A rare earth permanent magnet containing cerium

Abstract

The present invention belongs to the technical field of rare earth permanent magnet materials and relates to a cerium-containing rare earth permanent magnet. The chemical formula of the permanent magnet is as follows: (Ce x RE 1‑x ) 30 Fe 69.1‑y B 0.9 TM y , wherein: 0.018≤x≤0.18, 0.5≤y≤2.5; RE is one or more of Pr, Nd, Dy, Tb, Ho; TM is one or more of Ga, Co, Al, Cu, Nb, Zr, Ti; in the permanent magnet, the rare earth Ce element replacing RE is CeFe 2 phase exists at the grain boundary, and the main phase of the permanent magnet has RE 2 Fe 14 B phase structure; the permanent magnet is obtained by preparing quick-setting sheets, crushing and powdering, magnetic field orientation molding, sintering and heat treatment. The present invention is a high-performance and low-cost rare earth permanent magnet containing cerium. The rare earth permanent magnet is doped with a certain amount of high-abundance rare earth Ce in the neodymium iron boron magnet. Compared with the existing neodymium iron boron magnets on the market, the cost of raw materials is greatly reduced, but the magnetic properties of the permanent magnet can still be maintained without reduction, and it has significant cost and price advantages.

Description

Technical Field

[0001] The invention belongs to the technical field of rare earth permanent magnet materials, and in particular relates to a high-performance and low-cost cerium-containing rare earth permanent magnet. Background Art

[0002] In recent years, with the rapid development of new energy vehicles, wind power generation and energy-efficient home appliances, the demand for rare earth permanent magnet materials has been increasing day by day. The price of high-abundance rare earth Ce is only 2.6% of PrNd. Using the abundant and low-priced rare earth Ce in the preparation of permanent magnet materials can not only significantly reduce costs, but also double the rare earth raw materials that can be used in NdFeB manufacturing. However, Ce2Fe 14 The intrinsic properties of compound B are significantly lower than those of Nd2Fe 14 B. Adding Ce to NdFeB magnets will significantly reduce the magnetic properties of the magnets (see IEEE. Trans. Magn. 2014, 50: 2102605). Chinese patent CN104575920B proposes a rare earth permanent magnet and its preparation method. When the Ce substitution amount is 24% to 32%, the magnet has a higher coercive force; when the Ce substitution amount is less than 24%, with the increase of Ce content, the remanence Br, coercive force Hcj and magnetic energy product (BH) of the magnet max The Chinese patent CN 110148507B previously filed by the applicant of this application proposed a 'grain boundary diffusion cerium magnet containing REFe2 phase and its preparation method', in which the Ce substitution amount is 20% to 85%, and the original cerium magnet contains 2-14-1 main phase, REFe2 phase and rare earth-rich phase; the original magnet contains both REFe2 phase and rare earth-rich phase in the grain boundary, and the rare earth-rich phase is generally Nd-rich phase, and part of Nd enters the grain boundary to form rare earth-rich phase but fails to completely enter Nd2Fe 14 B main phase, failed to fully utilize Nd2Fe 14 Due to the high intrinsic performance of the B phase, the overall magnetic properties of the magnet are relatively low; when the Ce substitution amount is 20%, the remanent magnetism Br of the magnet is only 12.59kGs, and the magnetic energy product (BH) max is only 38.25MGOe. In the preparation process of this technical solution, coating, evaporation, electrophoretic deposition and magnetron sputtering are used to carry out grain boundary diffusion treatment at 850℃~1000℃, and rare earth elements such as Tb and Dy and their compounds are diffused into the interior of the magnet to form a complex multiphase structure inside the magnet, thereby improving the coercive force of the magnet. Grain boundary diffusion of rare earth elements adds additional process flows, increases the raw material input and manufacturing cost of the magnet, and grain boundary diffusion cannot increase the remanent magnetism Br and magnetic energy product (BH) max of cerium-containing magnets, and may even slightly reduce them. Summary of the invention

[0003] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a cerium-containing rare earth permanent magnet, which is a neodymium iron boron magnet doped with high-abundance rare earth Ce. Compared with the existing neodymium iron boron magnets on the market, the cost of the rare earth permanent magnet is greatly reduced, but it can still maintain magnetic properties comparable to those of the neodymium iron boron magnets.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A cerium-containing rare earth permanent magnet, the chemical formula of the permanent magnet is as follows by mass percentage: (Ce x RE 1-x ) 30 Fe 69.1- y B 0.9 TM y , wherein: 0.018≤x≤0.18, 0.5≤y≤2.5; RE is one or more of Pr, Nd, Dy, Tb, Ho; TM is one or more of Ga, Co, Al, Cu, Nb, Zr, Ti; in the permanent magnet, the rare earth Ce element replacing RE exists in the form of CeFe2 phase at the grain boundary, and the main phase of the permanent magnet has RE2Fe 14 B phase structure;

[0006] The cerium-containing rare earth permanent magnet is obtained by preparing raw materials, preparing quick-setting sheets, crushing and powdering, magnetic field orientation molding, sintering and heat treatment steps, wherein:

[0007] The sintering system in the sintering step is 1030° C. to 1060° C., kept warm for 2 to 5 hours, and then cooled to below 200° C. at a controlled rate of 20 to 30° C. / min.

[0008] Preferably, y is 0.5-1.8.

[0009] More preferably, the y is 0.5-1.2.

[0010] The permanent magnet has the following combination of magnetic properties equivalent to those of NdFeB permanent magnets when in use:

[0011] The remanence Br is 14.35~14.50kGs, the coercive force H cj 12.21~12.50kOe and magnetic energy product (BH) m It is 50.15~51.57MGOe.

[0012] A method for preparing a cerium-containing sintered rare earth permanent magnet, the method comprising the following steps: preparing a quick-setting sheet, crushing and powdering, magnetic field orientation molding and pressing, sintering and heat treatment,

[0013] In the step of preparing raw materials, the raw materials are prepared according to the following magnet components, and the chemical formula of the magnet components is as follows in terms of mass percentage: (Ce x RE 1-x ) 30 Fe 69.1-y B 0.9 TM y , where: 0.018≤x≤0.18, 0.5≤y≤2.5; RE is one or more of Pr, Nd, Dy, Tb, Ho, TM is one or more of Ga, Co, Al, Cu, Nb, Zr, Ti;

[0014] In the sintering and heat treatment steps, the blank is placed in a high vacuum sintering furnace for sintering at a sintering temperature of 1030-1060°C for 2-5 hours, then cooled to below 200°C at a controlled rate of 20-30°C / min, and then tempered at 900-920°C and 450-650°C for 2 hours respectively;

[0015] In the permanent magnet obtained by this method, the rare earth Ce element replacing RE exists in the form of CeFe2 phase at the grain boundary, and the main phase of the permanent magnet has RE2Fe 14 B phase structure.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] In the prior art, the technical difficulty of preparing high-performance and low-cost cerium-containing rare earth permanent magnets is that: 14 The intrinsic properties of compound B are significantly lower than those of Nd2Fe 14 B. Adding Ce to NdFeB magnets will significantly reduce the magnetic properties of the magnets (IEEE. Trans. Magn. 2014, 50: 2102605).

[0018] The alloy composition of the rare earth permanent magnet of the present invention is designed with a relatively excessive iron content, so that the rare earth Ce does not enter or enters less into the RE2Fe 14 B magnetic main phase, and exists in the form of CeFe2 phase at the grain boundary; the neodymium in the magnet alloy mainly remains in its RE2Fe 14 B main phase, thereby maintaining the magnet with high remanence; at the same time, a small amount of doping elements such as Ga, Co, Al, Cu, Nb, Zr, Ti, etc. are added and their addition amount is reasonably designed to improve the microstructure of the cerium-containing permanent magnet and avoid the agglomeration of CeFe2 phase at the grain boundary (see the attached manual Figure 1 ), and finally when the cerium addition amount in the magnet is within a certain composition range, that is, 0.018≤x≤0.18, the permanent magnet can still maintain high magnetic properties. The present invention has significant cost and price advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the microstructure of the cerium-containing rare earth permanent magnet of the present invention, wherein the dark gray phase is RE2Fe 14 B is the main phase, and the light gray phase is the CeFe2 phase. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0021] A cerium-containing rare earth permanent magnet, the chemical formula of the rare earth permanent magnet is as follows by mass percentage: (Ce x RE 1-x ) 30 Fe 69.1-y B 0.9 TM y , where: 0.018≤x≤0.18, 0.5≤y≤2.5; RE is one or more of Pr, Nd, Dy, Tb, Ho; TM is one or more of Ga, Co, Al, Cu, Nb, Zr, Ti.

[0022] Preferably, RE is one or two rare earth elements selected from Pr and Nd.

[0023] Preferably, the TM content is 0.5-1.8, that is, 0.5≤b≤1.8.

[0024] More preferably, the TM content is 0.5-1.2, that is, 0.5≤b≤1.2.

[0025] The main phase of the permanent magnet with this composition ratio is RE2Fe 14 B phase, the grain boundary phase is CeFe2 phase.

[0026] The permanent magnet is prepared by the following steps: preparing quick-setting sheets, crushing and powdering, magnetic field orientation molding and pressing, sintering and heat treatment.

[0027] The specific preparation method comprises the following steps:

[0028] S1. Prepare raw materials: Prepare raw materials according to the designed ingredients.

[0029] S2. Preparation of quick-setting sheet: Melting the prepared raw materials to prepare quick-setting tape. First, the raw materials are placed in a quick-setting furnace crucible and vacuum induction smelting is performed under argon protection. After the raw materials are fully melted to form an alloy, the temperature is maintained at 1400-1500°C, and the alloy liquid is poured onto a water-cooled copper roller with a linear speed of 1.0-2.0 m / s to prepare a quick-setting sheet with an average thickness of 0.28-0.32 mm.

[0030] S3, crushing and powdering: the quick-setting sheet is loaded into a hydrogen crushing furnace for hydrogen crushing, and hydrogen is absorbed at room temperature and pressure of 0.1-0.2MPa, and then dehydrogenation treatment is carried out at a dehydrogenation temperature of 500-600℃ for 2-6 hours. An appropriate amount of antioxidant is added to the dehydrogenated powder, and the powder is respectively jet-milled to form magnetic powder with an average particle size of 3.0-3.5μm.

[0031] S4, magnetic field orientation molding and pressing: The magnetic powder is oriented and molded in a 2T magnetic field press, and then cold isostatically pressed into a blank with a density of 3.8-4.8 g / cm 3 .

[0032] S5. Sintering and heat treatment: The blank is placed in a high vacuum sintering furnace for sintering at a sintering temperature of 1030-1060°C for 4 hours, then cooled to below 200°C at a controlled rate of 20-30°C / min, and then tempered at 900-920°C and 450-650°C for 2 hours respectively.

[0033] Example 1

[0034] A rare earth permanent magnet, the chemical formula of which is (Ce 0.018 RE 0.982 ) 30 Fe 68.6 B 0.9 TM 0.5 (TM = Co, Al, Cu, Zr; RE = Pr, Nd) (wt.%), the Ce content in the rare earth permanent magnet accounts for 1.8% of the total rare earth content. The rare earth permanent magnet is prepared according to the above preparation method.

[0035] Example 2

[0036] A rare earth permanent magnet, the chemical formula of which is (Ce 0.18 RE0 .82 ) 30 Fe 67.9 B 0.9 TM 1.2 (TM = Co, Al, Cu, Ga, Nb; RE = Nd, Pr, Ho) (wt.%), the Ce content in the rare earth permanent magnet accounts for 18% of the total rare earth content. The rare earth permanent magnet is prepared according to the above preparation method.

[0037] Example 3

[0038] A rare earth permanent magnet, the chemical formula of which is (Ce 0.18 RE 0.82 ) 30 Fe 67.3 B 0.9 TM 1.8(TM = Co, Al, Cu, Ga, Ti; RE = Nd, Pr, Dy) (wt.%), the Ce content in the rare earth permanent magnet accounts for 18% of the total rare earth content. The rare earth permanent magnet is prepared according to the above preparation method.

[0039] Comparative Example 1

[0040] A rare earth permanent magnet, whose chemical formula is RE 30 Fe 69 B 1.0 (RE=Nd, Pr) (wt.%), the rare earth permanent magnet does not contain Ce, and the rare earth permanent magnet is prepared by the same preparation method as Example 1-3.

[0041] Columnar samples with a size of 10×10 mm were processed by wire cutting on the rare earth permanent magnets of Comparative Example 1 and Examples 1-3, and the magnetic properties of the magnets were measured using a NIM-2000HF rare earth permanent magnet standard measuring device. The magnetic property test data are shown in Table 1.

[0042] Table 1 Magnetic properties test data of rare earth permanent magnets of Comparative Example 1 and Examples 1-3

[0043] serial number Ce content (%) <![CDATA[B r / kGs]]> <![CDATA[H cj / kOe]]> <![CDATA[(BH) m / MGOe]]> Comparative Example 1 0 14.32 12.19 49.58 Example 1 1.8 14.50 12.21 51.57 Example 2 18 14.38 12.25 50.40 Example 3 18 14.35 12.50 50.15

[0044] The cerium-containing rare earth permanent magnet of the present invention is designed with reasonable composition so that rare earth Ce does not enter or enters less into RE2Fe 14 B magnetic main phase, so that when the cerium addition in the magnet is within a certain composition range, that is, 0.018≤x≤0.18, the magnetic properties of the magnet can still be maintained, including: remanence, coercive force and magnetic energy product are not reduced. Compared with the existing NdFeB permanent magnets on the market, the rare earth permanent magnet of the present invention has a significantly reduced cost and has significant cost and price advantages.

[0045] The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it should not be understood as limiting the patent scope of the present invention.

Claims

1. A cerium-containing rare earth permanent magnet, characterized in that: The chemical formula of the permanent magnet is as follows: (Ce x RE 1-x ) 30 Fe 69.1-y B 0.9 TM y , wherein: 0.018≤x≤0.18, 0.5≤y≤2.5; RE is one or more of Pr, Nd, Dy, Tb, Ho; TM is one or more of Ga, Co, Al, Cu, Nb, Zr, Ti; in the permanent magnet, the rare earth Ce element replacing RE exists in the form of CeFe2 phase at the grain boundary, and the main phase of the permanent magnet has RE2Fe 14 B phase structure; The cerium-containing rare earth permanent magnet is obtained by preparing raw materials, preparing quick-setting sheets, crushing and powdering, magnetic field orientation molding, sintering and heat treatment steps, wherein: The sintering temperature in the sintering step is 1030°C to 1060°C, kept at this temperature for 2 to 5 hours, and then cooled to below 200°C at a controlled rate of 20 to 30°C / min; The permanent magnet has the following combination of magnetic properties equivalent to those of NdFeB permanent magnets when in use: The remanence Br is 14.35~14.50kGs, the coercive force H cj 12.21~12.50kOe and magnetic energy product (BH) m It is 50.15~51.57MGOe.

2. The cerium-containing rare earth permanent magnet according to claim 1, characterized in that: The y is 0.5-1.

8.

3. The cerium-containing rare earth permanent magnet according to claim 2, characterized in that: The y is 0.5-1.

2.

4. A method for preparing a cerium-containing rare earth permanent magnet as claimed in claim 1, the method comprising the following steps: preparing raw materials, preparing quick-setting sheets, crushing and powdering, magnetic field orientation molding and pressing, sintering and heat treatment, characterized in that: In the step of preparing raw materials, the raw materials are prepared according to the following magnet components, and the chemical formula of the magnet components is as follows in terms of mass percentage: (Ce x RE 1-x ) 30 Fe 69.1-y B 0.9 TM y , where: 0.018≤x≤0.18, 0.5≤y≤2.5; RE is one or more of Pr, Nd, Dy, Tb, Ho, TM is one or more of Ga, Co, Al, Cu, Nb, Zr, Ti; In the sintering and heat treatment steps, the blank is placed in a high vacuum sintering furnace for sintering at a sintering temperature of 1030-1060°C for 2-5 hours, then cooled to below 200°C at a controlled rate of 20-30°C / min, and then tempered at 900-920°C and 450-650°C for 2 hours respectively; In the permanent magnet obtained by this method, the rare earth Ce element replacing RE exists in the form of CeFe2 phase at the grain boundary, and the main phase of the permanent magnet has RE2Fe 14 B phase structure.

Images