Shell layer magnetic hardening single crystal permanent magnet powder, preparation method and application

Abstract

The invention discloses shell layer magnetic hardening single crystal permanent magnet powder, a preparation method and application. The invention relates to single crystal permanent magnet powder with a magnetically hardened shell layer, which is characterized in that the single crystal permanent magnet powder comprises the following components in atomic percent: (R11-alpha R2 alpha) xFe (100-x-y-z-vM (1y) M (2z) Bv (formula 2), wherein R1 is at least one of Nd and Pr; r2 is at least one of La, Ce, Ho, Gd, Tb, Dy and Y; 0 < = alt; 0.8; 14 < = x < = 28; m1 is at least one of Cu, Al and Ga, and y is more than or equal to 3 and less than or equal to 40.0; and M2 is at least one of Co, Si, Zr, Hf, Nb, Ti and V. The rare earth-rich coating film is used for improving the magnetic performance of the RE2Fe14B micron single crystal magnetic powder, and the anisotropy of the bonded neodymium iron boron material is achieved.

Description

Technical Field:

[0001] The present invention relates to the technical field of rare earth magnetic materials, and particularly relates to a shell-magnetized single-crystal permanent magnet powder, a preparation method and an application thereof. Background Art:

[0002] Rare earth permanent magnet materials are widely used in the fields of electronic information, energy-saving household appliances, new energy vehicles, wind power generation, industrial robots, aerospace and the like. In recent years, the output of rare earth permanent magnet materials mainly based on NdFeB has been continuously increasing. In 2022, the domestic output in China reached 2.1 million tons. NdFeB permanent magnet materials are usually used in four forms, namely anisotropic sintered magnets, anisotropic hot-pressed / hot-deformed magnets, anisotropic HDDR magnetic powders and isotropic rapidly quenched magnetic powders. Among them, there are mainly two types used for bonded permanent magnet materials, anisotropic HDDR magnetic powders and isotropic rapidly quenched magnetic powders. Among them, the molded bonded magnet using rapidly quenched magnetic powder as the raw material is the most main product form of NdFeB type bonded permanent magnet materials at present.

[0003] The main manufacturing process of anisotropic HDDR magnetic powder is as follows: alloy cast sheets are first subjected to high-temperature annealing and crushing to prepare low-magnetic-performance coarse powder composed of single-crystal particles with a diameter of about 100 μm. The single-crystal coarse powder becomes high-performance anisotropic magnetic powder after being subjected to HDDR (Hydrogenation-Hisproportionation-Hesorption-Recombination) treatment. HDDR magnetic powder is composed of main-phase grains with a diameter of 400 nm and grain boundary phases, and the main-phase orientations of its fine grains are roughly the same. Although the (BH) max of anisotropic HDDR magnetic powder is as high as 42 MGOe, and the (BH) max of the oriented molded bonded magnet can reach 22 MGOe, due to the fact that the HDDR process is difficult to produce stably on a large scale, and the substitution of lanthanum and cerium will cause a significant decrease in (BH) max Therefore, the output of HDDR magnetic powder is very low. The main manufacturing process of isotropic rapidly quenched magnetic powder is as follows: the alloy melt is melted, and the melt is poured onto a high-speed rotating water-cooled copper roller, and a sheet-like strip with a nanocrystalline structure is obtained through rapid cooling and then broken into magnetic powder for preparing bonded magnets. The rapidly quenched magnetic powder also has the microstructural characteristics of Nd 2 Fe 14 B main phase + rare-earth-rich grain boundary phase. The main-phase grain size is 20 - 40 nm. This kind of magnetic powder is isotropic. The annual output in China is nearly 10,000 tons and is mainly used in the form of molded bonded magnets. The (BH) max range of the rapidly quenched magnetic powder is 5 - 16 MGOe, and the (BH) maxThe range is 3 - 13 MGO. The molded bonded magnet made of rapidly quenched magnetic powder has the characteristics of simple process, high dimensional accuracy, complex shape, flexible magnetization method, high magnetic powder utilization rate, etc., and has unique advantages in the field of micro-special motors. However, the rapidly quenched magnetic powder is isotropic, and its remanence can only be slightly higher than half of the saturation magnetization intensity (J s ), which results in the (BH) max of the magnetic powder itself being generally lower than 20 MGO. After further dilution by the organic binder, the (BH) max of the molded bonded magnet is only 3 - 13 MGO, and its application field is restricted by the insufficient magnetic energy product. To further improve the (BH) max of the bonded magnet, it can only be achieved by orientation bonding molding, which requires anisotropic magnetic powder that can be oriented. For example, the (BH) max of the anisotropic HDDR magnetic powder is as high as 42 MGO, and the (BH) max of the oriented molded bonded magnet can reach 22 MGO. Since it is difficult to achieve large-scale stable production of the HDDR-NdFeB magnetic powder itself, and the substitution of lanthanum and cerium will cause a significant decrease in (BH) max , the output of the HDDR magnetic powder is very low. Therefore, the bonded NdFeB material has always been mainly the isotropic molded bonded magnet. How to realize the anisotropy of the bonded NdFeB material is an urgent problem to be solved. Summary of the Invention:

[0004] The present invention solves the problems existing in the prior art, and provides a shell-layer magnetically hardened single-crystal permanent magnetic powder, a preparation method and an application. The present invention improves the magnetic properties of the RE 2 Fe 14 B micron single-crystal magnetic powder by using a rare-earth-rich coating film, and realizes the anisotropy of the bonded NdFeB material.

[0005] One of the purposes of the present invention is to provide a shell-layer composition regulating additive, which is composed of oxygen, auxiliary element calcium, effective elements capable of forming a rare-earth-rich coating film, and inevitable impurity elements. The composition of the effective elements in atomic percentage is:

[0006] (R1 1-β R2 β ) 100-a-b TM a Al b (Formula - 1)

[0007] Wherein, R1 is at least one of Nd and Pr; R2 is at least one of La (lanthanum), Ce (cerium), Ho (holmium), Gd (Gd), Tb (terbium), Dy (dysprosium) and Y (yttrium); 0≤β<0.5; transition metal element TM is at least one of Cu (copper), Ga (gallium), Fe (iron), Co (cobalt), Si (silicon), Zr (zirconium), Hf (hafnium), Nb (niobium), Ti (titanium), V (vanadium), B (boron), Zn (zinc), 0≤a≤40.0; 1≤b≤40.0; 3 <a+b<60。

[0008] The shell component regulating auxiliary agent is a multi-phase complex containing calcium.

[0009] Preferably, the atomic number of the auxiliary element calcium is 20%-200% of the atomic number of all effective elements. More than 95 at% of the calcium element is generally present in the shell composition regulating auxiliary agent in the form of calcium oxide or calcium hydroxide.

[0010] The second object of the present invention is to provide a method for preparing the shell composition regulating auxiliary agent, which is prepared by a direct batching and mixing process, comprising the following steps:

[0011] S1. Preparation of composite oxides: rare earth metal elements R1, R2, transition metal element TM and Al element raw materials are prepared in the proportion shown in Formula 1, and insoluble solid powder raw materials are first mixed evenly, and the mixing method is wet mixing to obtain composite oxide slurry, the concentration of solid powder in the slurry is 20-500g / L, and the concentration of effective element ions is 0.2-10mol / L, and oxides, alkalis or inorganic salts containing calcium are added as auxiliary materials, and the number of calcium atoms in the auxiliary materials is 20%-200% of the number of all effective element atoms, and then the slurry is dried to obtain dry composite oxides;

[0012] S2. Calcination of composite oxides: calcining the dried composite oxides in air at 500°C-1100°C for 0.5-10h to obtain calcined composite oxides, wherein the calcined composite oxides are a multiphase mixture of multiple oxides and composite oxides, wherein the multiple oxides and composite oxide phases account for more than 95wt% of the multiphase mixture, and the effective elements in the multiphase mixture except calcium, oxygen and unavoidable impurity elements meet the ratio specified in Formula-1;

[0013] S3. Reduction treatment of the calcined composite oxide to obtain a shell composition regulating additive: When the content of the oxide reducible by a reducing gas in the calcined composite oxide is greater than 10%, reduction treatment is carried out; when the content of the oxide reducible by a reducing gas is less than 10%, no reduction treatment is required. The reduction treatment process: Remove the oxygen in the transition metal oxide from the calcined composite oxide to be reduced in a reducing gas at 500°C - 980°C; after the reduction treatment is completed, the calcined composite oxide is transformed into a shell composition regulating additive composed of a transition metal, a rare earth oxide, and a rare earth composite oxide, and the transition metal, the rare earth oxide, the rare earth composite oxide, and the calcium oxide phase account for more than 95 wt% of the shell composition regulating additive.

[0014] When more than 20 at% of the effective elements are fed in the form of soluble salts and the remaining raw materials are fed in the form of insoluble solid powders, the direct batching and mixing process is suitable. Among them, the diameter of the solid insoluble particles should be less than 1 μm, preferably less than 600 nm. The steps of the direct batching and mixing process are as follows: It is carried out in 3 steps, making a composite oxide slurry, calcining the composite oxide slurry, and reducing the calcined composite oxide to obtain a shell composition regulating additive.

[0015] The direct batching and mixing process specifically includes the following steps:

[0016] S1. Preparation of composite oxide: First, mix the insoluble solid powder raw materials evenly, and the mixing method is wet mixing. First, add the poorly soluble solid powder raw materials into water for grinding or stirring; secondly, add the water-soluble raw materials, and co-precipitate the soluble raw materials by titrating the precipitating agent. During the titration process, the slurry needs to be continuously stirred until all the soluble elements are precipitated, so as to mix the raw materials of different components evenly. When using a low-solubility precipitating agent such as calcium hydroxide, the precipitating agent can be first added to the slurry, and the soluble transition metal and rare earth salts are prepared into a solution and dropped into the slurry. The concentration of the solid powder in the slurry is 20 - 500 g / L, and the concentration of the effective element ions is 0.2 - 10 mol / L. Precipitating agents such as oxalic acid, oxalates, carbonates, bicarbonates, sodium hydroxide, potassium hydroxide, calcium hydroxide, urea or other precipitating agents can be used to precipitate the soluble salts of transition metal elements, rare earth elements, and transition metal doped elements and mix them evenly in the slurry. The concentration of the ions in the precipitating agent that form precipitates with the effective elements is 0.2 - 4 mol / L. After precipitation, the brine needs to be filtered off. After obtaining the slurry with the proportion of effective elements meeting the requirements of (Formula - 1), add auxiliary materials calcium oxide or calcium hydroxide or calcium carbonate, or a mixture of the three auxiliary materials. The atomic number of the auxiliary element calcium is 20% - 200% of the total atomic number of all effective elements; it is required that the average particle diameter of the auxiliary materials should be less than 600 nm, preferably less than 300 nm. When using a low-solubility precipitating agent such as calcium hydroxide, the precipitating agent can be added to the slurry at one time, and then the soluble transition metal and rare earth salts are prepared into a solution and dropped into the slurry, so as to directly prepare the composite oxide slurry. Filter off the water in the composite oxide slurry and dry it to obtain a dry composite oxide.

[0017] S2. Calcination of composite oxide: Calcinate the dried composite oxide in air at 500 °C - 1100 °C for 0.5 - 10 h to decompose the components such as calcium hydroxide, calcium carbonate, rare earth hydroxide, rare earth carbonate, transition metal hydroxide, and transition metal carbonate in the composite oxide that need to be converted into oxides, and some oxides will further react to form composite oxides. The calcined material is called calcined composite oxide. The calcined composite oxide becomes a multiphase mixture composed of multiple oxides and composite oxides, and these oxide and composite oxide phases account for more than 95 wt% of the multiphase mixture. The effective elements in the mixture except calcium, oxygen, and impurity elements meet the proportion requirements of (Formula - 2). The phases in the calcined composite oxide can be divided into the following five categories:

[0018] The first category, composite oxide phases formed by rare earth oxides and oxides of transition metal elements TM and Al, including but not limited to REAlO 3 、RETMO 3 、RE(TM,Al)O 3 、RE 3TM 5 O 12 、RE 3 (TM,Al) 5 O 12 ;

[0019] The second category is rare earth oxides, including but not limited to RE 2 O 3 、REO 2 ;

[0020] The third category is oxides of transition metals and transition metal-doped elements, including but not limited to TMO, TM 2 O 3 、Al 2 O 3 、(TM,Al)O、(TM,Al) 2 O 3 and other forms of transition metal oxide phases;

[0021] The fourth category is calcium oxide formed by the decomposition of auxiliary materials.

[0022] In the above expressions, RE represents at least one of rare earth elements R1 and R2. The calcined composite oxide may also contain CaTM 2 O 4 、CaAl 2 O 4 、Ca(TM,Al) 2 O 4 、Ca 2 TM 2 O 5 、Ca 2 (TM,Al) 2 O 4 or one or more of these composite oxides containing calcium, and these calcium-containing composite oxides account for less than 10 wt% of the calcined composite oxide.

[0023] Microstructural characteristics of the calcined composite oxide: Ultra-fine particles such as rare earth oxides, rare earth-containing composite oxides, calcium oxide, and transition metal oxides are uniformly distributed.

[0024] S3. Reduction treatment of the calcined composite oxide to obtain the shell composition regulating additive: When the content of oxides in the calcined composite oxide of the shell composition regulating additive that can be reduced by reducing gases such as hydrogen, carbon monoxide, and methane is greater than 10 at%, reduction treatment is required. When the content of oxides is less than 10 at%, reduction treatment is not required, and it is the shell composition regulating additive. Reduction treatment process: Remove the oxygen in the transition metal oxide of the calcined composite oxide that needs to be reduced in reducing gases such as hydrogen, methane, natural gas, and carbon monoxide at 500°C - 980°C; after the reduction treatment is completed, the calcined composite oxide is transformed into the shell composition regulating additive composed of transition metals, rare earth oxides, and rare earth composite oxides, and these metals, oxides, composite oxides, and calcium oxide phases account for more than 95 wt% of the precursor material.

[0025] The phases of the shell composition regulating additive obtained through reduction treatment can be divided into the following four categories:

[0026] The first category is unreduced rare earth oxides, transition metal doped element oxides, and composite oxide phases formed by rare earth oxides and transition metal oxides and transition metal doped elements, including but not limited to RE 2 O 3 、REO 2 、RETMO 3 、REAlO 3 、RE(TM,Al)O 3 、RE 3 TM 5 O 12 、RE 3 (TM,Al) 5 O 12 ;

[0027] The second category is the reduced transition metal TM;

[0028] The third category is calcium oxide formed by the decomposition of auxiliary materials, and calcium oxide may also form CaTM 2 O 4 、CaAl 2 O 4 、Ca(TM,Al) 2 O 4 、Ca 2 TM 2 O 5 、Ca 2 (TM,Al) 2 O 4 or one or more of the composite oxides, and these calcium-containing composite oxides account for less than 5 wt% of the precursor material. The above-mentioned metals, oxides, composite oxides, and calcium oxide phases account for more than 95 wt% of the precursor material. In the above description, RE represents at least one of the rare earth elements R1 and R2.

[0029] The shell composition regulating additive has the following microscopic characteristics: ultrafine particles such as rare earth oxides, composite oxides containing rare earths, calcium oxide, and transition metal (oxides) are evenly distributed.

[0030] The third object of the present invention is to provide a method for preparing the shell composition regulating additive, which is prepared by a pre-calcination-mixing process, comprising the following steps:

[0031] S1, rare earth metal elements R1, R2, transition metal element TM and Al element raw materials are mixed in the proportion shown in formula-1, with rare earth metal oxides and transition metal oxides as main raw materials, and a primary mixture is prepared by mixing and calcining;

[0032] S2. A secondary mixture is prepared by using a primary mixture and auxiliary materials that meet the requirements of particle size and phase structure as main raw materials, wherein the auxiliary materials are oxides, alkalis or inorganic salts containing calcium, and the number of calcium atoms in the auxiliary materials is 20-200% of the number of atoms of all effective elements; the dried secondary mixture is calcined again to decompose the calcium hydroxide or calcium carbonate in the secondary mixture into calcium oxide, and a multiphase mixture consisting of a plurality of oxides and composite oxides is obtained, wherein the plurality of oxides and composite oxide phases account for more than 95wt% of the multiphase mixture, and the effective elements in the multiphase mixture except calcium, oxygen and unavoidable impurity elements meet the ratio specified in Formula-1;

[0033] S3. When the content of oxides that can be reduced by reducing gas in the multiphase mixture is greater than 10%, reduction treatment is carried out. When the content of oxides that can be reduced by reducing gas is less than 10%, reduction treatment is not required. Reduction treatment process: the multiphase mixture that needs reduction treatment is placed in a reducing gas at 500℃-1000℃ to remove oxygen in the transition metal oxide; after the reduction treatment is completed, the multiple mixtures are converted into a shell composition regulating agent composed of transition metals, rare earth oxides, and rare earth composite oxides, and the transition metals, rare earth oxides, rare earth composite oxides and calcium oxide phases account for more than 95wt% of the shell composition regulating agent.

[0034] Preferably, in step S1, the uniformly mixed and dried mixture is calcined in air at 600° C.-1200° C. for 1-10 hours to obtain a primary mixture.

[0035] Preferably, in step S3, the reducing gas is selected from one of hydrogen, methane, natural gas and carbon monoxide.

[0036] When the effective elements in the form of soluble salts are less than 20 at%, and the remaining raw materials are fed in the form of insoluble solid powders, the pre-sintering-mixing process is suitable. The diameter of the insoluble solid particles should be less than 1 μm, preferably less than 600 nm. The pre-sintering-mixing process specifically includes the following steps:

[0037] S1. Prepare the primary mixture. Using rare earth oxides and transition metal oxides that meet the purity and particle size requirements as the main raw materials, proportion the materials according to the effective element ratio specified in Formula - 1. Calcinate the uniformly mixed and dried mixture in air at 600°C - 1200°C for 1 - 10 hours to obtain the primary mixture. After calcination, the primary mixture becomes a multiphase mixture composed of various oxides and composite oxides, and these oxide and composite oxide phases account for more than 95 wt% of the multiphase mixture.

[0038] The phases in the primary mixture can be divided into the following four categories:

[0039] The first category is the composite oxide phases formed by rare earth oxides and oxides of transition metal elements TM and Al, including but not limited to REAlO 3 , RETMO 3 , RE(TM,Al)O 3 , RE 3 TM 5 O 12 , RE 3 (TM,Al) 5 O 12 ;

[0040] The second category is rare earth oxides, including but not limited to RE 2 O 3 , REO 2 ;

[0041] The third category is oxides of transition metals and transition metal doping elements, including but not limited to TMO, TM 2 O 3 , Al 2 O 3 , (TM,Al)O, (TM,Al) 2 O 3 and other forms of oxide phases of transition metals;

[0042] The fourth category is calcium oxide formed by the decomposition of auxiliary materials.

[0043] In the above expressions, RE represents at least one of rare earth elements R1 and R2.

[0044] The microstructural characteristics of the multiphase mixture obtained by calcination: ultrafine particles of rare earth oxides, rare earth-containing composite oxides, calcium oxide, transition metal oxides, etc. are uniformly distributed.

[0045] In order to mix the raw materials evenly and facilitate full reaction, the mixing methods of the raw materials in the primary mixture include the following 3 types:

[0046] Mixing method 1: When all raw materials are solid powders, the raw material powders that meet the requirements of particle diameter and purity are directly mechanically mixed evenly by using methods such as high-intensity mixers and ball mills.

[0047] Mixing method 2: When all raw materials are solid insoluble substances, water can also be added and mechanically mixed by using methods such as high-intensity mixers, ball mills, and stirred mills. After mixing evenly, most of the water is separated by using equipment such as filter presses and suction filters, and the mixed material is dried by using rotary kilns and dryers; this method requires that the dissolution loss of each raw material in water is less than 1 wt%, and the total dissolution loss of all raw materials is less than 3 wt%.

[0048] Mixing method 3: When some raw materials are soluble salts, first mechanically mix the solid insoluble raw materials evenly in water by using methods such as high-intensity mixers, ball mills, and stirred mills; add the soluble raw materials into the ground and mixed evenly slurry according to the ratio required by the formula and mix evenly. It is required that the total concentration of rare earth and transition metal elements in the soluble salt is lower than 4 mol / L, preferably lower than 2 mol / L; prepare a solution of the precipitant corresponding to the soluble salt with a concentration lower than 4 mol / L, preferably lower than 2 mol / L; use a stirrer to stir the slurry and drop in the precipitant solution, so as to precipitate the rare earth and transition metal elements in the slurry and uniformly mix them into the slurry; when there are both soluble rare earth and transition metal doping element raw materials, strong bases such as sodium hydroxide, potassium hydroxide, and calcium hydroxide can be used for precipitation; when there is only soluble rare earth raw material, common rare earth precipitants such as oxalic acid, ammonium oxalate, ammonium bicarbonate, and urea can be used for precipitation; when using a low-solubility precipitant such as calcium hydroxide, the precipitant can be first added to the slurry, and then the soluble transition metal and rare earth salts are prepared into a solution and dropped into the slurry; after precipitation, stand for 0 - 20 hours, use equipment such as filter presses and suction filters to separate most of the water, and use rotary kilns and dryers to dry the mixed material; this method requires that the total dissolution loss of all raw materials is less than 3 wt%.

[0049] S2. Prepare the secondary mixed material: Re-crush the primary mixed material, adjust the proportion of effective elements, add auxiliary materials, and calcine after mixing evenly to form the secondary mixed material.

[0050] The preparation steps of the secondary mixed material are as follows: Re-crush and grind the primary mixed material into powders with a particle diameter of 50 - 10000 nm, add auxiliary materials and mix evenly; the atomic number of the auxiliary element calcium is 20% - 200% of the atomic numbers of all effective elements; the dried secondary mixed material is calcined in air at 500°C - 1200°C for 0.5 - 10 h to decompose calcium hydroxide or calcium carbonate in the secondary mixed material into calcium oxide.

[0051] There are the following two mixing methods for the secondary mixed material:

[0052] Mixing method 1: directly mechanically dry mix using methods such as a high-intensity mixer and a ball mill;

[0053] Mixing method 2: mechanically mix in water using methods such as a high-intensity mixer, a ball mill, and a stirred mill. After mixing evenly, separate most of the water and dry the mixed material. The preferred method is wet grinding and mixing in water.

[0054] The secondary mixed material is a multiphase mixture composed of multiple oxides and composite oxides. These oxides and composite oxide phases account for more than 95 wt% of the multiphase mixture, and the effective elements in the mixture other than calcium, oxygen, and impurity elements conform to the ratio specified in (Equation - 1).

[0055] The phases in the secondary mixed material can be divided into the following five categories:

[0056] The first category: composite oxide phases formed by rare earth oxides and oxides of transition metal elements TM and Al, including but not limited to REAlO 3 、RETMO 3 、RE(TM,Al)O 3 、RE 3 TM 5 O 12 、RE 3 (TM,Al) 5 O 12 ;

[0057] The second category: rare earth oxides, including but not limited to RE 2 O 3 、REO 2 ;

[0058] The third category: oxides of transition metals and transition metal doping elements, including but not limited to TMO, TM 2 O 3 、Al 2 O 3 、(TM,Al)O、(TM,Al) 2 O 3 and other forms of oxide phases of transition metals;

[0059] The fourth category: calcium oxide formed by the decomposition of auxiliary materials.

[0060] In the above expressions, RE represents at least one of rare earth elements R1 and R2. The secondary mixed material may also contain CaTM 2 O 4 、CaAl 2 O 4 、Ca(TM,Al) 2 O 4 、Ca 2 TM 2 O 5, Ca 2 (TM, Al) 2 O 4 One or more composite oxides, and these calcium-containing composite oxides account for less than 10 wt% of the calcined composite oxides.

[0061] Microstructural characteristics of the secondary mixture: Ultra-fine particles such as rare earth oxides, rare earth-containing composite oxides, calcium oxide, and transition metal oxides are evenly distributed.

[0062] S3. The secondary mixture is reduced to form a shell composition regulating aid. When the content of oxides in the shell composition regulating aid that can be reduced by reducing gases such as hydrogen, carbon monoxide, and methane is greater than 10 at%, reduction treatment is required; when the content of oxides is less than 10 at%, reduction treatment is not required.

[0063] The secondary mixture that needs reduction treatment is reduced to remove oxygen in the transition metal oxides in reducing gases such as hydrogen, methane, natural gas, and carbon monoxide at 500°C - 1000°C. After the reduction treatment is completed, the secondary mixed raw material is converted into a multifunctional precursor for producing rare earth transition metal compound powders. This precursor is a multiphase mixture composed of phases such as transition metals, rare earth oxides, and rare earth composite oxides, and the effective elements in the mixture except for oxygen, calcium, and impurity elements conform to the ratio specified in (Equation - 1).

[0064] The phases in the precursor can be classified into the following four categories:

[0065] The first category, unreduced rare earth oxides, transition metal doped element oxides, and composite oxide phases formed by rare earth oxides and transition metal oxides and transition metal doped elements, including but not limited to RE 2 O 3 , REO 2 , RETMO 3 , REAlO 3 , RE(TM, Al)O 3 , RE 3 TM 5 O 12 , RE 3 (TM, Al) 5 O 12 ;

[0066] The second category, reduced transition metal TM;

[0067] The third category, calcium oxide formed by the decomposition of auxiliary materials, and calcium oxide may also form CaTM 2 O 4 , CaAl 2 O 4 , Ca(TM, Al) 2 O4 , Ca 2 TM 2 O 5 , Ca 2 (TM, Al) 2 O 4 One or more composite oxides, and these calcium-containing composite oxides account for less than 5 wt% of the precursor. The above metals, oxides, composite oxides and calcium oxide phases account for more than 95 wt% of the precursor. In the above description, RE represents at least one of the rare earth elements R1 and R2.

[0068] The shell composition regulating additive has the following microscopic characteristics: ultra-fine particles such as rare earth oxides, rare earth-containing composite oxides, calcium oxide, transition metals (oxides), etc. are evenly distributed.

[0069] When the shell composition regulating additive with the above microstructure is subjected to reduction diffusion treatment to regulate the shell structure of R 2 Fe 14 B powder, ultra-fine particles such as rare earth oxides, rare earth-containing composite oxides, transition metals (oxides), etc. are reduced to the metallic state by calcium, and at the same time, reaction by-product calcium oxide is formed. Various ultra-fine metal particles are embedded in ultra-fine calcium oxide particles, and it is difficult to form continuous or coarse-grained phases. Under the action of surface energy, the Ostwald ripening process occurs, and the atoms in the ultra-fine metal particles can only diffuse directionally to the surface of the coarse particles of R 2 Fe 14 B, and a coating film with a chemical composition similar to the proportion of effective elements in the shell regulating additive is formed, thus completing the coating of the powder and the regulation of the shell composition.

[0070] The fourth object of the present invention is to provide a shell magnetically hardened single crystal permanent magnet powder, and the compositional components of the shell magnetically hardened single crystal permanent magnet powder expressed in atomic percentage are:

[0071] (R1 1-α R2 α ) x Fe 100-x-y-z-v M1 y M2 z B v (Formula - 2)

[0072] Wherein, R1 is at least one of Nd and Pr; R2 is at least one of La, Ce, Ho, Gd, Tb, Dy and Y; 0 ≤ α < 0.8; 14 ≤ x ≤ 28; M1 is at least one of Cu, Al, Ga elements, 0.1 ≤ y ≤ 10.0; M2 is at least one of Co, Si, Zr, Hf, Nb, Ti, V elements, 0 ≤ z ≤ 10.0; 2.5 ≤ v ≤ 6.0.

[0073] The described shell-magnetohardened single-crystal permanent magnet powder has the following microstructure, magnetic properties, and antioxidant characteristics:

[0074] Microstructure characteristics: The volume ratio of single-crystal grains is not less than 50V%. The magnetic powder particles are composed of two parts: the main phase R 2 Fe 14 B single crystal and a rare-earth-rich coating film. The rare-earth-rich coating film with a thickness of 2 - 50 nm wraps around the main-phase grains. The rare-earth elements in the rare-earth-rich coating film are not less than 20 at%, and the Al element content is not less than 2 at%. The particles have an equiaxed shape or are nearly spherical, with complete grains and a smooth surface;

[0075] Magnetic property characteristics: After the magnetic powder is oriented by a magnetic field, 9.0 kGs < remanence (B r ) < 15.5 kGs, 4 kOe < intrinsic coercivity (H cj ) < 25 kOe, 20 MGOe < maximum magnetic energy product (BH max ) < 54 MGOe;

[0076] Antioxidant characteristics: The magnetic powder has good antioxidant properties. After being sealed with binders such as epoxy resin and nylon, after aging treatment in air at 120 °C for 500 hours, the irreversible damage of the remanence is less than 10%, and the decrease in coercivity is less than 20%.

[0077] The fifth object of the present invention is to provide a preparation method for the shell-magnetohardened single-crystal permanent magnet powder, including the following steps:

[0078] S1. Batching and mixing: Mix the shell composition regulating auxiliary agent with RE 2 Fe 14 B single-crystal powder particles evenly. The addition amount of the shell composition regulating auxiliary agent is 5 - 40 wt% of the RE 2 Fe 14 B single-crystal powder;

[0079] S2. Shell structure regulating heat treatment: Perform shell structure regulating heat treatment on the evenly mixed mixture in a vacuum or inert gas. The temperature of the shell structure regulating heat treatment is: (the melting point of RE 2 Fe 14 B or the peritectic reaction temperature in the equilibrium phase diagram) * 65% < the temperature of the shell structure regulating heat treatment < (the melting point of RE 2 Fe 14 B or the peritectic reaction temperature in the equilibrium phase diagram) * 85%, and the time of the shell structure regulating heat treatment is 0.5 - 5 hours;

[0080] S3. Separating calcium oxide: The material after the shell structure regulating heat treatment contains by-product calcium oxide. Remove the calcium oxide in the material to obtain the shell-magnetohardened single-crystal permanent magnet powder.

[0081] Generally speaking, RE 2 Fe 14 The single-crystal magnetic powder of RE-Fe-B is formed by ingot casting and grinding and is used in the production of sintered neodymium iron boron; or the scrapped neodymium iron boron material is re-cleaned, calcined, calcium thermally reduced and ground to form single-crystal magnetic powder. These magnetic powders usually have irregular shapes, rough surfaces, sharp corners, etc., making it difficult to obtain high coercivity and being prone to oxidation.

[0082] The present invention proposes to transform the conventional single-crystal neodymium iron boron magnetic powder into RE-Fe-B micron single-crystal magnetic powder with a rare-earth-rich coating film, and regulate the coercivity of the magnetic powder through the composition and morphology of the rare-earth-rich coating film. The magnetism with improved magnetic properties obtained by this method can be called shell-magnetically hardened single-crystal permanent magnet powder. Then how to form a coating film on the RE-Fe-B single-crystal magnetic powder and control its chemical composition, while keeping the grains in a discrete state all the time is the basic technical problem in the preparation of such magnetic powders. 2 Fe 14 B micron single-crystal magnetic powder, and regulate the coercivity of the magnetic powder through the composition and morphology of the rare-earth-rich coating film. The magnetism with improved magnetic properties obtained by this method can be called shell-magnetically hardened single-crystal permanent magnet powder. Then how to form a coating film on the RE-Fe-B single-crystal magnetic powder and control its chemical composition, while keeping the grains in a discrete state all the time is the basic technical problem in the preparation of such magnetic powders. 2 Fe 14 B single-crystal magnetic powder and control its chemical composition, while keeping the grains in a discrete state all the time is the basic technical problem in the preparation of such magnetic powders.

[0083] The present invention proposes to use low-cost oxides such as rare-earth oxides, copper oxide, aluminum oxide, iron oxide, cobalt oxide, etc. as the main raw materials and produce a shell composition regulating aid with a complex-phase structure through a supporting process, control the diffusion paths and directions of various atoms during reduction diffusion, and at the same time form an effective isolation layer to effectively prevent the RE-Fe-B grains from sintering with each other to form polycrystalline particles. The RE-Fe-B single-crystal magnetic powder with a rare-earth-rich coating film is prepared through the shell composition regulating aid provided by the present invention, and a reduction-directional diffusion treatment (Reduction-Directional Diffusion Process, hereinafter referred to as RDDP) is carried out, that is, the diffusion paths and directions of various elements during heat treatment are controlled through the structural design of the shell composition regulating aid. 2 Fe 14 B grains from sintering with each other to form polycrystalline particles. The RE-Fe-B single-crystal magnetic powder with a rare-earth-rich coating film is prepared through the shell composition regulating aid provided by the present invention, and a reduction-directional diffusion treatment (Reduction-Directional Diffusion Process, hereinafter referred to as RDDP) is carried out, that is, the diffusion paths and directions of various elements during heat treatment are controlled through the structural design of the shell composition regulating aid. 2 Fe 14 B single-crystal magnetic powder, and a reduction-directional diffusion treatment (Reduction-Directional Diffusion Process, hereinafter referred to as RDDP) is carried out, that is, the diffusion paths and directions of various elements during heat treatment are controlled through the structural design of the shell composition regulating aid.

[0084] Preferably, the powder particle diameter of the shell composition regulating aid described in step S1 is less than 1 / 10 of the diameter of the RE-Fe-B single-crystal powder particles. 2 Fe 14 B single-crystal powder particles.

[0085] The preparation method of the shell-magnetically hardened single-crystal permanent magnet powder specifically includes the following steps:

[0086] S1. Weighing and mixing, mixing the shell composition regulating aid with RE-Fe-B single-crystal powder particles evenly, and the addition amount of the shell composition regulating aid is 2 Fe 14 B single-crystal powder particles evenly, and the addition amount of the shell composition regulating aid is 2 Fe14 5 - 40 wt% of single crystal B powder. The shell structure regulation treatment is applicable to R with 2 μm < particle diameter < 10 μm 2 Fe 14 single crystal B powder. Before batching, in order to facilitate uniform mixing and separate RE 2 Fe 14 single crystal B powder particles, it is necessary to match the particle sizes of the raw materials, that is, the particle diameter of the shell component regulation auxiliary agent powder should be less than that of RE 2 Fe 14 single crystal B powder particles by 1 / 10.

[0087] The mixing methods include dry mixing and wet mixing. In dry mixing, directly mix RE 2 Fe 14 single crystal B powder and the shell component regulation auxiliary agent evenly on mixing equipment such as a three - dimensional mixing tank, a high - intensity mixer, and a ball mill. In wet mixing, add a stable organic solvent that does not react with the raw materials, such as methanol, ethanol, heptane, gasoline, etc., to the shell component regulation auxiliary agent and RE 2 Fe 14 single crystal B powder, and then mix evenly on mixing equipment such as a three - dimensional mixing tank, a high - intensity mixer, and a ball mill. In addition, metal calcium particles need to be added to the mixture, and the weight should be 1.2 - 3.0 times the amount required to reduce all rare earth oxides and transition metal oxides. The wet - mixed material needs to be dried after mixing evenly.

[0088] S2. Shell structure regulation heat treatment: Perform shell structure regulation heat treatment on the evenly - mixed mixture in a vacuum or inert gas. The method for determining the temperature (absolute temperature) of the shell structure regulation heat treatment is: (the melting point of RE 2 Fe 14 B or the peritectic reaction temperature in the equilibrium phase diagram) * 65% < shell structure regulation heat treatment temperature < (the melting point of RE 2 Fe 14 B or the peritectic reaction temperature in the equilibrium phase diagram) * 85%. The shell structure regulation heat treatment time is 0.5 - 5 hours.

[0089] S3. Separate calcium oxide: The material after shell structure regulation heat treatment contains the by - product calcium oxide, and the calcium oxide in the material is removed. In the present invention, deionized water or dilute acetic acid prepared with deionized water is used to remove calcium oxide. The magnetic powder does not need to be ground and can maintain the state during shell structure regulation heat treatment. Therefore, the shell - magnetically hardened single - crystal magnetic powder of the present invention has an equiaxed shape or nearly spherical particles, complete grains, and a smooth surface, which is beneficial to obtaining high coercivity, dispersibility, and fluidity.

[0090] A sixth object of the present invention is to provide an application of the shell-layer magnetically hardened single-crystal permanent magnet powder in the preparation of rare-earth permanent magnet materials. The rare-earth permanent magnet materials include permanent magnet composite materials, sintered permanent magnet materials, injection-molded NdFeB permanent magnet materials, 3D printing magnetic materials, etc.

[0091] Conventional RE 2 Fe 14 B single-crystal powder has a very low coercivity and is prone to oxidation or even ignition. Therefore, conventional RE 2 Fe 14 B magnetic powder cannot be used as a permanent magnet material. In addition, RE 2 Fe 14 B magnetic powder with a high La or Ce content has a low raw material cost, but its magnetic properties are worse than those of Nd 2 Fe 14 B. For example, (Nd 0.4 Ce 0.6 ) 2 Fe 14 B and (Nd 0.4 La 0.6 ) 2 Fe 14 B magnetic powder has the advantage of low raw material cost, but this composition further causes insufficient coercivity of the magnetic powder. Through the regulation and treatment of the shell structure, a coating layer rich in Pr, Nd, Tb, and Dy is formed on the RE 2 Fe 14 B single-crystal magnetic powder, which can greatly improve the coercivity. Moreover, the Pr, Nd, Tb, and Dy atoms in the coating layer can also enter the RE 2 Fe 14 B grains with a high La or Ce content and replace the surface La and Ce atoms to form a shell with high coercivity. In addition, through the doping of aluminum element, on the one hand, it can improve the wettability of the coating film on the magnetic powder and enhance the coating effect; on the other hand, the aluminum element can also improve the antioxidant ability of the coating film and prevent the coating film from being oxidized and damaged during the production and use of the magnetic powder. Therefore, by using the shell structure regulation additive described in the present invention and the matching heat treatment, the conventional RE 2 Fe 14 B crystals without a coating film and with low coercivity can be transformed into high-performance single-crystal permanent magnet powders with a coating film, high coercivity, and antioxidant ability. It can also be said that this shell-layer magnetically hardened single-crystal permanent magnet powder is realized by forming a coating film on the magnetic powder.

[0092] Compared with the prior art, the present invention has the following advantages:

[0093] 1. The shell-layer magnetically hardened single-crystal permanent magnet powder proposed by the present invention is convenient to obtain a high degree of orientation during orientation molding as a single-crystal magnetic powder, and is expected to have the advantages of high magnetic properties, a wide range of raw materials, and easy large-scale production;

[0094] 2. In the shell-magnetically hardened single-crystal permanent magnet powder, Nd 2 Fe 14 in the main phase of B can be partially replaced by La and Ce elements with high abundances, opening up a new material carrier for the efficient utilization of rare earth resources with high abundances;

[0095] 3. In the present invention, the preparation of the shell composition regulating auxiliary agent can use metal oxides as the main raw materials, and the composite oxides formed by recycling sintered NdFeB waste, processing sludge, etc. can also be directly used to prepare the shell-magnetically hardened single-crystal permanent magnet powder, promising to explore new methods for recycling resources;

[0096] 4. In the present invention, the preparation of the shell composition regulating auxiliary agent uses metal oxides as the main raw materials, and the metal elements in the form of soluble salts can be less than 30 at.% of all metal elements. Therefore, the salt-containing waste liquid generated by precipitation can be greatly reduced, and a large amount of precipitants can be saved; using oxides to largely replace soluble salts can also reduce the raw material cost. Therefore, the process proposed by the present invention has the characteristics of low raw material cost and wide source, and has excellent environmental protection and economic benefits;

[0097] 5. In the present invention, the preparation process of the shell composition regulating auxiliary agent is formulated mainly by wet mixing of solid powders and supplemented by chemical precipitation, and has the characteristics of simple, efficient, stable and controllable process operation, high repeatability, and easy realization of automated production;

[0098] 6. Since the shell-magnetically hardened single-crystal permanent magnet powder provided by the present invention has the characteristics of high single-crystal ratio, spherical or nearly spherical particles, and smooth surface, etc., it has the advantages of high compression density, easy orientation, high filling rate, good fluidity, and high magnetic properties when using molding processes such as injection molding and magnetic field orientation molding to produce materials such as permanent magnet composites. Description of the Drawings:

[0099] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative labor.

[0100] Figure 1 It is a typical microscopic morphology image of the shell-magnetically hardened NdFeB single-crystal magnetic powder in Example 1. Detailed Embodiments:

[0101] The following embodiments are further descriptions of the present invention, rather than limitations of the present invention.

[0102] In order to make the purpose, technical solutions and advantages of the present invention clearer, the embodiments and implementation schemes of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one example is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0103] The fuel cell membrane electrode activation method and technical effects of the present invention are described below in conjunction with specific embodiments.

[0104] Example 1

[0105] Oxide is used as the main raw material to prepare the shell composition regulating additive and the NdFeB single crystal powder is prepared by shell composition regulating heat treatment.

[0106] Take industrial neodymium oxide, copper oxide, aluminum oxide, iron oxide, cobalt oxide, and gallium oxide with a purity of 99wt%, and ball-mill these oxide raw materials into particles with a diameter between 50-160nm and d 50 =110nm powder. The above raw materials are prepared according to the effective element ratio shown in Table 1, and are mixed evenly using a ball mill, and then the mixture is calcined at 900°C for 3 hours to form a primary mixture. Each primary mixture is crushed again, and an auxiliary material calcium oxide with a purity of 99wt% is added, and the atomic number of the auxiliary element calcium is 20%-200% of the atomic number of all effective elements (see Table 2 for details), 600mL of water is added, and the mixture is ball milled and mixed evenly using a ball mill, so that the diameter of the solid particles in the mixture is between 40-150nm, d 50 =86nm. The mixture is filtered and dried, and the dried mixture is calcined again in air at 720°C for 3h to decompose the calcium hydroxide or calcium carbonate in the mixture into calcium oxide, thereby forming a shell composition regulating auxiliary agent that can be used to prepare shell magnetic hardening NdFeB magnetic powder.

[0107] According to Table 3, the shell composition control additives and Nd 2 Fe 14 B single crystal powder is mixed, the raw material Nd 2 Fe 14 B single crystal powder is the jet mill powder used for conventional sintering of NdFeB, with an average particle diameter of d 50 =3μm; the shell composition regulating agent and Nd 2 Fe 14The B single crystal powder particles are mixed evenly, and then metallic calcium particles are added to the mixture according to Table 3 and stirred evenly. The evenly mixed mixture is subjected to shell structure regulation heat treatment in inert gas argon at 850 °C for 2 hours. The material after shell structure regulation heat treatment is used to remove calcium oxide with deionized water, thereby obtaining shell magnetic hardened neodymium iron boron single crystal permanent magnet powder. Table 4 shows the magnetic properties of the shell magnetic hardened Nd 2 Fe 14 B single crystal permanent magnet powder.

[0108] As can be seen from Table 4, through shell magnetic hardening heat treatment, the magnetic powder for sintered neodymium iron boron with a coercivity lower than 2 kOe and unable to be directly used as permanent magnet powder is processed into single crystal magnetic powder with both high coercivity and high magnetic energy product. Appropriate addition of auxiliary materials helps the dispersion of magnetic powder, thereby obtaining a higher squareness and improving the remanence of magnetic powder. By adjusting the ratio of composition additives and raw neodymium iron boron magnetic powder, shell hardened magnetic powder with higher coercivity can be obtained. Because as the content of shell regulation additives increases, the rare earth rich coating layer formed on the surface of magnetic powder will also be more, which is conducive to forming a more complete and thicker coating layer, and is conducive to obtaining higher coercivity; Since the coating layer contains Al element, it is conducive to forming a dense oxide film on the surface, so a more complete and thicker coating film is also conducive to improving the oxidation resistance of magnetic powder. Figure 1 Shows the typical microscopic morphology image of the shell magnetic hardened neodymium iron boron single crystal magnetic powder.

[0109] Table 1. Raw materials of the primary mixture (weight unit, g)

[0110]

[0111] Table 2. Raw material ratio of shell composition regulation additives (weight unit, g)

[0112]

[0113] Table 3. Raw material formula of shell magnetic hardened Nd 2 Fe 14 B single crystal permanent magnet powder (weight unit, g)

[0114]

[0115]

[0116] Table 4. Magnetic properties of shell magnetic hardened Nd 2 Fe 14 B single crystal permanent magnet powder

[0117]

[0118]

[0119] Example 2

[0120] Using rare earth, transition metal salts and calcium oxide as the main raw materials, directly prepare the shell composition regulating additive by proportioning, and prepare the neodymium iron boron single crystal powder through the heat treatment for regulating the shell composition.

[0121] Prepare the shell composition regulating auxiliary agent according to the composite oxide slurry formula shown in Table 5. Using nitrates of Nd, Pr, Ce, Dy, Al, Cu, Fe, Co, Ga with a purity of 99.9wt% and calcium oxide as raw materials, first put calcium oxide into 1L of deionized water, and ball-mill the hydroxide into a slurry with a particle size less than 400nm; then prepare an aqueous solution of 1.0mol / L of the nitrates of the effective elements, and the specific element ratios and dosages are in accordance with the ratios listed in Table 5. Use a stirrer to mix the calcium hydroxide slurry evenly and keep stirring, and drip the nitrate solution into the continuously stirred slurry. After continuously stirring for 2 hours, filter out the water, and re-add deionized water and wash 2 times to wash away the by-product calcium nitrate of the precipitation reaction. Separate most of the water from the mixture using a suction filter device, dry the mixture in a dryer, and calcine the dried mixture in air at 980°C for 2h; re-grind the calcined mixture into a powder with a particle size less than 500nm, thus forming a shell composition regulating auxiliary agent that can be used to prepare the shell magnetic hardening neodymium iron boron magnetic powder.

[0122] According to Table 6, proportion the shell composition regulating auxiliary agent and Nd 2 Fe 14 B single crystal powder. The raw material Nd 2 Fe 14 B single crystal powder is the jet mill powder used for conventional sintered neodymium iron boron, with an average particle diameter d 50 =3μm; use a ball mill to mix the shell composition regulating auxiliary agent and Nd 2 Fe 14 B single crystal powder particles evenly, and then add metal calcium particles to the mixture according to Table 6 and stir evenly. Carry out heat treatment for regulating the shell structure on the evenly mixed mixture in an inert gas argon at 850°C, and the heat treatment time is 2 hours. Use deionized water to remove calcium oxide from the material after the heat treatment for regulating the shell structure, so as to obtain the shell magnetic hardening neodymium iron boron single crystal permanent magnet powder. Table 7 shows the magnetic properties of the shell magnetic hardening Nd 2 Fe 14 B single crystal permanent magnet powder.

[0123] As can be seen from Table 7, through shell magnetic hardening heat treatment, the magnetic powder for sintered NdFeB with a coercivity lower than 2 kOe and unable to be directly used as permanent magnet powder was processed into single-crystal magnetic powder with both high coercivity and high magnetic energy product. Appropriate addition of auxiliary materials helps the dispersion of magnetic powder, thereby obtaining a higher squareness and improving the remanence of magnetic powder. By adjusting the ratio of composition additives to raw NdFeB magnetic powder, shell-hardened magnetic powder with higher coercivity can be obtained. Because as the content of shell control additives increases, the rare-earth-rich coating layer formed on the surface of magnetic powder will be more, which is conducive to forming a more complete and thicker coating layer, and is conducive to obtaining higher coercivity; since the coating layer contains Al element, it is conducive to forming a dense oxide film on the surface, so a more complete and thicker coating film is also conducive to improving the antioxidant ability of magnetic powder.

[0124] Table 5. Composite oxide slurry formula

[0125]

[0126] Table 6. Raw material formula (weight unit, g) of shell magnetic hardened Nd 2 Fe 14 B single-crystal permanent magnet powder

[0127]

[0128]

[0129] Table 7. Magnetic properties of shell magnetic hardened Nd 2 Fe 14 B single-crystal permanent magnet powder

[0130]

[0131] The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A shell component regulating auxiliary agent, Features: The shell composition regulating additive is composed of oxygen, auxiliary element calcium, effective elements capable of forming a rare earth-rich coating film, and unavoidable impurity elements. The composition of the effective elements expressed in atomic percentage is: (R1 1-β R2 β ) 100-a-b TM a Al b (Formula - 1) Wherein, R1 is at least one of Nd and Pr; R2 is at least one of La, Ce, Ho, Gd, Tb, Dy and Y; 0≤β<0.5; transition metal element TM is at least one of Cu, Ga, Fe, Co, Si, Zr, Hf, Nb, Ti, V, B and Zn, 0≤a≤40.0; 1≤b≤40.0; 3 <a+b<60。 2. The shell composition regulating auxiliary agent according to claim 1, It is characterized in that The atomic number of the auxiliary element calcium is 20%-200% of the atomic number of all effective elements.

3. A method for preparing the shell component regulating auxiliary agent according to claim 1 or 2, It is characterized in that Prepared by direct batching and mixing process, including the following steps: S1. Preparation of composite oxides: rare earth metal elements R1, R2, transition metal element TM and Al element raw materials are prepared in the proportion shown in Formula 1, and insoluble solid powder raw materials are first mixed evenly, and the mixing method is wet mixing to obtain composite oxide slurry, the concentration of solid powder in the slurry is 20-500g / L, and the concentration of effective element ions is 0.2-10mol / L, and oxides, alkalis or inorganic salts containing calcium are added as auxiliary materials, and the number of calcium atoms in the auxiliary materials is 20%-200% of the number of all effective element atoms, and then the slurry is dried to obtain dry composite oxides; S2. Calcination of composite oxides: calcining the dried composite oxides in air at 500°C-1100°C for 0.5-10h to obtain calcined composite oxides, wherein the calcined composite oxides are a multiphase mixture of multiple oxides and composite oxides, wherein the multiple oxides and composite oxide phases account for more than 95wt% of the multiphase mixture, and the effective elements in the multiphase mixture except calcium, oxygen and unavoidable impurity elements meet the ratio specified in Formula-1; S3, calcining the composite oxide and performing reduction treatment to obtain a shell composition regulating aid: when the content of the oxide that can be reduced by the reducing gas in the calcined composite oxide is greater than 10%, the reduction treatment is performed; when the content of the oxide that can be reduced by the reducing gas is less than 10%, the reduction treatment is not required, and the reduction treatment process is: removing oxygen from the transition metal oxide in the calcined composite oxide that needs to be reduced in a reducing gas at 500°C-980°C; After the reduction treatment is completed, the calcined composite oxide is converted into a shell composition regulating agent composed of transition metals, rare earth oxides, and rare earth composite oxides, and the transition metals, rare earth oxides, rare earth composite oxides and calcium oxide phases account for more than 95wt% of the shell composition regulating agent.

4. A method for preparing the shell component regulating auxiliary agent according to claim 1 or 2, It is characterized in that The method is prepared by a pre-sintering-mixing process, comprising the following steps: S1, rare earth metal elements R1, R2, transition metal element TM and Al element raw materials are mixed in the proportion shown in formula-1, with rare earth metal oxides and transition metal oxides as main raw materials, and a primary mixture is prepared by mixing and calcining; S2. A secondary mixture is prepared by using a primary mixture and auxiliary materials that meet the requirements of particle size and phase structure as main raw materials, wherein the auxiliary materials are oxides, alkalis or inorganic salts containing calcium, and the number of calcium atoms in the auxiliary materials is 20-200% of the number of atoms of all effective elements; the dried secondary mixture is calcined again to decompose the calcium hydroxide or calcium carbonate in the secondary mixture into calcium oxide, and a multiphase mixture consisting of a plurality of oxides and composite oxides is obtained, wherein the plurality of oxides and composite oxide phases account for more than 95wt% of the multiphase mixture, and the effective elements in the multiphase mixture except calcium, oxygen and unavoidable impurity elements meet the ratio specified in Formula-1; S3. When the content of oxides that can be reduced by reducing gas in the multiphase mixture is greater than 10%, reduction treatment is carried out. When the content of oxides that can be reduced by reducing gas is less than 10%, reduction treatment is not required. Reduction treatment process: the multiphase mixture that needs reduction treatment is placed in a reducing gas at 500℃-1000℃ to remove oxygen in the transition metal oxide; after the reduction treatment is completed, the multiple mixtures are converted into a shell composition regulating agent composed of transition metals, rare earth oxides, and rare earth composite oxides, and the transition metals, rare earth oxides, rare earth composite oxides and calcium oxide phases account for more than 95wt% of the shell composition regulating agent.

5. A shell magnetic hardening single crystal permanent magnet powder, It is characterized in that The shell magnetic hardening single crystal permanent magnet powder has the following composition expressed in atomic percentage: (R1 1-α R2 α ) x Fe 100-x-y-z-v M1 y M2 z B v (Formula - 2) Wherein, R1 is at least one of Nd and Pr; R2 is at least one of La, Ce, Ho, Gd, Tb, Dy and Y; 0≤α<0.8; 14≤x≤28; M1 is at least one of Cu, Al and Ga, 0.1≤y≤10.0; M2 is at least one of Co, Si, Zr, Hf, Nb, Ti and V, 0≤z≤10.0; 2.5≤v≤6.0; The volume ratio of the single crystal particles of the shell-magnetically hardened single crystal permanent magnet powder is not less than 50V%, and the magnetic powder particles are composed of two parts: a main phase R 2 Fe 14 B single crystal and a rare earth-rich coating film. The rare earth-rich coating film with a thickness of 2-50 nm wraps around the main phase grains. The rare earth elements in the rare earth-rich coating film are not less than 20 at%, and the Al element content is not less than 2 at%. The particles have an equiaxed shape or are nearly spherical, with complete grains and a smooth surface.

6. The method for preparing the shell magnetic hardening single crystal permanent magnetic powder according to claim 5, It is characterized in that The steps include: S1. Ingredients and mixing: Mix the shell composition regulating auxiliary agent described in claim 1 with RE 2 Fe 14 B single crystal powder particles are mixed evenly, and the amount of shell composition control additive added is RE 2 Fe 14 5-40wt% of B single crystal powder; S2. Shell structure regulation heat treatment: The uniformly mixed mixture is subjected to shell structure regulation heat treatment in a vacuum or inert gas. The temperature of the shell structure regulation heat treatment is: (the melting point of RE 2 Fe 14 B or the peritectic reaction temperature in the equilibrium phase diagram) * 65% < the temperature of the shell structure regulation heat treatment < (the melting point of RE 2 Fe 14 B or the peritectic reaction temperature in the equilibrium phase diagram) * 85%, and the time of the shell structure regulation heat treatment is 0.5 - 5 hours; S3. Separating calcium oxide: The material subjected to shell structure regulation heat treatment contains by-product calcium oxide, and the calcium oxide in the material is removed to obtain the shell magnetic hardening single crystal permanent magnet powder.

7. The preparation method according to claim 6, It is characterized in that The powder particle diameter of the shell composition regulating aid described in step S1 is less than 1 / 10 of the diameter of the 2 Fe 14 single crystal B powder particles.

8. Use of the shell magnetic hardening single crystal permanent magnetic powder according to claim 5 in the preparation of rare earth permanent magnetic materials.

Images