Neodymium iron boron rare earth permanent magnet, its manufacturing method and applications

Abstract

The present invention discloses a neodymium iron boron rare earth permanent magnet and its manufacturing method and application. This neodymium-iron-boron rare earth permanent magnet contains 28.5-33 wt% R, RL contains Pr, and Pr≧14 wt%, RH contains one or more of Dy, Tb, Gd, and Ho, and is composed of 12-20 wt% Co, 0.5-1.5 wt% Al, 0.3-1.5 wt% X, 0.88-1.05 wt% B, and the balance is Fe. Its microstructure includes a main phase M, a grain boundary phase A, and a grain boundary phase B, and the main phase M is R2(Fe, Co). 14 The main phase is 90-94%, the grain boundary phase A is R(Fe,Co)2, the grain boundary phase A is 5-8%, and the grain boundary phase B is R4(Fe,Co)3, the grain boundary phase B is 1-2%. This neodymium iron boron rare earth permanent magnet has a high Co content, a high Curie temperature, a low temperature coefficient, and at the same time, excellent mechanical properties, a high magnetic energy product, and a high coercive force.

Description

[Technical Field]

[0001] The present invention relates to a neodymium iron boron rare earth permanent magnet, its manufacturing method, and applications. [Background technology]

[0002] Conventional neodymium-iron-boron rare earth permanent magnets have a remanence temperature coefficient (α) of approximately -0.1% / °C to -0.12% / °C and a coercivity temperature coefficient (β) of approximately -0.6% / °C to -0.8% / °C. This means that their magnetic properties decay rapidly with increasing temperature, and their typical operating temperature does not exceed 200°C, limiting their application in high-temperature applications. Samarium-cobalt permanent magnets, on the other hand, have low temperature coefficients, with a remanence temperature coefficient (α) of approximately -0.035% / °C and a coercivity temperature coefficient (β) of approximately -0.25% / °C. However, they suffer from high brittleness, poor bending strength, and a low magnetic energy product, making it difficult to meet the increasingly high mechanical reliability and energy efficiency requirements of permanent magnet motors.

[0003] Chinese patent application CN1067134A discloses a method for producing a low temperature coefficient neodymium iron boron magnet, and adds elements such as Co, Mo, Al, and Dy2O3 to produce a rare earth permanent magnet with a low temperature coefficient. However, the magnets produced by this method have low remanence and magnetic energy product, poor coercivity, and the amount of Co added is small, so the improvement in the temperature coefficient is limited.

[0004] Chinese patent application CN1308344A discloses a heat-resistant, low-temperature coefficient magnet containing elements such as Co and Ga, which can reach a service temperature of 150°C. However, the amount of Co added is small, resulting in a low Curie temperature and limited improvement in the temperature coefficient of remanence. Furthermore, due to the presence of a soft magnetic phase containing Co after the addition of Co, the remanence is low and the coercivity is poor. Even with the addition of large amounts of high-coercivity elements such as Dy and Tb, the coercivity remains below 2000 kA / m.

[0005] Chinese patent application CN1696324A discloses a high-coercivity magnet that can withstand high temperatures and contains Co, Cu, Al, and Nb. However, the magnetic energy product is low and the improvement in temperature coefficient is limited. In addition, the manufacturing process requires rapid cooling of the sintered magnet to prevent the precipitation of soft magnetic phases, making the manufacturing process complicated and unsuitable for large-scale production.

[0006] Chinese Patent CN101364465B discloses a Co-containing rare earth permanent magnet with the addition of nano-TiO2, ZrO2, MgO, and ZnO nanocrystals. The addition of large amounts of Dy, Tb, Pr, etc. increases the coercive force of the magnet and reduces irreversible loss of magnetic flux, but the amount of Co added is small, and the temperature coefficient is not significantly improved.

[0007] In summary, current conventional technologies have product defects, such as low Co addition, low Curie temperature, little improvement in the temperature coefficient of remanence, and low coercivity. At the same time, to prevent the precipitation of soft magnetic phases during the manufacturing process after the addition of Co and ensure the magnet's coercivity, large amounts of heavy rare earth elements must be added during manufacturing, and special techniques such as rapid cooling must be used, which increases manufacturing difficulties and costs. Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention provides a neodymium iron boron rare earth permanent magnet, its manufacturing method, and applications, to address the shortcomings of conventional neodymium iron boron rare earth permanent magnets, such as low Co content, low Curie temperature, insignificant improvement in temperature coefficient of remanence, and low coercivity. The neodymium iron boron rare earth permanent magnet described in the present invention has a high Co content, a high Curie temperature, a low temperature coefficient, and at the same time, excellent mechanical properties, a high magnetic energy product, and a high coercivity. [Means for solving the problem]

[0009] To achieve the above object, the present invention adopts the following technical solutions.

[0010] The present invention provides a neodymium iron boron rare earth permanent magnet, comprising the following components in the following amounts: R: 28.5 to 33 wt%, R is a rare earth element, R includes a light rare earth element R and a heavy rare earth element R, R includes Pr, Pr is 14 wt% or more, and R includes one or more of Dy, Tb, Gd, and Ho; Co: 12 to 20 wt% Al: 0.5 to 1.5 wt% X: 0.3 to 1.5 wt%, where X is one or more of Cu, Ga, Bi, Sn, Nb, Zr, and Ti; B: 0.88~1.05wt%, The balance is Fe, Here, wt% means the mass percentage of the neodymium iron boron rare earth permanent magnet, and the total of each component is 100 wt%. The microstructure of the neodymium-iron-boron rare earth permanent magnet includes a main phase M, a grain boundary phase A, and a grain boundary phase B, and the main phase M is R2(Fe, Co). 14 B, the volume percentage of the main phase is 90 to 94%, the grain boundary phase A is R(Fe, Co)2, the volume percentage of the grain boundary phase A is 5 to 8%, and the grain boundary phase B is R4(Fe, Co)3, and the volume percentage of the grain boundary phase B is 1 to 2%.

[0011] The present invention selects high Co (12-20wt%), Pr≧14wt%, and Al (0.5-1.5wt%), and 17 The formation of phases is suppressed, which reduces the temperature coefficient while improving the residual magnetic flux density, coercive force, magnetic energy product and mechanical properties. The main phase M is R2 (Fe, Co). 14 B, which is the main source of the magnet's magnetic properties. 14By substituting some of the Fe atoms in the main phase B and raising the Curie temperature of the main phase, the volume percentage of the main phase M is high and the total volume percentage of the grain boundary phases A and B is low, resulting in a magnet with a high remanence and a relatively good temperature coefficient (small absolute value), but a relatively low coercivity. Because NdFeB fracture is a typical grain boundary fracture, the grain boundary phase connects the main phase grains and prevents crack propagation. A decrease in the total volume ratio of the grain boundary phase reduces mechanical properties. However, compared to conventional NdFeB, the presence of the Co-rich grain boundary phase A gives it an MgCu2-type cubic crystal structure and more slip systems than conventional hexagonal NdFeB phases. Therefore, its strength during deformation is superior to that of conventional NdFeB magnets, and its mechanical properties are still superior to conventional low-Co and Co-free magnets.

[0012] In the present invention, the Pr content is preferably 14 wt% to 24 wt%, for example, 14 wt%, 15 wt%, 16 wt%, 18 wt%, 20 wt%, 23 wt%, or 24 wt%.

[0013] In the present invention, the RL may further contain Nd, and the content of Nd is preferably 1 wt% to 14 wt%, for example, 14 wt%, 10 wt%, 12 wt%, 7.5 wt%, 9 wt%, 10 wt%, 6 wt%, 2 wt%, or 1 wt%.

[0014] In the present invention, the content of RH is preferably 2 wt% to 9 wt%, for example, 4.5 wt%, 7 wt%, 9 wt%, 7.5 wt%, 8 wt%, 6 wt%, 2 wt%, or 5 wt%.

[0015] Preferably, the RH contains Dy, and the content of Dy is 0.2 wt% to 5 wt%, for example, 3 wt%, 1.5 wt%, 5 wt%, 4 wt%, 0.2 wt%, 2 wt%, or 1 wt%.

[0016] Preferably, the RH contains Tb, and the content of Tb is 1 wt% to 5 wt%, for example, 2.5 wt%, 3 wt%, 4 wt%, 2 wt%, 1 wt%, 1.8 wt%, 1.5 wt%, or 5 wt%.

[0017] Preferably, the RH contains Gd, and the Gd content is 0.5 wt% to 1 wt%.

[0018] Preferably, the RH contains Ho, and the content of Ho is 0.5 wt% to 2 wt%, for example, 1 wt%, 0.5 wt%, 2 wt%, or 1.5 wt%.

[0019] In the present invention, the Co content is, for example, 13 wt%, 19 wt%, 12 wt%, 15 wt%, 17 wt%, 20 wt%, 16 wt%, or 18 wt%.

[0020] In the present invention, the Al content is, for example, 0.8 wt%, 0.7 wt%, 0.6 wt%, 0.5 wt%, 1.5 wt%, 0.55 wt%, 1.1 wt%, or 1.3 wt%.

[0021] Preferably, X contains Cu, and the Cu content is 0.15 wt% to 0.3 wt%, for example, 0.2 wt%, 0.15 wt%, or 0.3 wt%.

[0022] Preferably, X includes Ga, and the Ga content is 0.3 wt% to 0.6 wt%, for example, 0.5 wt%, 0.3 wt%, or 0.6 wt%.

[0023] Preferably, X contains Bi, and the content of Bi is 0.1 wt% to 0.2 wt%.

[0024] Preferably, the X contains Sn, and the content of Sn is 0.1 wt% to 0.3 wt%.

[0025] Preferably, the X contains Nb, and the content of Nb is 0.1 wt% to 0.3 wt%, for example, 0.2 wt%.

[0026] Preferably, the X contains Zr, and the content of Zr is 0.1 wt% to 0.2 wt%.

[0027] Preferably, X contains Ti, and the content of Ti is 0.1 wt% to 0.3 wt%, for example, 0.15 wt% or 0.2 wt%.

[0028] In the present invention, preferably, the main phase M contains each component in the following amounts: R: 26.6~30.55wt%, where Pr: >12.5wt%, Nd: 0~12.5wt%, RH: 1.85~9.0wt%, Co: 11.8 to 20 wt% B: 0.88~1.01wt%, Fe: 48.5 to 58.5 wt%, Here, wt% means the mass percentage in the main phase M, and the total of all components is 100 wt%.

[0029] Preferably, the main phase M further comprises one or more of Al, Cu, Zr, Ga and O.

[0030] In the present invention, the grain boundary phase A is an RT2 phase, has an MgCu2 type structure, and is paramagnetic at room temperature. The grain boundary phase A is a grain boundary phase that is "rich in Nd and Co and poor in Fe."

[0031] Preferably, the grain boundary phase A contains the following components in the following amounts: R: 52.8-62wt%, where Pr: 24-50wt%, Nd: 0-26.5wt%, RH: 2.0-10wt%, Co: 15 to 25 wt%, Fe: 12 to 25 wt% Al: 0.19 to 0.55 wt%, X: 0.1 to 0.6 wt%, O: 0 to 0.5 wt%, Here, wt% means the mass percentage in the grain boundary phase A, and the total of each component is 100 wt%.

[0032] In the present invention, the grain boundary phase B is an R4T3-based phase with a Nd4Co3-type structure. The grain boundary phase B is "rich in Nd and poor in Co and Fe." The grain boundary phase B is similar to the Nd-rich phase in conventional low-Co alloys, and its components are mainly rare earth metals and their oxides or R-(T, X) alloy phases, where T is Fe or Co and X is one or more of the aforementioned Cu, Ga, Bi, Sn, Nb, Zr, and Ti, which mainly plays a demagnetizing role between crystal grains and can increase coercivity.

[0033] Preferably, the grain boundary phase B contains the following components in the following amounts: R: 75-90.3wt%, where Pr: 42.5-90wt%, Nd: 0-42.5wt%, RH: 0.3-1.5wt%, Co: 6 to 10 wt% Fe: 2 to 10 wt% Al: 0 to 0.2 wt%, X: 1.0 to 10 wt% O: 0.5 to 1.5 wt% Here, wt % means the mass percentage in the grain boundary phase B.

[0034] Preferably, the Co content c(A) in the grain boundary phase A is greater than the Co content c(M) in the main phase M, and c(A)-c(M) > 3 wt%. This ensures that the grain boundary phase A contains sufficient Co elements to form an RT2-based paramagnetic phase, which is advantageous for improving the coercive force of the magnet.

[0035] Preferably, the content of RH in the grain boundary phase A is greater than that in the main phase M and greater than that in the grain boundary phase B. RH is concentrated in the grain boundary phase A, improving the magnetic properties of the Co-rich grain boundaries and preventing deterioration of the coercivity of the magnet.

[0036] Preferably, the content of RH in the grain boundary phase B is less than that in the main phase M and less than that in the grain boundary phase A. A low content of RH in the grain boundary phase B allows more RH to be obtained from the grain boundary phase A or the main phase M, which is advantageous for improving the coercive force of the magnet.

[0037] Preferably, the content of X (particularly Cu and Ga) in the grain boundary phase B is greater than that in the main phase M and greater than that in the grain boundary phase A. When the X element is distributed in the main phase, it reduces the remanence of the main phase, but when distributed in the grain boundary phase B, it can form an R-X grain boundary alloy phase without affecting the remanence, increase the demagnetizing coupling between crystal grains, and improve the coercive force of the magnet.

[0038] In the present invention, the neodymium iron boron rare earth permanent magnet may also contain a hetero phase such as a rare earth oxide phase RO or a ZrB2 / TiB2 phase.

[0039] Here, the content of the heterophase may be 0.05% to 0.55%, for example, 0.22%, 0.25%, 0.19%, 0.20%, 0.29%, 0.19%, 0.55%, 0.23%, 0.09%, 0.21%, 0.18%, 0.37%, or 0.41%.

[0040] In the present invention, the volume percentage of the main phase is, for example, 90.45%, 90.00%, 91.81%, 92.73%, 92.11%, 93.66%, 93.23%, 92.81%, 93.45%, 93.22%, 91.53% or 92.33%.

[0041] In the present invention, the volume percentage of the grain boundary phase A is, for example, 5.00%, 8.00%, 7.81%, 6.45%, 6.23%, 6.80%, 5.12%, 5.89%, 6.32%, 5.84%, 5.79%, 7.05% or 6.43%.

[0042] In the present invention, the volume percentage of the grain boundary phase B is, for example, 0.78%, 1.30%, 2.00%, 1.54%, 0.75%, 0.90%, 0.67%, 0.65%, 0.78%, 0.50%, 0.81%, 1.05%, or 0.83%.

[0043] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 94.00% main phase M, 5.00% grain boundary phase A, 0.78% grain boundary phase B, and 0.22% heterophase.

[0044] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 90.45% main phase M, 8.00% grain boundary phase A, 1.30% grain boundary phase B, and 0.25% heterophase.

[0045] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 90.00% main phase M, 7.81% grain boundary phase A, 2.00% grain boundary phase B, and 0.19% heterophase.

[0046] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 91.81% main phase M, 6.45% grain boundary phase A, 1.54% grain boundary phase B, and 0.2% heterophase.

[0047] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.73% main phase M, 6.23% grain boundary phase A, 0.75% grain boundary phase B, and 0.29% heterophase.

[0048] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.11% main phase M, 6.80% grain boundary phase A, 0.90% grain boundary phase B, and 0.19% heterophase.

[0049] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.66% main phase M, 5.12% grain boundary phase A, 0.67% grain boundary phase B, and 0.55% heterophase.

[0050] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.23% main phase M, 5.89% grain boundary phase A, 0.65% grain boundary phase B, and 0.23% heterophase.

[0051] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.81% main phase M, 6.32% grain boundary phase A, 0.78% grain boundary phase B, and 0.09% heterophase.

[0052] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.45% main phase M, 5.84% grain boundary phase A, 0.50% grain boundary phase B, and 0.21% heterophase.

[0053] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.22% main phase M, 5.79% grain boundary phase A, 0.81% grain boundary phase B, and 0.18% heterophase.

[0054] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 91.53% main phase M, 7.05% grain boundary phase A, 1.05% grain boundary phase B, and 0.37% heterophase.

[0055] In one specific embodiment, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.33% main phase M, 6.43% grain boundary phase A, 0.83% grain boundary phase B, and 0.41% heterophase.

[0056] In the present invention, the neodymium iron boron rare earth permanent magnet preferably has a temperature coefficient of residual magnetic flux density at 20 to 100°C of |α|<0.056% / °C and a temperature coefficient of coercivity at 20 to 100°C of |β|<0.55% / °C.

[0057] In the present invention, the neodymium iron boron rare earth permanent magnet preferably has a Curie temperature Tc>450°C.

[0058] In the present invention, the coercive force Hcj of the neodymium iron boron rare earth permanent magnet preferably satisfies Hcj≧25 kOe.

[0059] The present invention further provides a method for producing a neodymium iron boron rare earth permanent magnet, the method comprising sequentially subjecting the raw material composition of the neodymium iron boron rare earth permanent magnet to the steps of smelting, casting, hydro-crushing, molding, sintering and aging.

[0060] In the present invention, the melting and refining can be carried out by a method commonly used in the art, for example, by melting and refining in a high-frequency vacuum induction melting furnace.

[0061] Here, the degree of vacuum in the high-frequency vacuum induction melting furnace is 5×10 ‐2 It may be Pa.

[0062] The temperature of the smelting may be 1600°C or less.

[0063] The melting and refining is generally carried out in an alumina crucible, which introduces a portion of Al into the neodymium-iron-boron rare earth permanent magnet.

[0064] In the present invention, the casting step may be a typical casting step in this field, for example, by passing a molten liquid obtained by melting and smelting in an Ar gas atmosphere through a rotating roller wheel to cool it.

[0065] Here, the pressure of the Ar gas atmosphere is 5.5×10 4 Pa is preferred.

[0066] Here, the cooling rate is preferably 10 2 ℃ / sec~10 4 °C / sec. The cooling can be achieved by passing cooling water through the roller wheels. Preferably, the inlet temperature of the cooling water is ≦25°C.

[0067] In the present invention, the hydrocracking process may be a conventional hydrocracking process in this field, for example, hydrogen absorption, dehydrogenation and cooling treatment.

[0068] Here, the hydrogen absorption can be performed under the condition of a hydrogen gas pressure of 0.05 to 0.25 MPa, and the dehydrogenation can be performed under the condition of evacuation and temperature increase.

[0069] In the present invention, after the hydrocracking, pulverization can be carried out according to a conventional method in the art, and the pulverization process can be a conventional pulverization process in the art, such as jet mill pulverization.

[0070] The jet mill pulverization can be carried out in a nitrogen gas atmosphere containing 100 ppm or less of an oxidizing gas, where the oxidizing gas means oxygen and / or moisture.

[0071] The pressure in the grinding chamber of the jet mill may be 0.58 MPa.

[0072] The jet milling may be carried out for a period of 3 hours.

[0073] The particle size of the powder after the pulverization is preferably 3.5 to 4.5 μm.

[0074] After the grinding, a lubricant such as zinc stearate can be added to the powder according to a conventional method in the art. The amount of the lubricant added may be 0.10 to 0.15% of the weight of the powder after mixing, for example, 0.12%.

[0075] In the present invention, the molding process may be a conventional molding process in this field, such as a magnetic field orientation molding method, in which the pressure of the orientation press molding is more than 80 MPa, the orientation magnetic field is more than 1.2 T, and the pressure holding time is 4 to 6 seconds.

[0076] After the magnetic field orientation molding, the magnet can be further densified using a cold isostatic pressing press, and the pressure of the cold isostatic pressing is 150 to 160 MPa.

[0077] In the present invention, the sintering step may be a typical sintering step in this field, for example, by performing preheating, sintering, and cooling under vacuum conditions.

[0078] Here, the vacuum condition is, for example, 5×10 ‐3 It is Pa.

[0079] The preheating temperature may be 300 to 600° C. The preheating time may be 1 to 2 hours. Preferably, the preheating is performed at temperatures of 300° C. and 600° C. for 1 hour each.

[0080] The sintering temperature may be a common sintering temperature in this field, for example, 1040 to 1090°C.

[0081] The sintering time may be a normal sintering time in the art, for example, 4 hours.

[0082] Before the cooling, Ar gas can be introduced to adjust the pressure to 0.05 to 0.1 MPa.

[0083] Preferably, the sintering does not involve a rapid cooling step, where the rapid cooling step means a cooling step with a cooling rate of 80° C. / min or more.

[0084] In the present invention, the aging treatment includes a first stage aging treatment and a second stage aging treatment.

[0085] Here, the temperature of the first stage aging treatment is preferably 860 to 960°C, for example, 900°C. In the first stage aging treatment, the temperature is raised to 860 to 960°C at a rate of 3 to 5°C / min. The temperature rise may start from room temperature. The time period of the first stage aging treatment may be 3 hours.

[0086] Here, the temperature of the second stage aging treatment is preferably 430 to 600°C. In the second stage aging treatment, the temperature is raised to 430 to 600°C at a rate of 3 to 5°C / min. The temperature rise may start from room temperature. The time period of the second stage aging treatment may be 3 hours.

[0087] In the present invention, the room temperature means 25°C ± 5°C.

[0088] The present invention further provides the application of the neodymium iron boron rare earth permanent magnet in electronic components.

[0089] Here, the electronic components may be those conventional in the art, for example electronic components in a motor.

[0090] By arbitrarily combining the above-mentioned preferred conditions in accordance with common knowledge in this field, each preferred embodiment of the present invention can be obtained.

[0091] All of the reagents and raw materials used in the present invention are commercially available. [Effects of the Invention]

[0092] The positive and inventive effects of the present invention are as follows:

[0093] When a high content of Co is added to the neodymium iron boron rare earth permanent magnet of the present invention, the combination of elements such as Pr and Al forms a uniformly distributed low melting point grain boundary phase with an RT2 type and R4T3 type structure, which is different from the R2Co type structure in conventional high Co magnets. 17This avoids the drawback of soft magnetic phases such as those mentioned above appearing and significantly reducing coercivity. The magnet of the present invention has a high remanence (11.5-13.5 kGs), coercivity (which can reach 28 kOe or more), and squareness (>95%), as well as a low temperature coefficient of remanence (|α|<0.056% / °C, 20-100°C) and a low temperature coefficient of coercivity (|β|<0.55% / °C, 20-100°C). The magnet also has a high Curie temperature (Tc>450°C) and excellent heat resistance. [Brief explanation of the drawings]

[0094] [Figure 1] FIG. 1 is a scanning electron microscope (SEM-BSE) backscattered electron image of different phases of the neodymium iron boron rare earth permanent magnet in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0095] The present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the above examples. In the following examples, experimental methods for which specific conditions are not specified are selected according to conventional methods and conditions or product specifications. Examples 1 to 13 and Comparative Examples 1 to 7

[0096] The components of the raw material compositions for the neodymium iron boron rare earth permanent magnets in Examples 1 to 13 and Comparative Examples 1 to 7 are shown in Table 1. Materials are mixed according to the components of the raw material compositions for the neodymium iron boron rare earth permanent magnets in Table 1, and the following steps are carried out in order.

[0097] (1) Melting and smelting process: The raw materials prepared according to the ingredients shown in Table 1 were placed in an alumina crucible and melted in a high-frequency vacuum induction furnace at a temperature of 5 × 10 -2 Vacuum melting and smelting is carried out at temperatures below 1600°C in a vacuum of 100 Pa.

[0098] (2) Casting process: 5.5 x 10 4In an Ar gas atmosphere at 10 Pa pressure, the molten liquid after vacuum melting and smelting is passed through a rotating roller wheel for casting, and then cooling water (inlet water temperature ≦ 25 ° C) is poured into the roller wheel. 2 ℃ / sec~10 4 Cool at a rate of °C / sec.

[0099] (3) Hydrogen crushing process: At room temperature, hydrogen gas with a purity of 99.9% is introduced into the hydrogen crushing furnace, the hydrogen gas pressure is maintained at 0.15 MPa, and after sufficient hydrogen is absorbed, the temperature is raised while evacuating, and sufficient dehydrogenation is carried out. After that, the furnace is cooled, and the powder after hydrogen crushing is removed.

[0100] (4) Jet mill pulverization: The powder after hydrogen crushing is jet milled for 3 hours under conditions of a nitrogen atmosphere containing 100 ppm or less of oxidizing gas and a crushing chamber pressure of 0.58 MPa to obtain a fine powder. The oxidizing gas means oxygen and / or moisture.

[0101] (5) Zinc stearate is added to the powder after jet mill pulverization, and the amount of zinc stearate added is 0.12% of the powder weight after mixing, and then the mixture is thoroughly mixed using a V-type mixer.

[0102] (6) Magnetic field molding process: Using a perpendicular orientation type magnetic field molding machine, the powder containing the zinc stearate is subjected to a molding pressure of over 80 MPa in an oriented magnetic field of 1.6 T, and the pressure is maintained for 4 to 6 seconds. Then, using an isostatic press molding machine, the powder is pressed by cold isostatic pressing at a pressure of 150 to 160 MPa to further densify the magnet.

[0103] (7) Sintering process: Each compact is transported to a sintering furnace and sintered to a mass of 5 × 10 ‐3 The sintering was carried out under vacuum at 300°C and 600°C for 1 hour each, and then sintered at 1040°C for 4 hours. Ar gas was then introduced to adjust the pressure to 0.1 MPa, and the sintered sintered sintered material was cooled to room temperature at a cooling rate of less than 80°C / min.

[0104] (9) Aging process: The sintered body is heated in high-purity Ar gas from room temperature to 900°C at a heating rate of 5°C / min, subjected to heat treatment for 3 hours (first stage aging), cooled to room temperature, and then heated from room temperature to 600°C at a heating rate of 5°C / min, subjected to heat treatment for 3 hours (second stage aging) to obtain a neodymium-iron-boron rare earth permanent magnet.

[0105] Table 1. Components (wt%) of the raw material composition of neodymium-iron-boron rare earth permanent magnets JPEG2025535234000002.jpg160154 Effect Example 1: Phase composition and component detection of neodymium iron boron rare earth permanent magnet

[0106] FIG. 1 shows a scanning electron microscope (SEM-BSE) image of different phases of the neodymium iron boron rare earth permanent magnet in Example 1, in which the main phase M, the grain boundary phase A, and the grain boundary phase B are shown.

[0107] Table 2 shows the volume percentage of each phase in the neodymium iron boron rare earth permanent magnets of Examples 1 to 13 and Comparative Examples 1 to 7, and Table 3 shows the component composition of each phase.

[0108] Table 2. Phase composition of neodymium-iron-boron rare earth permanent magnets JPEG2025535234000003.jpg181126

[0109] The percentages in Table 2 are volume percentages and are estimated based on the stereoscopic Delesse Law, i.e., V V (Element volume percentage) = A A (cross-sectional element area percentage), and the area percentage of an element on a random cross section is equal to its volume percentage.

[0110] Table 3. Composition of each phase of neodymium-iron-boron rare earth permanent magnet JPEG2025535234000004.jpg23672 Effect Example 2: Testing the magnetic properties of magnets

[0111] The magnetic properties of neodymium iron boron rare earth permanent magnets are measured using the China Academy of Metrology's PFM-14 pulse magnetic property measuring instrument. Table 4 shows the results of the magnetic property detection.

[0112] Table 4 Magnetic properties of neodymium iron boron rare earth permanent magnets JPEG2025535234000005.jpg192153

[0113] As can be seen from Table 4, the permanent magnets of the examples of the present invention have high remanence, coercivity, and squareness ratio, as well as low temperature coefficients of remanence and coercivity. They also have high Curie temperatures and excellent heat resistance.

Claims

1. A neodymium iron boron rare earth permanent magnet, comprising the following components in the following amounts: R: 28.5 to 33 wt%, R is a rare earth element, R includes a light rare earth element R and a heavy rare earth element R, R includes Pr, Pr is 14 wt% or more, and R includes one or more of Dy, Tb, Gd, and Ho; Co: 12-20wt%, Al: 0.5 to 1.5 wt%, X: 0.3 to 1.5 wt%, where X is one or more of Cu, Ga, Bi, Sn, Nb, Zr, and Ti; B: 0.88-1.05wt%, The balance is Fe, Here, wt% means the mass percentage of the neodymium iron boron rare earth permanent magnet, and the total of each component is 100 wt%. The microstructure of the neodymium-iron-boron rare earth permanent magnet includes a main phase M, a grain boundary phase A, and a grain boundary phase B, and the main phase M is R ２ (Fe, Co) １４ B, the volume percentage of the main phase M is 90 to 94%, and the grain boundary phase A is R (Fe, Co). ２ The volume percentage of the grain boundary phase A is 5 to 8%, and the grain boundary phase B is R ４ (Fe, Co) ３ and the volume percentage of the grain boundary phase B is 1 to 2%. A neodymium iron boron rare earth permanent magnet characterized by:

2. the Pr content is 14 wt % to 24 wt %, for example, 14 wt %, 15 wt %, 16 wt %, 18 wt %, 20 wt %, 23 wt %, or 24 wt %; and / or the RL further comprises Nd, and the content of the Nd is preferably 1 wt % to 14 wt %, for example 14 wt %, 10 wt %, 12 wt %, 7.5 wt %, 9 wt %, 10 wt %, 6 wt %, 2 wt %, or 1 wt %; and / or the RH content is 2 wt % to 9 wt %, for example, 4.5 wt %, 7 wt %, 9 wt %, 7.5 wt %, 8 wt %, 6 wt %, 2 wt %, or 5 wt %; and / or the RH contains Dy, and the Dy content is 0.2 wt % to 5 wt %, for example, 3 wt %, 1.5 wt %, 5 wt %, 4 wt %, 0.2 wt %, 2 wt %, or 1 wt %; and / or the RH contains Tb, and the content of Tb is 1 wt % to 5 wt %, for example, 2.5 wt %, 3 wt %, 4 wt %, 2 wt %, 1 wt %, 1.8 wt %, 1.5 wt %, or 5 wt %; and / or the RH contains Gd, and the Gd content is 0.5 wt % to 1 wt %; and / or the RH contains Ho, and the content of Ho is 0.5 wt % to 2 wt %, for example, 1 wt %, 0.5 wt %, 2 wt %, or 1.5 wt %; and / or the Co content is 13 wt%, 19 wt%, 12 wt%, 15 wt%, 17 wt%, 20 wt%, 16 wt%, or 18 wt%, and / or the Al content is 0.8 wt%, 0.7 wt%, 0.6 wt%, 0.5 wt%, 1.5 wt%, 0.55 wt%, 1.1 wt%, or 1.3 wt%; and / or X includes Cu, and the Cu content is 0.15 wt % to 0.3 wt %, for example, 0.2 wt %, 0.15 wt %, or 0.3 wt %; and / or the X includes Ga, and the Ga content is 0.3 wt % to 0.6 wt %, for example, 0.5 wt %, 0.3 wt %, or 0.6 wt %; and / or, X contains Bi, and the content of Bi is 0.1 wt% to 0.2 wt%, and / or, the X contains Sn, and the content of Sn is 0.1 wt% to 0.3 wt%; and / or the X contains Nb, and the content of Nb is 0.1 wt% to 0.3 wt%, for example, 0.2 wt%; and / or, the X contains Zr, and the content of Zr is 0.1 wt% to 0.2 wt%; and / or X contains Ti, and the content of Ti is 0.1 wt% to 0.3 wt%, for example, 0.15 wt% or 0.2 wt%; 2. The neodymium iron boron rare earth permanent magnet according to claim 1.

3. The main phase M contains the following components in the following amounts: R: 26.6 to 30.55 wt%, where Pr: >12.5 wt%, Nd: 0 to 12.5 wt%, RH: 1.85 to 9.0 wt%, Co: 11.8-20wt%, B: 0.88-1.01wt%, Fe: 48.5 to 58.5 wt%, Here, wt% means the mass percentage in the main phase M, and the total of each component is 100 wt%. Preferably, the main phase M further includes one or more of Al, Cu, Zr, Ga, and O, And / or, the grain boundary phase A contains each component in the following amounts: R: 52.8 to 62 wt%, wherein Pr: 24 to 50 wt%, Nd: 0 to 26.5 wt%, RH: 2.0 to 10 wt%, Co: 15-25wt%, Fe: 12-25wt%, Al: 0.19-0.55wt%, X: 0.1 to 0.6 wt%, O: 0 to 0.5 wt%, Here, wt% means the mass percentage in the grain boundary phase A, and the total of each component is 100 wt%. And / or, the grain boundary phase B contains each component in the following amounts: R: 75 to 90.3 wt%, wherein Pr: 42.5 to 90 wt%, Nd: 0 to 42.5 wt%, RH: 0.3 to 1.5 wt%, Co: 6 to 10 wt%, Fe: 2-10wt%, Al: 0 to 0.2 wt%, X: 1.0-10wt%, O: 0.5 to 1.5 wt%, Here, wt% means the mass percentage in the grain boundary phase B.

2. The neodymium iron boron rare earth permanent magnet according to claim 1.

4. the Co content c(A) in the grain boundary phase A is greater than the Co content c(M) in the main phase M, and c(A)-c(M)>3 wt%; and / or the content of RH in the grain boundary phase A is greater than that in the main phase M and greater than that in the grain boundary phase B; and / or the content of RH in the grain boundary phase B is less than that in the main phase M and less than that in the grain boundary phase A; and / or the content of X in the grain boundary phase B is greater than that in the main phase M and greater than that in the grain boundary phase A; 2. The neodymium iron boron rare earth permanent magnet according to claim 1.

5. The neodymium iron boron rare earth permanent magnet further comprises a heterophase, and the content of the heterophase is preferably 0.05% to 0.55%, for example, 0.22%, 0.25%, 0.19%, 0.20%, 0.29%, 0.19%, 0.55%, 0.23%, 0.09%, 0.21%, 0.18%, 0.37%, or 0.41%; and / or the volume percentage of the main phase M is 90.45%, 90.00%, 91.81%, 92.73%, 92.11%, 93.66%, 93.23%, 92.81%, 93.45%, 93.22%, 91.53% or 92.33%; and / or the volume percentage of the grain boundary phase A is 5.00%, 8.00%, 7.81%, 6.45%, 6.23%, 6.80%, 5.12%, 5.89%, 6.32%, 5.84%, 5.79%, 7.05% or 6.43%, and / or the volume percentage of the grain boundary phase B is 0.78%, 1.30%, 2.00%, 1.54%, 0.75%, 0.90%, 0.67%, 0.65%, 0.78%, 0.50%, 0.81%, 1.05% or 0.83%; 2. The neodymium iron boron rare earth permanent magnet according to claim 1.

6. the microstructure of the neodymium iron boron rare earth permanent magnet comprises 94.00% main phase M, 5.00% grain boundary phase A, 0.78% grain boundary phase B, and 0.22% hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 90.45% of a main phase M, 8.00% of a grain boundary phase A, 1.30% of a grain boundary phase B, and 0.25% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 90.00% of a main phase M, 7.81% of a grain boundary phase A, 2.00% of a grain boundary phase B, and 0.19% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 91.81% of a main phase M, 6.45% of a grain boundary phase A, 1.54% of a grain boundary phase B, and 0.2% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.73% of a main phase M, 6.23% of a grain boundary phase A, 0.75% of a grain boundary phase B, and 0.29% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.11% of a main phase M, 6.80% of a grain boundary phase A, 0.90% of a grain boundary phase B, and 0.19% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.66% of a main phase M, 5.12% of a grain boundary phase A, 0.67% of a grain boundary phase B, and 0.55% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.23% of a main phase M, 5.89% of a grain boundary phase A, 0.65% of a grain boundary phase B, and 0.23% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.81% of a main phase M, 6.32% of a grain boundary phase A, 0.78% of a grain boundary phase B, and 0.09% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.45% of a main phase M, 5.84% of a grain boundary phase A, 0.50% of a grain boundary phase B, and 0.21% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 93.22% of a main phase M, 5.79% of a grain boundary phase A, 0.81% of a grain boundary phase B, and 0.18% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 91.53% of a main phase M, 7.05% of a grain boundary phase A, 1.05% of a grain boundary phase B, and 0.37% of a hetero phase; Alternatively, the microstructure of the neodymium iron boron rare earth permanent magnet comprises 92.33% of a main phase M, 6.43% of a grain boundary phase A, 0.83% of a grain boundary phase B, and 0.41% of a hetero phase.

2. The neodymium iron boron rare earth permanent magnet according to claim 1.

7. the neodymium iron boron rare earth permanent magnet has a temperature coefficient of remanence |α|<0.056% / °C at 20 to 100°C and a temperature coefficient of coercivity |β|<0.55% / °C at 20 to 100°C; and / or the Curie temperature Tc of the neodymium iron boron rare earth permanent magnet is greater than 450°C; And / or, the coercive force Hcj of the neodymium iron boron rare earth permanent magnet is 25 kOe or more.

2. The neodymium iron boron rare earth permanent magnet according to claim 1.

8. A method for producing the neodymium iron boron rare earth permanent magnet according to any one of claims 1 to 7, The raw material composition for the neodymium-iron-boron rare earth permanent magnet is subjected to the steps of melting, casting, hydro-crushing, molding, sintering and aging treatment in order. A method for producing a neodymium iron boron rare earth permanent magnet.

9. The melting and smelting may be carried out in a high frequency vacuum induction melting furnace, and the degree of vacuum in the high frequency vacuum induction melting furnace is preferably 5×10 ‐２ Pa, the temperature of the smelting is preferably 1600°C or less, and the smelting is preferably carried out in an alumina crucible; And / or, the casting may be performed by passing the molten liquid obtained by melting and smelting in an Ar gas atmosphere through a rotating roller wheel to cool it, and the pressure of the Ar gas atmosphere is preferably 5.5×10 ４ Pa, wherein the rate of cooling is preferably 10 ２ °C / sec~10 ４ °C / sec, said cooling being preferably achieved by injecting cooling water into the roller wheel, said cooling water having an inlet temperature of ≦25°C; and / or the hydrocrushing may be performed by hydrogen absorption, dehydrogenation, and cooling treatment, wherein the hydrogen absorption is preferably performed under a hydrogen gas pressure of 0.05 to 0.25 MPa, and the dehydrogenation is preferably performed under a condition of evacuation and heating; and / or further pulverization is carried out after the hydro-pulverization, the pulverization being preferably jet mill pulverization, the jet mill pulverization being preferably carried out in a nitrogen gas atmosphere with an oxidizing gas content of 100 ppm or less, the jet mill pulverization chamber pressure being preferably 0.58 MPa, the jet mill pulverization time being preferably 3 hours, the particle size of the powder after the pulverization being preferably 3.5 to 4.5 μm, and after the pulverization, a lubricant, for example, zinc stearate, being preferably added to the powder, the amount of the lubricant added being preferably 0.10 to 0.15% of the weight of the powder after mixing, for example 0.12%; and / or the molding step is a magnetic field orientation molding method, preferably, when using the magnetic field orientation molding method, the pressure of the orientation press molding is more than 80 MPa, the orientation magnetic field is more than 1.2 T, and the pressure holding time is 4 to 6 s; after the magnetic field orientation molding, a cold isostatic pressing can be continued, and the pressure of the cold isostatic pressing is preferably 150 to 160 MPa; And / or, the sintering may be performed by preheating, sintering, and cooling under vacuum conditions, and the vacuum conditions may be, for example, 5×10 ‐３ Pa, the preheating temperature is preferably 300 to 600°C, the preheating time is preferably 1 to 2 hours, more preferably, the preheating is performed at temperatures of 300°C and 600°C for 1 hour each, the sintering temperature is, for example, 1040 to 1090°C, the sintering time is, for example, 4 hours, and before the cooling, Ar gas can be introduced to adjust the pressure to 0.05 to 0.1 MPa, and preferably, a rapid cooling process is not used in the sintering, and / or the aging treatment includes a first-stage aging treatment and a second-stage aging treatment, wherein the temperature of the first-stage aging treatment is preferably 860 to 960°C, for example 900°C, the temperature rise rate from 860 to 960°C in the first-stage aging treatment is preferably 3 to 5°C / min, and the duration of the first-stage aging treatment is preferably 3 hours, wherein the temperature of the second-stage aging treatment is preferably 430 to 600°C, the temperature rise rate from 430 to 600°C in the second-stage aging treatment is preferably 3 to 5°C / min, and the duration of the second-stage aging treatment is preferably 3 hours; 9. The method for producing a neodymium iron boron rare earth permanent magnet according to claim 8.

10. 8. The neodymium iron boron rare earth permanent magnet according to claim 1, wherein the magnet is used in electronic components.

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