperature to generate carbon monoxide, the carbon monoxide is a strong reducing gas and is very beneficial to reducing iron oxide, the generated carbon monoxide firstly carries out gas-solid contact reaction with the iron oxide to remove part of generated iron simple substance, a reaction channel is opened, and the surface activity of the powder is enhanced. If the amount of oxygen introduced is too large, carbon dioxide is easily produced and does not play a role in reducing the reducing gas, and if the amount of oxygen introduced is too small, the amount of reducing gas produced is small and the amount of reduced iron oxide is small. After heating toThe remaining carbon reacts with unreacted iron oxide at around 800 ℃. 2C + O₂＝2CO，Fe₂O₃+3CO＝2Fe+3CO₂，2Fe₂O₃+3C＝4Fe+3CO₂. At the high temperature of 800-1050 ℃, the metal calcium reduces the rare earth oxide to form a rare earth simple substance and the iron simple substance reduces and diffuses to form a rare earth alloy block. The excessive unreacted carbon powder and the generated carbon dioxide can continuously react at high temperature to generate carbon monoxide, so that the whole reduction and diffusion process is carried out in a reducing atmosphere, and the method is very favorable for forming pure-phase rare earth alloy. The furnace can be naturally cooled along with the furnace from 1050 ℃ to room temperature, and the furnace can also be opened for air cooling.

As a preferable technical scheme of the invention, before the nitriding reaction in the step (2), the nitriding reaction is vacuumized until the vacuum degree is less than or equal to 0.01 Pa.

Preferably, the vacuum is pumped and then filled with nitrogen-containing gas.

Preferably, the nitrogen-containing gas comprises a mixed gas of hydrogen and any one or a combination of at least two of nitrous oxide, nitrogen, nitric oxide, nitrogen dioxide, nitrous oxide, dinitrogen tetroxide, dinitrogen pentoxide, or ammonia gas, typical but non-limiting examples of such combinations being: nitrous oxide and nitrous oxide in combination, nitrous oxide and nitrogen in combination, nitrogen and nitric oxide in combination, nitric oxide and nitrogen dioxide in combination, nitrogen dioxide and nitrous oxide in combination, nitrous oxide and dinitrogen tetroxide in combination, nitrous tetroxide and dinitrogen pentoxide in combination, nitrous pentoxide and ammonia in combination, ammonia and nitrous oxide in combination, or nitrous oxide, nitrous oxide and nitrogen in combination, and the like.

In the invention, the nitrogen-containing gas filled in the nitriding process contains a small amount of hydrogen, so that the nitriding reaction can be accelerated to carry out in a certain reducing atmosphere, and the oxidation is prevented.

Preferably, the nitriding reaction in step (2) is carried out at a reaction temperature of 350 to 580 ℃, such as 360 ℃, 380 ℃, 400 ℃, 420 ℃, 450 ℃, 480 ℃, 500 ℃, 520 ℃, 550 ℃ or 570 ℃, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

In the invention, the nitriding reaction temperature is too low, the nitriding reaction is incomplete, the magnetic property is low due to low nitrogen content, the temperature is too high, and the generated gap rare earth alloy is easy to decompose to generate alpha Fe, so that the magnetic property is deteriorated.

In the invention, furnace cooling can be adopted to cool to room temperature after nitriding is finished, and air cooling and water cooling can also be adopted.

Preferably, the nitriding reaction in the step (2) comprises a first temperature rise, a first heat preservation, a second temperature rise, a second heat preservation, a third temperature rise and a third heat preservation.

Preferably, the temperature range of the first temperature rise is 20 to 120 ℃, such as 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃ or 110 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first temperature rise time is 10-80 min, such as 20min, 30min, 40min, 50min, 60min or 70min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the first heat preservation time is 1-60 min, such as 5min, 10min, 20min, 30min, 40min or 50min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature range of the second temperature rise is 120 to 300 ℃, such as 150 ℃, 160 ℃, 180 ℃, 200 ℃, 220 ℃, 250 ℃ or 280 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the time of the second temperature rise is 10-60 min, such as 15min, 20min, 25min, 30min, 35min, 40min, 45min, 50min or 55min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the second heat preservation time is 1-120 min, such as 5min, 10min, 20min, 50min, 80min, 100min or 110min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the temperature range of the third temperature rise is 300 to the reaction temperature.

Preferably, the time of the third temperature rise is 10-90 min, such as 20min, 30min, 40min, 50min, 60min, 70min or 80min, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the third temperature preservation time is 1-600 min, such as 10min, 50min, 100min, 150min, 200min, 250min, 300min, 350min, 400min, 450min, 500min or 550min, but not limited to the enumerated values, and other non-enumerated values in the range of the enumerated values are also applicable.

As a preferable technical scheme of the invention, the second heat treatment in the step (3) comprises the steps of laying sodium borohydride on the upper surface and the lower surface of the block product and performing a heating reaction.

Preferably, the amount of sodium borohydride added is 0.5-5% by mass of the bulk product, such as 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, or 4.5%, but not limited to the recited values, and other values not recited in this range are also applicable.

In the invention, sodium borohydride can form reducing hot steam at the heat treatment temperature, the internal stress of powder of the interstitial rare earth permanent magnetic alloy material is reduced and the nail rolling effect of a domain wall is enhanced under the heat treatment of the reducing steam, and in addition, gas in gaps of the block body under the heat treatment is beneficial to desorption. These all contribute to a further improvement of the final magnetic properties.

Preferably, the temperature of the second heat treatment is 200 to 450 ℃, such as 220 ℃, 250 ℃, 280 ℃, 300 ℃, 320 ℃, 350 ℃, 380 ℃, 400 ℃, 420 ℃ or 440 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the vacuum degree of the second heat treatment is less than or equal to 0.1 Pa.

Preferably, the second heat treatment has a temperature rise rate of < 10 ℃/min, such as 1 ℃/min, 2 ℃/min, 3 ℃/min, 4 ℃/min, 5 ℃/min, 6 ℃/min, 7 ℃/min, 8 ℃/min, or 9 ℃/min, and the like, but is not limited to the recited values, and other values not recited within the range of values are equally applicable.

Preferably, the time of the second heat treatment is 10 to 300min, such as 20min, 50min, 80min, 100min, 120min, 150min, 180min, 200min, 220min, 250min or 280min, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

As a preferable technical scheme of the invention, the collapsing and cleaning in the step (3) comprises the steps of putting the product after the second heat treatment into water, and cleaning the product by using acetic acid and clear water until the calcium content in the supernatant is less than 500ppm after the product is collapsed into powder.

In the invention, the cleaning function is to remove the reducing agent after the high-temperature solid-phase diffusion reaction, the metal calcium is reduced to be calcium oxide, and the metal calcium is changed to be calcium hydroxide when meeting water and separated from the powder.

Preferably, the drying of step (3) is vacuum drying.

Preferably, the vacuum degree of the vacuum drying in step (3) is less than or equal to 100Pa, such as 10Pa, 20Pa, 30Pa, 40Pa, 50Pa, 60Pa, 70Pa, 80Pa, or 90Pa, but not limited to the recited values, and other values in the range are also applicable.

Preferably, the temperature of the vacuum drying in step (3) is 90-200 ℃, such as 100 ℃, 110 ℃, 120 ℃, 130 ℃, 140 ℃, 150 ℃, 160 ℃, 170 ℃, 180 ℃ or 190 ℃, but not limited to the recited values, and other values not recited in the range of the values are also applicable.

As a preferred technical scheme of the invention, the preparation method of the gap rare earth permanent magnet alloy material comprises the following steps:

(1) performing ball milling mixing on the oxide powder A, the oxide powder D and the iron oxide powder for 1-20 h, performing first heat treatment, and mixing the mixed powder after heat treatment with activated carbon, calcium particles and calcium oxide to obtain a mixed raw material, wherein the addition amount of the activated carbon is 1.0-1.3 times of the reaction equivalent, the addition amount of the calcium particles is 1.1-1.5 times of the reaction equivalent, and the use amount of the calcium oxide is 0.5-10% of the total mass of the mixed powder and the reducing agent;

the heat treatment comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-150 ℃, the time is 2-50 min, and the time of the first heat preservation is 1-60 min; the temperature range of the second temperature rise is 150-300 ℃, the time is 2-50 min, and the time of the second heat preservation is 1-120 min; the temperature range of the third temperature rise is 300-700 ℃, the time is 50-150 min, and the time of the third heat preservation is 1-120 min;

(2) carrying out reduction diffusion sintering on the mixed raw material obtained in the step (1), wherein the reduction diffusion sintering is carried out under the condition of vacuumizing, vacuumizing is carried out until the vacuum degree is less than or equal to 0.01Pa after the reduction diffusion sintering is finished, and nitrogen-containing gas is filled into the mixed raw material for nitriding reaction to obtain a block product;

the reduction diffusion sintering comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise, third heat preservation, fourth temperature rise and fourth heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 10-80 min, and the time of the first heat preservation is 1-60 min; the temperature range of the second temperature rise is 120-400 ℃, the time is 20-60 min, and the time of the second heat preservation is 1-150 min; stopping vacuumizing and filling oxygen when the second temperature rise is finished, wherein the filling amount of the oxygen is 0.01-0.05 atmospheric pressure; the temperature range of the third temperature rise is 400-800 ℃, the time is 10-90 min, and the time of the third heat preservation is 1-200 min; the temperature range of the fourth temperature rise is 800-1050 ℃, the time is 5-50 min, and the time of the fourth heat preservation is 1-300 min;

the nitriding reaction comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 10-80 min, and the time of the first heat preservation is 1-60 min; the temperature range of the second temperature rise is 120-300 ℃, the time is 10-60 min, and the time of the second heat preservation is 1-120 min; the temperature range of the third temperature rise is 300-reaction temperature, the time is 10-90 min, the time of the third heat preservation is 1-600 min, and the reaction temperature of the nitriding reaction is 350-580 ℃;

(3) performing second heat treatment on the block product obtained in the step (2), and then performing collapsing cleaning, wherein the vacuum degree is less than or equal to 100Pa, and the powder of the gap rare earth permanent magnet alloy material is obtained after vacuum drying at the temperature of 90-200 ℃;

the second heat treatment comprises the steps of laying sodium borohydride on the upper surface and the lower surface of the block product and performing a heating reaction, wherein the adding amount of the sodium borohydride is 0.5-5% of the mass of the block product, the temperature of the second heat treatment is 200-450 ℃, the vacuum degree is less than or equal to 0.1Pa, the heating rate is less than 10 ℃/min, and the time is 10-300 min;

and the collapse cleaning comprises the steps of putting the product after the second heat treatment into water, and cleaning the product by using acetic acid and clear water until the calcium content in the supernatant is less than 500ppm after the product is collapsed into powder.

Compared with the prior art, the invention has at least the following beneficial effects:

(1) the invention provides a gap rare earth permanent magnet alloy material and a preparation method thereof, and the preparation method has the advantages of low raw material cost, simple and controllable reduction diffusion process, no pre-reduction and high alloy phase purity;

(2) the invention provides a gap rare earth permanent magnet alloy material and a preparation method thereof.

Detailed Description

For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.

Example 1

The embodiment provides a preparation method of a gap rare earth permanent magnet alloy material, which comprises the following steps:

(1) will be provided withSm with purity of 99.5%₂O₃And Fe with a purity of 99.5%₂O₃Putting the powder into a ball mill according to an atomic ratio of 2:17, wherein the ratio of material to ball to water is 1:15:1.4, performing ball milling and mixing for 10 hours, performing spray granulation at 120 ℃, performing first heat treatment, and mixing the heat-treated mixed powder with activated carbon, calcium particles and calcium oxide to obtain a mixed raw material, wherein the addition amount of the activated carbon is 1.2 times of the reaction equivalent, the particle size D50 is less than or equal to 1 mu m, the addition amount of the calcium particles is 1.2 times of the reaction equivalent, the particle size D50 is less than or equal to 5mm, and the use amount of the calcium oxide is 1% of the total mass of the mixed powder and the reducing agent;

the heat treatment comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-150 ℃, the time is 20min, and the time of the first heat preservation is 30 min; the temperature range of the second temperature rise is 150-300 ℃, the time is 40min, and the time of the second heat preservation is 30 min; the temperature range of the third temperature rise is 300-700 ℃, the time is 100min, the time of the third heat preservation is 30min, and the furnace is naturally cooled to the room temperature;

(2) carrying out reduction diffusion sintering on the mixed raw material in the step (1), wherein the reduction diffusion sintering is carried out under the condition of vacuumizing, vacuumizing is carried out until the vacuum degree is less than or equal to 0.01Pa after the reduction diffusion sintering is finished, and ammonia gas with 0.4 atmospheric pressure, nitrogen with 0.2 atmospheric pressure and hydrogen with 0.1 atmospheric pressure are filled into the mixture for nitriding reaction to obtain a block product;

the reduction diffusion sintering comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise, third heat preservation, fourth temperature rise and fourth heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 70min, and the time of the first heat preservation is 60 min; the temperature range of the second temperature rise is 120-400 ℃, the time is 40min, and the time of the second heat preservation is 120 min; stopping vacuumizing and filling oxygen and argon when the second temperature rise is finished, wherein the filling amount of the oxygen is 0.02 atmospheric pressure, and the filling amount of the argon is 0.4 atmospheric pressure; the temperature range of the third temperature rise is 400-800 ℃, the time is 30min, and the time of the third heat preservation is 150 min; the fourth temperature rise temperature range is 800-1050 ℃, the time is 30min, the fourth heat preservation time is 260min, and the natural cooling is carried out to the room temperature;

the nitriding reaction comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 40min, and the time of the first heat preservation is 60 min; the temperature range of the second temperature rise is 120-300 ℃, the time is 40min, and the time of the second heat preservation is 40 min; the temperature range of the third temperature rise is 300-reaction temperature ℃, the time is 35min, the time of the third heat preservation is 400min, and the reaction temperature of the nitriding reaction is 550 ℃;

(3) performing second heat treatment on the block product obtained in the step (2), and then performing collapsing cleaning, wherein the vacuum degree is less than or equal to 100Pa, and the powder of the gap rare earth permanent magnet alloy material is obtained after vacuum drying at the temperature of 120 ℃;

the second heat treatment comprises the steps of paving sodium borohydride on the upper surface and the lower surface of the block product and performing a heating reaction, wherein the adding amount of the sodium borohydride is 2% of the mass of the block product, the temperature of the second heat treatment is 400 ℃, the vacuum degree is less than or equal to 0.1Pa, the heating rate is 5 ℃/min, and the time is 200 min;

and the collapse cleaning comprises the steps of putting the product after the second heat treatment into water, and cleaning the product into powder by using acetic acid and clear water until the content of calcium in supernate is less than 500ppm by ICP detection.

The chemical formula of the gap rare earth permanent magnet alloy material prepared by the embodiment is Sm₂Fe₁₇N_3.1。

Mixing the prepared gap rare earth permanent magnet alloy powder with 10% of PA12, granulating by a granulator, and injection molding into a cylinder with the diameter of 30mm and the height of 25mm to test the magnetic performance. Br 7180Gs, Hcj15600Oe (BH)_max9.5 MGOe。

Example 2

The embodiment provides a preparation method of a gap rare earth permanent magnet alloy material, which comprises the following steps:

(1) sm with purity of 99.5%₂O₃99.5% of Nd₂O₃(the atomic ratio of the two is 80:20) and Fe with the purity of 99.5%₂O₃The powder is prepared from (Sm + Nd): placing the mixture in a ball mill according to the Fe atomic ratio of 2:17, wherein the proportion of materials, balls and water is 1:15:1.4, carrying out spray granulation at 120 ℃ after ball milling and mixing for 10 hours, carrying out first heat treatment, mixing the mixed powder after heat treatment with activated carbon, calcium particles and calcium oxide to obtain a mixed raw material, wherein the addition amount of the activated carbon is 1.3 times of the reaction equivalent, the particle size D50 is less than or equal to 1 mu m, the addition amount of the calcium particles is 1.3 times of the reaction equivalent, the particle size D50 is less than or equal to 5mm, and the using amount of the calcium oxide is 1% of the total mass of the mixed powder and the reducing agent;

the heat treatment comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-150 ℃, the time is 20min, and the time of the first heat preservation is 30 min; the temperature range of the second temperature rise is 150-300 ℃, the time is 40min, and the time of the second heat preservation is 60 min; the temperature range of the third temperature rise is 300-700 ℃, the time is 100min, the time of the third heat preservation is 30min, and the furnace is naturally cooled to the room temperature;

(2) carrying out reduction diffusion sintering on the mixed raw material in the step (1), wherein the reduction diffusion sintering is carried out under the condition of vacuumizing, vacuumizing is carried out until the vacuum degree is less than or equal to 0.01Pa after the reduction diffusion sintering is finished, and ammonia gas with 0.4 atmospheric pressure, nitrogen with 0.2 atmospheric pressure and hydrogen with 0.1 atmospheric pressure are filled into the mixture for nitriding reaction to obtain a block product;

the reduction diffusion sintering comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise, third heat preservation, fourth temperature rise and fourth heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 70min, and the time of the first heat preservation is 60 min; the temperature range of the second temperature rise is 120-400 ℃, the time is 40min, and the time of the second heat preservation is 120 min; stopping vacuumizing and filling oxygen and argon when the second temperature rise is finished, wherein the filling amount of the oxygen is 0.02 atmospheric pressure, and the filling amount of the argon is 0.4 atmospheric pressure; the temperature range of the third temperature rise is 400-800 ℃, the time is 30min, and the time of the third heat preservation is 120 min; the fourth temperature rise temperature range is 800-1050 ℃, the time is 30min, the fourth heat preservation time is 280min, and the temperature is naturally cooled to the room temperature;

the nitriding reaction comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 40min, and the time of the first heat preservation is 60 min; the temperature range of the second temperature rise is 120-300 ℃, the time is 40min, and the time of the second heat preservation is 100 min; the temperature range of the third temperature rise is 300-reaction temperature ℃, the time is 35min, the time of the third heat preservation is 350min, and the reaction temperature of the nitriding reaction is 530 ℃;

(3) performing second heat treatment on the block product obtained in the step (2), and then performing collapsing cleaning, wherein the vacuum degree is less than or equal to 100Pa, and the powder of the gap rare earth permanent magnet alloy material is obtained after vacuum drying at the temperature of 120 ℃;

the second heat treatment comprises the steps of paving sodium borohydride on the upper surface and the lower surface of the block product and performing a heating reaction, wherein the adding amount of the sodium borohydride is 2% of the mass of the block product, the temperature of the second heat treatment is 400 ℃, the vacuum degree is less than or equal to 0.1Pa, the heating rate is 8 ℃/min, and the time is 200 min;

and the collapse cleaning comprises the steps of putting the product after the second heat treatment into water, and cleaning the product into powder by using acetic acid and clear water until the content of calcium in supernate is less than 500ppm by ICP detection.

The chemical formula of the gap rare earth permanent magnet alloy material prepared by the embodiment is Sm_1.6Nd_0.4Fe₁₇N_3.2。

Mixing the prepared gap rare earth permanent magnet alloy powder with 10% of PA12, granulating by a granulator, and injection molding to obtain the product with the diameter of 3Magnetic properties were measured on cylinders 0mm and 25mm high. Br 7324Gs, Hcj16250Oe (BH)_max10.5 MGOe。

Example 3

The embodiment provides a preparation method of a gap rare earth permanent magnet alloy material, which comprises the following steps:

(1) sm with purity of 99.5%₂O₃99.5% of Nd₂O₃(the atomic ratio of the two is 80:20) and Fe with the purity of 99.5%₂O₃Putting powder and 99.5% MnO (the atomic ratio of the MnO to the MnO is 95:5) in an atomic ratio of 2:17 into a ball mill, wherein the ratio of the material to the ball to water is 1:15:1.4, carrying out spray granulation at 120 ℃ after ball milling and mixing for 10 hours, carrying out first heat treatment, mixing the mixed powder after the heat treatment with activated carbon, calcium particles and calcium oxide to obtain a mixed raw material, wherein the addition amount of the activated carbon is 1.4 times of the reaction equivalent, the particle size D50 is less than or equal to 1 mu m, the addition amount of the calcium particles is 1.3 times of the reaction equivalent, the particle size D50 is less than or equal to 5mm, and the dosage of the calcium oxide is 1% of the total mass of the mixed powder and the reducing agent;

the heat treatment comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-150 ℃, the time is 20min, and the time of the first heat preservation is 30 min; the temperature range of the second temperature rise is 150-300 ℃, the time is 40min, and the time of the second heat preservation is 60 min; the temperature range of the third temperature rise is 300-700 ℃, the time is 100min, the time of the third heat preservation is 30min, and the furnace is naturally cooled to the room temperature;

(2) carrying out reduction diffusion sintering on the mixed raw material in the step (1), wherein the reduction diffusion sintering is carried out under the condition of vacuumizing, vacuumizing is carried out until the vacuum degree is less than or equal to 0.01Pa after the reduction diffusion sintering is finished, and ammonia gas with 0.4 atmospheric pressure, nitrogen with 0.2 atmospheric pressure and hydrogen with 0.1 atmospheric pressure are filled into the mixture for nitriding reaction to obtain a block product;

the reduction diffusion sintering comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise, third heat preservation, fourth temperature rise and fourth heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 70min, and the time of the first heat preservation is 60 min; the temperature range of the second temperature rise is 120-400 ℃, the time is 40min, and the time of the second heat preservation is 140 min; stopping vacuumizing and filling oxygen and argon when the second temperature rise is finished, wherein the filling amount of the oxygen is 0.03 atmosphere, and the filling amount of the argon is 0.4 atmosphere; the temperature range of the third temperature rise is 400-800 ℃, the time is 30min, and the time of the third heat preservation is 150 min; the fourth temperature rise temperature range is 800-1050 ℃, the time is 30min, the fourth heat preservation time is 300min, and the temperature is naturally cooled to the room temperature;

the nitriding reaction comprises first temperature rise, first heat preservation, second temperature rise, second heat preservation, third temperature rise and third heat preservation;

the temperature range of the first temperature rise is 20-120 ℃, the time is 40min, and the time of the first heat preservation is 60 min; the temperature range of the second temperature rise is 120-300 ℃, the time is 40min, and the time of the second heat preservation is 100 min; the temperature range of the third temperature rise is 300-reaction temperature ℃, the time is 35min, the time of the third heat preservation is 350min, and the reaction temperature of the nitriding reaction is 530 ℃;

(3) performing second heat treatment on the block product obtained in the step (2), and then performing collapsing cleaning, wherein the vacuum degree is less than or equal to 100Pa, and the powder of the gap rare earth permanent magnet alloy material is obtained after vacuum drying at the temperature of 120 ℃;

the second heat treatment comprises the steps of paving sodium borohydride on the upper surface and the lower surface of the block product and performing a heating reaction, wherein the adding amount of the sodium borohydride is 2% of the mass of the block product, the temperature of the second heat treatment is 400 ℃, the vacuum degree is less than or equal to 0.1Pa, the heating rate is 8 ℃/min, and the time is 200 min;

and the collapse cleaning comprises the steps of putting the product after the second heat treatment into water, and cleaning the product into powder by using acetic acid and clear water until the content of calcium in supernate is less than 500ppm by ICP detection.

The interstitial rare earth permanent magnet alloy material prepared by the embodimentHas the chemical formula of Sm_1.6Nd_0.4Fe_16.15Mn_0.85N_3.3。

Mixing the prepared gap rare earth permanent magnet alloy powder with 10% of PA12, granulating by a granulator, and injection molding into a cylinder with the diameter of 30mm and the height of 25mm to test the magnetic performance. Br 7218Gs, Hcj18200Oe, (BH)_max10 MGOe。

Comparative example 1

Weighing metal samarium and metal iron according to the atomic ratio of 2:17, wherein the weight of the metal samarium is 1.5 times of the weight of the weighed metal samarium, arc melting into uniform ingot under argon protection atmosphere, annealing at 1200 deg.C for 12h, coarse-crushing the alloy ingot, transferring into sand mill, sanding for 10h in alcohol medium, vacuum drying after sanding, detecting with a laser particle sizer D50 of 5 μm, putting the dried alloy powder into a nitriding furnace, vacuumizing, filling nitrogen with 2.0 atm, nitriding at 500 degree for 5h, sanding the nitrided powder for 5h in alcohol medium, vacuum drying after sanding, detecting D50 to be 1.2 μm by a laser particle sizer, after mixing with 10% PA12, the mixture was granulated by a granulator and injection-molded into a cylinder 30mm in diameter and 25mm in height, which was tested for magnetic properties of Br:5400Gs, Hcj:7500Oe, (BH)._max5 MGOe。

The applicant states that the present invention is illustrated by the above examples to show the detailed process equipment and process flow of the present invention, but the present invention is not limited to the above detailed process equipment and process flow, i.e. it does not mean that the present invention must rely on the above detailed process equipment and process flow to be implemented. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.