Double-layer composite permanent ferrite tile and preparation method thereof

Abstract

The application discloses a double-layer composite permanent ferrite magnetic tile and a preparation method thereof, and belongs to the technical field of permanent ferrite permanent magnet materials. The double-layer composite permanent ferrite magnetic tile is of an arc-shaped integrated sintering structure, and is divided into a working surface high-performance layer and an assembly surface low-cost layer along the thickness direction. In addition, the application further provides a preparation method of the double-layer composite permanent ferrite magnetic tile, which comprises the following steps: adding low-cost strontium permanent ferrite raw materials, a ball mill dispersing agent and a sintering aid into a ball mill; adding high-performance strontium permanent ferrite raw materials, a ball mill dispersing agent and a sintering aid into the ball mill; injecting high-performance strontium permanent ferrite slurry from the outer arc side of a magnetic tile mold into a cavity, and pressing a double-layer composite permanent ferrite magnetic tile green body under the action of an orientation magnetic field; and placing the double-layer composite permanent ferrite magnetic tile green body in a kiln for sintering, so as to obtain a double-layer composite permanent ferrite magnetic tile biscuit. The application realizes low cost and no risk of falling off and cracking.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet ferrite materials technology, specifically to a double-layer composite permanent magnet ferrite tile and its preparation method. Background Technology

[0002] Permanent magnet ferrite tiles are widely used in household appliance motors, power tools, automotive auxiliary motors, and other fields. Currently, the mainstream solution in the industry is to prepare magnet tiles using a single formulation material: if all high-cobalt and rare-earth doped high-performance ferrites are used, the magnetic performance meets the standards, but the raw material cost is high, and fluctuations in cobalt prices have a significant impact on production costs; if all low-cost ordinary ferrites are used, the magnetic performance cannot meet the requirements of motor torque and air gap magnetic field, and the motor efficiency drops significantly.

[0003] When the motor is working, the magnetic tile mainly relies on the working surface near the air gap to participate in the main magnetic circuit to do work, while the work done in the assembly surface area is limited. Therefore, using a single high-performance material to manufacture it results in serious material waste and cost redundancy.

[0004] While existing technologies include gradient magnets and composite magnets, they often suffer from the following drawbacks: 1) The adhesive composite material has low interface strength and is prone to detachment during high-speed operation; 2) Achieving performance through a single powder orientation gradient results in poor performance and limited cost reduction; 3) The thermal expansion of different materials is not matched, which makes sintering prone to cracking.

[0005] Therefore, developing a double-layer ferrite magnetic tile that maintains performance on the working surface, reduces costs on the assembly surface, and achieves defect-free integral sintering has significant engineering value and economic benefits. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a double-layer composite permanent magnet ferrite tile and its preparation method, solving the technical problems of easy detachment and high cost in the prior art.

[0007] To achieve the above technical objectives, the present invention provides a double-layer composite permanent magnet ferrite tile, which is an arc-shaped integral sintered structure, divided into a high-performance working surface layer, a ceramic co-fired bonding interface, and a low-cost assembly surface layer along the thickness direction; the thickness of the high-performance working surface layer accounts for 10% to 50%; the thickness of the low-cost assembly surface layer accounts for 50% to 90%.

[0008] In any embodiment, a ceramic co-fired bonding interface or a transition matching layer is further included between the high-performance working surface layer and the low-cost assembly surface layer, wherein the ceramic co-fired bonding interface is between the high-performance working surface layer and the transition matching layer, and between the low-cost assembly surface layer and the transition matching layer, respectively.

[0009] In any embodiment, the high-performance layer of the working surface is made of high-performance strontium permanent magnet ferrite material, and the low-cost layer of the assembly surface is made of low-cost strontium ferrite or recycled materials.

[0010] In any embodiment, the high-performance strontium permanent magnet ferrite material is a grade of Y38 or higher under the SJ / T10410-2016 standard, and the low-cost strontium ferrite or recycled material is a grade of Y38 or lower under the SJ / T10410-2016 standard.

[0011] In any implementation, the difference in shrinkage rate between the high-performance working surface layer and the low-cost assembly surface layer is <1%.

[0012] Furthermore, this invention also proposes a method for preparing the above-mentioned double-layer composite permanent magnet ferrite tile, comprising the following steps: S1. Add low-cost strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, and then dehydrate until the slurry moisture content is 30%~40%; S2. Add high-performance strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, and then dehydrate until the slurry moisture content is 30%~40%; S3. The low-cost strontium permanent magnet ferrite slurry from step S1 is injected into the cavity of the magnetic tile mold and dehydrated under the action of an orientation magnetic field until the slurry moisture content is 20%~30%. S4. The high-performance strontium permanent magnet ferrite slurry from step S2 is injected into the cavity from the outer arc side of the magnetic tile mold, and pressed under the action of the orientation magnetic field to form a double-layer composite permanent magnet ferrite magnetic tile blank. S5. Place the green blank of the double-layer composite permanent magnet ferrite tile in a kiln for sintering to obtain the cooked blank of the double-layer composite permanent magnet ferrite tile.

[0013] Furthermore, this invention also proposes a method for preparing the above-mentioned double-layer composite permanent magnet ferrite tile, comprising the following steps: T1. Add low-cost strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, then dehydrate until the slurry moisture content is 30%~40%; T2. Add high-performance strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, then dehydrate until the slurry moisture content is 30%~40%; T3. The slurries from steps T1 and T2 are subjected to magnetic field orientation pressing, drying, pulverizing, and granulation to obtain low-cost strontium permanent magnet ferrite dry powder and high-performance strontium permanent magnet ferrite dry powder; the slurries from steps T1 and T2 are mixed and subjected to magnetic field orientation pressing, drying, pulverizing, and granulation to obtain transition matching layer dry powder. T4. The low-cost strontium permanent magnet ferrite dry powder, transition matching layer dry powder, and high-performance strontium permanent magnet ferrite dry powder from step T3 are filled into the magnetic tile mold cavity according to the thickness ratio, and pressed under the action of the orientation magnetic field to form a double-layer composite permanent magnet ferrite magnetic tile blank. T5. Place the green blank of the double-layer composite permanent magnet ferrite tile in a kiln for sintering to obtain the cooked blank of the double-layer composite permanent magnet ferrite tile.

[0014] In any embodiment, the sintering temperature in step S5 or T5 is 1100-1200℃.

[0015] In any embodiment, the sintering time in step S5 or T5 is 1.5-2.5 hours.

[0016] In any embodiment, in step T3, the slurries from steps T1 and T2 are mixed at a mass ratio of 1:1.

[0017] Compared with existing technologies, the beneficial effects of this invention include: The double-layer composite permanent magnet ferrite tile proposed in this invention has an arc-shaped integrated sintered structure, divided along the thickness direction into a high-performance working surface layer, a ceramic co-fired bonding interface, and a low-cost assembly surface layer. The thickness of the high-performance working surface layer accounts for 10% to 50% of the total thickness; the thickness of the low-cost assembly surface layer accounts for 50% to 90% of the total thickness. The amount of high-performance and expensive raw materials used is reduced by more than 50%, and the overall raw material cost is reduced by 20% to 40%. The magnetic properties of the working surface are close to those of high-performance magnetic tiles made with single-formulation materials using conventional processes, meeting the requirements for motor output torque and efficiency. The two layers are an arc-shaped integrated sintered structure with no bonding interface. The static compressive strength and vibration resistance meet the requirements for motor assembly and high-speed operation, eliminating the risk of detachment and cracking, thus achieving a low-cost solution with no risk of detachment and cracking.

[0018] Based on existing ferrite magnet tile production equipment and processes, only the filler process needs to be modified to achieve large-scale production. The product can directly replace traditional single-formula permanent magnet ferrite magnet tiles and can be used in household appliance motors, power tools, automotive auxiliary motors, etc., with significant cost advantages and the conditions for large-scale industrial production. Attached Figure Description

[0019] Figure 1 This is a photograph of a wet-pressed double-layer composite permanent magnet ferrite tile according to Embodiment 1 of the present invention.

[0020] Figure 2This is a schematic diagram of the cross-sectional structure of the wet-pressed double-layer composite permanent magnet ferrite tile of Embodiment 1 of the present invention.

[0021] Figure 3 This is a schematic diagram of the cross-sectional structure of a double-layer composite permanent magnet ferrite tile with a transition layer, dry-pressed according to Embodiment 2 of the present invention.

[0022] Figure 4 This is a photograph of a double-layer composite permanent magnet ferrite tile with a transition layer, dry-pressed according to Embodiment 2 of the present invention.

[0023] Figure 5 This is a schematic diagram of the magnetic tile assembly according to an embodiment of the present invention.

[0024] Explanation of reference numerals in the attached diagram: 0, Magnet tile; 1, High-performance layer on the working surface; 2, Low-cost layer on the assembly surface; 3, Ceramic co-fired bonding interface; 4, Transition matching layer; 5, Working surface; 6, Assembly surface; 7, Rotor core. Detailed Implementation

[0025] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0027] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0028] This specific embodiment provides a double-layer composite permanent magnet ferrite tile, which is an arc-shaped integral sintered structure, divided along the thickness direction into a high-performance working surface layer, a ceramic co-fired bonding interface, and a low-cost assembly surface layer. The thickness of the high-performance working surface layer accounts for 10% to 50%; the thickness of the low-cost assembly surface layer accounts for 50% to 90%. The high-performance working surface layer is responsible for providing the main air gap magnetic field and is usually doped with rare metal elements such as lanthanum and cobalt, resulting in higher costs. The low-cost assembly surface layer is responsible for structural support. The material of the high-performance working surface layer is high-performance strontium permanent magnet ferrite material, and the material of the low-cost assembly surface layer is low-cost strontium ferrite or recycled material. The high-performance strontium permanent magnet ferrite material is a grade of Y38 or higher under the SJ / T10410-2016 standard, and the low-cost strontium ferrite or recycled material is a grade of Y38 or lower under the SJ / T10410-2016 standard. The shrinkage difference between the high-performance working surface layer and the low-cost assembly surface layer is <1%.

[0029] In some embodiments, a ceramic co-fired bonding interface or a transition matching layer is further included between the high-performance working surface layer and the low-cost assembly surface layer; the ceramic co-fired bonding interface is between the high-performance working surface layer and the transition matching layer, and between the low-cost assembly surface layer and the transition matching layer, respectively.

[0030] It should be noted that sintered permanent magnet ferrite materials with grade Y38 or higher can be graded as Y40, Y41, Y41H (high coercivity grade), Y42, Y42H (high coercivity grade), Y43, etc.

[0031] It should be noted that sintered permanent magnet ferrite materials with grades below Y38 can be Y8T, Y25, Y26H-1, Y28, Y28H-1, Y28H-2, Y30H-1, Y30H-2, Y32, Y32H-1, Y32H-2, Y33, Y33H, Y33H-2, Y34, Y35, Y36-1-19, etc.

[0032] Furthermore, this specific embodiment also proposes a method for preparing the above-mentioned double-layer composite permanent magnet ferrite tile, including the following steps: S1. Add low-cost strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, and then dehydrate until the slurry moisture content is 30%~40%; S2. High-performance strontium permanent magnet ferrite raw materials, ball milling dispersant, and sintering aid are added to a ball mill, and the mixture is ball-milled and pulverized using water as the medium, followed by dehydration treatment until the slurry moisture content is 30%~40%. The ball milling dispersant includes at least one of sorbitol and calcium gluconate, with an addition amount of 0%~0.5%, preferably 0.3%. The sintering aid includes at least one of silicate, calcium carbonate, boric acid, quartz sand, and bismuth oxide, with an addition amount of 0.001%~0.3%. S3. The low-cost strontium permanent magnet ferrite slurry from step S1 is injected into the cavity of the magnetic tile mold and dehydrated under the action of an orientation magnetic field until the slurry moisture content is 20%~30%. S4. The high-performance strontium permanent magnet ferrite slurry from step S2 is injected into the cavity from the outer arc side of the magnetic tile mold, and pressed under the action of the orientation magnetic field to form a double-layer composite permanent magnet ferrite magnetic tile blank. S5. The double-layer composite permanent magnet ferrite tile green blank is placed in a kiln for sintering to obtain a double-layer composite permanent magnet ferrite tile finished blank. The sintering temperature is 1100-1200℃ and the sintering time is 1.5-2.5 hours.

[0033] Furthermore, this specific embodiment also proposes a method for preparing the above-mentioned double-layer composite permanent magnet ferrite tile, including the following steps: T1. Add low-cost strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, then dehydrate until the slurry moisture content is 30%~40%; T2. High-performance strontium permanent magnet ferrite raw materials, ball milling dispersant, and sintering aid are added to a ball mill, and the mixture is ball-milled and pulverized using water as the medium, followed by dehydration treatment until the slurry moisture content is 30%~40%. The ball milling dispersant includes at least one of sorbitol and calcium gluconate, with an addition amount of 0%~0.5%, preferably 0.3%. The sintering aid includes at least one of silicate, calcium carbonate, boric acid, quartz sand, and bismuth oxide, with an addition amount of 0.001%~0.3%. T3. The slurries from steps T1 and T2 are subjected to magnetic field orientation pressing, drying, pulverizing, and granulation to obtain low-cost strontium permanent magnet ferrite dry powder and high-performance strontium permanent magnet ferrite dry powder; the slurries from steps T1 and T2 are mixed at a mass ratio of 1:1 and then subjected to magnetic field orientation pressing, drying, pulverizing, and granulation to obtain transition matching layer dry powder. T4. The low-cost strontium permanent magnet ferrite dry powder, transition matching layer dry powder, and high-performance strontium permanent magnet ferrite dry powder from step T3 are filled into the magnetic tile mold cavity according to the thickness ratio, and pressed under the action of the orientation magnetic field to form a double-layer composite permanent magnet ferrite magnetic tile blank. T5. The double-layer composite permanent magnet ferrite tile green blank is placed in a kiln for sintering to obtain a double-layer composite permanent magnet ferrite tile finished blank. The sintering temperature is 1100-1200℃ and the sintering time is 1.5-2.5 hours.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0036] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0037] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0038] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0039] Example 1 (Wet pressing process)

[0040] Combination Figure 1 and Figure 2This embodiment proposes a double-layer composite permanent magnet ferrite tile 0, which is an arc-shaped integral sintered structure, divided along the thickness direction into a high-performance working surface layer 1, a ceramic co-fired bonding interface 3, and a low-cost assembly surface layer 2; the total thickness of the tile is 8mm, the outer arc surface is the working surface 5, and the inner arc surface is the assembly surface 6, wherein: High-performance layer 1 on the working surface: 4.0 mm thick (thickness percentage 50%), La-Co doped strontium permanent magnet ferrite, raw material grade Y40; Assembly surface low-cost layer 2: 4.0mm thick (thickness accounts for 50%), low-cost strontium permanent magnet ferrite, raw material performance is Y33H-2 grade; This embodiment proposes a method for preparing a double-layer composite permanent magnet ferrite tile, including the following steps: 1) Strontium permanent magnet ferrite raw materials of grades Y40 and Y33H-2 were respectively added with 0.3% sorbitol as ball milling dispersant, and 0.2% lithium silicate, 0.3% calcium carbonate and 0.1% boric acid as sintering aids. They were wet ball milled to an average particle size of 0.75um~0.85μm, and then dehydrated to a slurry moisture content of 35%, so that the difference in sintering shrinkage rate between the two slurries was <1%.

[0041] 2) Inject Y33H-2 low-cost slurry into the cavity of the magnetic tile mold and dehydrate it under micro-pressure under the action of the orientation magnetic field until the slurry moisture content is below 30%. The filling depth of Y33H-2 slurry is 10mm, and the filling depth after micro-pressure dehydration is 9mm.

[0042] 3) Y40 high-performance strontium permanent magnet ferrite slurry is injected into the cavity from the outer arc surface of the magnetic tile mold. The Y40 material filling depth is 10mm. Under the action of the orientation magnetic field, the magnetic tile green blank of the embodiment is pressed to obtain the green blank thickness of 12.2mm.

[0043] 4) The green ceramic tile blank of the embodiment was placed in a kiln for sintering at a temperature of 1190℃ and held for 2 hours to obtain the cooked ceramic tile blank of the embodiment with a thickness of 9mm.

[0044] 5) The blank of the magnetic tile in the embodiment is ground, and the inner and outer arc grinding amount is 0.5mm to obtain the finished double-layer composite permanent magnet ferrite magnetic tile. The thickness of the finished magnetic tile is 8mm, of which the high performance layer on the working surface is 4mm thick and the low cost layer on the assembly surface is 4mm thick. The product is free of cracks.

[0045] Example 2 (Dry Pressing Process) The magnetic tile dimensions in this embodiment are the same as in Embodiment 1. This embodiment proposes a method for preparing a double-layer composite permanent magnet ferrite tile, including the following steps: 1) The Y40 and Y33H-2 grade slurries in Example 1 were subjected to magnetic field orientation pressing, drying, crushing and granulation to obtain low-cost strontium permanent magnet ferrite dry powder and high-performance strontium permanent magnet ferrite dry powder.

[0046] 2) After mixing the Y40 and Y33H-2 grade slurries in Example 1 in a 1:1 ratio, the mixture is subjected to magnetic field orientation pressing, drying, crushing and granulation to obtain the transition matching layer dry powder. The shrinkage rate of the transition matching layer is between that of low-cost strontium permanent magnet ferrite dry powder and high-performance strontium permanent magnet ferrite dry powder.

[0047] 3) The low-cost strontium permanent magnet ferrite dry powder, transition matching layer dry powder, and high-performance strontium permanent magnet ferrite dry powder from steps 1) and 2) are filled into the magnetic tile mold cavity at filling depths of 11mm, 1mm, and 11mm respectively, and pressed under the action of the orientation magnetic field to form the magnetic tile green blank of Example 2 with a green blank thickness of 11mm.

[0048] 4) The green ceramic tile blank of Example 2 was placed in a kiln for sintering at a temperature of 1190℃ and held for 2 hours to obtain a cooked ceramic tile blank with a thickness of 8.6mm.

[0049] 5) The blank of the magnetic tile in Example 2 was ground, with the inner and outer arc grinding amount being 0.3mm, to obtain a double-layer composite permanent magnet ferrite magnetic tile finished product. The finished magnetic tile was 8mm thick, of which the high-performance layer on the working surface was about 3.8mm thick, the low-cost layer on the assembly surface was about 3.7mm thick, and the intermediate transition matching layer was about 0.5mm thick. The product was free of cracks.

[0050] Combination Figure 3 and Figure 4 The double-layer composite permanent magnet ferrite tile of this embodiment is an arc-shaped integrated sintered structure. Along the thickness direction, it is divided into a high-performance working surface layer 1, a ceramic co-fired bonding interface 3, a transition matching layer 3, a ceramic co-fired bonding interface 3, and a low-cost assembly surface layer 2. The total thickness of the tile is 8mm. The outer arc surface is the working surface 5, and the inner arc surface is the assembly surface 6.

[0051] Comparative Example 1 Magnets of the same size as those in Example 1 were prepared using only Y40 grade strontium permanent magnet ferrite raw materials and a conventional wet pressing process.

[0052] Comparative Example 2 Magnets of the same size as those in Example 1 were prepared using only Y33H-2 grade strontium permanent magnet ferrite raw materials and a conventional wet pressing process.

[0053] Comparative Example 3 Strontium permanent magnet ferrite raw materials of grade Y40 and Y33H-2 were mixed in a 1:1 ratio and then magnetic tiles of the same size as those in Example 1 were prepared by conventional wet pressing process.

[0054] Comparative Example 4 Magnets of the same size as those in Example 2 were prepared using only Y40 grade strontium permanent magnet ferrite raw materials and a conventional dry pressing process.

[0055] Comparative Example 5 Magnets of the same size as those in Example 2 were prepared using only Y33H-2 grade strontium permanent magnet ferrite raw materials and a conventional dry pressing process.

[0056] Comparative Example 6 Strontium permanent magnet ferrite raw materials of grade Y40 and Y33H-2 were mixed in a 1:1 ratio and then magnetic tiles of the same size as those in Example 2 were prepared by conventional dry pressing process.

[0057] Table 1 shows a comparison of the cost of the magnetic tile materials and the magnetic field strength of the working surface obtained by the embodiments and comparative examples of the present invention.

[0058] Table 1

[0059] As can be seen from Table 1, the double-layer composite permanent magnet ferrite tiles prepared in Examples 1 and 2 have the advantages of both magnetic field strength and cost.

[0060] The magnetic tiles from Example 1 are assembled into a permanent magnet motor rotor, such as... Figure 5 As shown, it includes a rotor core 7 and magnetic tiles 0, with 8 arc-shaped permanent magnet tiles 0 evenly pasted on the outer circle of the core 7.

[0061] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A double-layer composite permanent magnet ferrite tile, characterized in that, It is an arc-shaped integrated sintered structure, divided into a high-performance working surface layer, a ceramic co-fired bonding interface, and a low-cost assembly surface layer along the thickness direction; the thickness of the high-performance working surface layer accounts for 10% to 50%; the thickness of the low-cost assembly surface layer accounts for 50% to 90%.

2. The double-layer composite permanent magnet ferrite tile according to claim 1, characterized in that, A transition matching layer is also included between the high-performance working surface layer and the low-cost assembly surface layer. The ceramic co-fired bonding interface is located between the high-performance working surface layer and the transition matching layer, and between the low-cost assembly surface layer and the transition matching layer.

3. The double-layer composite permanent magnet ferrite tile according to claim 1, characterized in that, The high-performance layer of the working surface is made of high-performance strontium permanent magnet ferrite material, and the low-cost layer of the assembly surface is made of low-cost strontium ferrite or recycled materials.

4. The double-layer composite permanent magnet ferrite tile according to claim 2, characterized in that, The high-performance strontium permanent magnet ferrite material is of grade Y38 or higher under the SJ / T10410-2016 standard, and the low-cost strontium ferrite or recycled material is of grade Y38 or lower under the SJ / T10410-2016 standard.

5. The double-layer composite permanent magnet ferrite tile according to claim 1, characterized in that, The shrinkage rate difference between the high-performance layer on the working surface and the low-cost layer on the assembly surface is <1%.

6. A method for preparing a double-layer composite permanent magnet ferrite tile according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Add low-cost strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, and then dehydrate until the slurry moisture content is 30%~40%; S2. Add high-performance strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, and then dehydrate until the slurry moisture content is 30%~40%; S3. The low-cost strontium permanent magnet ferrite slurry from step S1 is injected into the cavity of the magnetic tile mold and dehydrated under the action of an orientation magnetic field until the slurry moisture content is 20%~30%. S4. The high-performance strontium permanent magnet ferrite slurry from step S2 is injected into the cavity from the outer arc side of the magnetic tile mold, and pressed under the action of the orientation magnetic field to form a double-layer composite permanent magnet ferrite magnetic tile blank. S5. Place the green blank of the double-layer composite permanent magnet ferrite tile in a kiln for sintering to obtain the cooked blank of the double-layer composite permanent magnet ferrite tile.

7. A method for preparing a double-layer composite permanent magnet ferrite tile according to any one of claims 1-5, characterized in that, Includes the following steps: T1. Add low-cost strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, then dehydrate until the slurry moisture content is 30%~40%; T2. Add high-performance strontium permanent magnet ferrite raw materials, ball milling dispersant and sintering aid to a ball mill, and ball mill and pulverize with water as the medium, then dehydrate until the slurry moisture content is 30%~40%; T3. The slurries from steps T1 and T2 are subjected to magnetic field orientation pressing, drying, pulverizing, and granulation to obtain low-cost strontium permanent magnet ferrite dry powder and high-performance strontium permanent magnet ferrite dry powder; the slurries from steps T1 and T2 are mixed and subjected to magnetic field orientation pressing, drying, pulverizing, and granulation to obtain transition matching layer dry powder. T4. The low-cost strontium permanent magnet ferrite dry powder, transition matching layer dry powder, and high-performance strontium permanent magnet ferrite dry powder from step T3 are filled into the magnetic tile mold cavity according to the thickness ratio, and pressed under the action of the orientation magnetic field to form a double-layer composite permanent magnet ferrite magnetic tile blank. T5. Place the green blank of the double-layer composite permanent magnet ferrite tile in a kiln for sintering to obtain the cooked blank of the double-layer composite permanent magnet ferrite tile.

8. The method for preparing double-layer composite permanent magnet ferrite tiles according to claim 6 or 7, characterized in that, In step S5 or T5, the sintering temperature is 1100-1200℃.

9. The method for preparing double-layer composite permanent magnet ferrite tiles according to claim 8, characterized in that, In step S5 or T5, the sintering time is 1.5-2.5 hours.

10. The method for preparing the double-layer composite permanent magnet ferrite tile according to claim 7, characterized in that, In step T3, the slurries from steps T1 and T2 are mixed at a mass ratio of 1:1.

Images