A high-performance lanthanum-cerium sintered NdFeB magnet material and its preparation method

Abstract

This invention discloses a high-performance lanthanum-cerium sintered NdFeB magnet material and its preparation method. It is prepared using LaCe NdFeB magnet alloy powder and a titanium carbide nanosheet composite as raw materials. The titanium carbide nanosheet composite contains one or more of TiC, Ti2C, and Ti3C2T, where T in Ti3C2T is an oxygen-containing functional group. In this invention, the LaCe NdFeB magnet alloy powder is modified using the titanium carbide nanosheet composite, resulting in rich chemical activity. This provides more heterogeneous nucleation sites within the magnet, acting as pinning points during grain growth to hinder the movement of magnetic domain walls, thereby enhancing the magnet's coercivity. The two-dimensional nanosheet structure, layered at the grain boundaries, hinders grain boundary migration and grain merging, effectively suppressing grain growth. Furthermore, the nanosheet structure forms continuous magnetic domain wall pinning points, preventing the nucleation and expansion of opposite magnetic domains.

Description

Technical Field

[0001] This invention relates to the field of rare earth permanent magnet materials technology, specifically to a high-performance lanthanum-cerium sintered NdFeB magnet material and its preparation method. Background Technology

[0002] In the field of rare earth permanent magnet materials, using the abundant rare earth elements lanthanum (La) and cerium (Ce) to replace scarce resources in the preparation of sintered NdFeB magnets has become a core strategy for balancing resource structure and reducing costs and increasing efficiency. However, the inherent magnetic defects of La / Ce—low atomic magnetic moments leading to the attenuation of the main phase saturation magnetization (Ms) and magnetocrystalline anisotropy field (HA), and the magnetic isolation failure and demagnetization domain nucleation caused by weakly magnetic impurities at grain boundaries—severely restrict the improvement of magnet coercivity (Hcj) and remanence (Br), limiting their application.

[0003] Existing technologies often optimize the performance of lanthanum and cerium-containing magnets through processes such as dual alloying, grain boundary diffusion, and the addition of auxiliary elements such as dysprosium (Dy), gadolinium (Gd), and holmium (Ho), aiming to achieve a synergistic breakthrough in cost and performance. Regarding auxiliary elements, patent document CN113782330A uses lanthanum and cerium-free alloy powder as an auxiliary alloying agent to mitigate the magnetic performance degradation caused by the addition of lanthanum and cerium. However, this method requires the independent preparation of two alloying phases, increasing the process complexity and easily leading to performance dispersion due to uneven composition of the main and auxiliary phases. Grain boundary diffusion has limited LaCe penetration, and La and Ce on the diffusion surface are easily oxidized to form non-magnetic impurities, resulting in a sharp drop in the magnet's coercivity. Therefore, the use of La and Ce in NdFeB magnets still faces technical challenges such as a sharp drop in magnet coercivity upon the addition of lanthanum and cerium, increased manufacturing costs due to process complexity, easy grain growth, and dependence on heavy rare earth elements.

[0004] To further address the existing problems, some researchers have added nanoparticles such as carbides and oxides to magnets, using them to exert grain boundary pinning effects in localized areas and modulate magnetic properties. However, directly adding inorganic powder additives, such as hard powders like carbides and oxides, to LaCe magnets still results in agglomeration and segregation of the additive powder due to differences in density and particle size, making it difficult for the additive particles to be uniformly dispersed in the magnet. Furthermore, the heterogeneous doping of agglomerated granular powder clumps in the magnet's grain boundaries may disrupt the continuity of the grain boundary microstructure, not only failing to effectively optimize the grain boundary phase but also potentially causing stress concentration or impurity defects, further degrading magnetic properties. In addition, nanoparticles can only provide isolated pinning points, with limited pinning effects and limited ability to improve coercivity.

[0005] Therefore, this patent application is filed. Summary of the Invention

[0006] To address the aforementioned technical challenges encountered when using La and Ce in NdFeB magnets, such as a sharp drop in coercivity, complex manufacturing processes, easy grain growth, and degraded magnetic properties due to heterogeneous doping, this invention provides a high-performance lanthanum-cerium sintered NdFeB magnet material and its preparation method. This method optimizes and adjusts the magnetic properties of LaCe sintered NdFeB magnets to meet the development needs of low-cost, high-performance LaCe sintered NdFeB magnets, breaking through the bottlenecks of cost control and performance assurance, and broadening the application possibilities of high-abundance rare earth elements in NdFeB magnets.

[0007] The present invention adopts the following technical solution:

[0008] The first objective of this invention is to provide a high-performance lanthanum-cerium sintered NdFeB magnet material, which is prepared from LaCe NdFeB magnet alloy powder and titanium carbide nanosheet composite as raw materials. The titanium carbide nanosheet composite is a nanosheet composite containing any one or more of TiC, Ti2C, and Ti3C2T, where T in Ti3C2T is an oxygen-containing functional group.

[0009] In this invention, titanium carbide nanosheets are used to modify LaCe NdFeB magnet alloy powder. The nanosheets exhibit different compound valence states, such as TiC, Ti2C, and Ti3C2T. These different valence states of TiC, Ti2C, and Ti3C2T exist within the grain boundaries, forming a multi-valence redox synergistic effect. This buffers grain boundary oxygen fluctuations through dynamic electron transfer, consumes free oxygen, inhibits Nd / Ce / La oxidation, stabilizes the main phase magnetic moment, blocks grain boundary oxidation pathways, and enhances coercivity. Simultaneously, the nanosheets are loaded with active functional groups such as -OH, =O, and -O, providing more heterogeneous nucleation sites within the magnet. These sites act as pinning points during grain growth, hindering the movement of magnetic domain walls and thus enhancing the magnet's coercivity. Therefore, the addition of this auxiliary agent improves the coercivity of lanthanum-cerium magnets through a dual mechanism of refining the main phase grain size and hindering domain wall movement. Meanwhile, this invention employs a two-dimensional nanosheet structure layered at the grain boundaries, which can form an effective grain boundary barrier during sintering, thereby hindering grain boundary migration and grain merging, effectively suppressing grain growth. Furthermore, the nanosheet structure forms continuous magnetic domain wall pinning points, hindering the nucleation and expansion of reverse magnetic domains. This solves the technical problems of uneven dispersion and heterogeneous doping encountered with nanoparticles, and there is no existing research on enhancing magnetism using nanosheets.

[0010] In summary, this invention modifies LaCe NdFeB magnet alloy powder using titanium carbide nanosheet composites, thereby significantly improving the magnetic properties of the previously poor-performing lanthanum cerium NdFeB magnets.

[0011] As a preferred design, the oxygen-containing functional group is at least one of -OH, =O, and -O;

[0012] And / or, the titanium carbide nanosheet composite also includes TiO2.

[0013] As a preferred design, the composition of the LaCe NdFeB magnet alloy powder, expressed as a mass fraction of La... 1.0-10.0 Ce 3.0-13.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 Preferably, it is La. 2.0 Ce 13.0 (Pr 0.25 Nd 0.75 ) 21.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 La 7.5 Ce 7.5 (Pr 0.25 Nd 0.75 ) 21. 0Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 More preferably, La 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 .

[0014] A second objective of this invention is to provide a method for preparing the high-performance lanthanum-cerium sintered NdFeB magnet material as described in any of the preceding claims, comprising:

[0015] Preparation of LaCe NdFeB magnet alloy powder;

[0016] Preparation of titanium carbide nanosheet composites;

[0017] Titanium carbide nanosheet composites were added to LaCe NdFeB magnet alloy powder. After the mixture was stirred evenly, it was magnetically pressed and isostatically pressed to obtain LaCe NdFeB magnet blanks.

[0018] LaCe NdFeB magnet blanks were sintered, followed by primary tempering and secondary tempering to obtain high-performance lanthanum-cerium sintered NdFeB magnet materials.

[0019] As a preferred design, the particle size range of the LaCe NdFeB magnet alloy powder is 2.9μm-4.5μm.

[0020] As a preferred design, the preparation process of the LaCe NdFeB magnet alloy powder is as follows:

[0021] Weigh out each alloying element according to the proportion, mix them, and then melt and cast them to obtain LaCe NdFeB magnet alloy quick-solidification sheets. Then, crush the LaCe NdFeB magnet alloy quick-solidification sheets with hydrogen and mill them under nitrogen protection to obtain LaCe NdFeB magnet alloy powder.

[0022] And / or; the melting temperature is 1400℃, the vacuum degree during the melting process is 0.05Pa, and the casting process adopts the thin strip continuous casting method;

[0023] And / or, hydrogen is absorbed at room temperature during hydrogen crushing and dehydrogenation is carried out at 590°C.

[0024] As a preferred design, the preparation process of the titanium carbide nanosheet composite is as follows:

[0025] Titanium aluminate carbide powder is acid-etched to form an aluminum phase, centrifuged, and ultrasonically exfoliated before being dispersed in an organic solvent to obtain a titanium carbide nanosheet composite.

[0026] In the preparation method of this invention, after Al is removed from the precursor Ti3AlC2, the remaining carbon combines with titanium to form local carbon enrichment, generating TiC and Ti2C. Due to the high reactivity of titanium, spontaneous oxidation occurs on the surface. Hydrochloric acid is an aqueous solution containing -OH groups, and the etching process is carried out under aerobic conditions. The reaction itself introduces oxygen from the solution and atmosphere, thereby generating oxygen-containing functional groups and titanium dioxide, forming Ti3C2T, where T is an oxygen-containing functional group. As a preferred design, the acid is any one or more of hydrochloric acid, sulfuric acid, and nitric acid, and the organic solvent is any one or a mixture of petroleum ether and isopropanol.

[0027] And / or, the organic solvent is a mixed solution of petroleum ether and isopropanol in a volume ratio of 1:1.

[0028] As a preferred design, the amount of titanium carbide nanosheet composite added accounts for 0.5 to 3.5 wt% of the weight of LaCe NdFeB magnet alloy powder. Preferably, it is 0.5 wt%, 1.5 wt%, or 2.5 wt%, and more preferably 1.5 wt%.

[0029] As a preferred design, the sintering temperature of the LaCe NdFeB magnet compact is 1070℃, the sintering time is 6h, the first-stage tempering temperature is 700℃, and the second-stage tempering temperature is 400℃.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] 1. This invention provides a high-performance lanthanum-cerium sintered NdFeB magnet material. Through the design of auxiliary additives, the auxiliary additives consist of titanium carbide nanosheets with different valence states, including TiC, Ti2C, Ti3C2T, and TiO2. During etching, the introduction of oxygen defects causes the nanosheets to exhibit different valence states of TiC, Ti2C, and Ti3C2T compounds, accompanied by a small amount of TiO2. The introduction of oxygen vacancies allows the surface of the main component, Ti3C2T, to be loaded with -OH, =O, and -O active functional groups. When the titanium carbide nanosheet composite is dispersed in an organic solvent and introduced into the magnet, it is distributed in a two-dimensional lamellar structure at the grain boundaries, forming an effective grain boundary barrier during sintering. This barrier hinders grain migration and grain merging, effectively suppressing grain growth. Furthermore, the nanosheet structure forms continuous magnetic domain wall pinning points, hindering the nucleation and expansion of reverse magnetic domains. Furthermore, the nanosheets exhibit different valence states of TiC, Ti2C, Ti3C2T, and TiO2 compounds. These different valence states can form a multi-valence redox synergy, buffering grain boundary oxygen fluctuations through dynamic electron transfer, consuming free oxygen, inhibiting Nd / Ce / La oxidation, stabilizing the main phase magnetic moment, blocking grain boundary oxidation pathways, and enhancing coercivity. Moreover, their surface is loaded with active functional groups such as -OH, =O, and -O, possessing abundant chemical activity. This provides more heterogeneous nucleation sites within the magnet, acting as pinning points during grain growth to hinder the movement of magnetic domain walls, thereby enhancing the magnet's coercivity. Therefore, the addition of this auxiliary additive can improve the coercivity of lanthanum-cerium magnets through a dual mechanism of refining the main phase grain size and hindering domain wall movement.

[0032] 2. The main component Ti3C2T in the auxiliary agent of the present invention is prepared and synthesized by acid etching of titanium aluminum carbide (Ti3AlC2). It has good dispersibility in organic solvents. After dispersion, it is added to the fine powder of magnet in liquid phase, which can effectively alleviate the particle agglomeration and segregation caused by the direct addition of metal compound powder. It ensures the uniform distribution of titanium carbide nanosheet composite, which is the main component of the additive, in the magnet. It avoids the concentration of local demagnetization field caused by the agglomeration of additive in the magnet, and achieves effective magnetic performance compensation for lanthanum-cerium magnets. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention. Example 1:

[0034] A high-performance lanthanum-cerium sintered NdFeB magnet material is prepared according to the following steps:

[0035] (1) The composition of the magnet alloy quick-setting sheet, expressed as a mass fraction, is La 2.0 Ce 13.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0. 1Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The raw material used for PrNd is commercially available Pr. 0.25 Nd 0.75 The alloy was prepared by placing the raw materials in a vacuum melting furnace in a specific ratio and melting them under a vacuum of approximately 0.05 Pa and a refining temperature of 1440℃. The molten alloy was then cast into LaCe NdFeB magnet alloy rapid-solidification sheets using a thin-strip continuous casting method.

[0036] (2) After the LaCe NdFeB magnet alloy rapid solidification sheet was subjected to hydrogen absorption at room temperature and dehydrogenation at 590℃, LaCe NdFeB magnet coarse powder was obtained. The coarse powder was further pulverized and refined in an air jet mill under nitrogen protection to obtain LaCe NdFeB magnet alloy powder with a particle size of 3.9μm;

[0037] (3) Take 40 mL of 5 mol·L⁻¹ solution. -1 Hydrochloric acid and 2g of lithium fluoride were mixed in a reactor, and then 10g of 400-mesh precursor titanium aluminum carbide (Ti3AlC2) powder was slowly added. The mixture was heated to 80℃ to etch the aluminum phase with acid, and the etched solid was obtained by filtration. The etched solid was washed until neutral, dried, and weighed. The solid was then weighed at 10g·L⁻¹. -1 The titanium carbide nanosheets were dispersed in petroleum ether at a mass concentration and ultrasonically exfoliated at 200W power for 1 hour to obtain a two-dimensional titanium carbide nanosheet composite (as an organic auxiliary additive).

[0038] (4) The above-mentioned organic auxiliary additives are added to the LaCe NdFeB magnet alloy powder at a ratio of 0.5wt% under nitrogen protection. After being mixed evenly by stirring in a high-efficiency mixer for 2 hours, the mixture is formed in a 2.0T magnetic field press and isostatically pressed at 180 MPa and held for 10 seconds to obtain the LaCe NdFeB magnet blank.

[0039] (5) The LaCe NdFeB magnet blank was sintered at 1070℃ for 6h, and then tempered at 700℃ for 3h and at 400℃ for 3h to obtain the LaCe NdFeB magnet.

[0040] (6) The LaCe neodymium iron boron magnet was processed into a cylinder with a diameter of 1cm and a height of 1cm by a wire cutting machine, and after being magnetized, it was used for magnetic performance testing by NIM62000. Example 2:

[0041] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 0.5 wt%. Everything else is the same as in Example 1. Example 3:

[0042] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 7.5 Ce 7.5 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 0.5 wt%. Everything else is the same as in Example 1. Example 4:

[0043] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 10.0 Ce 5.0 (Pr 0.25 Nd0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 0.5 wt%. Everything else is the same as in Example 1. Example 5:

[0044] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 1.5 wt%. Everything else is the same as in Example 1. Example 6:

[0045] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 2.5 wt%. Everything else is the same as in Example 1. Example 7:

[0046] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1Ga 0.1 The proportion of organic auxiliary additives is 3.5 wt%. Everything else is the same as in Example 1. Example 8:

[0047] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives was 1.5 wt%, and the organic dispersing solvent used in the preparation of the titanium carbide nanosheet composite was isopropanol. All other aspects were the same as in Example 1. Example 9:

[0048] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 1.5 wt%, and the organic dispersing solvent is a petroleum ether:isopropanol complex solution with a volume ratio of 1:1. All other aspects are the same as in Example 1.

[0049] Example 10:

[0050] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1The proportion of organic auxiliary additives is 1.5 wt%, and the organic dispersion solvent is a petroleum ether:isopropanol complex solution with a volume ratio of 2:1. All other aspects are the same as in Example 1.

[0051] Example 11:

[0052] In this embodiment, the LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67. 4B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The proportion of organic auxiliary additives is 1.5 wt%, and the organic dispersing solvent is a petroleum ether:isopropanol complex solution with a volume ratio of 1:2. All other aspects are the same as in Example 1.

[0053] Comparative Example 1:

[0054] The LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 No auxiliary additives were added. The rest of the process was the same as in Example 1.

[0055] Comparative Example 2:

[0056] The LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1The organic auxiliary additive was a petroleum ether:isopropanol complex solution with a volume ratio of 1:1, and the addition ratio was 1.5 wt% of the LaCe NdFeB magnet alloy powder. All other aspects were the same as in Example 1.

[0057] Comparative Example 3:

[0058] The LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The auxiliary additive was added by dispersing nano-particle titanium carbide (TiC) powder in a petroleum ether:isopropanol complex solution with a volume ratio of 1:1 after air jet milling, and then adding it to the LaCe NdFeB magnet alloy powder at an addition ratio of 1.5 wt%. All other steps were the same as in Example 1.

[0059] Comparative Example 4:

[0060] The LaCe neodymium iron boron magnet alloy quick-setting sheet is composed of La. 5.0 Ce 10.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 The auxiliary additive was added by directly adding the titanium carbide nanosheet composite solid, which had undergone acid etching, filtration, and drying after air jet milling, to the LaCe NdFeB magnetic powder without dispersing it in an organic solvent. The addition ratio was 1.5 wt%. All other steps were the same as in Example 1.

[0061] The magnetic properties of the LaCe neodymium iron boron magnets obtained in the above embodiments and comparative examples were tested, and the specific test results are shown in Table 1 below.

[0062] Table 1 Magnetic property data of LaCe NdFeB magnets

[0063]

[0064]

[0065] Comparative Example 1 and Example 2 show that the remanence and coercivity of LaCe NdFeB magnets are improved after adding 0.5wt% organic auxiliary additives. This is because the titanium carbide nanosheet composite in the organic auxiliary additives can effectively isolate grain boundaries and improve coercivity. At the same time, the introduction of organic dispersants is beneficial to the orientation of magnetic powder during the molding process and improves remanence.

[0066] Examples 1-4 show that, under the condition of fixed proportions of other elements, Hcj increases with increasing La content and decreases with decreasing Ce content, exhibiting a trend of gradually increasing Br and gradually decreasing Hcj. Under high Ce addition conditions, the LaCe magnet greatly enhances the pinning ability of grain boundaries to magnetic domain wall migration by forming a cerium-rich grain boundary phase with higher magnetocrystalline anisotropy, thus improving coercivity. However, the large amount of Ce entering the main phase leads to a sharp deterioration in Br. With increasing La content, Br increases because the intrinsic magnetic polarization of the magnet increases after La enters the main phase. Comparatively, the LaCe content in the LaCe NdFeB magnet is La... 5.0 Ce 10.0 At that time, Br and Hcj both showed better performance.

[0067] In La 5.0 Ce 10.0 Under the specified proportions, Examples 2 and 5-7 show that as the proportion of organic auxiliary additives increases from 0.5 wt% to 3.5 wt%, Br and Hcj both exhibit a trend of first increasing and then decreasing. When the proportion of organic auxiliary additives is 1.5 wt%, La... 5.0 Ce 10.0 The magnet exhibits the best Br and Hcj properties, but its performance decreases with increasing additive content. This may be because excessive additives introduce too much titanium carbide nanosheet composite, which may stack between grain boundaries and adversely affect the orientation of magnetic powder and the melting and rearrangement of grain boundaries during magnet sintering, thus affecting Br and Hcj.

[0068] Take La 5.0 Ce 10.0With the magnet as the matrix and the organic auxiliary additive ratio at 1.5 wt%, Examples 5 and 8-11 show that the magnet performance is optimal when the organic auxiliary additive dispersant is a petroleum ether:isopropanol complex solution with a volume ratio of 1:1. This is because the titanium carbide nanosheet composite exhibits better dispersibility and system stability in the 1:1 petroleum ether:isopropanol complex solution system, preventing self-flocculation of the titanium carbide nanosheet composite within the organic auxiliary additive and ensuring its uniformity after the addition of magnetic powder. In the solution system, isopropanol, containing -OH groups, forms hydrogen bonds with the -OH / -O functional groups on the surface of the titanium carbide nanosheet composite, acting as a molecular bridge to connect the nonpolar petroleum ether with the hydrophilic titanium carbide nanosheets. Simultaneously, isopropanol, due to its stronger polarity, preferentially adsorbs onto the surface of the titanium carbide nanosheet composite, forming a solvation layer and generating steric hindrance. The nonpolar petroleum ether in the system is synergistically dispersed and penetrates into the interlayer of the titanium carbide nanosheet composite, assisting in the exfoliation of the titanium carbide nanosheet composite layers through van der Waals forces and inhibiting the aggregation of the titanium carbide nanosheet composite.

[0069] Comparative Examples 2-4 and Example 9 show that when petroleum ether:isopropanol 1:1 solution and TiC nanoparticles / nanofa sheets are added as additives, the Br and Hcj values ​​are lower than those of lanthanum-cerium magnets prepared by adding an equal amount of the organic auxiliary additives described in this invention.

[0070] The above specific embodiments further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-performance lanthanum-cerium sintered NdFeB magnet material, characterized in that, The titanium carbide nanosheet composite was prepared using LaCe neodymium iron boron magnet alloy powder and titanium carbide nanosheet composite as raw materials. The titanium carbide nanosheet composite is a nanosheet composite containing any one or more of TiC, Ti2C, and Ti3C2T, where T in Ti3C2T is an oxygen-containing functional group. The preparation process of the titanium carbide nanosheet composite is as follows: Titanium aluminate carbide powder is acid-etched to form an aluminum phase, centrifuged, and ultrasonically exfoliated before being dispersed in an organic solvent to obtain a titanium carbide nanosheet composite. The acid is any one or more of hydrochloric acid, sulfuric acid, and nitric acid, and the organic solvent is any one or a mixture of petroleum ether and isopropanol.

2. The high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 1, characterized in that, The oxygen-containing functional group is at least one of -OH, =O, and -O; And / or, the titanium carbide nanosheet composite also includes TiO2.

3. The high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 1, characterized in that, The composition of the LaCe NdFeB magnet alloy powder, expressed as a mass fraction of La... 1.0-10.0 Ce 3.0-13.0 (Pr 0.25 Nd 0.75 ) 16.0 Fe 67.4 B 0.9 Co 0.1 Zr 0.1 Ti 0.1 Al 0.2 Cu 0.1 Ga 0.1 .

4. A method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to any one of claims 1 to 3, characterized in that, include: Preparation of LaCe NdFeB magnet alloy powder; Preparation of titanium carbide nanosheet composites; Titanium carbide nanosheet composites were added to LaCe NdFeB magnet alloy powder. After the mixture was stirred evenly, it was magnetically pressed and isostatically pressed to obtain LaCe NdFeB magnet blanks. LaCe NdFeB magnet blanks were sintered, followed by primary tempering and secondary tempering to obtain high-performance lanthanum-cerium sintered NdFeB magnet materials.

5. The method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 4, characterized in that, The particle size range of the LaCe neodymium iron boron magnet alloy powder is 2.9μm-4.5μm.

6. The method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 4, characterized in that, The preparation process of the LaCe NdFeB magnet alloy powder is as follows: Weigh out each alloying element according to the proportion, mix them, and then melt and cast them to obtain LaCe NdFeB magnet alloy quick-solidification sheets. Then, crush the LaCe NdFeB magnet alloy quick-solidification sheets with hydrogen and mill them under nitrogen protection to obtain LaCe NdFeB magnet alloy powder. And / or; the melting temperature is 1400℃, the vacuum degree during the melting process is 0.05Pa, and the casting process adopts the thin strip continuous casting method; And / or, hydrogen is absorbed at room temperature during hydrogen crushing and dehydrogenation is carried out at 590°C.

7. The method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 4, characterized in that, The preparation process of titanium carbide nanosheet composite is as follows: Titanium aluminate carbide powder is acid-etched to obtain an aluminum phase, centrifuged, and ultrasonically exfoliated before being dispersed in an organic solvent to obtain a titanium carbide nanosheet composite.

8. The method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 7, characterized in that, The acid is any one or more of hydrochloric acid, sulfuric acid, and nitric acid, and the organic solvent is any one or a mixture of petroleum ether and isopropanol. And / or, the organic solvent is a mixed solution of petroleum ether and isopropanol in a volume ratio of 1:

1.

9. The method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 4, characterized in that, The amount of titanium carbide nanosheet composite added accounts for 0.5~3.5 wt% of the weight of LaCe NdFeB magnet alloy powder.

10. The method for preparing a high-performance lanthanum-cerium sintered NdFeB magnet material according to claim 4, characterized in that, The sintering temperature of the LaCe NdFeB magnet compact was 1070℃, the sintering time was 6h, the first tempering temperature was 700℃, and the second tempering temperature was 400℃.

Images