Vacuum pressure sintering equipment for rare earth permanent magnet material

Abstract

The utility model discloses a vacuum pressure sintering equipment for rare earth permanent magnet material, including: furnace body, heating system, vacuumizing system, control system and pressurization system, pressurization system includes with the furnace body intercommunication first interface, is used for transporting inert gas to the furnace body in the process of sintering rare earth permanent magnet material, therefore, the pressure in the furnace body is increased. The equipment is additionally provided with a pressurizing system, adopts a pressurizing sintering technology to sinter a rare earth permanent magnet material, reduces the sintering temperature of an alloy green body, adds inert gas into the furnace body, increases the pressure in the furnace body, realizes grain size refinement under the dual action of temperature and pressure, and enables an intergranular phase to fully flow to realize uniform distribution; main phase grains are isolated from one another, and the coercive force of the rare earth permanent magnet material is improved. The equipment can reduce the sintering temperature, reduce the energy consumption, shorten the sintering time and improve the production efficiency, and the rare earth permanent magnetic material obtained by sintering has good comprehensive magnetic performance.

Description

Technical Field

[0001] The utility model relates to the technical field of rare earth permanent magnet material manufacturing equipment, in particular to vacuum pressure sintering equipment for rare earth permanent magnet materials. Background Art

[0002] Rare earth permanent magnet NdFeB is currently the type of permanent magnet material with the highest magnetic properties. It is widely used in energy, transportation, communications and other fields, and has become an indispensable functional material in today's society. With the rapid growth of demand for high-end and emerging industries, the demand for higher performance magnets is increasing. In such an environment, if sintered rare earth permanent magnet NdFeB wants to have better market competitiveness, it must develop towards high coercivity and low cost.

[0003] The existing rare earth permanent magnet NdFeB sintering process often adopts a vacuum sintering process. The vacuum sintering furnace used usually includes a vacuum chamber, a heating system, a vacuum pumping system and a control system. It has low production efficiency and high energy consumption, and it is difficult to achieve grain refinement to improve the coercive force of NdFeB.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the utility model. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Utility Model Content

[0005] The (main) purpose of the utility model is to provide a vacuum pressure sintering device for rare earth permanent magnet materials to solve the technical problems of low production efficiency and high energy consumption in the above-mentioned prior art.

[0006] To this end, the utility model provides a vacuum pressure sintering device for rare earth permanent magnetic materials.

[0007] Preferably, the utility model may also have the following technical features:

[0008] A vacuum pressure sintering device for rare earth permanent magnet materials comprises: a furnace body, a heating system, a vacuum pumping system and a control system, and also comprises a pressure system. The pressure system comprises a first interface communicated with the furnace body and is used to transport inert gas to the furnace body during the sintering of rare earth permanent magnet materials to increase the pressure in the furnace body.

[0009] Preferably, the pressurizing system further comprises a flow controller installed near the first interface, for controlling the amount of the inert gas entering into the furnace body.

[0010] Preferably, the furnace wall of the furnace body and the vacuum pumping system are both provided with pressure devices, and the pressure devices are connected to the control system to monitor the gas pressure in the furnace body.

[0011] Preferably, when the equipment is in working state, the gas pressure in the furnace body is 0.001Pa-0.1MPa.

[0012] Preferably, when the equipment is in working state, the gas pressure in the furnace body is 0.1Pa-10Pa.

[0013] Preferably, the pressure applied by the pressurizing system is 0 MPa to 10 MPa.

[0014] Preferably, the pressure applied by the pressurizing system is 0.1 MPa to 5 MPa.

[0015] Preferably, it also includes an observation mirror arranged on the top of the furnace body.

[0016] The beneficial effects of the utility model compared with the prior art include:

[0017] The equipment of the utility model is provided with a pressurizing system, and adopts a pressurized sintering technology to sinter rare earth permanent magnet materials, reduce the sintering temperature of the alloy green body, and at the same time add an inert gas into the furnace body to increase the pressure in the furnace body. Under the dual effects of temperature and pressure, the fluidity of the rare earth-rich liquid phase is enhanced, the growth of grains is restricted, the grain size is refined, the fluidity of the intercrystalline phase is enhanced, and the intercrystalline phase is prompted to fully flow and achieve uniform distribution, the main phase grains are isolated from each other, the demagnetization coupling effect is strengthened, and the coercive force of the rare earth permanent magnet material is improved. The equipment has a simple structure and is easy to operate, reduces the sintering temperature, reduces energy consumption, and shortens the sintering time, improves production efficiency, and the rare earth permanent magnet material obtained by sintering has good comprehensive magnetic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a specific implementation method of the utility model.

[0019] Figure 2 It is a schematic diagram of the microstructure involved in the utility model.

[0020] Description of the symbols in the accompanying drawings:

[0021] 1. Second interface; 2. Pressure gauge; 3. Temperature sensor; 4. Heating chamber wall; 5. Heating chamber cover; 6. First interface; 7. Observation mirror; 8. First valve; 9. Furnace cover; 10. Pressure sensor, 11. Heating electrode; 12. Heating element; 13. Furnace wall; 14. Base; 15. Furnace bottom. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below in conjunction with specific implementations and in conjunction with the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope and application of the present invention.

[0023] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein like reference numerals refer to like parts unless otherwise specifically stated.

[0024] A vacuum pressure sintering device for rare earth permanent magnet materials. This embodiment takes the sintering of rare earth permanent magnet neodymium iron boron (Nd-Fe-B) as an example to illustrate the vacuum pressure sintering device mentioned in the utility model. Figure 1 As shown, it includes a furnace body, a heating system, a vacuum system, a control system and a pressurizing system. The pressurizing system includes a first interface 6 communicated with the furnace body, which is used to transport inert gas to the furnace body during the sintering of rare earth permanent magnet materials to increase the pressure in the furnace body. Specifically, the pressurizing system includes an inert gas source, a first interface 6 and a first valve 8. The gas source can be an inert gas cylinder, which is arranged outside the furnace body. The inert gas can be added into the furnace body through the first interface 6 and the first valve 8 to increase the pressure in the furnace body. In some other examples, the pressurizing system also includes a flow controller installed near the first interface to control the amount of the inert gas entering the furnace body.

[0025] Specifically, the furnace body can be a cylinder, including a furnace cover 9, a furnace wall 13 and a furnace bottom 15, all of which are made of stainless steel. The joints of each part are sealed with sealing gaskets to prevent air leakage. A cooling water channel is provided in the furnace body to circulate and cool the furnace body.

[0026] The heating system includes a base 14, a heating chamber wall 4, a heating chamber cover 5, a temperature sensor 3, a heating electrode 11 and a heating element 12. The base 14 is a high-temperature resistant hard metal. Preferably, the high-temperature resistant hard metal is an alloy of one or more of tungsten, molybdenum, titanium and tantalum, or an alloy material containing the above metals. When adding materials, the furnace cover 9 and the heating chamber cover 5 are opened from the top, and the material to be sintered is placed on the base 14, and the base 14 is circular. The heating element 12 is isostatic graphite, cylindrical, and the heating element 12 is surrounded by a cylindrical heating chamber surrounded by the heating chamber wall 4 and the heating chamber cover 5, and is used to heat the entire heating chamber. The heating chamber is lined with high-temperature resistant graphite carbon felt, and the heating element 12 is connected to the heating electrode 11 through a graphite connector. The temperature sensor 3 is connected to the control system to monitor the temperature in the heating chamber. Specifically, the temperature range in the heating chamber is 20°C to 2000°C, preferably 20°C to 1500°C.

[0027] A vacuum system is arranged outside the furnace body, and a second interface 1 connected to the vacuum system is arranged on the furnace wall 13, which is used to vacuum the entire internal chamber of the furnace body. Specifically, the vacuum system may include a vacuum pump and a second valve, and the vacuum pump is used to vacuum the entire internal chamber of the furnace body. Specifically, a pressure device is arranged on the furnace wall 13 of the furnace body and the vacuum system, and the pressure device is connected to the control system to monitor the gas pressure of the furnace body. Specifically, a pressure gauge 2 may be arranged on the second interface 1 of the vacuum system, and a pressure sensor 10 may be arranged on the furnace wall 13. When the above-mentioned equipment is in working state, the gas pressure in the furnace body is 0.001Pa~0.1MPa, preferably 0.1Pa~10Pa. Specifically, during the sintering of rare earth permanent magnet NdFeB, the rare earth permanent magnet green body is placed in the base 14, and after the furnace cover 9 is closed, vacuuming is started. When the required vacuum degree (0.001Pa~0.1MPa, preferably 0.1Pa~10Pa) is reached, the heating system starts to work and heats to the set sintering temperature (900℃~1200℃), the vacuuming system is turned off, and the pressurizing system is turned on to introduce high-purity inert gas into the furnace body. The pressure applied by the pressurizing system is 0MPa~10MPa, preferably 0.1MPa~5MPa, and the heat is kept for 10~120 minutes. After, in this process, due to the effect of the pressure system, the sintering temperature is 50°C lower than the sintering temperature without the pressure system (only under a vacuum environment). In this way, the sintering temperature is reduced, which can significantly reduce energy consumption and shorten the sintering time. Under the dual effects of high temperature and pressure, the fluidity of the rare earth-rich liquid phase is enhanced, low-temperature densification is achieved, grain growth is restricted, and the grain size is refined to within 15 μm, so that the intergranular phase fluidity is enhanced, and the intergranular phase is prompted to fully flow and achieve uniform distribution, improve the microstructure of the magnet, and obtain a high coercive force rare earth permanent magnet neodymium iron boron (Nd-Fe-B) with good comprehensive magnetic properties. After the insulation is completed, the heating system is turned off, sintering is stopped, and high-purity inert gas is continued to be introduced into the furnace body to cool the sintered rare earth permanent magnet neodymium iron boron to room temperature, and then the furnace cover 9 is opened to take out the product. In the cooling stage, inert gas is introduced to achieve rapid cooling.

[0028] Specifically, the microstructure of ordinary vacuum sintering and vacuum pressure sintering can be found in Figure 2 The left side (a) shows the microstructure of ordinary vacuum sintering, and the right side (d) shows the microstructure of vacuum pressure sintering. It can be clearly seen that the magnet microstructure in (d) is finer and more evenly distributed.

[0029] Specifically, the relevant performance parameters of ordinary vacuum sintering and vacuum pressure sintering are compared in the following table:

[0030]

[0031] Residual magnetic induction intensity, intrinsic coercive force and maximum magnetic energy product are the main indicators to measure the performance of permanent magnetic material products. Residual magnetic induction intensity refers to the magnetic induction intensity of a magnet when it is magnetized to technical saturation by an external magnetic field in a closed circuit environment and the external magnetic field is removed; intrinsic coercive force is the reverse magnetic field intensity required to reduce the magnetization intensity of the magnet to zero; the maximum magnetic energy product represents the magnetic energy density established by the space between the two magnetic poles of the magnet, that is, the static magnetic energy per unit volume of the air gap, which is the maximum value of the product of residual magnetic induction intensity Br and intrinsic coercive force Hcj, and its size directly indicates the performance of the magnet. It can be seen from the above table that the rare earth permanent magnet neodymium iron boron (Nd-Fe-B) sintered at 1000℃ under vacuum pressure has better performance than that sintered at 1060℃ under ordinary vacuum, and the sintering temperature is 60℃ lower, which significantly reduces energy consumption and shortens sintering time.

[0032] Specifically, in order to conveniently observe the sintering condition of the rare earth permanent magnet neodymium iron boron (Nd—Fe—B), an observation mirror 7 may be provided on the top of the furnace body.

[0033] The specific method of sintering rare earth permanent magnet neodymium iron boron (Nd-Fe-B) using the above-mentioned equipment is as follows: open the furnace cover 9, place the rare earth permanent magnet green body on the base 14, and close the furnace cover 9; turn on the vacuum pump to draw the required vacuum environment; turn on the heating, first keep the green body at three temperature gradients of 300°C, 600°C, and 800°C for 10 to 120 minutes respectively, so as to eliminate volatile impurities in the magnet as much as possible, and make the surface of the magnet initially dense, to prevent the magnet from being severely oxidized in subsequent processes; continue to heat up to the set sintering temperature, turn off the vacuum system, turn on the pressurization system, and introduce high-purity inert gas into the furnace body, and the pressure is maintained at 0.1MPa to 5MPa. After keeping warm for 10 to 120 minutes, turn off the heating system and stop sintering; after the sintering program stops, continue to introduce high-purity inert gas into the furnace body to cool the magnet to room temperature, then open the furnace cover 9 and take out the product.

[0034] Those skilled in the art will appreciate that numerous variations to the above description are possible, and that the examples and figures are intended only to describe one or more specific implementations.

[0035] Although exemplary embodiments of the present invention have been described and described, it will be understood by those skilled in the art that various changes and substitutions may be made thereto without departing from the spirit of the present invention. In addition, many modifications may be made to adapt specific situations to the teachings of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but the present invention may also include all embodiments and their equivalents that fall within the scope of the present invention.

Claims

1. A vacuum pressure sintering device for rare earth permanent magnet materials, comprising a furnace body, a heating system, a vacuum pumping system and a control system, characterized in that: It also includes a pressurizing system, which includes a first interface in communication with the furnace body and is used to deliver inert gas to the furnace body during the sintering of the rare earth permanent magnet material to increase the pressure in the furnace body; The pressurizing system further comprises a flow controller installed near the first interface, for controlling the amount of the inert gas entering the furnace body; The furnace wall of the furnace body and the vacuum pumping system are both provided with pressure devices, and the pressure devices are connected with the control system to monitor the gas pressure in the furnace body.

2. A vacuum pressure sintering device for rare earth permanent magnet materials according to claim 1, characterized in that: When the equipment is in working state, the gas pressure in the furnace body is 0.001Pa~0.1MPa.

3. A vacuum pressure sintering device for rare earth permanent magnet materials as claimed in claim 2, characterized in that: When the equipment is in working state, the gas pressure in the furnace body is 0.1Pa-10Pa.

4. A vacuum pressure sintering device for rare earth permanent magnetic materials as claimed in claim 3, characterized in that: The pressure applied by the pressurizing system is 0 MPa to 10 MPa.

5. A vacuum pressure sintering device for rare earth permanent magnet materials as claimed in claim 4, characterized in that: The pressure applied by the pressurizing system is 0.1 MPa to 5 MPa.

6. A vacuum pressure sintering device for rare earth permanent magnet materials according to claim 1, characterized in that: It also includes an observation mirror arranged on the top of the furnace body.

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