Sintered neodymium iron boron multi-pole magnetic ring with high comprehensive magnetic performance and preparation method thereof

Abstract

The invention discloses a sintered neodymium iron boron multi-pole magnetic ring with high comprehensive magnetic performance and a preparation method thereof, and relates to the technical field of permanent magnet materials, the sintered neodymium iron boron multi-pole magnetic ring is prepared from the following components by weight: 9-10 parts of lean rare earth alloy A, 0.1-1 part of rich rare earth alloy B, 0.8-1.2 parts of alloy C, 0.01-0.03 part of a lubricant, and 0.01-0.03 part of aviation gasoline; and the alloy C comprises the following components in percentage by mass: 29 to 32 weight percent of rare earth element, 0.05 to 0.2 weight percent of Ta, 0.1 to 0.3 weight percent of In, 0.02 to 0.08 weight percent of Re, 0.08 to 0.2 weight percent of W, 0.1 to 0.4 weight percent of Mo, 0.1 to 0.5 weight percent of Ge, 0.9 to 1.2 weight percent of B and the balance of Fe. The multi-pole magnetic ring is excellent in comprehensive magnetic performance and low in cracking rate.

Description

Technical Field

[0001] The present invention relates to the technical field of permanent magnetic materials, and in particular to a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties and a preparation method thereof. Background Art

[0002] In modern industry and technology, the demand for high-performance permanent magnet materials is growing. Sintered NdFeB permanent magnets, due to their excellent magnetic properties, are widely used in a wide range of fields, including motors, sensors, and medical devices. Multi-pole magnetic rings, as a special permanent magnet structure, offer advantages such as high precision, smooth operation, and low noise in high-performance permanent magnet motors and sensors. They are the preferred choice for high-speed, high-precision control motors and play a vital role in industrial automation equipment and intelligent devices.

[0003] Traditional sintered NdFeB multi-pole magnetic rings face numerous challenges during their production. Firstly, the powder filling process in the mold is difficult due to the diverse sizes of the magnetic rings, especially small ones. This leads to poor dispersion and uneven distribution of the magnetic powder, which in turn affects the overall magnetic properties of the rings. Secondly, during the demolding process, existing processes can easily cause the compacts to not form, resulting in low pressing yields and difficulty improving production efficiency. Existing sintered NdFeB multi-pole magnetic rings also suffer from various technical flaws, such as insufficient surface magnetic strength, uneven magnetic property distribution, and cracking caused by anisotropic sintering shrinkage.

[0004] To address the above-mentioned issues, a Chinese invention patent with authorization announcement number CN112164575B discloses a method for manufacturing a small-sized sintered NdFeB multi-pole magnetic ring. The method uses a pneumatic pressing device to press and form sintered NdFeB powder, then removes the pressed blank and performs isostatic pressing, high-temperature sintering, tempering, trepanning, and grinding to obtain a sintered NdFeB multi-pole magnetic ring. The pneumatic pressing device includes an orientation mechanism and a pressing mold, wherein the orientation mechanism is composed of an even number of sintered NdFeB magnetic tiles evenly spaced along the circumferential direction, and the sintered NdFeB magnetic tiles form a mold mounting cavity around the mold, and the pressing mold is correspondingly installed in the mold mounting cavity. The technical solution of this invention can effectively manufacture small-sized sintered NdFeB multi-pole magnetic rings. The manufacturing process is relatively convenient, the equipment investment cost is low, the magnetic properties of the multi-stage magnetic rings produced are good, and the pressing pass rate and overall efficiency are also improved. However, the patent only optimizes the magnetic properties from the perspective of preparation process and equipment, without studying the comprehensive magnetic properties of the multi-pole magnetic ring from the perspective of component formulation. In addition, the comprehensive magnetic properties of the sintered NdFeB multi-pole magnetic ring produced by this patent still need to be further improved.

[0005] It can be seen that the development of a high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring with excellent comprehensive magnetic properties and low cracking rate and its preparation method meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the permanent magnet material field. Summary of the Invention

[0006] The main purpose of the present invention is to provide a high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring with excellent comprehensive magnetic performance and low cracking rate and a preparation method thereof.

[0007] To achieve the above objectives, the present invention provides a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties, which is made of the following components by weight: 9-10 parts of a poor rare earth alloy A, 0.1-1 parts of a rich rare earth alloy B, 0.8-1.2 parts of an alloy C, 0.01-0.03 parts of a lubricant, and 0.01-0.03 parts of aviation gasoline; the composition of the poor rare earth alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2 wherein TM is one or more of Al, Cu, Co, Mn, and Ga, and HM is one or more of Nb, Zr, Hf, Ti, and V; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and 28.5≤a1≤29.5, 0<b1≤2, 0<c1≤0.3, 0.93≤d1≤1.02, 31.5≤a2≤33, 0<b2≤0.5, 0<c2≤0.1, and 0.88≤d2≤0.92; and the alloy C comprises the following components by mass percentage: rare earth elements 29-32wt%, Ta 0.05-0.2wt%, In 0.1-0.3wt%, Re 0.02-0.08wt%, W 0.08-0.2wt%, Mo 0.1-0.4wt%, Ge 0.1-0.5wt%, B 0.9-1.2wt%, the balance is Fe.

[0008] Preferably, the mass percentage of Pr in the PrNd is 60-80wt%.

[0009] Preferably, the aviation gasoline is No. 75 aviation gasoline; and the lubricant is zinc stearate.

[0010] Preferably, the rare earth elements are Nd, Ce, and Gd mixed in a mass ratio of (1-3):1:(0.8-1.2).

[0011] Another object of the present invention is to provide a method for preparing the sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties, comprising the following steps: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

[0012] Preferably, the smelting temperature of the rare earth-poor alloy A is 1455-1505° C., the casting temperature is 1445-1475° C., and the initial thickness of the slabs obtained by smelting is 0.15-0.45 mm.

[0013] Preferably, the smelting temperature of the rare earth-rich alloy B is 1455-1505° C., the casting temperature is 1400-1445° C., and the initial thickness of the slabs obtained by smelting is 0.15-0.45 mm.

[0014] Preferably, the melting temperature of the alloy C is 1450-1500° C., the casting temperature is 1420-1450° C., and the initial thickness of the slab obtained by melting is 0.15-0.45 mm.

[0015] Preferably, the average particle size of the jet-milled powder of the rare earth-poor alloy A is 2.9-3.1 μm; the average particle size of the jet-milled powder of the rare earth-rich alloy B is 2.6-2.8 μm; and the average particle size of the jet-milled powder of the alloy C is 2.5-3.0 μm.

[0016] Preferably, the isostatic pressing process in step S4 adopts a segmented pressure holding process, with the pressure in the first stage being 150-180 MPa and the pressure holding time being 20-40 s, the pressure in the second stage being 200-220 MPa and the pressure holding time being 40-60 s, followed by pressure relief to 100-150 MPa, the pressure holding time being 5-20 s, and finally the pressure relief to zero.

[0017] Preferably, the sintering in step S5 is a multi-stage sintering in a vacuum sintering furnace, wherein the first stage sintering temperature is 150-200°C, the time is 1-2h, the second stage sintering temperature is 350-550°C, the time is 1-2h, the third stage sintering temperature is 1000-1050°C, and the sintering time is 6-12h; the vacuum degree in the sintering furnace is 5×10 -2 Below Pa.

[0018] Preferably, the aging treatment in step S5 adopts a three-stage aging process, wherein the first stage aging treatment temperature is 600-860°C and the time is 2-4 hours, the second stage aging treatment temperature is 360-600°C and the time is 2-4 hours, and the third stage aging treatment temperature is 450-510°C and the time is 2-4 hours.

[0019] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties disclosed in the present invention has a simple preparation process, convenient operation and control, low dependence on equipment, high preparation efficiency and finished product qualification rate, is suitable for continuous large-scale production, and has high promotion and application value.

[0020] (2) The high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring disclosed in the present invention is made of the following components in parts by weight: 9-10 parts of rare earth-poor alloy A, 0.1-1 parts of rare earth-rich alloy B, 0.8-1.2 parts of alloy C, 0.01-0.03 parts of lubricant, and 0.01-0.03 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2wherein TM is one or more of Al, Cu, Co, Mn, and Ga, and HM is one or more of Nb, Zr, Hf, Ti, and V; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and 28.5≤a1≤29.5, 0<b1≤2, 0<c1≤0.3, 0.93≤d1≤1.02, 31.5≤a2≤33, 0<b2≤0.5, 0<c2≤0.1, and 0.88≤d2≤0.92; and the alloy C comprises the following components by mass percentage: rare earth elements 29-32wt%, Ta 0.05-0.2wt%, In 0.1-0.3wt%, Re 0.02-0.08wt%, W 0.08-0.2wt%, Mo 0.1-0.4wt%, Ge 0.1-0.5wt%, B 0.9-1.2wt%, the balance is Fe. Through the mutual coordination and joint action of various components and ingredients, the manufactured multi-pole magnetic ring has excellent comprehensive magnetic properties and low cracking rate. First, through the mutual matching of rare earth-rich alloy B, poor rare earth alloy A and alloy C, a uniform distribution of grain boundary phases inside the low rare earth magnet is achieved, thereby resolving the contradiction between the residual magnetism and the internal crack ratio of the magnetic ring product. Secondly, through the segmented isostatic pressing and holding process, the stress segregation phenomenon caused by the anisotropy of the forming orientation of the annular product is alleviated, and the internal crack rate of the magnetic ring is reduced. In addition, a multi-stage sintering / aging process is used to promote the degassing and degreasing of the magnetic ring during the liquid phase densification process, which on the one hand reduces the proportion of internal cracks, and on the other hand optimizes the structure of the grain boundary phase inside the magnetic ring, which is conducive to the batch preparation of high-performance magnetic rings and the improvement of the comprehensive magnetic properties of the magnet.

[0021] (3) In the sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties disclosed in the present invention, the (PrNd) content of the rare earth-poor alloy A is controlled at 28.5-29.5wt%, which serves as the main phase to provide a high remanence foundation; the (PrNd) content of the rare earth-rich alloy B is increased to 31.5-33wt%, and a rare earth-rich phase is formed through grain boundary diffusion, significantly enhancing the coercivity. This dual alloy process not only reduces the amount of heavy rare earth, but also optimizes the magnetic properties by strengthening the grain boundary phase. TM elements such as Al, Cu, and Co can lower the melting point of the grain boundary phase, promote the uniform distribution of the grain boundary liquid phase during sintering, and improve the bonding strength between magnetic powders; HM elements such as Nb, Zr, and Hf can refine the grain size, inhibit the movement of magnetic domain walls, and enhance the intrinsic coercivity.

[0022] (4) The high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring disclosed in the present invention uses a multi-component microalloying technology of alloy C to break through the performance bottleneck; the grain refining effect of Ta and W forms TaC and WC nano-precipitates, pinning the grain boundary migration, reducing the average grain size and improving the coercive force; the grain boundary wettability of In is improved, reducing the grain boundary surface energy, promoting the rare earth-rich phase to uniformly cover the main phase grains, and reducing the magnetic performance fluctuation; the corrosion resistance of Ge is enhanced, forming a dense oxide layer at the grain boundary, effectively extending the service life; the various elemental components cooperate with each other to make the manufactured multi-level magnetic ring product have excellent comprehensive magnetic performance and low cracking rate.

[0023] (5) The high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring disclosed in the present invention has better comprehensive magnetic performance, lower cracking rate and longer service life through reasonable selection of preparation process parameters. DETAILED DESCRIPTION

[0024] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0025] Example 1: A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties is made of the following components by weight: 9 parts of rare earth-poor alloy A, 0.1 parts of rare earth-rich alloy B, 0.8 parts of alloy C, 0.01 parts of lubricant, and 0.01 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2 ; wherein TM is Al, HM is Nb; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and 28.5=a1, b1=0.2, c1=0.1, 0.93=d1, 31.5=a2, b2=0.1, c2=0.03, and 0.88=d2; the alloy C includes the following components in mass percentage: rare earth elements 29wt%, Ta 0.05wt%, In 0.1wt%, Re 0.02wt%, W 0.08wt%, Mo 0.1wt%, Ge 0.1wt%, B 0.9wt%, and the balance is Fe.

[0026] The mass percentage of Pr in the PrNd is 60wt%; the aviation gasoline is No. 75 aviation gasoline; the lubricant is zinc stearate; and the rare earth elements are Nd, Ce, and Gd mixed in a mass ratio of 1:1:0.8.

[0027] A method for preparing the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring comprises the following steps: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

[0028] The melting temperature of the rare earth-poor alloy A is 1455°C, the casting temperature is 1445°C, and the initial sheet thickness of the sheet obtained by melting is 0.45mm; the melting temperature of the rare earth-rich alloy B is 1455°C, the casting temperature is 1400°C, and the initial sheet thickness of the sheet obtained by melting is 0.45mm; the melting temperature of the alloy C is 1450°C, the casting temperature is 1420°C, and the initial sheet thickness of the sheet obtained by melting is 0.45mm.

[0029] The average particle size of the jet-milled powder of the rare earth-poor alloy A is 2.9 μm; the average particle size of the jet-milled powder of the rare earth-rich alloy B is 2.6 μm; and the average particle size of the jet-milled powder of the alloy C is 2.5 μm.

[0030] The isostatic pressing process in step S4 adopts a segmented pressure holding process, with the pressure of the first stage being 150 MPa and the pressure holding time being 20 s, the pressure of the second stage being 200 MPa and the pressure holding time being 40 s, then the pressure is unloaded to 100 MPa and the pressure holding time is 5 s, and finally the pressure is released to zero.

[0031] The sintering in step S5 is a multi-stage sintering process in a vacuum sintering furnace. The first stage is sintered at a temperature of 150°C for 1 hour, the second stage is sintered at a temperature of 350°C for 1 hour, and the third stage is sintered at a temperature of 1000°C for 6 hours. The vacuum degree in the sintering furnace is 5×10 -2 Pa or less; the aging treatment in step S5 adopts a three-stage aging process, the first stage aging treatment temperature is 600 ℃, the time is 2h, the second stage aging treatment temperature is 360 ℃, the time is 2h, the third stage aging treatment temperature is 450 ℃, the time is 2h.

[0032] Example 2: A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties is made of the following components by weight: 9.3 parts of rare earth-poor alloy A, 0.3 parts of rare earth-rich alloy B, 0.9 parts of alloy C, 0.015 parts of lubricant, and 0.015 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2 ; wherein TM is Cu, HM is Zr; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and 28.9=a1, b1=0.5, c1=0.15, 0.95=d1, 32=a2, b2=0.2, c2=0.03, and 0.89=d2; the alloy C includes the following components in mass percentage: rare earth elements 30wt%, Ta 0.09wt%, In 0.15wt%, Re 0.04wt%, W 0.12wt%, Mo 0.2wt%, Ge 0.2wt%, B 1wt%, and the balance is Fe.

[0033] The mass percentage of Pr in the PrNd is 65wt%; the aviation gasoline is No. 75 aviation gasoline; the lubricant is zinc stearate; and the rare earth elements are Nd, Ce, and Gd mixed in a mass ratio of 1.5:1:0.9.

[0034] A method for preparing the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring comprises the following steps: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

[0035] The melting temperature of the rare earth-poor alloy A is 1470°C, the casting temperature is 1455°C, and the initial sheet thickness of the sheet obtained by melting is 0.35mm; the melting temperature of the rare earth-rich alloy B is 1475°C, the casting temperature is 1420°C, and the initial sheet thickness of the sheet obtained by melting is 0.35mm; the melting temperature of the alloy C is 1470°C, the casting temperature is 1430°C, and the initial sheet thickness of the sheet obtained by melting is 0.35mm.

[0036] The average particle size of the airflow-milled powder of the rare earth-poor alloy A is 3.0 μm; the average particle size of the airflow-milled powder of the rare earth-rich alloy B is 2.7 μm; the average particle size of the airflow-milled powder of the alloy C is 2.6 μm; the isostatic pressing process in step S4 adopts a segmented pressure holding process, with a first-stage pressure of 160 MPa and a pressure holding time of 25 s, a second-stage pressure of 205 MPa and a pressure holding time of 45 s, followed by pressure relief to 110 MPa, a pressure holding time of 8 s, and finally pressure relief to zero.

[0037] The sintering in step S5 is a multi-stage sintering process in a vacuum sintering furnace. The first stage is sintered at a temperature of 160°C for 1.2 h, the second stage is sintered at a temperature of 400°C for 1.2 h, and the third stage is sintered at a temperature of 1015°C for 7 h. The vacuum degree in the sintering furnace is 5×10 -2 Pa or less; the aging treatment in step S5 adopts a three-stage aging process, the first stage aging treatment temperature is 700 ° C, the time is 2.5h, the second stage aging treatment temperature is 450 ° C, the time is 2.5h, the third stage aging treatment temperature is 470 ° C, the time is 2.5h.

[0038] Example 3: A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties is made of the following components by weight: 9.5 parts of rare earth-poor alloy A, 0.6 parts of rare earth-rich alloy B, 1 part of alloy C, 0.02 parts of lubricant, and 0.02 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2 ; wherein TM is Co, HM is Hf; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and 29=a1, b1=1, c1=0.15, 0.98=d1, 32.2=a2, b2=0.35, c2=0.05, and 0.9=d2; the alloy C includes the following components in mass percentage: rare earth elements 31wt%, Ta 0.13wt%, In 0.15wt%, Re 0.05wt%, W 0.13wt%, Mo 0.25wt%, Ge 0.3wt%, B 1wt%, and the balance is Fe.

[0039] The mass percentage of Pr in the PrNd is 70wt%; the aviation gasoline is No. 75 aviation gasoline; the lubricant is zinc stearate; and the rare earth elements are Nd, Ce, and Gd mixed in a mass ratio of 2:1:1.

[0040] A method for preparing the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring comprises the following steps: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

[0041] The smelting temperature of the rare earth-poor alloy A is 1480°C, the casting temperature is 1460°C, and the initial sheet thickness of the smelted sheet is 0.3mm; the smelting temperature of the rare earth-rich alloy B is 1480°C, the casting temperature is 1425°C, and the initial sheet thickness of the smelted sheet is 0.3mm; the smelting temperature of the alloy C is 1475°C, the casting temperature is 1435°C, and the initial sheet thickness of the smelted sheet is 0.3mm; the average particle size of the airflow-milled powder of the rare earth-poor alloy A is 3μm; the average particle size of the airflow-milled powder of the rare earth-rich alloy B is 2.7μm; and the average particle size of the airflow-milled powder of the alloy C is 2.8μm.

[0042] The isostatic pressing process in step S4 adopts a segmented pressure holding process, with the pressure of the first stage being 165 MPa and the pressure holding time being 30 s, the pressure of the second stage being 210 MPa and the pressure holding time being 50 s, then the pressure is unloaded to 130 MPa and the pressure holding time is 13 s, and finally the pressure is released to zero.

[0043] The sintering in step S5 is a multi-stage sintering process in a vacuum sintering furnace. The first stage is sintered at a temperature of 180°C for 1.5 h, the second stage is sintered at a temperature of 450°C for 1.5 h, and the third stage is sintered at a temperature of 1030°C for 9 h. The vacuum degree in the sintering furnace is 5×10 -2 Pa or less; the aging treatment in step S5 adopts a three-stage aging process, the first stage aging treatment temperature is 740 ° C, the time is 3h, the second stage aging treatment temperature is 460 ° C, the time is 3h, the third stage aging treatment temperature is 480 ° C, the time is 3h.

[0044] Example 4: A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties is made of the following components by weight: 9.9 parts of rare earth-poor alloy A, 0.9 parts of rare earth-rich alloy B, 1.1 parts of alloy C, 0.025 parts of lubricant, and 0.025 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 Bd2 Fe 100-a2-b2-c2-d2 ; Wherein, TM is a mixture of Al, Cu, Co, Mn, and Ga in a mass ratio of 1:2:1:1:0.2, and HM is a mixture of Nb, Zr, Hf, Ti, and V in a mass ratio of 0.8:1:1.2:1:2; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and a1=29.3, b1=1.7, c1=0.25, d1=1, a2=32.5, b2=0.4, c2=0.08, and d2=0.91; the alloy C includes the following components in mass percentage: rare earth elements 31wt%, Ta 0.18wt%, In 0.25wt%, Re 0.07wt%, W 0.18wt%, Mo 0.35wt%, Ge 0.4wt%, B 1.1wt%, and the balance is Fe.

[0045] The mass percentage of Pr in the PrNd is 75wt%; the aviation gasoline is No. 75 aviation gasoline; the lubricant is zinc stearate; and the rare earth elements are Nd, Ce, and Gd mixed in a mass ratio of 2.5:1:1.1.

[0046] A method for preparing the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring comprises the following steps: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

[0047] The melting temperature of the rare earth-poor alloy A is 1500°C, the casting temperature is 1470°C, and the initial sheet thickness of the sheet obtained by melting is 0.2mm; the melting temperature of the rare earth-rich alloy B is 1500°C, the casting temperature is 1440°C, and the initial sheet thickness of the sheet obtained by melting is 0.2mm; the melting temperature of the alloy C is 1490°C, the casting temperature is 1445°C, and the initial sheet thickness of the sheet obtained by melting is 0.2mm.

[0048] The average particle size of the jet-milled powder of the rare earth-poor alloy A is 3.1 μm; the average particle size of the jet-milled powder of the rare earth-rich alloy B is 2.8 μm; and the average particle size of the jet-milled powder of the alloy C is 2.9 μm.

[0049] The isostatic pressing process in step S4 adopts a staged pressure holding process, with the pressure of the first stage being 175 MPa and the pressure holding time being 35 s, the pressure of the second stage being 215 MPa and the pressure holding time being 55 s, then the pressure is released to 140 MPa and the pressure holding time being 18 s, and finally the pressure is released to zero; the sintering in step S5 is a multi-stage sintering in a vacuum sintering furnace, with the sintering temperature of the first stage being 190°C and the time being 1.8 h, the sintering temperature of the second stage being 530°C and the time being 1.8 h, and the sintering temperature of the third stage being 1040°C and the sintering time being 11 h; the vacuum degree in the sintering furnace is 5×10 -2 Below Pa.

[0050] The aging treatment in step S5 adopts a three-stage aging process, with the first stage aging treatment temperature being 840°C and the time being 3.5 hours, the second stage aging treatment temperature being 580°C and the time being 3.5 hours, and the third stage aging treatment temperature being 500°C and the time being 3.5 hours.

[0051] Example 5: A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties is made of the following components by weight: 10 parts of rare earth-poor alloy A, 1 part of rare earth-rich alloy B, 1.2 parts of alloy C, 0.03 parts of lubricant, and 0.03 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2; wherein TM is Ga, HM is Ti; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and a1=29.5, b1=2, c1=0.3, d1=1.02, a2=33, b2=0.5, c2=0.1, and d2=0.92; the alloy C includes the following components in mass percentage: rare earth elements 32wt%, Ta 0.2wt%, In 0.3wt%, Re 0.08wt%, W 0.2wt%, Mo 0.4wt%, Ge 0.5wt%, B 1.2wt%, and the balance is Fe.

[0052] The mass percentage of Pr in the PrNd is 80wt%; the aviation gasoline is No. 75 aviation gasoline; the lubricant is zinc stearate; and the rare earth elements are Nd, Ce, and Gd mixed in a mass ratio of 3:1:1.2.

[0053] A method for preparing the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring comprises the following steps: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

[0054] The melting temperature of the rare earth-poor alloy A is 1505°C, the casting temperature is 1475°C, and the initial thickness of the sheet obtained by melting is 0.15mm; the melting temperature of the rare earth-rich alloy B is 1505°C, the casting temperature is 1445°C, and the initial thickness of the sheet obtained by melting is 0.15mm; the melting temperature of the alloy C is 1500°C, the casting temperature is 1450°C, and the initial thickness of the sheet obtained by melting is 0.15mm.

[0055] The average particle size of the airflow-milled powder of the rare earth-poor alloy A is 3.1 μm; the average particle size of the airflow-milled powder of the rare earth-rich alloy B is 2.8 μm; the average particle size of the airflow-milled powder of the alloy C is 3.0 μm; the isostatic pressing process in step S4 adopts a segmented pressure holding process, with a first-stage pressure of 180 MPa and a pressure holding time of 40 s, a second-stage pressure of 220 MPa and a pressure holding time of 60 s, followed by pressure relief to 150 MPa, a pressure holding time of 20 s, and finally pressure relief to zero.

[0056] The sintering in step S5 is a multi-stage sintering process in a vacuum sintering furnace. The first stage is sintered at a temperature of 200°C for 2 hours, the second stage is sintered at a temperature of 550°C for 2 hours, and the third stage is sintered at a temperature of 1050°C for 12 hours. The vacuum degree in the sintering furnace is 5×10 -2 Below Pa.

[0057] The aging treatment in step S5 adopts a three-stage aging process, with the first stage aging treatment temperature being 860°C and the time being 4 hours, the second stage aging treatment temperature being 600°C and the time being 4 hours, and the third stage aging treatment temperature being 510°C and the time being 4 hours.

[0058] Comparative Example 1 A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties and a preparation method thereof are basically the same as those in Example 1, except that an equal amount of rare earth-rich alloy B is used instead of alloy C.

[0059] Comparative Example 2 A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties and a preparation method thereof are basically the same as those in Example 1, except that an equal amount of alloy C is used instead of rare earth-rich alloy B.

[0060] In order to further illustrate the beneficial technical effects of the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic rings involved in the embodiments of the present invention, relevant performance tests were carried out on the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic rings involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1. The test method is as follows: the magnetic properties of the multi-pole magnetic rings are tested with reference to GB / T 3217-2013; in the continuous production process, the molding conditions of 1,000 magnetic rings are counted, and the proportion of the number of magnetic rings that are qualified in molding to the total production quantity is calculated to obtain the pressing qualification rate. The test results are shown in Table 1.

[0061] Table 1 Performance test results of sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties project Remanence of magnetic ring Br Coercivity Hcj Pressing pass rate unit kG KOe % Example 1 14.03 25.63 99 Example 2 14.10 25.07 99 Example 3 14.31 24.75 100 Example 4 14.50 24.24 100 Example 5 14.74 24.08 100 Comparative Example 1 12.80 21.32 93 Comparative Example 2 13.00 20.45 90 As can be seen from Table 1, the high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring disclosed in the embodiment of the present invention has better comprehensive magnetic properties and higher pressing qualification rate than the comparative example product; the combined use of rare earth-rich alloy B and alloy C is beneficial to improving the above performance.

[0062] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties, characterized in that: The invention is prepared from the following components by weight: 9-10 parts of rare earth-poor alloy A, 0.1-1 parts of rare earth-rich alloy B, 0.8-1.2 parts of alloy C, 0.01-0.03 parts of lubricant, and 0.01-0.03 parts of aviation gasoline; the composition of the rare earth-poor alloy A is (PrNd) a1 (TM) b1 (HM) c1 B d1 Fe 100-a1-b1-1c-d1 The composition of the rare earth-rich alloy B is (PrNd) a2 (TM) b2 (HM) c2 B d2 Fe 100-a2-b2-c2-d2 wherein TM is one or more of Al, Cu, Co, Mn, and Ga, and HM is one or more of Nb, Zr, Hf, Ti, and V; a1, b1, c1, d1, a2, b2, c2, and d2 all represent weight percentages, and 28.5≤a1≤29.5, 0<b1≤2, 0<c1≤0.3, 0.93≤d1≤1.02, 31.5≤a2≤33, 0<b2≤0.5, 0<c2≤0.1, and 0.88≤d2≤0.92; and the alloy C comprises the following components by mass percentage: rare earth elements 29-32wt%, Ta 0.05-0.2wt%, In 0.1-0.3wt%, Re 0.02-0.08wt%, W 0.08-0.2wt%, Mo 0.1-0.4wt%, Ge 0.1-0.5wt%, B 0.9-1.2wt%, the balance is Fe.

2. The high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring according to claim 1, characterized in that: The mass percentage of Pr in the PrNd is 60-80wt%; the aviation gasoline is No. 75 aviation gasoline; and the lubricant is zinc stearate.

3. The high comprehensive magnetic performance sintered NdFeB multi-pole magnetic ring according to claim 1, characterized in that: The rare earth elements are Nd, Ce and Gd mixed in a mass ratio of (1-3):1:(0.8-1.2).

4. A method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to any one of claims 1 to 3, characterized in that: The steps include: Step S1, smelting and slicing: preparing the materials according to the composition of the poor rare earth alloy A, the rich rare earth alloy B, and the alloy C, and sequentially performing smelting, casting, slicing, and screening to obtain the poor rare earth alloy A casting sheet, the rich rare earth alloy B casting sheet, and the alloy C casting sheet; Step S2, powder preparation: placing the sieved rare earth-poor alloy A flakes, rare earth-rich alloy B flakes, and alloy C flakes in a hydrogen crushing furnace to hydrogen crush into coarse powders; then using a jet milling process under nitrogen protection to obtain jet milled powder of rare earth-poor alloy A, jet milled powder of rare earth-rich alloy B, and jet milled powder of alloy C, respectively; Step S3, powder mixing: mixing the jet-milled powder of the rare earth-poor alloy A, the rare earth-rich alloy B, the jet-milled powder of the alloy C, a lubricant, and aviation gasoline, and stirring uniformly to obtain a mixed powder; Step S4, orientation molding and isostatic pressing: the mixed powder is vertically oriented and pressed in a 1.2T magnetic field, and then pressed into a blank by an isostatic pressing process; Step S5, sintering and aging treatment: the blank prepared in step S4 is sintered; and then subjected to aging treatment to obtain a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties.

5. The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to claim 4, characterized in that: The smelting temperature of the rare earth-poor alloy A is 1455-1505°C, the casting temperature is 1445-1475°C, and the initial thickness of the sheet obtained by smelting is 0.15-0.45mm; the smelting temperature of the rare earth-rich alloy B is 1455-1505°C, the casting temperature is 1400-1445°C, and the initial thickness of the sheet obtained by smelting is 0.15-0.45mm.

6. The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to claim 4, characterized in that: The smelting temperature of the alloy C is 1450-1500° C., the casting temperature is 1420-1450° C., and the initial thickness of the slab obtained by smelting is 0.15-0.45 mm.

7. The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to claim 4, characterized in that: The average particle size of the jet-milled powder of the rare earth-poor alloy A is 2.9-3.1 μm; the average particle size of the jet-milled powder of the rare earth-rich alloy B is 2.6-2.8 μm; and the average particle size of the jet-milled powder of the alloy C is 2.5-3.0 μm.

8. The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to claim 4, characterized in that: The isostatic pressing process in step S4 adopts a segmented pressure holding process. The pressure in the first stage is 150-180 MPa, the pressure holding time is 20-40 seconds, the pressure in the second stage is 200-220 MPa, the pressure holding time is 40-60 seconds, and then the pressure is released to 100-150 MPa, the pressure holding time is 5-20 seconds, and finally the pressure is released to zero.

9. The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to claim 4, characterized in that: The sintering in step S5 is a multi-stage sintering carried out in a vacuum sintering furnace. The sintering temperature of the first stage is 150-200°C and the time is 1-2 hours. The sintering temperature of the second stage is 350-550°C and the time is 1-2 hours. The sintering temperature of the third stage is 1000-1050°C and the sintering time is 6-12 hours. The vacuum degree in the sintering furnace is below 5×10-2Pa.

10. The method for preparing a sintered NdFeB multi-pole magnetic ring with high comprehensive magnetic properties according to claim 4, characterized in that: The aging treatment in step S5 adopts a three-stage aging process, wherein the first stage aging treatment temperature is 600-860°C and the time is 2-4 hours, the second stage aging treatment temperature is 360-600°C and the time is 2-4 hours, and the third stage aging treatment temperature is 450-510°C and the time is 2-4 hours.