Device and method for preparing high-performance rare earth permanent magnet through ultrafast high-temperature sintering
Through the design of multiple constant temperature heating chambers and tempering chambers of continuous sintering furnaces and heat treatment furnaces, the problem of difficult to control the sintering and insulation time is solved, and the high-performance preparation of rare earth permanent magnets is achieved, and the residual magnetism and coercivity are improved.
Patent Information
- Application Number
- CN202510667152.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-22
- Publication Date
- 2025-07-25
AI Technical Summary
In the existing heavy rare earth introduction process, the sintering and insulating time is difficult to accurately control, resulting in inaccurate thickness of the core-shell structure, affecting the residual magnetic and coercive performance of the rare earth permanent magnet.
Using a continuous sintering furnace and a continuous heat treatment furnace, through the design of multiple constant temperature heating chambers and tempering chambers, rapid heating and precision can be achieved to ensure temperature, control the shell thickness of the core-shell structure, form a nano-scale thin shell layer, and optimize the magnet structure.
The remanent magnetism and coercive force of rare earth permanent magnets are synchronously improved, the magnet structure is more uniform, the grain boundaries are clear, and the magnetic performance is better.
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Figure CN120376269A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of rare earth permanent magnet preparation, and in particular to a device and method for preparing high-performance rare earth permanent magnets by ultrafast high-temperature sintering. Background Art
[0002] In order to meet the ultra-high performance requirements of permanent magnets in the fields of new energy vehicles, energy-saving home appliances, etc., it is necessary to use ordinary Nd2Fe 14 Heavy rare earth Dy / Tb is introduced into B to form a Dy / Tb-rich core-shell structure on the surface of the main phase grains, thereby improving the magnetic properties. 14 When Dy / Tb is introduced into the B structure, Dy / Tb will replace Nd, but since the ionic radius of Dy is smaller than that of Nd, it will cause lattice distortion, thereby strengthening the asymmetry of the local crystal field and improving the magnetocrystalline anisotropy.
[0003] At present, the processes of grain boundary diffusion, dual alloy or casting with heavy rare earth film are generally used to produce Nd2Fe 14 Dy / Tb is introduced into the B structure, but no matter which process is used, ordinary gradient sintering is used in the sintering stage. However, since the temperature change of ordinary gradient sintering takes a certain amount of time and the heating rate is slow, it is difficult to accurately control the holding time of the product, which makes it impossible to accurately control the shell thickness of the core-shell structure. If the holding time is insufficient, the temperature of the core of the magnet fails to reach the required sintering temperature, resulting in the inability of the core-shell structure to completely wrap the main phase grains. Although the coercive force can be increased, the remanence is reduced due to the existence of a discontinuous core-shell structure. If the sintering temperature is high or the holding time is too long, the heavy rare earth elements excessively replace the Nd element, making the shell of the Dy / Tb-rich core-shell structure too thick. 2+ , Tb 2+ The magnetic moment of Fe 3+ Reverse coupling partially offsets the magnetic moment contribution of the main phase grains, resulting in a decrease in the overall remanence. In addition, excessive enrichment of heavy rare earths at the grain boundaries will destroy the exchange coupling between the main phase grains, which in turn limits the further increase in coercivity. The substituted Nd and heavy rare earth elements are enriched in the grain boundary region in large quantities, and are very easy to react with impurities such as O\C\S, hindering the exchange coupling between grains and resulting in a decrease in magnetic properties.
[0004] Therefore, there is an urgent need for a method that can accurately control the holding time during the sintering stage. Summary of the invention
[0005] In order to overcome the technical defect of the existing heavy rare earth introduction process that the sintering holding time is difficult to accurately control, the present invention provides a device and method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering.
[0006] The device for preparing high-performance rare earth permanent magnets by ultrafast high-temperature sintering provided by the present invention comprises: Continuous sintering furnace, which is provided with a plurality of heating chambers arranged in sequence, each heating chamber is provided with a first constant temperature structure to keep the set temperature unchanged, the set temperatures of the plurality of heating chambers increase in sequence, the continuous sintering furnace is further provided with a cooling chamber, and the cooling chamber is located downstream of the plurality of heating chambers; Continuous heat treatment furnace, which is provided with a plurality of tempering chambers arranged in sequence, each tempering chamber includes a heating zone and a cooling zone arranged in sequence, the heating zone is provided with a second constant temperature structure to keep the set temperature unchanged, and the set temperatures of the heating zones of the plurality of tempering chambers decrease in sequence.
[0007] Optionally, the heating chambers include a degreasing chamber, a dehydrogenation chamber and a sintering chamber, the set temperature of the degreasing chamber is 100°C to 300°C, the set temperature of the dehydrogenation chamber is 500°C to 800°C, and the set temperature of the sintering chamber is 1000°C to 1060°C.
[0008] Optionally, the tempering chambers include a high-temperature tempering chamber, a medium-temperature tempering chamber and a low-temperature tempering chamber, the set temperature of the heating zone of the high-temperature tempering chamber is 850°C to 900°C, the set temperature of the heating zone of the medium-temperature tempering chamber is 500°C to 700°C, and the set temperature of the heating zone of the low-temperature tempering chamber is 400°C to 500°C.
[0009] Optionally, isolation gates are provided between adjacent heating chambers, between the heating chamber and the cooling chamber, between adjacent tempering chambers, and between the heating zone and the cooling zone.
[0010] Optionally, a heat preservation isolation distance is provided between the heating chamber with the highest set temperature and the adjacent upstream heating chamber.
[0011] The method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering provided by the present invention is characterized by successively including the following steps: S1. Prepare raw materials: The master alloy, which is a rare earth-iron-boron-based permanent magnet master phase alloy; The auxiliary alloy, which is a grain boundary modification alloy doped with heavy rare earths; S2. Prepare the blank: Prepare a mixed powder of the master alloy and the auxiliary alloy, and obtain an initial blank by magnetic orientation molding of the mixed powder; S3. Rapid sintering: Load the initial blank into the continuous sintering furnace and evacuate it, then send the initial blank into each heating chamber in sequence and keep it warm for a set time in each heating chamber, and finally send the initial blank into the cooling chamber to cool it to the set temperature; S4. Heat treatment: Send the initial blank after rapid sintering into the continuous heat treatment furnace, and complete the heat treatment through each tempering chamber in sequence and then take it out of the furnace; In each tempering chamber, it first passes through the heating zone and is held at a set duration, and then is sent to the cooling zone to be cooled to a set temperature.
[0012] Optionally, in step S1, the chemical formula of the master alloy is RE x Fe bal M y B, where RE is one or more of Nd, Pr, La, Ce, Ho, x is 26.5 wt% - 33 wt%, M is one or more of Al, Cu, Zr, Co, Ti, Nb, Ga, and y is 0.1 wt% - 1 wt%; the chemical formula of the auxiliary alloy is (Nd,Pr) X-a N a Fe bal B 0.9 , N is one or two of Dy, Tb, and a is 5 wt% - 10 wt%.
[0013] Optionally, in step S2, the master alloy and the auxiliary alloy are first made into flakes with an average thickness less than 3 μm by melt spinning, and then hydrogenated and cracked to obtain the master alloy coarse powder and the auxiliary alloy coarse powder. Finally, 10 wt% - 30 wt% of the auxiliary alloy coarse powder is added to the master alloy coarse powder and passed through a jet mill to obtain a mixed powder, and the average particle size of the mixed powder is 2 μm - 3.5 μm.
[0014] Optionally, in step S3, the initial blank first enters the degreasing chamber and is held at 100°C - 300°C for 2 h - 4 h; then enters the dehydrogenation chamber and is held at 500°C - 800°C for 2 h - 4 h; then enters the sintering chamber and is held at 1000°C - 1060°C for 10 min - 30 min; finally enters the cooling chamber and is cooled to below 600°C.
[0015] Optionally, in step S4, the initial blank after rapid sintering first enters the high-temperature tempering chamber, passes through its heating zone and is held at 850°C - 900°C for 2 h, passes through its cooling zone and is cooled to below 200°C; then enters the medium-temperature tempering chamber, passes through its heating zone and is held at 500°C - 900°C for 2 h, passes through its cooling zone and is cooled to room temperature; finally enters the low-temperature tempering chamber, passes through its heating zone and is held at 400°C - 500°C for 2 h, passes through its cooling zone and is cooled to room temperature and then taken out of the furnace.
[0016] The technical solution provided by the present invention has the following advantages compared with the prior art: The device for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering provided by the present invention includes a continuous sintering furnace. The continuous sintering furnace is provided with multiple heating chambers that can maintain a constant set temperature. During sintering, the initial blank can quickly enter each heating chamber with an increasing temperature through movement without waiting for temperature rise, and the holding time at each temperature can be precisely controlled. Thus, the shell thickness of the Dy / Tb-rich core-shell structure can be precisely controlled, forming a nano-scale thin shell layer on the surface of the main-phase grains, and synchronously improving the remanence and coercivity through synergistic rapid densification. Moreover, this device also includes a continuous heat treatment furnace. The continuous heat treatment furnace is provided with multiple tempering chambers containing heating zones that can maintain a constant set temperature, and the holding time at each tempering temperature can be precisely controlled to optimize the microstructure of the sintered magnet, making the grain boundary phase distribution more uniform and the grain boundaries clearer, and thus better magnetic properties can be obtained.
[0017] The method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering provided by the present invention has the same advantages. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present invention and used together with the specification to explain the principles of the present invention.
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0020] Figure 1 It shows a schematic structural diagram of the continuous sintering furnace in the embodiment of the present invention; Figure 2 It shows a schematic structural diagram of the continuous heat treatment furnace in the embodiment of the present invention; Figure 3 It shows a schematic flow diagram of the method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] In order to more clearly understand the above objects, features, and advantages of the present invention, the following will further describe the solutions of the present invention. It should be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.
[0022] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.
[0023] In the following description, many specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present invention, rather than all the embodiments.
[0024] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Embodiment 1
[0025] Refer to Figure 1 and Figure 2 This embodiment provides a device for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering, including a continuous sintering furnace and a continuous heat treatment furnace.
[0026] Among them, the continuous sintering furnace is provided with a plurality of heating chambers arranged in sequence, and each heating chamber is provided with a first constant temperature structure to keep the set temperature unchanged. The set temperatures of the plurality of heating chambers increase in sequence. The continuous sintering furnace is also provided with a cooling chamber, and the cooling chamber is located downstream of the plurality of heating chambers.
[0027] It is easy to understand that the first constant temperature structure is the whole set of structures formed by the controller, temperature sensor and heating component; when the temperature sensor detects that the temperature value is less than the set temperature, the controller controls the heating component to continue heating; when the temperature sensor detects that the temperature value is equal to the set temperature, the controller controls the heating component to stop heating. In this way, through dynamic adjustment, the temperature of the heating chamber is maintained constant. This belongs to the mature technology in this field and will not be elaborated here.
[0028] Specifically, the heating chamber includes a degreasing chamber, a dehydrogenation chamber and a sintering chamber. The set temperature of the degreasing chamber is 100°C to 300°C, the set temperature of the dehydrogenation chamber is 500°C to 800°C, and the set temperature of the sintering chamber is 1000°C to 1060°C.
[0029] Specifically, isolation gates are provided between adjacent heating chambers and between the heating chamber and the cooling chamber to ensure the independence of the temperature control of each heating chamber and avoid mutual influence.
[0030] Specifically, a heat preservation isolation distance is provided between the heating chamber with the highest set temperature and the adjacent upstream heating chamber. Since the heating chamber with the highest set temperature is generally the sintering chamber, with a temperature of 1000°C to 1060°C, which is relatively high, a heat preservation isolation distance is set to avoid affecting the temperature control of the preheating chamber.
[0031] Among them, the continuous heat treatment furnace is provided with a plurality of tempering chambers arranged in sequence. Each tempering chamber includes a heating zone and a cooling zone arranged in sequence. The heating zone is provided with a second constant temperature structure to keep the set temperature unchanged. The set temperatures of the heating zones of the plurality of tempering chambers decrease in sequence.
[0032] It is easy to understand that the second constant temperature structure is the whole set of structures formed by the controller, the temperature sensor and the heating component; when the temperature value detected by the temperature sensor is less than the set temperature, the controller controls the heating component to continue heating; when the temperature value detected by the temperature sensor is equal to the set temperature, the controller controls the heating component to stop heating, so that the temperature of the heating zone is maintained constant through dynamic adjustment. This belongs to the mature technology in this field and will not be elaborated here.
[0033] Specifically, the tempering chamber includes a high-temperature tempering chamber, a medium-temperature tempering chamber and a low-temperature tempering chamber. The set temperature of the heating zone of the high-temperature tempering chamber is 850°C to 900°C, the set temperature of the heating zone of the medium-temperature tempering chamber is 500°C to 700°C, and the set temperature of the heating zone of the low-temperature tempering chamber is 400°C to 500°C.
[0034] Specifically, isolation gates are provided between adjacent tempering chambers and between the heating zone and the cooling zone to ensure the independence of temperature control in each zone and avoid mutual influence. Example 2
[0035] Refer to Figure 3 , the present invention provides a method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering, including steps S1 to S4.
[0036] S1. Prepare raw materials: a master alloy, which is a rare earth-iron-boron-based permanent magnet main phase alloy; an auxiliary alloy, which is a grain boundary modification alloy doped with heavy rare earths.
[0037] Specifically, the chemical formula of the master alloy is RE x Fe bal M y B, where RE is one or more of Nd, Pr, La, Ce, Ho, x is 26.5 wt% to 33 wt%, M is one or more of Al, Cu, Zr, Co, Ti, Nb, Ga, and y is 0.1 wt% to 1 wt%; the chemical formula of the auxiliary alloy is (Nd,Pr) X-a N a Fe bal B 0.9 , N is one or two of Dy, Tb, and a is 5 wt% to 10 wt%.
[0038] S2. Blank preparation: Prepare a mixed powder of the master alloy and the auxiliary alloy, and obtain an initial blank by magnetically oriented forming of the mixed powder.
[0039] Specifically, first, the master alloy and the auxiliary alloy are made into flakes with an average thickness of less than 3 μm by melting and spinning, then the master alloy coarse powder and the auxiliary alloy coarse powder are obtained by hydrogen embrittlement, and finally 10 wt% to 30 wt% of the auxiliary alloy coarse powder is added to the master alloy coarse powder and the mixed powder is obtained through a jet mill. The average particle size of the mixed powder is 2 μm to 3.5 μm.
[0040] S3. Quick sintering: Load the initial blank into a continuous sintering furnace and evacuate it, then send the initial blank into each heating chamber in sequence and keep it at a set duration in each heating chamber, and finally send the initial blank into the cooling chamber to cool it to a set temperature.
[0041] Specifically, the initial blank first enters the degreasing chamber and is kept at 100°C - 300°C for 2h - 4h; then enters the dehydrogenation chamber and is kept at 500°C - 800°C for 2h - 4h; then enters the sintering chamber and is kept at 1000°C - 1060°C for 10min - 30min; finally enters the cooling chamber and is cooled to below 600°C.
[0042] S4. Heat treatment: Send the initial blank after quick sintering into a continuous heat treatment furnace, and pass through each tempering chamber in sequence to complete the heat treatment and then take it out of the furnace; in each tempering chamber, first pass through the heating zone and keep it at a set duration, and then send it into the cooling zone to cool it to a set temperature.
[0043] Specifically, the initial blank after quick sintering first enters the high-temperature tempering chamber, passes through its heating zone and is kept at 850°C - 900°C for 2h, passes through its cooling zone and is cooled to below 200°C; then enters the medium-temperature tempering chamber, passes through its heating zone and is kept at 500°C - 900°C for 2h, passes through its cooling zone and is cooled to room temperature; finally enters the low-temperature tempering chamber, passes through its heating zone and is kept at 400°C - 500°C for 2h, passes through its cooling zone and is cooled to room temperature and then taken out of the furnace.
[0044] The advantages of this method are demonstrated through five experiments below.
[0045] Experiment 1 S1. Prepare raw materials: Master alloy (Nd,Pr) 28.8 Fe bal Co 0.1 Al 0.1 Cu 0.1 B; Auxiliary alloy (Nd,Pr) 27 Dy 1.8 Fe bal B 0.9 ; S2. Blank preparation: The master alloy and the auxiliary alloy are made into flakes with an average thickness of 2.8 µm by melting and flaking, and the coarse powders of the two alloys are obtained by hydrogen crushing. After adding 30wt% of the coarse powder of the auxiliary alloy to the coarse powder of the master alloy, the mixed powder is obtained through a jet mill with an average particle size of 3.5 µm, and the mixed powder is magnetically oriented and formed to obtain the initial blank; S3. Quick sintering: Load the initial blank into a continuous sintering furnace and evacuate it to 0.5×10 -3Pa. The initial blank first enters the degreasing chamber and is kept at 100 °C for 2 h; then it enters the dehydrogenation chamber and is kept at 500 °C for 2 h; then it enters the sintering chamber and is kept at 1000 °C for 30 min; finally, it enters the cooling chamber, the isolation gate is closed and argon is introduced, and the initial blank is cooled to below 600 °C by a high-power blower; S4. Heat treatment: The initial blank after rapid sintering continues to move forward to a continuous heat treatment furnace. First, it enters the high-temperature tempering chamber, passes through its heating zone and is kept at 850 °C for 2 h, passes through its cooling zone and is cooled to below 200 °C; then it enters the medium-temperature tempering chamber, passes through its heating zone and is kept at 500 °C for 2 h, passes through its cooling zone and is cooled to room temperature; finally, it enters the low-temperature tempering chamber, passes through its heating zone and is kept at 400 °C for 2 h, passes through its cooling zone and is cooled to room temperature and then taken out of the furnace.
[0046] Experiment 2 S1. Prepare raw materials: master alloy (Nd, Pr) 28.8 Fe bal Co 0.1 Al 0.1 Cu 0.1 B; auxiliary alloy (Nd, Pr) 27 Dy 1.8 Fe bal B 0.9 ; S2. Blank preparation: The master alloy and the auxiliary alloy are made into flakes with an average thickness of 2.8 µm by melting and spinning, and the coarse powders of the two alloys are obtained by hydrogen crushing. After adding 10 wt% of the coarse powder of the auxiliary alloy to the coarse powder of the master alloy, the mixed powder is obtained by a jet mill, with an average particle size of 3.5 µm. The mixed powder is magnetically oriented and formed to obtain the initial blank; S3. Rapid sintering: The initial blank is loaded into a continuous sintering furnace and evacuated to 0.5×10 -3 Pa. The initial blank first enters the degreasing chamber and is kept at 300 °C for 2 h; then it enters the dehydrogenation chamber and is kept at 800 °C for 2 h; then it enters the sintering chamber and is kept at 1060 °C for 30 min; finally, it enters the cooling chamber, the isolation gate is closed and argon is introduced, and the initial blank is cooled to below 600 °C by a high-power blower; S4. Heat treatment: The initial blank after rapid sintering continues to move forward to a continuous heat treatment furnace. First, it enters the high-temperature tempering chamber, passes through its heating zone and is kept at 850 °C for 2 h, passes through its cooling zone and is cooled to below 200 °C; then it enters the medium-temperature tempering chamber, passes through its heating zone and is kept at 700 °C for 2 h, passes through its cooling zone and is cooled to room temperature; finally, it enters the low-temperature tempering chamber, passes through its heating zone and is kept at 500 °C for 2 h, passes through its cooling zone and is cooled to room temperature and then taken out of the furnace.
[0047] Experiment 3 S1. Prepare raw materials: master alloy (Nd, Pr) 28.8 Fe bal Co 0.1 Al 0.1 Cu 0.1 B; secondary alloy (Nd, Pr) 27 Dy 1.8 Fe bal B 0.9 ; S2. Blank preparation: The master alloy and the secondary alloy are made into flakes with an average thickness of 2.8 µm by melting and flaking, and the coarse powders of the two alloys are obtained by hydrogen crushing. After adding 10 wt% of the coarse powder of the secondary alloy to the coarse powder of the master alloy, a mixed powder with an average particle size of 3.5 µm is obtained through a jet mill. The mixed powder is magnetically oriented and formed to obtain an initial blank; S3. Rapid sintering: The initial blank is loaded into a continuous sintering furnace and evacuated to 0.5×10 -3 Pa. The initial blank first enters the degreasing chamber and is kept at 200 °C for 2 h; then it enters the dehydrogenation chamber and is kept at 600 °C for 2 h; then it enters the sintering chamber and is kept at 1030 °C for 30 min; finally, it enters the cooling chamber, the isolation gate is closed and argon is introduced, and the initial blank is cooled to below 600 °C by a high-power blower; S4. Heat treatment: The initial blank after rapid sintering continues to move forward to a continuous heat treatment furnace. First, it enters the high-temperature tempering chamber, passes through its heating zone and is kept at 900 °C for 2 h, passes through its cooling zone and is cooled to below 200 °C; then it enters the medium-temperature tempering chamber, passes through its heating zone and is kept at 600 °C for 2 h, passes through its cooling zone and is cooled to room temperature; finally, it enters the low-temperature tempering chamber, passes through its heating zone and is kept at 450 °C for 2 h, passes through its cooling zone and is cooled to room temperature and then taken out of the furnace.
[0048] Experiment Four S1. Prepare raw materials: master alloy (Nd, Pr) 28.8 Fe bal Co 0.1 Al 0.1 Cu 0.1 B; secondary alloy (Nd, Pr) 27 Dy 1.8 Fe bal B 0.9 ; S2. Blank preparation: The master alloy and the secondary alloy are made into flakes with an average thickness of 2.8 µm by melting and flaking, and the coarse powders of the two alloys are obtained by hydrogen crushing. After adding 10 wt% of the coarse powder of the secondary alloy to the coarse powder of the master alloy, a mixed powder with an average particle size of 3.5 µm is obtained through a jet mill. The mixed powder is magnetically oriented and formed to obtain an initial blank; S3. Fast sintering: Load the initial blank into a common vacuum sintering furnace and evacuate it to 0.5×10 -3 Pa, then start heating: Heat it up to 200°C at a rate of 10°C / min and hold for 2 h; Heat it up to 600°C at a rate of 10°C / min and hold for 2 h; Heat it up to 1030°C at a rate of 15°C / min and hold for 30 min; Cool it down to below 600°C; Heat it up to 900°C at a rate of 15°C / min and hold for 2 h, then cool it down to below 200°C; Heat it up to 600°C at a rate of 10°C / min and hold for 2 h, then cool it down to room temperature; Heat it up to 450°C at a rate of 10°C / min and hold for 2 h, then cool it down to room temperature and take it out of the furnace.
[0049] Experiment Five S1. Prepare raw materials: master alloy (Nd,Pr) 28.8 Fe bal Co 0.1 Al 0.1 Cu 0.1 B; S2. Blank preparation: The master alloy is made into flakes with an average thickness of 2.8 µm by melting and spinning, and then hydrogenated and crushed to obtain coarse powder with an average particle size of 3.5 µm. The mixed powder is magnetically oriented and formed to obtain the initial blank; S3. Fast sintering: Load the initial blank into a common vacuum sintering furnace and evacuate it to 0.5×10 -3 Pa, then start heating: Heat it up to 200°C at a rate of 10°C / min and hold for 2 h; Heat it up to 600°C at a rate of 10°C / min and hold for 2 h; Heat it up to 1030°C at a rate of 15°C / min and hold for 30 min; Cool it down to below 600°C; Heat it up to 900°C at a rate of 15°C / min and hold for 2 h, then cool it down to below 200°C; Heat it up to 600°C at a rate of 10°C / min and hold for 2 h, then cool it down to room temperature; Heat it up to 450°C at a rate of 10°C / min and hold for 2 h, then cool it down to room temperature and take it out of the furnace.
[0050] The experimental data are statistically as follows: Inspection Items Residual Magnetism / kGs Coercive Force / kOe Magnetic Energy Product / MGOe Experiment 1 13.2 21.4 41.4 Experiment 2 13. 6 23.2 43.2 Experiment 3 13.4 22.5 42.6 Experiment 4 12.25 19.7 39.5 Experiment 5 12.38 14.3 35.4 Experiments 1 to 3 are the experimental results of the rare earth permanent magnets prepared by the method of this embodiment; Experiment 4 is the experimental result of the rare earth permanent magnet prepared by the existing method; Experiment 5 is different from Experiment 4 only in that the auxiliary alloy is not added.
[0051] As can be seen from the above table, the remanence, coercivity, and maximum energy product of the rare earth permanent magnets prepared by this method are all significantly greater than those of the rare earth permanent magnets prepared by the existing method. It can be seen that the rare earth permanent magnets prepared by this method have better magnetic properties. In addition, adding the auxiliary alloy can significantly improve the coercivity and maximum energy product of the rare earth permanent magnet, but the remanence will decrease slightly.
[0052] The above are only the specific embodiments of the present invention, enabling those skilled in the art to understand or implement the present invention. Although the foregoing embodiments have been described in detail, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.
Claims
1. An apparatus for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering, characterized in that, Including: A continuous sintering furnace, which is provided with a plurality of heating chambers arranged in sequence. Each heating chamber is provided with a first constant temperature structure to keep the set temperature unchanged, and the set temperatures of the plurality of heating chambers increase in sequence. The continuous sintering furnace is also provided with a cooling chamber, and the cooling chamber is located downstream of the plurality of heating chambers; A continuous heat treatment furnace, which is provided with a plurality of tempering chambers arranged in sequence. Each tempering chamber includes a heating zone and a cooling zone arranged in sequence. The heating zone is provided with a second constant temperature structure to keep the set temperature unchanged, and the set temperatures of the heating zones of the plurality of tempering chambers decrease in sequence.
2. The device for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to claim 1, characterized in that, The heating chambers include a degreasing chamber, a dehydrogenation chamber and a sintering chamber. The set temperature of the degreasing chamber is 100°C to 300°C, the set temperature of the dehydrogenation chamber is 500°C to 800°C, and the set temperature of the sintering chamber is 1000°C to 1060°C.
3. The device for preparing high-performance rare-earth permanent magnets by ultra-fast high-temperature sintering according to claim 1, wherein The tempering chambers include a high-temperature tempering chamber, a medium-temperature tempering chamber and a low-temperature tempering chamber. The set temperature of the heating zone of the high-temperature tempering chamber is 850°C to 900°C, the set temperature of the heating zone of the medium-temperature tempering chamber is 500°C to 700°C, and the set temperature of the heating zone of the low-temperature tempering chamber is 400°C to 500°C.
4. The device for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to any one of claims 1 to 3, characterized in that, Isolation gates are provided between adjacent heating chambers, between the heating chamber and the cooling chamber, between adjacent tempering chambers, and between the heating zone and the cooling zone.
5. The device for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to claim 4, wherein A heat preservation isolation distance is provided between the heating chamber with the highest set temperature and the adjacent upstream heating chamber.
6. A method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering, characterized in that, Sequentially including the following steps: S1. Prepare raw materials: The main alloy, which is a rare earth-iron-boron-based permanent magnet main phase alloy; The auxiliary alloy, which is a grain boundary modification alloy doped with heavy rare earths; S2. Blank preparation: Prepare a mixed powder of the main alloy and the auxiliary alloy, and obtain an initial blank by magnetic orientation forming of the mixed powder; S3. Rapid sintering: Load the initial blank into the continuous sintering furnace and evacuate it, then send the initial blank into each heating chamber in sequence and keep it warm for a set time in each heating chamber, and finally send the initial blank into the cooling chamber to cool to the set temperature; S4. Heat treatment: Send the initial blank after rapid sintering into the continuous heat treatment furnace, and complete the heat treatment and then take it out of the furnace after passing through each tempering chamber in sequence; In each tempering chamber, first pass through the heating zone and keep it warm for a set time, and then send it into the cooling zone to cool to the set temperature.
7. The method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to claim 6, characterized in that: In step S1, the chemical formula of the master alloy is RE x Fe bal M y B, where RE is one or more of Nd, Pr, La, Ce, Ho, x is 26.5 wt% - 33 wt%, M is one or more of Al, Cu, Zr, Co, Ti, Nb, Ga, and y is 0.1 wt% - 1 wt%; the chemical formula of the subsidiary alloy is (Nd,Pr) X-a N a Fe bal B 0.9 , N is one or both of Dy and Tb, and a is 5 wt% - 10 wt%.
8. The method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to claim 6, characterized in that, In step S2, first, the main alloy and the auxiliary alloy are made into flakes with an average thickness of less than 3 μm by melting and spinning, then the main alloy coarse powder and the auxiliary alloy coarse powder are obtained by hydrogen breaking, and finally 10 wt% to 30 wt% of the auxiliary alloy coarse powder is added to the main alloy coarse powder and the mixed powder is obtained through a jet mill. The average particle size of the mixed powder is 2 μm to 3.5 μm.
9. The method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to claim 6, wherein, In step S3, the initial blank first enters the degreasing chamber and is kept warm at 100°C to 300°C for 2 h to 4 h; then enters the dehydrogenation chamber and is kept warm at 500°C to 800°C for 2 h to 4 h; then enters the sintering chamber and is kept warm at 1000°C to 1060°C for 10 min to 30 min; finally enters the cooling chamber and cools to below 600°C.
10. The method for preparing high-performance rare earth permanent magnets by ultra-fast high-temperature sintering according to claim 6, wherein In step S4, the initial blank after rapid sintering first enters the high-temperature tempering chamber, passes through its heating zone and is kept at 850°C - 900°C for 2 hours, passes through its cooling zone and is cooled to below 200°C; then it enters the medium-temperature tempering chamber, passes through its heating zone and is kept at 500°C - 900°C for 2 hours, passes through its cooling zone and is cooled to room temperature; finally, it enters the low-temperature tempering chamber, passes through its heating zone and is kept at 400°C - 500°C for 2 hours, passes through its cooling zone and is cooled to room temperature before leaving the furnace.