High-flux-density permanent ferrite tile and method of making same

Abstract

The application belongs to the technical field of permanent magnet ferrite tile preparation, and particularly relates to a high-flux-density permanent magnet ferrite tile and a preparation method thereof. The preparation method comprises the following steps: permanent magnet ferrite slurry is prepared into a permanent magnet ferrite tile through pressing, high-temperature pre-sintering, size grinding, cleaning and impurity removal, and high-temperature resintering; the permanent magnet ferrite slurry comprises permanent magnet ferrite preparation raw materials and a treating agent; the treating agent comprises a mixture of lithium silicate, ammonium bicarbonate and sorbitol. The preparation method of the high-flux-density permanent magnet ferrite tile provided by the application adopts the mixture of lithium silicate, ammonium bicarbonate and sorbitol as the treating agent, can precipitate free strontium ions generated in the ball milling process, improve the molding pressing orientation effect and the green body density uniformity, and improve the magnetic flux density and mechanical strength of the tile. The preparation method of the high-flux-density permanent magnet ferrite tile provided by the application can reduce the surface roughness through the high-temperature resintering process, and further improve the magnetic flux density and mechanical strength of the tile.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet ferrite tile preparation technology, specifically relating to a high magnetic flux density permanent magnet ferrite tile and its preparation method. Background Technology

[0002] Permanent magnet ferrite tiles, as the magnetic field source of motors, are a key component of motors, and their technological development directly affects the efficiency, reliability, and application range of motors. Currently, with the rapid development of new energy vehicles, energy-saving home appliances, and industrial automation, higher requirements are being placed on the magnetic flux density, mechanical strength, and surface roughness of permanent magnet ferrite tiles. The current manufacturing process for permanent magnet ferrite tiles is: ball milling → dehydration → molding → sintering → grinding → finished product. Permanent magnet ferrite tiles produced according to this process have the following problems: (1) The magnetic flux density of the magnetic tile is not at its optimal level, resulting in wasted performance; (2) When the magnetic tiles are processed by diamond grinding wheel, grinding marks and microcracks will be generated, which will reduce the mechanical strength of the magnetic tiles and there is a risk of slag falling off during transportation and motor use. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a high flux density permanent magnet ferrite tile and its preparation method, thus resolving at least one aspect of the above-mentioned technical issues.

[0004] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing high flux density permanent magnet ferrite tiles, comprising the following steps: Permanent magnet ferrite slurry is used to make permanent magnet ferrite tiles; The permanent magnet ferrite slurry contains raw materials for the preparation of permanent magnet ferrite and processing agents; The treatment agent consists of a mixture of lithium silicate, ammonium bicarbonate, and sorbitol.

[0005] In some possible implementations, the mass ratio of lithium silicate, ammonium bicarbonate and sorbitol is (0.8~1):1:1.

[0006] In some possible implementations, the amount of the treatment agent is 0.6% to 1.5% of the raw materials for preparing permanent magnet ferrite.

[0007] In some possible implementations, the raw materials for preparing permanent magnet ferrites include the following elemental composition: Sr, Ca, La, Fe, Co and O, in a molar ratio of (0.05~0.2):(0.4~0.5):(0.4~0.5):(9~12):(0.2~0.5):19.

[0008] In some possible implementations, the preparation of the permanent magnet ferrite slurry includes the following steps: The raw materials for preparing permanent magnet ferrite are ball-milled, dehydrated, and then mixed with a treatment agent.

[0009] In some possible implementations, the particle size D50 of the slurry obtained by the ball milling process is 0.6 μm to 0.8 μm.

[0010] In some possible implementations, the material-to-liquid ratio of the ball milling process is 1:(1.5~2).

[0011] In some possible implementations, the moisture content of the slurry after dewatering is 25% to 37%.

[0012] In some possible implementations, the process of forming permanent magnet ferrite tiles from the permanent magnet ferrite slurry includes the following steps: The permanent magnet ferrite slurry is pressed into a green body and then sintered.

[0013] In some possible implementations, the sintering process includes the following steps: After pre-sintering, the green blanks are dimensionally ground and cleaned to remove impurities, resulting in semi-finished products. The semi-finished product is then re-sintered.

[0014] In some possible implementations, the pre-sintering temperature is 1180℃~1200℃.

[0015] In some possible implementations, the pre-sintering holding time is 2h to 3h.

[0016] In some possible implementations, the pre-sintering temperature is not lower than the re-sintering temperature.

[0017] In some possible implementations, the temperature difference between the pre-sintering temperature and the re-sintering temperature is 0°C to 20°C.

[0018] In some possible implementations, the holding time for the re-sintering is 2h to 3h.

[0019] Secondly, the present invention provides a high flux density permanent magnet ferrite tile prepared by the above-mentioned preparation method, wherein the flux density of the high flux density permanent magnet ferrite tile is 2.06 mWb / cm². 3 ~2.1mWb / cm 3 .

[0020] In some possible implementations, the average mechanical strength of the high flux density permanent magnet ferrite tile is 100 N / mm². 2 ~120N / mm 2 .

[0021] The method for preparing high flux density permanent magnet ferrite tiles provided by this invention has at least the following beneficial technical effects compared with the prior art: (1) The preparation method of high magnetic flux density permanent magnet ferrite tile provided by the present invention uses a mixture of lithium silicate, ammonium bicarbonate and sorbitol as the treatment agent, which can precipitate free strontium ions generated in the ball milling process, improve the molding and pressing orientation effect and the uniformity of green density, and improve the magnetic flux density and mechanical strength of the tile.

[0022] (2) The method for preparing high flux density permanent magnet ferrite tiles provided by the present invention can reduce surface roughness through a high-temperature re-firing process, thereby further improving the flux density and mechanical strength of the tiles. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of this drawing or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this drawing. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0024] Figure 1 A 100x magnification micrograph of the surface wear marks on the high flux density permanent magnet ferrite tile provided in Embodiment 1 of the present invention; Figure 2 This is a 100x magnification micrograph of the surface wear marks on the permanent magnet ferrite tile provided in Embodiment 2 of the present invention.

[0025] The purpose, features, and advantages of this accompanying drawing will be further explained in conjunction with the embodiments and with reference to the accompanying drawing. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described and illustrated below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0027] Obviously, the following description is merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0028] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand the invention and is not intended to limit the subject matter of the claims.

[0029] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0030] [Preparation method of high flux density permanent magnet ferrite tiles] This invention provides a method for preparing high flux density permanent magnet ferrite tiles, comprising the following steps: S10. Permanent magnet ferrite slurry is used to make permanent magnet ferrite tiles; The permanent magnet ferrite slurry contains raw materials for the preparation of permanent magnet ferrite and processing agents; The treatment agent consists of a mixture of lithium silicate, ammonium bicarbonate, and sorbitol.

[0031] The method for preparing high flux density permanent magnet ferrite tiles provided in this invention uses a mixture of lithium silicate, ammonium bicarbonate and sorbitol as the treatment agent, which can precipitate free strontium ions generated in the ball milling process, improve the molding and pressing orientation effect and the uniformity of green density, and improve the flux density and mechanical strength of the magnet tiles.

[0032] In some embodiments, in step S10 above, the raw materials for preparing permanent magnet ferrite include the following elemental components: Sr, Ca, La, Fe, Co and O.

[0033] In some embodiments, the molar ratio of Sr, Ca, La, Fe, Co and O is 0.05~0.2:0.4~0.5:0.4~0.5:9~12:0.2~0.5:19.

[0034] In some embodiments, in step S10 above, the mass ratio of lithium silicate, ammonium bicarbonate and sorbitol is (0.8~1):1:1.

[0035] In some embodiments, the preparation of the permanent magnet ferrite slurry in step S10 above includes the following steps: S101. The raw materials for preparing permanent magnet ferrite are ball-milled, dehydrated, and then mixed with a treatment agent.

[0036] In some embodiments, in step S101 above, the particle size D50 of the slurry obtained by ball milling is 0.6 μm to 0.8 μm.

[0037] In some specific embodiments, in step S101 above, the ball milling medium is water.

[0038] In some specific embodiments, in step S101 above, the material-to-liquid ratio for ball milling is 1:(1.5~2).

[0039] The feed-to-liquid ratio refers to the ratio of raw materials for preparing permanent magnet ferrite to the ball milling media.

[0040] In some specific embodiments, in step S101 above, the moisture content of the slurry after dewatering is 25%~37%.

[0041] In some specific embodiments, in step S101 above, the dewatering process involves using a centrifugal dewatering machine to remove excess water from the slurry. It should be noted that the centrifugal dewatering machine is a conventional centrifuge. Therefore, it is not specifically limited in this embodiment of the invention.

[0042] In some embodiments, in step S10 above, the process of forming permanent magnet ferrite tiles from permanent magnet ferrite slurry includes the following steps: S102. The permanent magnet ferrite slurry is pressed into a green body and then sintered.

[0043] In some embodiments, the sintering process in step S102 above includes the following steps: S1021. After pre-sintering the green body, post-processing is carried out to obtain a semi-finished product.

[0044] S1022. Re-sinter the semi-finished product.

[0045] In this case, the pre-sintering of the green body followed by post-treatment and then re-sintering can reduce the surface roughness of the magnetic tile and further improve its magnetic flux density and mechanical strength. It should be noted that post-sintering dimensional grinding and cleaning are conventional techniques in the field, generally employing high-speed grinding with a grinding wheel and ultrasonic cleaning. Therefore, they are not specifically limited in this embodiment of the invention.

[0046] In some embodiments, in step S1021 above, the pre-sintering temperature is 1180~1200℃.

[0047] In some embodiments, in step S1021 above, the pre-sintering holding time is 2h to 3h.

[0048] In some embodiments, the pre-sintering temperature is not lower than the re-sintering temperature.

[0049] In some embodiments, the temperature difference between the pre-sintering temperature and the re-sintering temperature is 0°C to 20°C. Too low a temperature will result in no improvement in magnetic flux density, while too high a temperature will lead to excessive growth of the magnetic tile grains, resulting in a significant decrease in magnetic flux density.

[0050] In some embodiments, in step S1021 above, the post-processing includes dimensional grinding and cleaning to remove impurities. It should be noted that dimensional grinding and cleaning are conventional operations in the art, and therefore, are not specifically limited in the embodiments of the present invention.

[0051] In some embodiments, in step S1022 above, the holding time for re-sintering is 2h to 3h.

[0052] High flux density permanent magnet ferrite tiles A second aspect of the present invention provides a high flux density permanent magnet ferrite tile prepared by the above-described preparation method.

[0053] In some embodiments, the magnetic flux density of the high flux density permanent magnet ferrite tile is 2.06 mWb / cm². 3 ~2.1mWb / cm 3 .

[0054] In some embodiments, the magnetic flux density of the high flux density permanent magnet ferrite tile is 2.064 mWb / cm². 3 ~2.082mWb / cm 3 .

[0055] In some embodiments, the average mechanical strength of the high flux density permanent magnet ferrite tile is 100 N / mm². 2 ~120N / mm 2 .

[0056] In some embodiments, the average mechanical strength of the high flux density permanent magnet ferrite tile is 112 N / mm². 2 ~118N / mm 2 .

[0057] The following description, in conjunction with specific embodiments, provides further details.

[0058] Example 1 Example 1 provides a method for preparing a high flux density permanent magnet ferrite tile, the steps of which are as follows: E10. Preparation of permanent magnet ferrite slurry The raw materials for preparing permanent magnet ferrite are ball-milled and then dehydrated before being mixed with a treatment agent to obtain a permanent magnet ferrite slurry. The elemental composition of the raw materials for preparing permanent magnet ferrite is Sr, Ca, La, Fe, Co and O, with a molar ratio of 0.1:0.45:0.45:11.55:0.45:19.

[0059] The particle size D50 of the slurry obtained by ball milling is 0.78 μm.

[0060] The ball milling medium used in the ball milling process is water, and the material-to-liquid ratio is 1:1.67.

[0061] The moisture content of the slurry after dewatering is 35%.

[0062] The treatment agent is a mixture of lithium silicate, ammonium bicarbonate and sorbitol in a mass ratio of 1:1:1; the amount of treatment agent used is 1.2% of the raw materials for preparing permanent magnet ferrite.

[0063] E20. Sintering After the permanent magnet ferrite slurry is pressed into a green blank, the green blank is pre-sintered and then subjected to dimensional grinding and cleaning to obtain a semi-finished product; the semi-finished product is then re-sintered to obtain the high magnetic flux density permanent magnet ferrite tile of this embodiment. The pre-sintering temperature is 1190℃, and the holding time is 2 hours. The re-sintering temperature was 1180℃, and the holding time was 2 hours.

[0064] Example 2 Example 2 provides a method for preparing a high flux density permanent magnet ferrite tile, the steps of which are basically the same as those in Example 1, except that: In step E10, the mixture of lithium silicate, ammonium bicarbonate and sorbitol is in a mass ratio of 0.8:1:1; the amount of the treatment agent is 0.9% of the raw materials for preparing permanent magnet ferrite.

[0065] Example 3 Example 3 provides a method for preparing a high flux density permanent magnet ferrite tile, the steps of which are basically the same as those in Example 1, except that: In step E10, the amount of the treatment agent is 1.5% of the raw materials used in the preparation of permanent magnet ferrite.

[0066] Example 4 Example 4 provides a method for preparing a high flux density permanent magnet ferrite tile, the steps of which are basically the same as those in Example 1, except that: In step E20, the pre-sintering temperature is 1180℃, and the holding time is 2 hours; The re-sintering temperature was 1180℃, and the holding time was 3 hours.

[0067] Example 5 Example 5 provides a method for preparing a high flux density permanent magnet ferrite tile, the steps of which are basically the same as those in Example 1, except that: In step E20, the pre-sintering temperature is 1200℃, and the holding time is 2 hours; The re-sintering temperature was 1180℃, and the holding time was 2 hours.

[0068] Comparative Example 1 Comparative Example 1 provides a method for preparing permanent magnet ferrite tiles, the steps of which are basically the same as those in Example 1, except that: No treatment agent was added in step E10.

[0069] Comparative Example 2 Comparative Example 2 provides a method for preparing permanent magnet ferrite tiles, the steps of which are basically the same as those in Example 1, except that: In step E20, the permanent magnet ferrite slurry is pressed into a green blank, which is then sintered, and then subjected to dimensional grinding and cleaning to remove impurities, in order to obtain a permanent magnet ferrite tile. The sintering temperature is 1190℃ and the holding time is 2h.

[0070] Comparative Example 3 Comparative Example 3 provides a method for preparing permanent magnet ferrite tiles, the steps of which are basically the same as those in Example 1, except that: In step E20, the re-sintering temperature is 1160℃.

[0071] Comparative Example 4 Comparative Example 4 provides a method for preparing permanent magnet ferrite tiles, the steps of which are basically the same as those in Example 5, except that: In step E20, the re-sintering temperature is 1205℃.

[0072] To verify the advancement of the permanent magnet ferrite tile and its preparation method provided in the embodiments of the present invention, the magnetic flux, magnetic flux density and mechanical strength of the permanent magnet ferrite tiles prepared in the embodiments and comparative examples of the present invention were tested, and the results are shown in Table 1 below.

[0073] Table 1

[0074] From Table 1 above, at least the following conclusions can be drawn: (1) In Comparative Example 1, the magnetic flux density was significantly reduced when no treatment agent was added. It can be seen that the preparation method of high magnetic flux density permanent magnet ferrite tiles provided in the embodiments of the present invention uses a mixture of lithium silicate, ammonium bicarbonate and sorbitol as a treatment agent, which can precipitate free strontium ions generated in the ball milling process, improve the molding and pressing orientation effect and the uniformity of green density, and improve the magnetic flux density and mechanical strength of the magnetic tiles.

[0075] (2) Comparative Example 2 underwent only one sintering process. Although the magnetic flux and magnetic flux density of the magnetic tile did not decrease significantly, its average mechanical strength decreased substantially. Comparative Example 3 used a lower re-firing temperature, which had little effect on the magnetic flux density of the magnetic tile, but the average mechanical strength of the magnetic tile decreased significantly. Comparative Example 4 used a higher re-firing temperature, which improved the average mechanical strength of the magnetic tile, but its average radial magnetic flux decreased significantly. Therefore, the method for preparing high magnetic flux density permanent magnet ferrite tiles provided in this embodiment of the invention can reduce surface roughness and further improve the magnetic flux density and mechanical strength of the magnetic tile through a high-temperature re-firing process and sintering temperature control.

[0076] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for preparing a high flux density permanent magnet ferrite tile, characterized in that, Includes the following steps: Permanent magnet ferrite slurry is used to make permanent magnet ferrite tiles; The permanent magnet ferrite slurry contains raw materials for the preparation of permanent magnet ferrite and processing agents; The treatment agent consists of a mixture of lithium silicate, ammonium bicarbonate, and sorbitol.

2. The method for preparing high flux density permanent magnet ferrite tiles according to claim 1, characterized in that, The mass ratio of lithium silicate, ammonium bicarbonate and sorbitol is (0.8~1):1:1; And / or, the amount of the treatment agent is 0.6% to 1.5% of the raw materials for preparing permanent magnet ferrite.

3. The method for preparing high flux density permanent magnet ferrite tiles according to claim 1 or 2, characterized in that, The raw materials for preparing the permanent magnet ferrite include the following elemental components: Sr, Ca, La, Fe, Co and O, with a molar ratio of 0.05~0.2:0.4~0.5:0.4~0.5:9~12:0.2~0.5:

19.

4. The method for preparing high flux density permanent magnet ferrite tiles according to any one of claims 1 to 3, characterized in that, The preparation of the permanent magnet ferrite slurry includes the following steps: The raw materials for preparing permanent magnet ferrite are ball-milled, dehydrated, and then mixed with a treatment agent.

5. The method for preparing high flux density permanent magnet ferrite tiles according to claim 4, characterized in that, It satisfies at least one of the following characteristics (1) to (3): (1) The particle size D50 of the slurry obtained by ball milling is 0.6μm~0.8μm; (2) The material-to-liquid ratio in the ball milling process is 1:1.5~2; (3) The moisture content of the slurry after dehydration is 25%~37%.

6. The method for preparing high flux density permanent magnet ferrite tiles according to any one of claims 1 to 5, characterized in that, The process of fabricating permanent magnet ferrite tiles from permanent magnet ferrite slurry includes the following steps: The permanent magnet ferrite slurry is pressed into a green body and then sintered.

7. The method for preparing high flux density permanent magnet ferrite tiles according to claim 6, characterized in that, The sintering process includes the following steps: After pre-sintering, the green body undergoes post-processing to obtain a semi-finished product; The semi-finished product is then re-sintered.

8. The method for preparing high flux density permanent magnet ferrite tiles according to claim 7, characterized in that, It satisfies at least one of the following characteristics (1) to (5): (1) The pre-sintering temperature is 1180℃~1200℃; (2) The heat preservation time for pre-sintering is 2h~3h; (3) The pre-sintering temperature is not lower than the re-sintering temperature; (4) The temperature difference between the pre-sintering temperature and the re-sintering temperature is 0℃~20℃; (5) The holding time for the re-sintering is 2h~3h.

9. A high flux density permanent magnet ferrite tile prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The high flux density permanent magnet ferrite tile has a flux density of 2.06 mWb / cm². 3 ~2.1mWb / cm 3 .

10. The high flux density permanent magnet ferrite tile according to claim 9, characterized in that, The value is 100 N / mm. 2 ~120N / mm 2 .

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