A water-based tape casting slurry and a method for water-based tape casting of magnetoelectric composite ceramic sheets

Abstract

The application discloses a water-based tape casting slurry of a magnetoelectric composite ceramic sheet and a method for preparing the magnetoelectric composite ceramic sheet by water-based tape casting. 0.5 Na 0.4 K 0.1 TiO3, magnetic powder hexaferrite BaFe 12 O 19 , polyacrylic acid, polyurethane emulsion and polyacrylic acid emulsion mixture, polyethylene glycol and deionized water. The water-based tape casting process for preparing the magnetoelectric composite ceramic sheet comprises slurry preparation, tape casting, drying and sintering into a film, wherein a magnetic field is applied during the drying process of the wet film, and a composite structure of the magnetic powder oriented in the ferroelectric matrix is constructed. The magnetoelectric composite ceramic sheet prepared by the application has ferroelectricity and ferromagnetism, has a high magnetoelectric voltage coefficient and a magnetic dielectric response, and can be used in the fields of functional devices such as magnetoelectric sensors and energy converters; meanwhile, the ceramic sheet preparation process is simple, the conditions are easy to control, is environment-friendly and is suitable for batch production.

Description

Technical Field

[0001] The invention belongs to the technical field of functional ceramic materials and their preparation, and particularly relates to a water-based tape casting slurry for a magnetoelectric composite ceramic sheet and a method for preparing the magnetoelectric composite ceramic sheet by water-based tape casting. Background Art

[0002] With the rapid development of information technology, the miniaturization, downsizing, and integration of electronic devices have become increasingly important. Single-functional information materials are unable to meet the demands of miniaturization and diversification in new electronic components. The development of new materials and the design of functional materials that integrate multiple physical properties are urgently needed. Multiferromagnetic-electric functional composites possess the characteristics of both single ferroelectric and ferromagnetic materials. The ferroelectric and magnetic phases themselves lack magnetoelectric effects. However, the coupling between ferroelectric and magnetic order enables the coexisting ferroelectric-ferromagnetic system to produce a novel functional effect at room temperature—the magnetoelectric coupling effect. In classic bulk magnetoelectric composites, the magnetoelectric effect is the product of the magnetostrictive effect of the magnetic phase and the piezoelectric effect of the ferroelectric-piezoelectric phase. That is, the electrical and magnetic coupling between the two phases in the magnetoelectric composite is achieved through mechanical strain-stress transfer. When the magnetoelectric composite is exposed to a magnetic field, the magnetic phase experiences strain due to the magnetostrictive effect. This strain is transferred to the piezoelectric phase, generating electric polarization due to the piezoelectric effect. That is, it realizes the mutual conversion and regulation of electrical energy and magnetic energy, electrical information and magnetic information, so that it has huge potential application value in the fields of electronic materials and devices such as magnetic or electric field sensors, polymorphic storage elements, energy harvesting and new spin electronic devices.

[0003] Most existing magnetoelectric composite materials are formed by bonding a single magnetic phase layer and a piezoelectric phase layer together. For example, Chinese patent publication number CN102034926B discloses a magnetoelectric laminate structure with piezoelectric material layers connected in series. The structure consists of a top magnetostrictive material layer, a middle piezoelectric material layer, and a bottom magnetostrictive material layer. A polymer binder binds these three layers together into a single structure. Chinese patent CN106505147B, on the other hand, cuts a piezoelectric ceramic block to produce a fiber array of piezoelectric phases parallel to the length (axial direction) of the piezoelectric ceramic. Magnetic particles added to the binder are then filled into the gaps between the piezoelectric phases. The layers are then dried, cured, and thinned to produce a piezoelectric / magnetic phase composite layer. Existing technologies have always combined a single magnetic phase layer and a piezoelectric phase layer to form a magnetoelectric composite material.

[0004] More importantly, the composite materials obtained by the current methods of preparing magnetoelectric composite materials have low density, low degree of interface bonding between the magnetic phase and the piezoelectric phase, and limited interface strain coupling; especially in multilayer magnetoelectric composite structures, the magnetoelectric coupling effect is greatly affected by the interface and is difficult to significantly improve.

[0005] Currently, existing technologies do not cover much research on magnetoelectric composite ceramic materials. Most studies are only focused on improving the magnetoelectric coupling performance of magnetoelectric composite ceramic materials by changing the composition and type of magnetic materials, optimizing the volume content, and adjusting the input field strength. However, the above methods have very limited effects on improving the magnetoelectric coupling performance. Summary of the Invention

[0006] The present invention aims to provide a water-based tape-casting slurry for magnetoelectric composite ceramics. The resulting slurry facilitates the preparation of microstructurally oriented ceramic sheets from this system, resulting in products of excellent quality and performance. Another object of the present invention is to provide a method for preparing magnetoelectric composite ceramic sheets using the aforementioned slurry via a water-based tape-casting process.

[0007] The present invention can be achieved through the following technical solutions:

[0008] The invention discloses a water-based tape-casting slurry for magnetoelectric composite ceramic sheets. The raw materials thereof include 30-50% by mass of ferroelectric ceramic powder, 8-20% by mass of magnetic powder, 0.4-1.8% by mass of dispersant, 9-14% by mass of adhesive, 4-9% by mass of plasticizer and 15-27% by mass of deionized water.

[0009] Preferably, the ferroelectric ceramic powder is Bi 0.5 Na 0.4 K 0.1 TiO3, the particle size of which is 0.5 to 2 microns; the magnetic powder is hexagonal ferrite BaFe 12 O 19 , its particle size is 1 to 3 microns; the mass ratio of the ferroelectric ceramic powder to the magnetic powder is 5:1 to 3:2.

[0010] Furthermore, the dispersant is one of polyacrylic acid, ammonium polyacrylate or ammonium polymethacrylate; the binder is a mixture of polyurethane emulsion and polyacrylic acid emulsion, wherein the polyurethane emulsion accounts for 25 to 45% of the total weight percentage of the mixture; the plasticizer is one of polyethylene glycol or glycerol, and the mass ratio of its addition amount to the binder is 1:4 to 3:4.

[0011] The water-based casting method of the present invention is used to prepare magnetoelectric composite ceramic sheets with high magnetoelectric coupling performance and good process characteristics. To obtain ceramic sheets made of this system material, the present invention uses water as a solvent and organic additives as a water-based casting slurry. The present invention achieves good dispersion in water by adding polyacrylic acid or ammonium polyacrylate dispersants and utilizing the point repulsion and steric hindrance caused by the adsorption of negatively charged groups on the surface of the ferroelectric ceramic powder after decomposition. A mixture of polyurethane emulsion and polyacrylic acid emulsion is used as a binder, and other organic additives are used to synergistically optimize the slurry components, thereby overcoming the adverse effects of the two-component ceramic material system of magnetic and piezoelectric phases on water-based casting. At the same time, during the casting process, due to the rheological behavior of the slurry shear thinning, the orientation of the magnetic component in the slurry can be achieved under a relatively low magnetic field. The obtained green sheets have high flatness, good softness, uniform microstructure, and are not easily deformed or cracked after drying and firing, thus ensuring the comprehensive performance of the ceramic sheets.

[0012] Another object of the present invention is achieved through the following technical solutions:

[0013] The present invention provides a method for preparing a magnetoelectric composite ceramic sheet by water-based tape casting, using the above-mentioned water-based tape casting slurry, comprising the following steps:

[0014] (1) Preparation: Weigh the raw materials according to the above proportions and set aside;

[0015] (2) Slurry preparation: The weighed dispersant is uniformly dispersed in deionized water, ceramic powder is added thereto, ball milled for 6 to 12 hours, and the pH value is adjusted to 9 to 10; then a binder and a plasticizer are added, and ball milling is continued for 8 to 12 hours at a ball mill speed of 300 to 500 r / min; ultrasonic degassing is performed for 40 minutes, and the slurry is allowed to stand to obtain a stable casting slurry with a certain viscosity;

[0016] (3) tape casting: the tape casting slurry is tape cast on a tape casting machine at a casting speed of 0.3 to 0.5 m / min and a scraper height of 0.8 to 2 mm; the tape-cast sheet is dried at a temperature of 25 to 50° C. for 4 to 6 hours, and then peeled off from the base tape to obtain a ceramic green film tape; during the drying process, a permanent magnet is placed perpendicular to the film surface to apply a directional magnetic field until solidification and the magnet is removed;

[0017] (4) Sintering to form a film: The green film strip obtained in step (3) is cut into the desired shape and sintered at high temperature to obtain a ceramic sheet material; the high temperature sintering is carried out by heating the temperature to 600°C at a rate of 0.5-1.0°C / min and keeping the temperature for 1 hour, then heating the temperature to 1120°C at a rate of 1-2°C / min and keeping the temperature for 2-4 hours.

[0018] Preferably, the viscosity of the casting slurry in step (3) is 500 to 1700 mPa·s.

[0019] Preferably, the directional magnetic field in step (3) is 100 to 300 Oe;

[0020] During the drying process, a permanent magnet is placed perpendicular to the film surface to apply a directional magnetic field. After curing, there is no need to change the direction of the magnetic field.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The magnetoelectric composite ceramic sheet produced by the present invention has high magnetoelectric coupling performance. The magnetic field orientation treatment is used to achieve directional arrangement of the strongly anisotropic sheet-like magnetic units in the ferroelectric matrix. The ordered magnetostrictive sheet-like units will produce an additive effect under the action of the magnetic field, thereby enhancing the magnetostriction of the material, improving the interfacial strain transfer between the ferromagnetic units and the ferroelectric matrix, and helping to enhance the magnetoelectric coupling effect of the composite system.

[0023] (2) The present invention starts from the microstructure design and changes the orientation arrangement of the filling magnetic powder by adjusting the magnetic field direction during the material forming process to form an anisotropic composite structure, thereby achieving high magnetoelectric and magnetodielectric adjustability of the composite material's magnetoelectric coupling performance; the magnetoelectric coupling effect is closely related to the microstructure of the composite material's constituent phases. The present invention enhances the magnetoelectric coupling effect by designing the material's microstructure, which can become an important technical method for enhancing the magnetoelectric coupling effect of composite ceramics;

[0024] (3) The water-based casting process is simple and easy to prepare, can meet environmental protection requirements, and has low production costs and is suitable for large-scale industrial production. This method is not only suitable for Bi 0.5 Na 0.4 K 0.1 TiO3 based magnetoelectric composite materials, and also suitable for BaTiO3 based, Na 0.5 K 0.5 NbO3-based lead-free ceramic powders. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a process flow chart for preparing a magnetoelectric composite ceramic sheet by water-based tape casting according to the present invention;

[0026] Figure 2 The relationship curve between shear rate and viscosity of the slurry prepared in the embodiment of the present invention;

[0027] Figure 3 Schematic diagram of the microstructure of the magnetoelectric composite ceramic sheet prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0029] The water-based tape-casting slurry of the magnetoelectric composite ceramic sheet disclosed in the present invention is composed of ferroelectric ceramic powder Bi 0.5 Na 0.4 K 0.1 TiO3, magnetic powder hexagonal ferrite BaFe 12 O 19 , polyacrylic acid, polyvinyl alcohol and polyacrylic acid emulsion mixture, polyethylene glycol and deionized water. The method for preparing magnetoelectric composite ceramic sheets by water-based tape casting process is as follows:

[0030] Example 1

[0031] (1) Material preparation: Weigh the raw materials according to the following proportions and set aside: 33.75 g of ferroelectric ceramic powder (particle size 0.5-2 μm); 33.75 g of BaFe 12 O 19 11.25g of polyacrylic acid (particle size 1-3 microns); 0.8g of polyacrylic acid; 9.5g of a mixture of polyvinyl alcohol and polyacrylic acid emulsion (the mass ratio of the two is 2:3); 6.0g of polyethylene glycol; 15.0g of deionized water;

[0032] (2) Slurry preparation: add the dispersant weighed in step (1) to deionized water, stir magnetically for 1 hour, and fully disperse; add the ferroelectric ceramic powder and magnetic powder hexagonal ferrite BaFe weighed in step (1) to the slurry. 12 O 19 , ball milling for 8 hours at a ball milling speed of 300 r / min to obtain a uniform mixture, and adjusting the pH value to 10; then adding the binder and plasticizer weighed in step (1) to the mixture, and ball milling for a second time for 10 hours at a ball milling speed of 200 r / min; ultrasonic degassing for 40 minutes and letting it stand to obtain a stable casting slurry with a viscosity of 1270 mPa·s, which is set aside;

[0033] (3) Tape casting: The tape casting slurry prepared in step (2) was tape cast on a tape casting machine, with the tape casting speed set to 1 m / min and the scraper height set to 1.0 mm. The tape-cast sheet was dried at 45° C. for 6 hours and then peeled off from the base tape to obtain a substrate green sheet with a thickness of 0.8 mm and a ceramic green film tape. During the drying process, a directional magnetic field of 300 Oe was applied perpendicular to the film surface.

[0034] (4) Sintering to form a film: The green film strip obtained in step (3) was cut into a size of 0.8 mm × 30 mm × 20 mm, placed in a tubular sintering furnace for high-temperature sintering, raised to 600 ° C at a rate of 0.5 ° C / min for debinding, and kept warm for 2 hours; then continued to raise to 1120 ° C at a rate of 1 ° C / min and kept warm for 3 hours to obtain a ceramic sheet.

[0035] After ultrasonic cleaning of the magnetoelectric composite sheet, low-temperature conductive silver paste was applied to both sides of the sheet. After drying, the sheet was placed in silicone oil at 110°C for voltage polarization treatment with an electric field of 5kV / mm. After polarization for 1 hour, the sheet was taken out and the magnetoelectric comprehensive performance test was performed. Figure 1 Process flow chart for preparing magnetoelectric composite ceramic sheets by water-based tape casting; Figure 2 The relationship curve between shear rate and viscosity of the slurry prepared in Example 1 is shown, and the slurry exhibits shear thinning characteristics; Figure 3 The microscopic morphology of the magnetoelectric composite ceramic sheet prepared in Example 1 shows that the flaky magnetic powder is oriented and arranged in the ferroelectric matrix to form a granular composite material. The magnetoelectric comprehensive performance of the magnetoelectric composite ceramic sheet prepared in Example 1 is shown in the table. The prepared magnetoelectric ceramic sheet has a high magnetoelectric voltage coefficient and can achieve efficient conversion of magnetic energy and electrical energy. The obtained magnetoelectric coupling coefficient is significantly higher than that of 0.75BaTiO3-0.25BaFe 12 O 19 (2.95mV / cm·Oe)(A.Srinivas,MMRaja,D.Sivaprahasam,P.Saravanan,Process.Appl.Ceram.7[1](2013)29–35),BaFe 12 O 19 -P(VDF-TrFE)(2.0mV / cm·Oe)(J.Gutiérrez, A.Lasheras, JMBarandiarán, et.al, IEEE T.Magn.2015,51(11):1–4.) and Na 0.5 K 0.5 NbO3-BaFe 12 O 19 (4.08mV / cm·Oe)(Y.Kumar,KLYadav,J.Shah,et.al,J.Adv.Ceram.2019,8(3):333–344)Magnetoelectric composite materials.

[0036] Example 2

[0037] (1) Preparation: Weigh the raw materials according to the following proportions and set aside. Ferroelectric ceramic powder (particle size 0.5-2 μm) 34.0 g; BaFe 12 O 19(particle size 1-3 microns) 17.0g; polyacrylic acid 1.08g; polyvinyl alcohol and polyacrylic acid emulsion mixture (mass ratio of the two is 2:3) 11.65g; polyethylene glycol 6.18g; deionized water 14.81g;

[0038] (2) Slurry preparation: add the dispersant weighed in step (1) to deionized water, stir magnetically for 1 hour, and fully disperse; add the ferroelectric ceramic powder and magnetic powder BaFe 12 O 19 , ball milling for 9 hours at a ball milling speed of 300 r / min to obtain a uniform mixture, and adjusting the pH value to 10; then adding the binder and plasticizer weighed in step (1) to the mixture, and ball milling for a second time for 10 hours at a ball milling speed of 200 r / min; ultrasonic degassing for 40 minutes and letting it stand to obtain a stable casting slurry with a viscosity of 1360 mPa·s, which is set aside;

[0039] (3) Tape casting: The tape casting slurry prepared in step (2) is tape cast on a tape casting machine, the tape casting speed is set to 1 m / min, the scraper height is set to 1.2 mm, the tape-cast thin sheet is dried at 45°C for 6 hours, and then peeled off from the base tape to obtain a substrate green sheet with a thickness of 0.9 mm and a ceramic green film tape; during the drying process, a directional magnetic field of 300 Oe is applied perpendicular to the film surface.

[0040] (4) Sintering to form a film: The green film strip obtained in step (3) was cut into a size of 0.9 mm × 30 mm × 20 mm, placed in a tubular sintering furnace for high-temperature sintering, raised to 600 ° C at a rate of 0.5 ° C / min for debinding, and kept warm for 2 h; then continued to rise to 1120 ° C at a rate of 1.5 ° C / min and kept warm for 3 h to obtain a ceramic sheet.

[0041] Example 3

[0042] (1) Preparation: Weigh the raw materials according to the following proportions and set aside. Ferroelectric ceramic powder (particle size 0.5-2 microns) 42.5g; BaFe 12 O 19 8.5g of glycerol (particle size 1-3 microns); 1.11g of ammonium polyacrylate; 10.2g of a mixture of polyvinyl alcohol and polyacrylic acid emulsion (the mass ratio of the two is 2:3); 6.8g of glycerol; 15.9g of deionized water;

[0043] (2) Slurry preparation: add the dispersant weighed in step (1) to deionized water, stir magnetically for 1 hour, and fully disperse; add the ferroelectric ceramic powder and magnetic powder BaFe 12 O 19, ball milling for 10 hours at a ball milling speed of 300 r / min to obtain a uniform mixture, and adjusting the pH value to 10; then adding the binder and plasticizer weighed in step (1) to the mixture, and ball milling for a second time for 8 hours at a ball milling speed of 250 r / min; ultrasonic degassing for 40 minutes and letting it stand to obtain a stable casting slurry with a viscosity of 1010 mPa·s, which is set aside;

[0044] (3) Tape casting: The tape casting slurry prepared in step (2) was tape cast on a tape casting machine, with the tape casting speed set to 1 m / min and the scraper height set to 1.5 mm. The tape-cast sheet was dried at 45° C. for 6 hours and then peeled off from the base tape to obtain a substrate green sheet with a thickness of 1.15 mm and a ceramic green film tape. During the drying process, a directional magnetic field of 300 Oe was applied perpendicular to the film surface.

[0045] (4) Sintering to form a film: The green film strip obtained in step (3) is cut into a size of 1.15 mm × 30 mm × 20 mm, placed in a tubular sintering furnace for high-temperature sintering, raised to 600 ° C at a rate of 0.5 ° C / min for debinding, and kept warm for 2 hours; then continued to raise to 1120 ° C at a rate of 1.5 ° C / min and kept warm for 3 hours to obtain a ceramic sheet.

[0046] After ultrasonic cleaning of the magnetoelectric composite sheet, low-temperature conductive silver paste was applied on both sides of the sheet. After drying, the sheet was placed in silicone oil at 110°C for voltage polarization treatment with an electric field of 5kV / mm. After polarization for 1 hour, the sheet was taken out and the magnetoelectric comprehensive performance test was performed.

[0047] Example 4

[0048] (1) Preparation: Weigh the raw materials according to the following proportions and set aside. Ferroelectric ceramic powder (particle size 0.5-2 microns) 32.3g; BaFe 12 O 19 (particle size 1-3 microns) 19.55g; ammonium polyacrylate 1.11g; polyvinyl alcohol and polyacrylic acid emulsion mixture (mass ratio of the two is 2:3) 9.35g; glycerol 6.38g; deionized water 16.32g;

[0049] (2) Slurry preparation: add the dispersant weighed in step (1) to deionized water, stir magnetically for 1 hour, and fully disperse; add the ferroelectric ceramic powder and magnetic powder BaFe 12 O 19, ball milling for 10 hours at a ball milling speed of 300 r / min to obtain a uniform mixture, and adjusting the pH value to 10; then adding the binder and plasticizer weighed in step (1) to the mixture, and ball milling for a second time for 8 hours at a ball milling speed of 250 r / min; ultrasonic degassing for 40 minutes and letting it stand to obtain a stable casting slurry with a viscosity of 1430 mPa·s, which is set aside;

[0050] (3) Tape casting: The tape casting slurry prepared in step (2) was tape cast on a tape casting machine, with the tape casting speed set to 1 m / min and the scraper height set to 1.5 mm. The tape-cast sheet was dried at 45° C. for 6 hours and then peeled off from the base tape to obtain a substrate green sheet with a thickness of 1.2 mm and a ceramic green film tape. During the drying process, a directional magnetic field of 300 Oe was applied perpendicular to the film surface.

[0051] (4) Sintering to form a film: The green film strip obtained in step (3) is cut into a size of 1.2 mm × 30 mm × 20 mm, placed in a tubular sintering furnace for high-temperature sintering, raised to 600 ° C at a rate of 1.0 ° C / min for debinding, and kept warm for 2 hours; then continued to raise to 1200 ° C at a rate of 1.5 ° C / min and kept warm for 3 hours to obtain a ceramic sheet.

[0052] After ultrasonic cleaning of the magnetoelectric composite sheet, low-temperature conductive silver paste was applied on both sides of the sheet. After drying, the sheet was placed in silicone oil at 110°C for voltage polarization treatment with an electric field of 5kV / mm. After polarization for 1 hour, the sheet was taken out and the magnetoelectric comprehensive performance test was performed.

[0053] Example 5

[0054] (1) Preparation: Weigh the raw materials according to the following proportions and set aside. Ferroelectric ceramic powder (particle size 0.5-2 μm) 40.8 g; BaFe 12 O 19 10.2g of polyol (particle size 1-3 microns); 1.02g of ammonium polymethacrylate; 6.38g of a mixture of polyvinyl alcohol and polyacrylic acid emulsion (mass ratio 1:3); 6.38g of glycerol; 15.55g of deionized water;

[0055] (2) Slurry preparation: add the dispersant weighed in step (1) to deionized water, stir magnetically for 1 hour, and fully disperse; add the ferroelectric ceramic powder and magnetic powder BaFe 12 O 19, ball milling for 8 hours at a ball milling speed of 300 r / min to obtain a uniform mixture, and adjusting the pH value to 10; then adding the binder and plasticizer weighed in step (1) to the mixture, and ball milling for a second time for 10 hours at a ball milling speed of 200 r / min; ultrasonic degassing for 40 minutes and letting it stand to obtain a stable casting slurry with a viscosity of 1210 mPa·s, which is set aside;

[0056] (3) Tape casting: The tape casting slurry prepared in step (2) was tape cast on a tape casting machine, with the tape casting speed set to 1 m / min and the scraper height set to 1.5 mm. The tape-cast sheet was dried at 45° C. for 6 hours and then peeled off from the base tape to obtain a substrate green sheet with a thickness of 1.18 mm and a ceramic green film tape. During the drying process, a directional magnetic field of 300 Oe was applied perpendicular to the film surface.

[0057] (4) Sintering to form a film: The green film strip obtained in step (3) is cut into a size of 1.18 mm × 30 mm × 20 mm, placed in a tubular sintering furnace for high-temperature sintering, raised to 600 ° C at a rate of 1.0 ° C / min for debinding, and kept warm for 2 hours; then continued to raise to 1120 ° C at a rate of 1.5 ° C / min and kept warm for 3 hours to obtain a ceramic sheet.

[0058] After ultrasonic cleaning of the magnetoelectric composite sheet, low-temperature conductive silver paste was applied on both sides of the sheet. After drying, the sheet was placed in silicone oil at 110°C for voltage polarization treatment with an electric field of 5kV / mm. After polarization for 1 hour, the sheet was taken out and the magnetoelectric comprehensive performance test was performed.

[0059] Performance Experiment

[0060] The performance parameters of the above embodiment after the magnetoelectric comprehensive performance test are shown in Table 1 below:

[0061] Table 1

[0062] Piezoelectric coefficient (pC / N) Magnetoelectric voltage coefficient (mV / cm·Oe) Magnetic dielectric tunability (%) Example 1 81.2 15.36 2.35 Example 2 66.2 19.83 2.71 Example 3 101.1 11.19 2.11 Example 4 53.4 21.89 2.99 Example 5 70.5 12.95 2.60

Claims

1. A water-based casting slurry for magnetoelectric composite ceramic sheets, characterized in that: The invention comprises 30-50% by mass of ferroelectric ceramic powder, 8-20% by mass of magnetic powder, 0.4-1.8% by mass of dispersant, 9-14% by mass of binder, 4-9% by mass of plasticizer and 15-27% by mass of deionized water; the ferroelectric ceramic powder is Bi 0.5 Na 0.4 K 0.1 TiO3, the particle size of which is 0.5~2 microns; the magnetic powder is hexagonal ferrite BaFe 12 O 19 The binder is a mixture of polyurethane emulsion and polyacrylic acid emulsion; the water-based casting slurry is prepared by raw material configuration to obtain a casting slurry, which is then cast and formed; the cast sheet is dried and peeled off from the base tape to obtain a ceramic green film; During the drying process, a permanent magnet is placed perpendicular to the film surface to apply a directional magnetic field.

2. The water-based casting slurry for magnetoelectric composite ceramic sheets according to claim 1, characterized in that: The particle size of the magnetic powder is 1 to 3 microns; the mass ratio of the ferroelectric ceramic powder to the magnetic powder is 5:1 to 3:

2.

3. The water-based casting slurry for magnetoelectric composite ceramic sheets according to claim 1, characterized in that: The dispersant is one of polyacrylic acid, ammonium polyacrylate or ammonium polymethacrylate.

4. The water-based casting slurry for magnetoelectric composite ceramic sheets according to claim 1, characterized in that: The binder is a mixture of polyurethane emulsion and polyacrylic acid emulsion, wherein the polyurethane emulsion accounts for 25-45% of the total weight percentage of the mixture.

5. The water-based casting slurry for magnetoelectric composite ceramic sheets according to claim 2, characterized in that: The plasticizer is one of polyethylene glycol or glycerol, and the mass ratio of the plasticizer added to the binder is 1:4 to 3:

4.

6. A method for preparing magnetoelectric composite ceramic sheets by water-based tape casting, characterized in that: The water-based casting slurry according to any one of claims 1 to 5 is used for preparation, and specifically comprises the following steps: Step (1) Preparation: weigh the raw materials in proportion and set aside; Step (2) slurry preparation: adding a dispersant to deionized water, then adding ferroelectric ceramic powder and magnetic powder thereto, ball milling for 6 to 12 hours, and adjusting the pH value to 9 to 10; then adding a binder and a plasticizer, and continuing ball milling for 8 to 12 hours; ultrasonically degassing and then allowing to stand to obtain a stable casting slurry with a certain viscosity; Step (3) tape casting: the tape casting slurry obtained in step (2) is tape cast on a tape casting machine; the tape-cast thin sheet is dried and peeled off from the base tape to obtain a ceramic green film; during the drying process, a permanent magnet is placed perpendicular to the film surface to apply a directional magnetic field until solidification and the magnet is removed; Step (4) Sintering to form a film: The green film obtained in step (3) is cut into a desired shape and sintered at a high temperature to obtain a ceramic sheet material.

7. The method for preparing magnetoelectric composite ceramic sheets by water-based tape casting according to claim 6, characterized in that: The viscosity of the casting slurry described in step (2) is 500~1700mPa·s.

8. The method for preparing magnetoelectric composite ceramic sheets by water-based tape casting according to claim 6, characterized in that: The magnitude of the directional magnetic field described in step (3) is 100~300 Oe.

9. The method for preparing magnetoelectric composite ceramic sheets by water-based tape casting according to claim 6, characterized in that: In step (3), the casting speed is 0.3-0.5 m / min, the scraper height is 0.8-2 mm, the drying temperature is 25-50° C., and the drying time is 4-6 hours.

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