Pipe-free control element-free super-easy processing sintered neodymium-iron-boron permanent magnet material and preparation method thereof

Abstract

The application relates to the field of permanent magnet materials, and particularly discloses a pipe-controlling-element-free super-easy-to-process sintered neodymium-iron-boron permanent magnet material and a preparation method thereof. The pipe-controlling-element-free super-easy-to-process sintered neodymium-iron-boron permanent magnet material comprises the following raw materials in mass percentage: praseodymium-neodymium alloy 22%-34.2%, cerium 0.8%-10%, aluminum 0.1%-0.8%, boron 0.85%-1.15%, copper 0.1%-0.5%, gallium 0.05%-0.4%, cobalt 0.1%-1%, and the balance is iron; and the sum of the mass percentages of the praseodymium-neodymium alloy and the cerium is 32%-35%. The pipe-controlling-element-free super-easy-to-process sintered neodymium-iron-boron permanent magnet material is prepared, production cost is reduced, good processability is achieved, and no pipe-controlling rare earth element is added.

Description

Technical Field

[0001] This application relates to the field of permanent magnet materials, and more specifically, it relates to a non-controlled element ultra-easy-to-process sintered NdFeB permanent magnet material and its preparation method. Background Technology

[0002] Neodymium iron boron (NdFeB) permanent magnets are widely used in new energy vehicles, wind power generation, consumer electronics, medical devices, and industrial robots due to their excellent energy product and coercivity. However, traditional NdFeB magnets heavily rely on rare earth elements such as praseodymium (Pr), neodymium (Nd), dysprosium (Dy), and terbium (Tb). Among these, heavy rare earth elements such as dysprosium and terbium are scarce and expensive, and some have been included in my country's export control list. In the prior art, the Chinese invention patent document with application number CN202011314655.8 partially replaces praseodymium-neodymium alloy with the highly abundant rare earth element cerium (Ce), and adds a small amount of elements such as cobalt, zirconium, copper, and aluminum, which reduces material costs while maintaining certain magnetic properties. However, zirconium is a refractory metal, and its addition will increase the hardness and brittleness of the magnet, reducing its machinability. On the other hand, this solution still relies on adding gadolinium (Gd) to compensate for the loss of coercivity, but gadolinium has been explicitly listed as an export-controlled item, thus failing to meet export control requirements and limiting its application in overseas markets.

[0003] Therefore, there is an urgent need to develop a new type of neodymium iron boron magnet that has high cerium content, good processability, and is completely free of regulated rare earth elements. Summary of the Invention

[0004] In order to develop a novel NdFeB magnet that combines high cerium content, good processability, and complete absence of controlled rare earth elements, this application presents a method for preparing an ultra-easy-to-process sintered NdFeB permanent magnet material without controlled elements.

[0005] Firstly, this application provides a non-controlled element-free, ultra-easy-to-process sintered NdFeB permanent magnet material, employing the following technical solution: A type of easily processed sintered NdFeB permanent magnet material without controlled elements comprises the following raw materials in weight percentage: praseodymium-neodymium alloy 22%-34.2%, cerium 0.8%-10%, aluminum 0.1%-0.8%, boron 0.85%-1.15%, copper 0.1%-0.5%, gallium 0.05%-0.4%, cobalt 0.1%-1%, with the balance being iron; The sum of the mass percentages of the praseodymium-neodymium alloy and cerium is 32%-35%.

[0006] Optionally, the mass fraction of praseodymium in the praseodymium-neodymium alloy is 20%-30%.

[0007] By adopting the above technical solution, a high-cerium-content rare-earth permanent magnet system is constructed through precise proportioning of praseodymium, neodymium, cerium, iron, boron, and trace amounts of aluminum, copper, gallium, and cobalt. Praseodymium and neodymium provide the basic magnetic properties, high-abundance cerium significantly reduces raw material costs, iron and boron ensure hard magnetic properties, and trace metal elements optimize the grain boundary structure. The permanent magnet material has low stress and moderate hardness, making it less prone to chipping and cracking during machining, and possesses the advantage of being extremely easy to process. Through synergistic inhibition of oxidation, segregation, and abnormal grain growth, the microscopic uniformity and density are improved. The material does not contain regulated heavy rare earth elements such as gadolinium, dysprosium, and terbium, achieving high cerium content, low cost, and easy processing.

[0008] Secondly, this application provides a method for preparing an easily processable sintered NdFeB permanent magnet material without controlled elements, comprising the following steps: (1) Under an inert gas atmosphere, the sintered powder, steel ingot powder, scrap powder and antioxidant are mixed evenly and sieved through an 80-120 mesh to obtain a mixed powder; (2) The mixed powder is molded under a pressure of 3-7 MPa, the oxygen content in the molding cavity is controlled below 500 ppm, and isostatic pressing is performed at 170-220 MPa to obtain an isostatic compact. (3) The isostatically pressed blank is sintered to obtain a super easy-to-process sintered NdFeB permanent magnet material without controlled elements.

[0009] By adopting the above technical solutions, the preparation process of this application effectively avoids powder oxidation by mixing and sieving powder in an inert gas atmosphere, ensuring uniform composition and consistent particle size of the mixed powder, laying the foundation for molding and sintering; compression molding and low oxygen control, combined with isostatic pressing, can significantly improve the density of the green body and reduce internal porosity and defects; in synergy with the sintering and cooling process, it further optimizes the microstructure of the magnet, inhibits abnormal grain growth and oxidation loss, and improves processability.

[0010] Optionally, the mass ratio of the sintered powder, steel ingot powder, and scrap powder is 50-60:10-20:20-40; the amount of antioxidant added is 0.1%-0.15% of the total mass of the sintered powder, steel ingot powder, and scrap powder.

[0011] Optionally, the method for preparing the spun powder includes the following steps: (1) The praseodymium-neodymium alloy, cerium, aluminum, boron, copper, gallium, cobalt and iron are fully melted to form molten steel, and stirred evenly by excitation current; (2) The temperature of the molten steel is adjusted to 1380-1430℃ and poured onto a rotating water-cooled surface to produce a peritectic reaction, generating 0.2-0.4mm of slab alloy; (3) The spun alloy is subjected to hydrogen blasting treatment to obtain spun alloy hydrogen blasting powder; (4) Mix the hydrogen-decomposed alloy powder and antioxidant, and perform air jet milling in an atmosphere with an oxygen content of 10-100ppm to obtain the spun alloy powder. The mass ratio of the spun alloy hydrogen-broken powder to the antioxidant is 1000:1-1.5; the particle size of the spun powder is 2.8-4μm; and the hydrogen content of the spun alloy hydrogen-broken powder is 600-2500ppm.

[0012] Optionally, the method for preparing the steel ingot powder includes the following steps: (1) Heat and melt praseodymium-neodymium alloy, cerium, aluminum, boron, copper, gallium, cobalt and iron to obtain molten steel; (2) The molten steel is poured into the ingot mold to undergo a peritectic reaction, producing an ingot of 15-30 mm; (3) The ingot is subjected to hydrogen crushing treatment to obtain hydrogen crushing powder of ingot; (4) Mix the hydrogen-decomposed powder of the ingot with an antioxidant and perform air jet milling in an atmosphere with an oxygen content of 10-100ppm to obtain steel ingot powder; The mass ratio of the ingot hydrogen-degrading powder to the antioxidant is 1000:1-1.5; the particle size of the ingot powder is 3.0-4.4μm; and the hydrogen content of the ingot hydrogen-degrading powder is 600-2500ppm.

[0013] Optionally, the boron content in the spun alloy is 0.85%-1.05% by mass; the boron content in the ingot is 1%-1.15% by mass.

[0014] Optionally, the method for preparing the scrap powder includes the following steps: (1) The cutting scraps, edge fragments and blank residues generated during the processing of spun alloys and ingots are recycled to produce scrap materials; (2) The scrap material is subjected to hydrogen pulverization to obtain scrap material hydrogen pulverization powder; (3) The scrap material is mixed with an antioxidant and subjected to air jet milling under an inert gas atmosphere to obtain scrap material powder; The mass ratio of the scrap material hydrogen-crushed powder to the antioxidant is 1000:1-1.5; the particle size of the scrap material powder is 2.8-4μm; and the hydrogen content of the scrap material hydrogen-crushed powder is 600-2500ppm.

[0015] Optionally, the antioxidant is selected from lipid antioxidants and aldehyde antioxidants.

[0016] By adopting the above technical solutions, the molten steel is rapidly solidified and the ingot steel is cast into shape, respectively giving the two alloys structural characteristics suitable for hydrogen pulverization. The scrap material is recycled to realize the resource utilization of raw materials. The hydrogen pulverization treatment can efficiently crush the alloy. With the help of antioxidants and precise atmosphere control, the particle size can be precisely controlled by air jet milling to avoid powder oxidation and particle size unevenness. Moreover, this process can effectively alleviate process problems such as oxidation, pulverization and particle size deviation in powder making, improve the micro-uniformity of powder, adapt to subsequent powder mixing and forming processes, and ensure the core advantages of the final magnet being free of controlled elements, high in cerium and easy to process. In addition, the process is controllable, energy-saving and environmentally friendly, and easy to control costs.

[0017] Optionally, the sintering process includes the following steps: With a vacuum degree less than 1 Pa, the isostatic pressing billet is heated, increasing the temperature to 300-450℃ and holding for 1-3 hours; increasing the temperature to 500-600℃ and holding for 1-3 hours; increasing the temperature to 720-900℃ and holding until the vacuum degree is less than 0.1 Pa; increasing the temperature to 980-1080℃ and holding for 3-7 hours, then cooling to below 80℃; increasing the temperature again to 700-900℃ and holding for 1-3 hours; cooling to below 80℃; increasing the temperature again to 470-680℃ and holding for 4-7 hours, then cooling to below 80℃.

[0018] By adopting the above technical solutions, raising the temperature to 300-450℃ and holding it at that temperature can volatilize the antioxidants added during powder preparation; raising the temperature to 500-600℃ and holding it at that temperature can decompose and release the hydrogen left over from hydrogen breakdown; raising the temperature to 720-900℃ and holding it at a vacuum below 0.1Pa causes the rich phase of the magnet to gradually liquefy, the magnet to begin to densify, and various gases in the magnet to gradually escape; raising the temperature to 980-1080℃ promotes the magnet to be fully densified without grain growth, and tempering further homogenizes the grain boundaries and eliminates internal stress, resulting in a new type of sintered NdFeB permanent magnet material that is completely free of controlled rare earth elements, has a high cerium content, good magnetic properties, and is extremely easy to process.

[0019] In summary, this application has the following beneficial effects: 1. This application preferably uses praseodymium and neodymium to provide basic magnetic properties, high cerium abundance to significantly reduce raw material costs, iron boron to ensure hard magnetic properties, and trace metal elements to optimize grain boundary structure; through component synergy to suppress oxidation, segregation and abnormal grain growth, micro-uniformity and density are improved, significantly reducing processing difficulty; the material does not contain regulated heavy rare earth elements such as gadolinium, dysprosium, and terbium, achieving high cerium content, low cost and easy processing.

[0020] 2. This application uses inert powder mixing to avoid powder oxidation and ensure that the mixed powder composition is uniform and the particle size is consistent. Compression molding and low oxygen control, combined with isostatic pressing, can significantly improve the density of the green body and reduce internal porosity and defects. In synergy with the sintering and cooling process, it further optimizes the microstructure of the magnet, inhibits abnormal grain growth and oxidation loss, and improves the processability of the material.

[0021] 3. This application utilizes rapid solidification of molten steel and casting of molten steel into ingots to impart structural characteristics suitable for hydrogen pulverization to both alloys, and the recycling of scrap materials realizes the resource utilization of raw materials; hydrogen pulverization can efficiently crush alloys, and with the help of antioxidants and precise atmosphere control, airflow grinding can precisely control particle size, avoiding powder oxidation and particle size unevenness; moreover, this process can effectively improve the micro-uniformity of powder, adapt to subsequent powder mixing and forming processes, and achieve the core advantages of magnets with no controlled elements, high cerium, and easy processing. Detailed Implementation

[0022] The following embodiments provide a further detailed description of this application.

[0023] Preparation example of spun powder Preparation Example 1 (1) Place 342g of praseodymium-neodymium alloy, 8g of cerium, 8g of aluminum, 10.5g of boron, 5g of copper, 4g of gallium, 10g of cobalt and 612.5g of iron in a vacuum rapid solidification furnace, heat to 1330℃ to melt, stir evenly with excitation current to obtain molten steel; (2) The molten steel obtained in step (1) is heated to 1430°C and poured onto a rotating water-cooled copper roller to produce a peritectic reaction and obtain a 0.2 mm slab alloy. (3) The spun alloy obtained in step (2) is added to the hydrogen dehydrogenation furnace to fully absorb hydrogen for 4 hours, and then heated to 570℃ to dehydrogenate for 7 hours to obtain spun alloy hydrogen dehydrogenation powder. The hydrogen content in the spun alloy hydrogen dehydrogenation powder is 2500ppm. (4) Mix 1000g of the hydrogen-broken alloy powder obtained in step (3) with 1.5g of oleic acid and perform air jet milling in an atmosphere with an oxygen content of 100ppm to obtain a particle size of 2.8μm.

[0024] Preparation Example 2 (1) Place 220g of praseodymium-neodymium alloy, 100g of cerium, 1g of aluminum, 8.5g of boron, 1g of copper, 0.5g of gallium, 1g of cobalt and 668g of iron in a vacuum rapid solidification furnace, heat to 1330℃ to melt, stir evenly with excitation current to obtain molten steel; (2) The molten steel obtained in step (1) is heated to 1380°C and poured onto a rotating water-cooled copper roller to produce a peritectic reaction and obtain a 0.4 mm slab alloy. (3) The spun alloy obtained in step (2) is added to the hydrogen dehydrogenation furnace to fully absorb hydrogen for 2 hours, and then heated to 530℃ to dehydrogenate for 3 hours to obtain spun alloy hydrogen dehydrogenation powder with a hydrogen content of 600ppm. (4) Mix 1000g of the hydrogen-broken alloy powder obtained in step (3) with 1g of oleic acid and perform air jet milling in an atmosphere with an oxygen content of 10ppm to obtain a particle size of 4μm.

[0025] Example of steel ingot powder preparation Preparation Example 1 (1) Place 342g of praseodymium-neodymium alloy, 8g of cerium, 8g of aluminum, 11.5g of boron, 5g of copper, 4g of gallium, 10g of cobalt and 611.5g of iron in a vacuum induction furnace and heat to 1330℃ to melt them to obtain molten steel; (2) The molten steel obtained in step (1) is poured into an iron ingot mold to undergo a peritectic reaction and a 30mm ingot is obtained. (3) The ingot obtained in step (2) is added to the hydrogen crushing furnace to fully absorb hydrogen for 4 hours, and then heated to 570℃ to dehydrogenate for 7 hours to obtain hydrogen crushing powder of ingot. The hydrogen content in the hydrogen crushing powder of ingot is 2500ppm. (4) Mix 1000g of the hydrogen-decomposed ingot powder obtained in step (3) with 1.5g of oleic acid and perform air jet milling in an atmosphere with an oxygen content of 100ppm to obtain steel ingot powder with a particle size of 4.4μm.

[0026] Preparation Example 2 (1) Place 342g of praseodymium-neodymium alloy, 8g of cerium, 8g of aluminum, 10g of boron, 5g of copper, 4g of gallium, 10g of cobalt and 613g of iron in a vacuum induction furnace and heat to 1330℃ to melt them to obtain molten steel. (2) The molten steel obtained in step (1) is poured into a copper ingot mold to undergo a peritectic reaction and a 15mm ingot is obtained. (3) The ingot obtained in step (2) is added to the hydrogen crushing furnace to fully absorb hydrogen for 2 hours, and then heated to 530℃ to dehydrogenate for 3 hours to obtain hydrogen crushing powder of ingot. The hydrogen content in the hydrogen crushing powder of ingot is 600ppm. (4) Mix 1000g of the hydrogen-depleted ingot powder obtained in step (3) with 1g of oleic acid and perform air jet milling in an atmosphere with an oxygen content of 10ppm to obtain steel ingot powder with a particle size of 3.0μm.

[0027] Example of preparation of scrap powder Preparation Example 1 (1) The cutting residue, edge fragments and blank scraps generated during the processing of the above-prepared slab alloy and the above-prepared ingot are recycled to obtain scrap material; (2) Add the scrap material to the hydrogen crusher to fully absorb hydrogen for 4 hours, raise the temperature to 570℃ to dehydrogenate for 7 hours, and obtain scrap material hydrogen crushing powder. The hydrogen content in the scrap material hydrogen crushing powder is 2500ppm. (3) Mix 1000g of scrap hydrogen-crushed powder and 1.5g of oleic acid, and perform air jet milling under nitrogen to obtain scrap powder with a particle size of 4μm.

[0028] Preparation Example 2 (1) The cutting residue, edge fragments and blank scraps generated during the processing of the above-prepared slab alloy and the above-prepared ingot are recycled to obtain scrap material; (2) Add the scrap material to the hydrogen crusher to fully absorb hydrogen for 2 hours, raise the temperature to 530℃ to dehydrogenate for 3 hours, and obtain scrap material hydrogen crushing powder. The hydrogen content in the scrap material hydrogen crushing powder is 600ppm. (3) Mix 1000g of scrap hydrogen-crushed powder and 1g of oleic acid, and perform air jet milling under nitrogen to obtain scrap powder with a particle size of 2.8μm. Example

[0029] Example 1: A method for preparing an easily processable sintered NdFeB permanent magnet material without controlled elements, comprising the following steps: (1) Under nitrogen gas at 1 MPa, 60 g of sintered powder, 20 g of steel ingot powder, 40 g of scrap powder and 0.18 g of oleic acid were mixed for 6 h and sieved through 120 mesh to obtain mixed powder; (2) The mixed powder obtained in step (1) is molded in a sealed magnetic field press under a pressure of 7 MPa. The oxygen content in the molding cavity is controlled to be below 500 ppm. Isostatic pressing is performed at 220 MPa to obtain an isostatic compact. (3) The isostatic pressing blank obtained in step (2) is loaded into a vacuum sintering furnace through a sealed loading car. Under the condition that the vacuum degree is less than 1 Pa, the isostatic pressing blank is heated to 450°C and held for 3 hours; heated to 600°C and held for 3 hours; heated to 900°C and held until the vacuum degree is less than 0.1 Pa; heated to 1080°C and held for 7 hours, then rapidly cooled to below 80°C; heated to 900°C again and held for 3 hours for first-stage tempering; rapidly cooled to below 80°C; heated to 680°C again and held for 7 hours for second-stage tempering, then rapidly cooled to below 80°C to obtain a non-controlled element ultra-easy-to-process sintered NdFeB permanent magnet material. The sintered powder was prepared using the method described in Example 1 of the sintered powder preparation; the steel ingot powder was prepared using the method described in Example 1 of the steel ingot powder preparation; and the scrap powder was prepared using the method described in Example 1 of the scrap powder preparation.

[0030] Example 2: A method for preparing an easily processable sintered NdFeB permanent magnet material without controlled elements, comprising the following steps: (1) Under nitrogen gas at 0.05 MPa, 50 g of sintered powder, 10 g of steel ingot powder, 20 g of scrap powder and 0.08 g of oleic acid were mixed for 3 h and sieved through an 80 mesh to obtain a mixed powder. (2) The mixed powder obtained in step (1) is molded in a sealed magnetic field press under a pressure of 3 MPa. The oxygen content in the molding cavity is controlled to be below 500 ppm. Isostatic pressing is performed at 170 MPa to obtain an isostatic compact. (3) The isostatic pressing blank obtained in step (2) is loaded into a vacuum sintering furnace through a sealed loading car. Under the condition that the vacuum degree is less than 1 Pa, the isostatic pressing blank is heated to 300°C and held for 1 hour; heated to 500°C and held for 1 hour; heated to 720°C and held until the vacuum degree is less than 0.1 Pa; heated to 980°C and held for 3 hours, then rapidly cooled to below 80°C; heated to 700°C again and held for 1 hour for first-stage tempering, then rapidly cooled to below 80°C; heated to 470°C again and held for 4 hours for second-stage tempering, then rapidly cooled to below 80°C, thus obtaining a super easy-to-process sintered NdFeB permanent magnet material without controlled elements. The sintered powder was prepared using the method described in Example 2 of the sintered powder preparation; the steel ingot powder was prepared using the method described in Example 2 of the steel ingot powder preparation; and the scrap powder was prepared using the method described in Example 2 of the scrap powder preparation.

[0031] Example 3: A method for preparing an easily processable sintered NdFeB permanent magnet material without controlled elements, comprising the following steps: (1) Under nitrogen gas at 1 MPa, 60 g of sintered powder, 20 g of steel ingot powder, 40 g of scrap powder and 0.12 g of oleic acid were mixed for 6 h and sieved through 100 mesh to obtain mixed powder. (2) The mixed powder obtained in step (1) is molded in a sealed magnetic field press under a pressure of 5 MPa. The oxygen content in the molding cavity is controlled to be below 500 ppm. Isostatic pressing is performed at 200 MPa to obtain an isostatic compact. (3) The isostatic pressing blank obtained in step (2) is loaded into a vacuum sintering furnace through a sealed loading car. Under the condition that the vacuum degree is less than 1 Pa, the isostatic pressing blank is heated to 450°C and held for 1 hour; heated to 600°C and held for 1 hour; heated to 900°C and held until the vacuum degree is less than 0.1 Pa; heated to 1080°C and held for 3 hours, then rapidly cooled to below 80°C; heated to 900°C again and held for 1 hour for first-stage tempering, then rapidly cooled to below 80°C; heated to 680°C again and held for 4 hours for second-stage tempering, then rapidly cooled to below 80°C, thus obtaining a non-controlled element ultra-easy-to-process sintered NdFeB permanent magnet material. The sintered powder was prepared using the method described in Example 1 of the sintered powder preparation; the steel ingot powder was prepared using the method described in Example 2 of the steel ingot powder preparation; and the scrap powder was prepared using the method described in Example 1 of the scrap powder preparation.

[0032] Example 4: A method for preparing an easily processable sintered NdFeB permanent magnet material without controlled elements, comprising the following steps: (1) Under nitrogen gas at 0.05 MPa, 50 g of sintered powder, 10 g of steel ingot powder, 20 g of scrap powder and 0.12 g of oleic acid were mixed for 3 h and sieved through 110 mesh to obtain mixed powder; (2) The mixed powder obtained in step (1) is molded in a sealed magnetic field press under a pressure of 5 MPa. The oxygen content in the molding cavity is controlled to be below 500 ppm. The isostatic pressing is performed at 190 MPa to obtain an isostatic compact. (3) The isostatic pressing blank obtained in step (2) is loaded into a vacuum sintering furnace through a sealed loading car. Under the condition that the vacuum degree is less than 1 Pa, the isostatic pressing blank is heated to 300°C and held for 3 hours; heated to 500°C and held for 3 hours; heated to 720°C and held until the vacuum degree is less than 0.1 Pa; heated to 980°C and held for 7 hours, then rapidly cooled to below 80°C; heated to 700°C again and held for 3 hours for first-stage tempering, then rapidly cooled to below 80°C; heated to 470°C again and held for 7 hours for second-stage tempering, then rapidly cooled to below 80°C, thus obtaining a super easy-to-process sintered NdFeB permanent magnet material without controlled elements. The sintered powder was prepared using the method described in Example 2 of the sintered powder preparation; the steel ingot powder was prepared using the method described in Example 1 of the steel ingot powder preparation; and the scrap powder was prepared using the method described in Example 2 of the scrap powder preparation.

[0033] Comparative Example 1: A non-controlled element ultra-easy-to-process sintered NdFeB permanent magnet material was replaced by an equal amount of NdFeB permanent magnet material; the NdFeB permanent magnet material was purchased from Shanghai Gelin Technology Co., Ltd.

[0034] Performance testing The controlled element-free, ultra-easy-to-process sintered NdFeB permanent magnet materials were prepared according to the methods in the examples and comparative examples, and their performance was tested according to the following methods. The test results are recorded in Table 1.

[0035] Example 1 14.05 2230 926 320 Example 2 14.03 2221 921 317 Example 3 13.98 2225 919 322 Example 4 13.95 2228 904 319 Comparative Example 1 14.01 2224 913 315

[0036] 1. The magnetic properties of the samples were tested using the standards GB / T13560-2017 Sintered NdFeB Permanent Magnet Materials and GB / T3217-92 Magnetic Test Methods for Permanent Magnet (Hard Magnet) Materials. Each sample was tested three times, and the average value was taken after measurement.

[0037] Table 1. Performance test results of permanent magnet materials prepared in the examples and comparative examples. As shown in Table 1, the control-free, ultra-easy-to-process sintered NdFeB permanent magnet materials prepared in Examples 1-4 of this application exhibit good magnetic properties, with a remanence of 13.95-14.05 kGs, intrinsic coercivity of 2221-2230 kA / m, magnetic coercivity of 904-926 kA / m, and maximum magnetic energy product of 317-322 kJ / m. 3 The permanent magnet material in Comparative Example 1 has a remanence of 14.01 kGs, an intrinsic coercivity of 2224 kA / m, a magnetic coercivity of 913 kA / m, and a maximum energy product of 315 kJ / m. 3 Therefore, the non-controlled element ultra-easy-to-process sintered NdFeB permanent magnet material of this application not only has magnetic properties comparable to ordinary NdFeB permanent magnet materials, but also achieves low cost through high cerium addition, while without adding any controlled elements or other elements such as niobium, zirconium, and titanium that affect machinability.

[0038] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A type of easily processed sintered NdFeB permanent magnet material without controlled elements, characterized in that, Raw materials including the following percentages by mass: Praseodymium-neodymium alloy 22%-34.2%, cerium 0.8%-10%, aluminum 0.1%-0.8%, boron 0.85%-1.15%, copper 0.1%-0.5%, gallium 0.05%-0.4%, cobalt 0.1%-1%, balance iron; The sum of the mass percentages of the praseodymium-neodymium alloy and cerium is 32%-35%.

2. The easily processed sintered NdFeB permanent magnet material without controlled elements according to claim 1, characterized in that, The mass fraction of praseodymium in the praseodymium-neodymium alloy is 20%-30%.

3. The preparation method of a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 2, characterized in that, Includes the following steps: (1) Under an inert gas atmosphere, the sintered powder, steel ingot powder, scrap powder and antioxidant are mixed evenly and sieved through an 80-120 mesh to obtain a mixed powder; (2) The mixed powder is molded under a pressure of 3-7 MPa, the oxygen content in the molding cavity is controlled below 500 ppm, and isostatic pressing is performed at 170-220 MPa to obtain an isostatic compact. (3) The isostatically pressed blank is sintered to obtain a super easy-to-process sintered NdFeB permanent magnet material without controlled elements.

4. The preparation method of a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 3, characterized in that, The mass ratio of the sintered powder, steel ingot powder, and scrap powder is 50-60:10-20:20-40; the amount of antioxidant added is 0.1%-0.15% of the total mass of the sintered powder, steel ingot powder, and scrap powder.

5. The preparation method of a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 3, characterized in that, The preparation method of the spun powder includes the following steps: (1) The praseodymium-neodymium alloy, cerium, aluminum, boron, copper, gallium, cobalt and iron are fully melted to form molten steel, and stirred evenly by excitation current; (2) The temperature of the molten steel is adjusted to 1380-1430℃ and poured onto a rotating water-cooled surface to produce a peritectic reaction, generating 0.2-0.4mm of slab alloy; (3) The spun alloy is subjected to hydrogen blasting treatment to obtain spun alloy hydrogen blasting powder; (4) Mix the hydrogen-decomposed alloy powder and antioxidant, and perform air jet milling in an atmosphere with an oxygen content of 10-100ppm to obtain the spun alloy powder. The mass ratio of the spun alloy hydrogen-broken powder to the antioxidant is 1000:1-1.5; the particle size of the spun powder is 2.8-4μm; and the hydrogen content of the spun alloy hydrogen-broken powder is 600-2500ppm.

6. The preparation method of a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 5, characterized in that, The method for preparing the steel ingot powder includes the following steps: (1) Heat and melt praseodymium-neodymium alloy, cerium, aluminum, boron, copper, gallium, cobalt and iron to obtain molten steel; (2) The molten steel is poured into the ingot mold to undergo a peritectic reaction, producing an ingot of 15-30 mm; (3) The ingot is subjected to hydrogen crushing treatment to obtain hydrogen crushing powder of ingot; (4) Mix the hydrogen-decomposed powder of the ingot with an antioxidant and perform air jet milling in an atmosphere with an oxygen content of 10-100ppm to obtain steel ingot powder; The mass ratio of the ingot hydrogen-degrading powder to the antioxidant is 1000:1-1.5; the particle size of the ingot powder is 3.0-4.4μm; and the hydrogen content of the ingot hydrogen-degrading powder is 600-2500ppm.

7. The preparation method of a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 6, characterized in that, The boron content in the spun alloy is 0.85%-1.05% by mass; the boron content in the ingot is 1%-1.15% by mass.

8. The preparation method of a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 3, characterized in that, The method for preparing the scrap powder includes the following steps: (1) The cutting scraps, edge fragments and blank residues generated during the processing of spun alloys and ingots are recycled to produce scrap materials; (2) The scrap material is subjected to hydrogen pulverization to obtain scrap material hydrogen pulverization powder; (3) The scrap material is mixed with an antioxidant and subjected to air jet milling under an inert gas atmosphere to obtain scrap material powder; The mass ratio of the scrap material hydrogen-crushed powder to the antioxidant is 1000:1-1.5; the particle size of the scrap material powder is 2.8-4μm; and the hydrogen content of the scrap material hydrogen-crushed powder is 600-2500ppm.

9. A method for preparing a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to any one of claims 3-8, characterized in that, The antioxidant is selected from lipid antioxidants and aldehyde antioxidants.

10. The method for preparing a control-free, ultra-easy-to-process sintered NdFeB permanent magnet material according to claim 3, characterized in that, The sintering process includes the following steps: With a vacuum degree less than 1 Pa, the isostatic pressing billet is heated, increasing the temperature to 300-450℃ and holding for 1-3 hours; increasing the temperature to 500-600℃ and holding for 1-3 hours; increasing the temperature to 720-900℃ and holding until the vacuum degree is less than 0.1 Pa; increasing the temperature to 980-1080℃ and holding for 3-7 hours, then cooling to below 80℃; increasing the temperature again to 700-900℃ and holding for 1-3 hours; cooling to below 80℃; increasing the temperature again to 470-680℃ and holding for 4-7 hours, then cooling to below 80℃.