A rare earth permanent magnet material and its preparation method and application

Abstract

The present invention discloses a rare earth permanent magnet material, its preparation method and application. The average particle size of the main phase grains of the rare earth permanent magnet material is 5 to 10 μm; the particle size distribution ratio of the main phase grains of the rare earth permanent magnet material conforms to the curve distribution law. The average particle size of the main phase grains of the rare earth permanent magnet material in the present invention is relatively large, and it can ensure high coercive force while improving the magnetization characteristics of the rare earth permanent magnet material; the rare earth permanent magnet material in the present invention can achieve a magnetic susceptibility of more than 95% when the external magnetic field is greater than 20 kOe; and after the magnetic susceptibility reaches more than 93%, the slope of the curve of the external magnetic field and the magnetic susceptibility is large, the magnetic susceptibility growth rate is fast, and the "step-like" curve can be eliminated; the thermal demagnetization rate at 120°C can reach more than 98%.

Description

Technical Field

[0001] The invention relates to a rare earth permanent magnetic material and a preparation method and application thereof. Background Art

[0002] Rare earth permanent magnets, due to their excellent magnetic properties, are widely used in electronics, automobiles, wind power plants, home appliances, elevators, and industrial robots. For example, they serve as energy sources in hard drives, mobile phones, headphones, and permanent magnet motors like elevator traction motors and generators. As demand for these materials continues to grow, higher requirements are being placed on their magnetic properties and magnetization characteristics. Generally, high magnetic properties make it difficult for rare earth permanent magnets to achieve saturation magnetization. Therefore, there is a need for a rare earth permanent magnet material that meets both these requirements.

[0003] In existing technologies, when a high magnetizing magnetic field cannot be provided due to limitations in the application area or other objective conditions, the magnetic susceptibility of the rare earth permanent magnet material is easily low, thus failing to meet the required magnetic flux. Typically, to compensate for the low magnetic susceptibility of the rare earth permanent magnet material, a rare earth permanent magnet material with higher remanence is selected to meet the required magnetic flux. However, this approach results in a waste of excessive magnetic performance.

[0004] Therefore, it is necessary to provide a rare earth permanent magnet material having excellent magnetic properties and excellent magnetization characteristics under low magnetizing magnetic fields. Summary of the Invention

[0005] To address the low magnetic properties of rare earth permanent magnets in the prior art, particularly poor magnetization characteristics at low magnetizing magnetic fields, the present invention provides a rare earth permanent magnet material, a preparation method, and applications thereof. By adjusting the particle size of the fine alloy powder in the raw material composition of the rare earth permanent magnet material, the present invention produces a rare earth permanent magnet material with large grain size, a particle size distribution of the main phase grains that conforms to the gamma probability density function, and optimized magnetization characteristics while maintaining coercivity. In particular, after the magnetic susceptibility reaches above 93%, the slope of the curve plotting the applied magnetic field against the magnetic susceptibility is large, the magnetic susceptibility increases rapidly, and the "step-like" curve is eliminated.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] One of the technical solutions provided by the present invention is: a rare earth permanent magnet material. The average particle size of the main phase grains of the rare earth permanent magnet material is 5 to 10 μm;

[0008] The particle size distribution ratio of the main phase grains of the rare earth permanent magnet material conforms to the curve distribution law of formula I:

[0009]

[0010]

[0011] Wherein, formula II is the Gamma function;

[0012] Y is the particle size distribution ratio of the main phase grains of the rare earth permanent magnet material, and x is the particle size of the main phase grains of the rare earth permanent magnet material;

[0013] Among them, a is 6.57-8.27, b is 0.90-1.03; or, a is 11.57-15.07, b is 0.52-0.71.

[0014] In the present invention, preferably, a=7.57, b=0.9008; or, preferably, a=12.07, b=0.5258.

[0015] In the present invention, the particle size of the main phase grains may be the diameter of the circumscribed circle of the metallographic particles of the sintered magnet in any cross section of the main phase grains.

[0016] In the present invention, the average particle size of the main phase grains of the rare earth permanent magnet material is preferably 6 to 8.5 μm, for example, 6.5 μm.

[0017] In the present invention, those skilled in the art know that Formula I should generally be understood as a type of Gamma probability density function.

[0018] In the present invention, in the rare earth permanent magnet material, the total distribution proportion of main phase grains with different particle sizes is 100%.

[0019] In the rare earth permanent magnet material, the main phase grains with a particle size of less than 1 μm may account for 0-1% of the distribution; the main phase grains with a particle size of 2-4 μm may account for 0.5-30.0%, preferably 2-25%; the main phase grains with a particle size of 5-7 μm may account for 20-50%, preferably 25-50%; the main phase grains with a particle size of 8-10 μm may account for 10-35%, preferably 20-35%; the main phase grains with a particle size of 11-13 μm may account for 4.5-30%, preferably 5-25%; the main phase grains with a particle size of 14 μm or more may account for 0.5-5%, preferably 1.5-10%.

[0020] Preferably, in the rare earth permanent magnet material, the main phase grains with a particle size of 1 μm account for 0-1%, more preferably 0%; the main phase grains with a particle size of 2 μm account for 0-2%, more preferably 1%; the main phase grains with a particle size of 3 μm account for 1.5-9%, more preferably 8%; the main phase grains with a particle size of 4 μm account for 2.5-12.5%, more preferably 11%; the main phase grains with a particle size of 5 μm account for 5.5-22.5%, more preferably 20%; the main phase grains with a particle size of 6 μm account for 12-17%, more preferably 13%; the main phase grains with a particle size of 7 μm account for 9.5-16.5%, more preferably 14%; the main phase grains with a particle size of 8 μm account for 8-16.5%, More preferably, it is 10%; the main phase grains with a particle size of 9 μm account for 7.5-12.5% ​​of the distribution, more preferably 8%; the main phase grains with a particle size of 10 μm account for 4.5-8% of the distribution, more preferably 5%; the main phase grains with a particle size of 11 μm account for 3.5-11% of the distribution, more preferably 4%; the main phase grains with a particle size of 12 μm account for 3-8.5% of the distribution, more preferably 3%; the main phase grains with a particle size of 13 μm account for 1-8% of the distribution, more preferably 1%; the main phase grains with a particle size of 14 μm account for 0.5-4% of the distribution, more preferably 2%; the main phase grains with a particle size of 15 μm account for 0-2.5% of the distribution, more preferably 0%; the main phase grains with a particle size of more than 16 μm account for 0-2.5% of the distribution, more preferably 0%.

[0021] In a specific embodiment of the present invention, in the rare earth permanent magnet material, the main phase grains with a particle size of 2 μm account for 1% of the distribution; the main phase grains with a particle size of 3 μm account for 8% of the distribution; the main phase grains with a particle size of 4 μm account for 11% of the distribution; the main phase grains with a particle size of 5 μm account for 20% of the distribution; the main phase grains with a particle size of 6 μm account for 13% of the distribution; the main phase grains with a particle size of 7 ...1% of the distribution; the main phase grains with a particle size of 5 μm account for 20% of the distribution; the main phase grains with a particle size of 6 μm account for 13% of the distribution; the main phase grains with a particle size of 7 μm account for 13% of the distribution. The main phase grains with a particle size of 8μm account for 14% of the distribution; the main phase grains with a particle size of 8μm account for 10% of the distribution; the main phase grains with a particle size of 9μm account for 8% of the distribution; the main phase grains with a particle size of 10μm account for 5% of the distribution; the main phase grains with a particle size of 11μm account for 4% of the distribution; the main phase grains with a particle size of 12μm account for 3% of the distribution; the main phase grains with a particle size of 13μm account for 1% of the distribution; the main phase grains with a particle size of 14μm account for 2% of the distribution.

[0022] In the present invention, the rare earth permanent magnet material can be a conventional rare earth permanent magnet material in the art. Those skilled in the art know that the rare earth permanent magnet material can generally be an alloy formed by a rare earth metal and a transition metal, such as a neodymium iron boron rare earth permanent magnet material.

[0023] The composition and content of the rare earth permanent magnet material may be the composition and content of conventional rare earth permanent magnet materials in the art.

[0024] The main phase of the rare earth permanent magnet material may be Nd2Fe 14 B.

[0025] The rare earth permanent magnet material may include rare earth elements including at least Nd, Fe, B, Co, Cu, Ga, and one or more of the following elements: Ti, Zr, Al, and Nb. The rare earth elements preferably also include one or more of Pr, Tb, Dy, and Ho.

[0026] The rare earth permanent magnet material preferably includes Pr, Nd, Tb, Dy, Fe, Co, Ti, Cu, Ga and B.

[0027] The content of the rare earth element may be 28-33 wt%, preferably 28.5-32.5 wt%, and more preferably 29.85-31.25 wt%. The content of Pr may be 6.5-7.6 wt%, preferably 6.5-7.5 wt%, and more preferably 7.05-7.38 wt%. The content of Nd may be 21-23.9 wt%, preferably 21.15-22.12 wt%. The content of Tb may be 0.6-1.5 wt%, preferably 0.6-1.4 wt%, and more preferably 1.30 wt%. The content of Co may be 0.40-1.70 wt%, preferably 0.50-1.6 wt%. The content of Ti may be 0.1-0.2 wt%, preferably 0.12-0.16 wt%. The content of Cu may be 0.1-0.5 wt%, preferably 0.12-0.45 wt%. The Ga content may be 0.1-0.4 wt%, preferably 0.12-0.3 wt%. The B content may be 0.9-1.1 wt%, preferably 0.9-1.05 wt%. The Dy content may be 0.35-0.6 wt%, preferably 0.5-0.6 wt%. The Fe content may be the remainder. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0028] Alternatively, the rare earth permanent magnet material preferably includes Pr, Nd, Tb, Dy, Fe, Al, Co, Cu, Ga, Zr and B.

[0029] The content of the rare earth element may be 28.5-32.5 wt%. The content of Pr may be 0-8 wt%, preferably 6.5-7.5 wt%, and more preferably 6.54-7.35 wt%. The content of Nd may be 20-30 wt%, preferably 20.76-23.0 wt%. The content of Tb may be 0.6-1.4 wt%, preferably 0.7-1.3 wt%. The content of Co may be 0.5-1.6 wt%, preferably 0.6-1.3 wt%. The content of Cu may be 0.10-0.50 wt%, preferably 0.12-0.45 wt%. The content of Zr may be 0.05-0.2 wt%, preferably 0.08-0.16 wt%. The content of Ga may be 0.1-0.3 wt%, preferably 0.15-0.25 wt%. The B content may be 0.88 to 1.06 wt%, preferably 0.90 to 1.03 wt%. The Al content may be 0 to 0.65 wt%, preferably 0.2 to 0.6 wt%. The Dy content may be 0.35 to 0.6 wt%, preferably 0.4 to 0.6 wt%. The Fe content may be the remainder. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0030] According to the conventional art, the sum of the mass percentages of the mass of each component to the total mass of the rare earth permanent magnet material should be 100%.

[0031] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: 7.13 wt.% Pr, 21.38 wt.% Nd, 1.30 wt.% Tb, the balance Fe, 0.50 wt.% Co, 0.16 wt.% Ti, 0.12 wt.% Cu, 0.12 wt.% Ga, 0.93 wt.% B, and 0.50 wt.% Dy. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0032] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: 7.38 wt.% Pr, 22.12 wt.% Nd, 1.30 wt.% Tb, the balance being Fe, 0.80 wt.% Co, 0.16 wt.% Ti, 0.15 wt.% Cu, 0.12 wt.% Ga, 0.90 wt.% B, and 0.45 wt.% Dy. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0033] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: 7.25 wt.% Pr, 21.75 wt.% Nd, 1.30 wt.% Tb, the balance being Fe, 1.60 wt.% Co, 0.16 wt.% Ti, 0.25 wt.% Cu, 0.12 wt.% Ga, 1.05 wt.% B, and 0.60 wt.% Dy. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0034] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: 7.05 wt.% Pr, 21.15 wt.% Nd, 1.30 wt.% Tb, the balance being Fe, 0.70 wt.% Co, 0.12 wt.% Ti, 0.45 wt.% Cu, 0.3 wt.% Ga, 1.0 wt.% B, and 0.35 wt.% Dy. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0035] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: 30.0 wt.% Nd, 1.0 wt.% Tb, 0.6 wt.% Co, 0.12 wt.% Cu, 0.08 wt.% Zr, 0.15 wt.% Ga, 1.03 wt.% B, 0.6 wt.% Dy, and the balance Fe. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0036] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: Pr 6.54 wt.%, Nd 20.76 wt.%, Al 0.2 wt.%, Tb 1.3 wt.%, Co 0.90 wt.%, Cu 0.25 wt.%, Zr 0.16 wt.%, Ga 0.25 wt.%, B 0.95 wt.%, Dy 0.4 wt.%, and Fe as the balance. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0037] In one embodiment of the present invention, the rare earth permanent magnet material preferably includes the following components by weight: Pr 7.35 wt.%, Nd 23 wt.%, Al 0.6 wt.%, Tb 0.7 wt.%, Co 1.3 wt.%, Cu 0.45 wt.%, Zr 0.16 wt.%, Ga 0.15 wt.%, B 0.90 wt.%, Dy 0.6 wt.%, and Fe as the balance. The percentages are the mass percentages of each component relative to the total mass of the rare earth permanent magnet material.

[0038] In the present invention, the raw material components and product components of the rare earth permanent magnet material are basically the same, except for natural losses during the preparation process; therefore, when the rare earth permanent magnet material is prepared according to its components, the heavy rare earth elements, such as Dy, added during the grain boundary diffusion treatment and the matrix elements of the rare earth permanent magnet material are known to those skilled in the art to be processed separately according to the actual preparation process requirements.

[0039] The second technical solution provided by the present invention is: a method for preparing rare earth permanent magnet materials. The preparation method comprises sequentially subjecting raw materials of the rare earth permanent magnet materials to smelting, casting, hydrogen crushing, air flow milling, forming, sintering and diffusion heat treatment;

[0040] After the jet milling process, alloy fine powder with a median particle size D50 of 5.5 to 8 μm is obtained;

[0041] The particle size distribution ratio of the main phase grains of the rare earth permanent magnet material prepared by the preparation method is the distribution ratio mentioned above.

[0042] In the present invention, the smelting can be carried out in a vacuum belt furnace.

[0043] The vacuum degree of the vacuum belt furnace may be less than 0.1 Pa, preferably less than 0.02 Pa.

[0044] The smelting temperature may be 1450-1550°C, preferably 1500-1550°C.

[0045] In the present invention, the casting operation and conditions can be conventional in the art, generally carried out in an inert atmosphere to obtain alloy strip sheets. 2 ℃ / second-10 4 ℃ / second. Preferably, the cooling speed is 5.5×10 4 Pa Ar atmosphere, with 10 2 ℃ / second-10 4 ℃ / second speed of cooling.

[0046] In the present invention, the hydrogen cracking generally includes a hydrogen absorption process and a dehydrogenation process. The alloy strip sheet can be subjected to hydrogen cracking treatment to obtain alloy powder.

[0047] The hydrogen absorption temperature may be 20-300°C, for example 25°C.

[0048] The hydrogen absorption pressure may be 0.12-0.19 MPa, for example 0.19 MPa.

[0049] The dehydrogenation time may be 0.5 to 5 hours, for example 2 hours.

[0050] The dehydrogenation temperature may be 450-600°C, for example 550°C.

[0051] In the present invention, the air jet mill may be a process of feeding the alloy powder into an air jet mill for further crushing to obtain fine alloy powder.

[0052] The air jet mill equipment can be conventional air jet mill equipment in the art.

[0053] The grinding pressure of the jet mill can be 0.3-0.5 MPa, for example 0.4 MPa.

[0054] The median particle size D50 of the alloy fine powder is preferably 6.5 to 7.5 μm, for example, 6.5 μm, 6.7 μm, 6.9 μm, 7.2 μm or 7.3 μm.

[0055] In the present invention, the molding operation and conditions may be conventional in the art, and are generally performed at a magnetic field strength of 1.8 T or higher and under nitrogen atmosphere protection.

[0056] In the present invention, the sintering operation and conditions may be conventional in the art.

[0057] The sintering temperature may be 1030-1090°C, preferably 1050-1080°C.

[0058] The sintering time may be 3 to 10 hours, preferably 5 hours.

[0059] In the present invention, the operation and conditions of the diffusion heat treatment may be conventional in the art, and generally include grain boundary diffusion treatment and secondary aging treatment.

[0060] The grain boundary diffusion treatment may be a conventional grain boundary diffusion treatment in the art, and the predetermined temperature in the grain boundary diffusion treatment may be 800-1000°C.

[0061] The temperature of the secondary aging treatment may be 400° C. to 560° C., for example, 450° C. to 490° C. The time of the secondary aging treatment may be 2 to 5 hours, for example, 3 hours.

[0062] The third technical solution provided by the present invention is: a rare earth permanent magnet material prepared by the above preparation method.

[0063] Wherein, the average particle size of the main phase grains of the rare earth permanent magnet material is as described above.

[0064] The particle size distribution ratio of the main phase grains of the rare earth permanent magnet material is as described above.

[0065] The raw material composition of the rare earth permanent magnet material is as described above.

[0066] The fourth technical solution provided by the present invention is: an application of the rare earth permanent magnet material as described above as an electronic component in a motor.

[0067] The application may be use as an electronic component in high-speed motors and / or household electrical appliances.

[0068] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0069] The reagents and raw materials used in the present invention are commercially available.

[0070] The positive and progressive effects of the present invention are: the average grain size of the main phase of the rare earth permanent magnet material is large, and the magnetic properties (remanence Br and coercivity Hcj) are excellent. While maintaining high coercivity, the magnetization characteristics of the rare earth permanent magnet material are improved. The rare earth permanent magnet material of the present invention can achieve a magnetic susceptibility of over 95% when the external magnetic field is greater than 20 kOe. Furthermore, when the magnetic susceptibility reaches over 93%, the slope of the curve plotting the applied magnetic field versus the magnetic susceptibility is large, the magnetic susceptibility increases rapidly, and the "step-like" curve is eliminated. Furthermore, the thermal demagnetization rate at 120°C can reach over 98%. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 Schematic diagram of the particle size distribution of the main phase grains of the rare earth permanent magnet material in Example 1.1.

[0072] Figure 2 Schematic diagram of the magnetic susceptibility of the rare earth permanent magnet material in Example 1.1 under different external magnetic field conditions.

[0073] Figure 3 Schematic diagram of the test standard for the main phase grain size of rare earth permanent magnet materials in Example 1.1. DETAILED DESCRIPTION

[0074] The present invention is further illustrated by way of examples below, but the present invention is not limited to the scope of the examples. Experimental methods in the following examples where specific conditions are not specified were performed according to conventional methods and conditions, or selected according to the product specifications.

[0075] Examples 1.1 to 1.4 and Comparative Examples 1 to 2

[0076] The components and contents of the rare earth permanent magnet material raw material compositions in Examples 1.1 to 1.4 and Comparative Examples 1 to 2 are shown in Table 1 below, wherein Dy is added during the grain boundary diffusion treatment.

[0077] Table 1

[0078]

[0079] The preparation method of the rare earth permanent magnet material in Examples 1.1 to 1.4 and Comparative Examples 1 to 2 comprises the following steps:

[0080] (1) Melting: According to the formula shown in Table 1, the prepared raw materials are placed in a vacuum belt furnace and heated at 1 × 10 -2 Pa under vacuum conditions and at a temperature of 1500 ° C, the molten liquid is obtained after complete melting; 4 Pa Ar atmosphere, with 10 2 ℃ / second-10 4 The alloy is cooled at a rate of ℃ / second and cast into alloy strips.

[0081] (2) Powdering: The alloy strips in step (1) are subjected to hydrogen crushing for coarse crushing, and then finely pulverized using a jet mill. Specifically, the hydrogen crushing furnace is evacuated at room temperature, and then hydrogen with a purity of 99.9% is introduced into the hydrogen crushing furnace, and the hydrogen pressure is maintained at 0.19 MPa and the temperature is 25°C. After sufficient hydrogen absorption, the temperature is raised to 550°C while evacuating the furnace, and the hydrogen is fully dehydrogenated for 2 hours. After cooling, the powder after hydrogen crushing is taken out; the powder after hydrogen crushing is subjected to jet milling for 3 hours under a nitrogen atmosphere with an oxidizing gas (oxygen or moisture) content of less than 120 ppm and a crushing chamber pressure of 0.4 MPa to obtain alloy fine powder. The median particle size D50 of the alloy fine powder is shown in Table 2.

[0082] Table 2

[0083]

[0084] (3) Powder mixing: The alloy fine powder in step (2) is mixed uniformly in a mixer.

[0085] (4) Molding: Use a right-angle orientation magnetic field molding machine, in an orientation magnetic field of 1.6T, at 0.35ton / cm 2 Under the molding pressure of 1.5 ton / cm, the alloy fine powder mixed in step (3) was molded into a cube with a side length of 25 mm. After the primary molding, it was demagnetized in a magnetic field of 0.2 T. In order to prevent the molded body from contacting the air after the primary molding, it was sealed and then a secondary molding machine (isostatic pressing machine) was used to press the molded body at 1.3 ton / cm 2 The secondary molding is performed under a pressure of 100 to obtain a molded body.

[0086] (5) Sintering: The molded body in step (4) is placed in a sintering furnace for sintering at 5×10 -3 Pa vacuum conditions, after maintaining at 300 ° C and 600 ° C for 1 hour each, sintering at a temperature of 1050 ~ 1080 ° C for 5 hours, then passing Ar gas to make the gas pressure reach 0.1 MPa, and then cooling to room temperature to obtain a sintered magnet.

[0087] (6) Diffusion heat treatment: The sintered body in step (5) is processed into a cube of 25 mm × 20 mm × 3 mm (where 3 mm is the orientation direction) and subjected to grain boundary diffusion treatment at a predetermined temperature of 800 to 1000°C; after the grain boundary diffusion treatment, a secondary aging treatment is performed for 3 hours at a temperature of 400 to 560°C.

[0088] Comparative Examples 1-2

[0089] The components and contents of the rare earth permanent magnet material raw material compositions in Comparative Examples 1 to 2 are the same as those in Example 1.1; in step (2) of the preparation method, after airflow milling, the median particle size D50 of the alloy fine powder is shown in Table 2, and the rest are the same as in Examples 1.1 to 1.4.

[0090] Examples 2.1 to 2.3

[0091] The components and contents of the raw material compositions of rare earth permanent magnet materials in Examples 2.1 to 2.3 are shown in Table 3 below, wherein Dy is added during the grain boundary diffusion treatment.

[0092] Table 3

[0093]

[0094] In step (2) of the preparation method of rare earth permanent magnet material in Examples 2.1 to 2.3, after air flow milling, the median particle size D50 of the alloy fine powder is shown in Table 4, and the rest are the same as in Examples 1.1 to 1.4.

[0095] Table 4

[0096] Example 2.1 Example 2.2 Example 2.3 Median particle size D50 (μm) 6.5 7.3 6.9

[0097] Effect embodiment

[0098] 1. Particle size distribution ratio of main phase grains

[0099] The main phase grain size in the above embodiments and comparative examples refers to the circumscribed circle diameter of the metallographic grains of the sintered magnet in any cross section of the main phase grains.

[0100] like Figure 3 As shown, polygons are main phase grains, d is the circumscribed circle diameter of the metallographic particles of the sintered magnet in Example 1.1, that is, the grain size of the main phase grains of the rare earth permanent magnet material in Example 1.1.

[0101] (1) Measurement and calculation

[0102] Measurement object: sintered body metallography.

[0103] Measurement tool: ImageJ software was used for measurement.

[0104] Measurement method: Draw three straight lines at random on the metallographic image to be measured, measure the particle size of each grain on each line segment, and perform statistical analysis on the results. The total number of the measured main phase grains is automatically recorded using ImageJ software.

[0105] Measure the total number of main phase grains and record it as A;

[0106] The number of main phase grains with a particle size of i μm is measured and recorded as B; where i μm is (i- 0.5) μm to (i+0.5) μm;

[0107] From the above, it can be calculated that the measured value of the particle size distribution ratio of the main phase grains with a particle size of i μm is

[0108]

[0109] ; Wherein, i takes values ​​of 1, 2, 3, 4... to n.

[0110] (2) Judgment method

[0111] Statistical methods are used to evaluate whether the particle size distribution ratio of the main phase grains in (1) above conforms to the curve distribution law in formula I.

[0112]

[0113]

[0114] Wherein, formula I is the Gamma probability density function, and formula II is the Gamma function;

[0115] Y is the particle size distribution ratio of the main phase grains of the rare earth permanent magnet material, and x is the particle size of the main phase grains of the rare earth permanent magnet material;

[0116] a is 6.57-8.27, b is 0.90-1.03; or, a is 11.57-15.07, b is 0.52-0.71.

[0117] (3) Judgment criteria

[0118] ① The measured values ​​of the particle size distribution ratio of the main phase grains in the above-mentioned embodiment and comparative example are plotted into a curve and compared with the function fitting curve of Formula I. If the plotted curve is near the function fitting curve of Formula I, it is preliminarily judged that the particle size distribution ratio of the main phase grains in the embodiment or comparative example conforms to the curve distribution law in Formula I.

[0119] like Figure 1, where a = 7.57 and b = 0.9008, the curve obtained by plotting the measured values ​​of the particle size distribution ratio of the main phase grains in Example 1.1 is near the function fitting curve of Formula I. Based on this, it is preliminarily determined that the particle size distribution ratio of the main phase grains in Example 1.1 conforms to the distribution pattern of the curve in Formula I. At the same time, when a = 12.07 and b = 0.5258, the curve obtained by plotting the measured values ​​of the particle size distribution ratio of the main phase grains in Example 1.1 is also near the function fitting curve of Formula I. It can be preliminarily determined that the particle size distribution ratio of the main phase grains in Example 1.1 conforms to the distribution pattern of the curve in Formula I.

[0120] ②Calculate the correlation coefficient R 2 , when R 2 When ≥0.6, the curve obtained by plotting the measured value of the particle size distribution ratio of the main phase grains of the rare earth permanent magnet material is near the function fitting curve of Formula I, and the correlation is strong.

[0121] The correlation determination coefficient R in the above embodiments and comparative examples is 2 The calculation results are shown in Table 6. Among them, R 2 ≥0.6, that is, the curve obtained by plotting the measured values ​​of the particle size distribution ratio of the main phase grains of the rare earth permanent magnet materials of Examples 1.1 to 1.4 and Examples 2.1 to 2.3 is near the function fitting curve of Formula I, and the correlation is strong. 2 It is obviously less than 0.6, that is, the curve obtained by plotting the measured values ​​of the particle size distribution ratio of the main phase grains of the rare earth permanent magnet materials of Comparative Examples 1 to 2 is far from the function fitting curve of Formula I, and the correlation degrees are general correlation and weak correlation, respectively.

[0122] Among them, the correlation coefficient R 2 The calculation method is: R 2 = regression sum of squares / total sum of squares; regression sum of squares = total sum of squares - residual sum of squares.

[0123] As mentioned above, the measured value of the main phase grain size distribution ratio with a particle size of i μm is y i The calculated value of the particle size distribution ratio of the main phase grains with a particle size of i μm calculated according to formula I is Y i , i takes values ​​of 1, 2, 3, 4... to n. Then:

[0124] Total square sum = measured value y of the main phase grain size distribution ratio with a grain size of i μm i The sum of the squares of

[0125] Residual sum of squares = (measured value y of the main phase grain size distribution ratio with a grain size of i μm) i-Calculated value Y of the particle size distribution ratio of the main phase grains with a particle size of i μm i ), that is,

[0126] Based on this,

[0127]

[0128] Table 5 shows the correlation judgment criteria.

[0129] Table 5

[0130] <![CDATA[R 2 ]]> Relevance 0～0.1 Weak correlation 0.1～0.6 General 0.6～1 Strong correlation

[0131] 2. Magnetic property evaluation: The magnetic properties were tested using the PFM-14 magnetic property measuring instrument from Hirst, a British company.

[0132] The magnetic properties test results are shown in Table 6.

[0133] 3. Magnetic susceptibility test:

[0134] The rare earth permanent magnet materials in the above-described embodiments or comparative examples were magnetized using a pulsed charging and demagnetization power supply, with an applied magnetic field of 18 to 50 kOe. Specifically, the rare earth permanent magnet materials were magnetized in increasing order of applied magnetic field strength. After magnetization, the total magnetic flux was measured using an NFX-1000 fluxmeter. The rare earth permanent magnet materials subjected to an applied magnetic field of 50 kOe were considered fully magnetized rare earth permanent magnet materials. The magnetic susceptibility was calculated as follows: magnetic susceptibility under different applied magnetic fields = (magnetic flux under different applied magnetic fields) / (magnetic flux at an external magnetic field of 50 kOe) × 100%.

[0135] The magnetic susceptibility of the rare earth permanent magnet materials in Example 1.1 and Comparative Example 1 is as follows: Figure 2 shown.

[0136] Depend on Figure 2 It can be seen that after the diffusion aging treatment, the magnetic susceptibility of the sintered magnet in Example 1.1 can reach above 95% when the external magnetic field is greater than 20 kOe. Moreover, after the magnetic susceptibility reaches above 93%, the slope of the curve of the external magnetic field vs. magnetic susceptibility is large, indicating that the magnetic susceptibility increases rapidly and no "step-like" curve appears.

[0137] After diffusion aging treatment, the sintered magnet in Comparative Example 1 has a significantly lower magnetic susceptibility than that in Example 1.1 when the applied magnetic field is greater than 20 kOe. Moreover, after the magnetic susceptibility reaches above 93%, the magnetic susceptibility increases at a slow rate, and the curve of the applied magnetic field versus the magnetic susceptibility exhibits a "step-like" appearance.

[0138] (4) Thermal demagnetization rate test

[0139] In the above examples and comparative examples, thermal demagnetization rate = (Φ(120℃) / Φ (20℃) )×100%.

[0140] Among them, Φ (20℃) Refers to the magnetic flux value of the magnet at room temperature (20°C); Φ (120℃) It is the magnetic flux value of the magnet measured after the magnet is kept in an environment of 120℃ for 10 minutes and then the ambient temperature is restored to room temperature (20℃).

[0141] The results are shown in Table 6.

[0142] Table 6

[0143]

[0144] It can be seen from the above data that the average particle size of the main phase grains of the rare earth permanent magnet material in the above embodiment is large, the magnetic properties (remanence Br and coercive force Hcj) are excellent, and it can ensure that the magnetization characteristics of the rare earth permanent magnet material are improved while the coercive force is high. The thermal demagnetization rate of the rare earth permanent magnet material in the above embodiment at 120°C can reach more than 98%.

Claims

1. A rare earth permanent magnet material, characterized in that: The average particle size of the main phase grains of the rare earth permanent magnet material is 5-10 μm; The particle size distribution ratio of the main phase grains of the rare earth permanent magnet material conforms to the curve distribution law of formula I: Formula I Formula II Wherein, formula II is the Gamma function; Y is the particle size distribution ratio of the main phase grains of the rare earth permanent magnet material, and x is the particle size of the main phase grains of the rare earth permanent magnet material; Among them, a is 6.57~8.27, b is 0.90~1.03; or, a is 11.57~15.07, b is 0.52~0.

71.

2. The rare earth permanent magnet material according to claim 1, wherein a=7.57, b=0.9008; or, a=12.07, b=0.5258; And / or, the average particle size of the main phase grains of the rare earth permanent magnet material is 6-8.5 μm.

3. The rare earth permanent magnet material according to claim 2, characterized in that: The average particle size of the main phase grains of the rare earth permanent magnet material is 6.5 μm.

4. The rare earth permanent magnet material according to claim 1, characterized in that In the rare earth permanent magnet material, the main phase grains with a particle size of less than 1 μm account for 0-1% of the distribution; the main phase grains with a particle size of 2-4 μm account for 0.5-30.0% of the distribution; the main phase grains with a particle size of 5-7 μm account for 20-50% of the distribution; the main phase grains with a particle size of 8-10 μm account for 10-35% of the distribution; the main phase grains with a particle size of 11-13 μm account for 4.5-30% of the distribution; and the main phase grains with a particle size of more than 14 μm account for 0.5-5% of the distribution.

5. The rare earth permanent magnet material according to claim 4, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 2 to 4 μm account for 2 to 25% of the distribution.

6. The rare earth permanent magnet material according to claim 4, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 5 to 7 μm account for 25 to 50% of the distribution.

7. The rare earth permanent magnet material according to claim 4, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 8 to 10 μm account for 20 to 35% of the distribution.

8. The rare earth permanent magnet material according to claim 4, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 11 to 13 μm account for 5 to 25% of the distribution.

9. The rare earth permanent magnet material according to claim 4, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 14 μm or more account for 1.5-10% of the distribution.

10. The rare earth permanent magnet material according to claim 1, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 1 μm account for 0-1% of the distribution; the main phase grains with a particle size of 2 μm account for 0-2% of the distribution; the main phase grains with a particle size of 3 μm account for 1.5-9% of the distribution; the main phase grains with a particle size of 4 μm account for 2.5-12.5% ​​of the distribution; the main phase grains with a particle size of 5 μm account for 5.5-22.5% of the distribution; the main phase grains with a particle size of 6 μm account for 12-17% of the distribution; the main phase grains with a particle size of 7 μm account for 9.5-16.5% of the distribution; the main phase grains with a particle size of 8 μm account for 1.5-12.5% ​​of the distribution; the main phase grains with a particle size of 5 μm account for 1.5-22.5% of the distribution; the main phase grains with a particle size of 6 μm account for 12-17% of the distribution; the main phase grains with a particle size of 7 μm account for 9.5-16.5% of the distribution; the main phase grains with a particle size of 8 μm account for 1.5-12.5% ​​of the distribution. The main phase grains with a particle size of 9μm account for 8~16.5% of the distribution; the main phase grains with a particle size of 9μm account for 7.5~12.5% ​​of the distribution; the main phase grains with a particle size of 10μm account for 4.5~8% of the distribution; the main phase grains with a particle size of 11μm account for 3.5~11% of the distribution; the main phase grains with a particle size of 12μm account for 3~8.5% of the distribution; the main phase grains with a particle size of 13μm account for 1~8% of the distribution; the main phase grains with a particle size of 14μm account for 0.5~4% of the distribution; the main phase grains with a particle size of 15μm account for 0~2.5% of the distribution; the main phase grains with a particle size of more than 16μm account for 0~2.5% of the distribution.

11. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 1 μm account for 0% of the distribution.

12. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 2 μm account for 1% of the distribution.

13. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 3 μm account for 8% of the distribution.

14. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 4 μm account for 11% of the distribution.

15. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 5 μm account for 20% of the distribution.

16. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 6 μm account for 13% of the distribution.

17. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 7 μm account for 14% of the distribution.

18. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 8 μm account for 10% of the distribution.

19. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 9 μm account for 8% of the distribution.

20. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 10 μm account for 5% of the distribution.

21. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 11 μm account for 4% of the distribution.

22. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 12 μm account for 3% of the distribution.

23. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 13 μm account for 1% of the distribution.

24. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 14 μm account for 2% of the distribution.

25. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the main phase grains with a particle size of 15 μm account for 0% of the distribution.

26. The rare earth permanent magnet material according to claim 10, characterized in that: In the rare earth permanent magnet material, the distribution proportion of main phase grains with a particle size of 16 μm or more is 0%.

27. The rare earth permanent magnet material according to claim 1, characterized in that: The rare earth permanent magnet material is neodymium iron boron rare earth permanent magnet material; And / or, the main phase of the rare earth permanent magnet material is Nd2Fe 14 B.

28. The rare earth permanent magnet material according to claim 1, characterized in that: The rare earth permanent magnet material includes rare earth elements including at least Nd, Fe, B, Co, Cu, Ga, and one or more of the following elements: Ti, Zr, Al and Nb.

29. The rare earth permanent magnet material according to claim 28, characterized in that: The rare earth permanent magnet material includes one or more of Pr, Tb, Dy and Ho.

30. The rare earth permanent magnet material according to claim 28, characterized in that: The rare earth permanent magnet material includes Pr, Nd, Tb, Dy, Fe, Co, Ti, Cu, Ga and B, or Pr, Nd, Tb, Dy, Fe, Al, Co, Cu, Ga, Zr and B.

31. A method for preparing a rare earth permanent magnet material according to any one of claims 1 to 26, characterized in that: The method comprises the following steps: sequentially performing smelting, casting, hydrogen cracking, air flow grinding, forming, sintering and diffusion heat treatment on raw materials of rare earth permanent magnet materials; After the jet milling process, alloy fine powder with a median particle size D50 of 5.5-8 μm is obtained; The particle size distribution ratio of the main phase grains of the rare earth permanent magnet material prepared by the preparation method is the distribution ratio as described in any one of claims 1 to 26.

32. The method for preparing a rare earth permanent magnetic material according to claim 31, wherein: The smelting is carried out in a vacuum belt furnace; And / or, the smelting temperature is 1450-1550°C; And / or, the hydrogen cracking includes a hydrogen absorption process and a dehydrogenation process; And / or, the grinding pressure of the jet mill is 0.3-0.5 MPa; and / or, the median particle size D50 of the alloy fine powder is 6.5-7.5 μm; And / or, the sintering temperature is 1030-1090°C; And / or, the sintering time is 3 to 10 hours; And / or, the diffusion heat treatment includes grain boundary diffusion treatment and secondary aging treatment.

33. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The vacuum degree of the vacuum belt spinning furnace is less than 0.1 Pa.

34. The method for preparing a rare earth permanent magnetic material according to claim 32, wherein: The temperature of the hydrogen absorption is 20-300°C.

35. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The hydrogen absorption pressure is 0.12~0.19MPa.

36. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The dehydrogenation time is 0.5~5h.

37. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The dehydrogenation temperature is 450-600°C.

38. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The median particle size D50 of the alloy fine powder is 6.5 μm, 6.7 μm, 6.9 μm, 7.2 μm or 7.3 μm.

39. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The sintering temperature is 1050-1080°C.

40. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The sintering time is 5 hours.

41. The method for preparing a rare earth permanent magnetic material according to claim 32, wherein: The predetermined temperature in the grain boundary diffusion treatment is 800-1000°C.

42. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The temperature of the secondary aging treatment is 400°C to 560°C.

43. The method for preparing the rare earth permanent magnetic material according to claim 32, wherein: The secondary aging treatment time is 2 to 5 hours.

44. A rare earth permanent magnetic material obtained by the method for preparing a rare earth permanent magnetic material according to any one of claims 31 to 43.

45. Use of the rare earth permanent magnet material according to any one of claims 1 to 30 or claim 44 as an electronic component in a motor.

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