Magnet with high burning resistance and preparation method thereof

Abstract

The invention discloses a magnet with high burning resistance and a preparation method thereof, the neodymium iron boron magnet material comprises the following components in percentage by weight: 30 wt% or more of R and 32 wt% or less of R, 61 wt% or more of T and 66 wt% or less of T, and T at least comprises Fe; b: 0.5 wt% < = B < = 2 wt%; m is larger than or equal to 3.0 wt% and smaller than or equal to 8 wt%, and M is one or more of Al, Cu, Nb, Zn, Ga, Ag, In, Sn, Bi, Cr and Ta; the raw material composition is subjected to smelting, heat treatment, hydrogen demolishing, jet milling, screening, mixing, pressing and sintering treatment, and the magnet with the high burning resistance is obtained. By adding low heavy rare earth Tb + Dy, heavy rare earth resources are saved, the formula cost is remarkably reduced, meanwhile, the heat resistance is remarkably improved by adding superfine Zr, Hf, Mo, W and Ni metal powder, fine powder screening and heat treatment processes are combined, it is guaranteed that the grain size of a main phase of sintered neodymium iron boron is 2-6 microns, neodymium-rich phases are evenly distributed, and good comprehensive performance is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of neodymium iron boron metal materials, and in particular relates to a magnet with high burning resistance and a preparation method thereof. Background Art

[0002] Since its appearance in 1983, NdFeB magnets have been widely used in computers, automobiles, medical treatment, wind power generation and other fields. At the same time, higher requirements are placed on the application performance of NdFeB magnets, especially their burning resistance. On the other hand, due to the limitation of heavy rare earth resources, it is necessary to reduce the dependence on heavy rare earth.

[0003] At present, in order to obtain high performance during the preparation of NdFeB magnets, a large amount of metal Dy and Tb is added, resulting in huge consumption of metal Dy and Tb; on the other hand, Dy and Tb are heavy rare earth elements with limited resources and high prices.

[0004] Metal Zr, metal Hf, metal W, metal Mo, and metal Ni are high melting point metals with excellent metal burning resistance. Ultrafine metal powders of each metal have excellent burning resistance, and the sintering heat treatment of NdFeB can play a role in hindering the growth of grains. At the same time, adding ultrafine powder in the powder making stage can improve the utilization rate of metal elements.

[0005] The formation of a stable high melting point phase effectively improves the comprehensive performance of NdFeB magnets, especially the burning resistance. At present, there are related studies on the addition of Zr\Hf\W\Mo\Ni metals, but there is a lack of research on comprehensive utilization. Summary of the invention

[0006] The object of the present invention is to provide a magnet with high burning resistance and a preparation method thereof, so as to solve the problems raised in the above background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a magnet with high burning resistance and a preparation method thereof, wherein the NdFeB magnet material comprises the following components by weight percentage:

[0008] R: 30wt%≤R≤32wt%,

[0009] T: 61wt%≤T≤66wt%, wherein T includes at least Fe;

[0010] B: 0.5wt%≤B≤2wt%;

[0011] M: 3.0wt%≤M≤8wt%, wherein M is one or more of Al, Cu, Nb, Zn, Ga, Ag, In, Sn, Bi, Cr, and Ta.

[0012] Preferably, the R is a rare earth element, and the R includes a light rare earth element RL and a heavy rare earth element RH.

[0013] Preferably, the heavy rare earth elements RH include Tb and Dy.

[0014] Preferably, the sum of the contents of Tb and Dy is: 0wt%<Tb+Dy≤1wt%.

[0015] A magnet with high burning resistance and a preparation method thereof, wherein a raw material composition is subjected to smelting, heat treatment, hydrogen cracking, air flow grinding, screening, mixing, pressing and sintering treatment to obtain the magnet with high burning resistance.

[0016] The specific steps include:

[0017] S10: forming a quick-setting sheet from the raw material mixture by smelting, and heat-treating the quick-setting sheet;

[0018] S20: using a hydrogen crushing method to feed the quick-setting sheet into a continuous hydrogen powder crushing furnace and crush it into coarse metal powder;

[0019] S30: adding an additive to the coarse metal powder, stirring and grinding into fine powder;

[0020] S40: screening the metal fine powder to obtain fine powder with an average particle size of 3 μm, and mixing the fine powder with ultrafine metal powder;

[0021] S50: pressing the metal mixed powder under an oriented magnetic field to obtain a blank;

[0022] S60: performing sintering and tempering treatments on the blank to obtain a magnet with high sintering resistance.

[0023] Preferably, the ultrafine metal powder is a mixture of Zr, Hf, Mo, W and Ni metal powders.

[0024] Preferably, in terms of weight percentage, the ultrafine metal powder 0wt%<

[0025] Zr+Hf+Mo+W+Ni≤0.5wt%.

[0026] Preferably, in step S10, the heat treatment temperature is 500-1100°C, the time is 2h-24h, and the rapid cooling temperature is -170-10°C.

[0027] Preferably, in step S20, the temperature of hydrogen crushing in the hydrogen powder crushing furnace is 400-600°C and the time is 6-24h;

[0028] The pressing pressure in step S50 is 200-600 Kg / cm2, the orientation field is (2-20)X104Oe, and the oxygen concentration during the pressing process is less than 0.01%;

[0029] In the step S60, the first sintering treatment temperature is 1000℃-1100℃, the sintering time is 1-6 hours, and then rapid cooling is performed; then the second sintering is performed, the second sintering temperature is 1000℃-1100℃, the sintering time is 1h-6h, and then the second rapid cooling is performed, and then the tempering treatment is performed, the first tempering temperature is 700℃-900℃, the tempering time is 0h-6h, and the second tempering time is 400℃-700℃, and the second tempering time is 1h-6h.

[0030] Technical effects and advantages of the present invention:

[0031] 1. The present invention saves heavy rare earth resources by adding low-heavy rare earth Tb+Dy, so that the formula cost is significantly reduced;

[0032] 2. The present invention significantly improves the burning resistance by adding ultrafine Zr, Hf, Mo, W, and Ni metal powders; at the same time, adding ultrafine powders in the powder making stage can improve the utilization rate of metal elements.

[0033] 3. In the present invention, the quick-setting sheet is heat-treated and rapidly cooled, so that the quick-setting sheet has a more uniform structure.

[0034] 4. The present invention combines fine powder screening and heat treatment processes to ensure that the grain size of the sintered NdFeB main phase is 2-6 μm and the Nd-rich phase is evenly distributed.

[0035] 5. The NdFeB magnets of the present invention have excellent heat resistance and good comprehensive capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a preparation flow chart of the present invention;

[0037] Figure 2 is a cross-sectional grain diagram of the present invention;

[0038] Figure 3 This is the microstructure diagram of the alloy sheet of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] like Figure 1-3 The specific implementation of a magnet with high burning resistance and a preparation method thereof of the present invention is shown:

[0041] Examples 1 to 9

[0042] The metal raw materials are mixed with a Tb+Dy content of 0-1%. In Examples 1-3, the ratio of ultrafine Zr+Hf+W+Mo+Ni powder is 0-0.3, wherein the ultrafine powder ratio Zr:Hf:W:Mo:Ni is 1:1:1:1:1;

[0043] In Examples 4 to 6, the ratio of ultrafine Zr+Hf+W+Mo+Ni powder is 0.3-0.5, wherein the ultrafine powder ratio Zr:Hf:W:Mo:Ni is 2:1:1:1:1;

[0044] In Examples 7 to 9, the ratio of ultrafine Zr+Hf+W+Mo+Ni powder is 0.3-0.5, wherein the ultrafine powder ratio Zr:Hf:W:Mo:Ni is 1:1:2:1:1;) it is melted in a 600Kg / time strip continuous casting smelting furnace, and quick-setting sheet casting is carried out at a roller linear speed of 0.2-4m per second, and finally a quick-setting sheet with a thickness of 0.2-0.4mm is obtained.

[0045] The quick-setting sheet is heat treated at a temperature of 500-1100°C for 2h-24h, and the rapid cooling temperature is -170-10°C.

[0046] The quick-setting sheets are sent to a continuous hydrogen powder crushing furnace for hydrogen crushing at a temperature of 400-600°C for 6-24 hours.

[0047] The crushed materials after hydrogen pulverization are prepared into fine powder, and specially prepared polyvinyl alcohol is added in the process, and finally a powder with extremely narrow distribution and average particle size of 1 to 4 μm is obtained.

[0048] The powder is sent to a magnetic orientation molding device for compression molding, with a pressure of 200-600 Kg / cm2, an orientation field of (2-20)X104Oe, and an oxygen concentration of less than 0.01% during the compression process.

[0049] Finally, a sintering treatment is carried out at (1000-1100)°C X (1-6) h, followed by rapid cooling, and then a tempering treatment is carried out at (1000-1100)°C X (1-6) h, rapid cooling, and then a tempering treatment is carried out at (700-900°C) X (0-6) h and (400-700)°C X (1-6) h.

[0050] Example Results

[0051]

[0052]

[0053] Burning resistance data:

[0054] Proven:

[0055] Conventional preparation method: Under the condition of 20-80℃, the absolute value of the remanence temperature coefficient α is ≤0.13, and the absolute value of the coercive force temperature coefficient β is ≤0.52;

[0056] This preparation method: under the condition of 20-80℃, the absolute value of the remanence temperature coefficient α is ≤0.11, and the absolute value of the coercive force temperature coefficient β is ≤0.47.

[0057] The invention saves heavy rare earth resources and significantly reduces the formulation cost by adding low-heavy rare earth Tb+Dy. Meanwhile, the addition of ultrafine Zr, Hf, Mo, W and Ni metal powders significantly improves the heat resistance. Combined with fine powder screening and heat treatment processes, the grain size of the sintered NdFeB main phase is ensured to be 2-6μm, the Nd-rich phase is evenly distributed, and the invention has good comprehensive performance.

[0058] The applicant further declares that the present invention illustrates the implementation method and device structure of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned implementation methods, that is, it does not mean that the present invention must rely on the above-mentioned methods and structures to be implemented. Those skilled in the art should understand that any improvement to the present invention, equivalent replacement of the implementation method selected by the present invention, addition of steps, selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

[0059] The present invention is not limited to the above-mentioned embodiments, and all methods that use structures and methods similar to the present invention to achieve the purpose of the present invention are within the protection scope of the present invention.

Claims

1. A magnet with high burning resistance, characterized in that: The NdFeB magnet material comprises the following components by weight percentage: R: 30wt%≤R≤32wt%, T: 6wt%≤T≤66wt%, wherein T includes at least Fe; B: 0.5wt%≤B≤2wt%; M: 3.0wt%≤M≤8wt%, wherein M is one or more of Al, Cu, Nb, Zn, Ga, Ag, In, Sn, Bi, Cr, and Ta.

2. The magnet with high burning resistance according to claim 1, characterized in that: The R is a rare earth element, and the R includes a light rare earth element RL and a heavy rare earth element RH.

3. The magnet with high burning resistance and the preparation method thereof according to claim 2, characterized in that: The heavy rare earth elements RH include Tb and Dy.

4. The magnet with high burning resistance according to claim 3, characterized in that: The sum of the contents of Tb and Dy is: 0wt%<Tb+Dy≤1wt%.

5. A magnet with high burning resistance as claimed in any one of claims 1 to 5 and a method for preparing the same, characterized in that: The magnet with high burning resistance is obtained by melting, heat treating, hydrogen cracking, air flow milling, screening, mixing, pressing and sintering the raw material composition as described in any one of claims 1 to 6.

6. A magnet with high burning resistance and a method for preparing the magnet according to claim 5, characterized in that: The specific steps include: S10: forming a quick-setting sheet from the raw material mixture by smelting, and heat-treating the quick-setting sheet; S20: using a hydrogen crushing method to feed the quick-setting sheet into a continuous hydrogen powder crushing furnace and crush it into coarse metal powder; S30: adding an additive to the coarse metal powder, stirring and grinding into fine powder; S40: screening the metal fine powder to obtain fine powder with an average particle size of 3 μm, and mixing the fine powder with ultrafine metal powder; S50: pressing the metal mixed powder under an oriented magnetic field to obtain a blank; S60: performing sintering and tempering treatments on the blank to obtain a magnet with high sintering resistance.

7. A magnet with high burning resistance and a method for preparing the magnet according to claim 6, characterized in that: The ultrafine metal powder is a mixture of Zr, Hf, Mo, W and Ni metal powders.

8. The method for preparing a magnet with high burning resistance according to claim 7, characterized in that: In terms of weight percentage, the ultrafine metal powder 0wt%< Zr+Hf+Mo+W+Ni≤0.5wt%.

9. The method for preparing a magnet with high burning resistance according to claim 6, characterized in that: In the step S10, the heat treatment temperature is 500-1100°C, the time is 2h-24h, and the rapid cooling temperature is -170-10°C.

10. The method for preparing a magnet with high burning resistance according to claim 6, characterized in that: In the step S20, the temperature of hydrogen crushing in the hydrogen powder crushing furnace is 400-600°C and the time is 6-24h; The pressing pressure in step S50 is 200-600 Kg / cm2, the orientation field is (2-20)X104Oe, and the oxygen concentration during the pressing process is less than 0.01%; In the step S60, the first sintering treatment temperature is: 1000℃-1100℃, the sintering time is: 1-6 hours, and then rapid cooling is performed; then a second sintering is performed, the secondary sintering temperature is: 1000℃-1100℃, the sintering time is: 1h-6h, then a second rapid cooling is performed, and then a tempering treatment is performed, the first tempering temperature is: 700℃-900℃, the tempering time is: 0h-6h, the secondary tempering time is: 400℃-700℃, and the secondary tempering time is: 1h-6h.

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