CN116003117A - High solid content soft magnetic Mn-Zn ferrite slurry for gel casting and preparation method thereof - Google Patents
High solid content soft magnetic Mn-Zn ferrite slurry for gel casting and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a high solid content soft magnetic Mn-Zn ferrite slurry for gel casting and a preparation method thereof, wherein the solid content of the slurry is more than or equal to 56vol%, the viscosity is less than 989cp, the shearing stress is less than 1888MPa, and the zeta potential absolute value is more than 36mV. The preparation method can eliminate ZnFe in the sintering process of the gel casting green compact in the later period by carrying out presintering treatment on ferrite powder 2 O 4 The adverse effect of abnormal expansion during generation is effectively improved, the particle size matching degree of powder components is effectively improved, the solid phase content of slurry is further improved, and the green body drying shrinkage rate and sintering are facilitatedThe shrinkage rate is reduced, so that a blank with high density, high strength and good uniformity is obtained, and the preparation of the manganese-zinc ferrite core with a complex shape by gel casting is facilitated; by controlling the pH value of the slurry, the Zeta potential absolute value of the slurry is increased, and the dispersibility of the slurry is enhanced while the high solid phase content is maintained; the method has simple flow and easy operation, and is suitable for industrialized popularization and application.
Description
Technical Field
The application relates to the technical field of ceramic preparation and molding, in particular to high-solid-phase-content soft magnetic Mn-Zn ferrite slurry for gel casting and a preparation method thereof.
Background
The Mn-Zn ferrite core is widely applied to various electronic components such as transformers, inductors, filters and the like, and relates to various fields. At present, the manganese-zinc ferrite is mainly prepared by adopting a ferrite powder compression molding method, so that the manganese-zinc ferrite core with a complex shape is difficult to mold, the processing time is long, and the time and effort are also very consumed in mold installation and compression debugging.
The gel injection molding technology is a molding technology which organically combines the traditional ceramic technology and polymer chemistry, adopts a high molecular substance with a three-dimensional network structure to prepare a suspension with uniform dispersion, low viscosity and high solid phase volume fraction into a uniform green body with net size molding and high strength and high density, and is proposed by Mark A, janney professor and the like of the national key laboratory of the Oak China in the early U.S. of the 90 th century. The gel casting technology can overcome the defects that the existing technology of specially made magnetic core blanks is limited in molding shape or the magnetic properties of magnetic core samples after sintering and grinding are low.
The difficulty with gel casting techniques is how to prepare slurries with low viscosity, good flowability, and high solid phase volume fraction. The improvement of the solid phase content is beneficial to reducing the drying shrinkage and sintering shrinkage of the blank and reducing deformation, so that the blank with high density, high strength and good uniformity is obtained.
Disclosure of Invention
The invention aims at providing a high solid content soft magnetic Mn-Zn ferrite slurry for gel casting and a preparation method thereof aiming at the current state of the art.
In order to achieve the above purpose, the present application adopts the following technical scheme:
a soft magnetic Mn-Zn ferrite slurry with high solid content for gel casting, wherein the solid content of the slurry is more than or equal to 56vol%.
Further, the viscosity of the slurry is less than 989cp, the shearing stress is less than 1888MPa, and the Zeta potential absolute value is more than 36mV.
The preparation method of the high solid content soft magnetic Mn-Zn ferrite slurry for gel casting, as shown in figure 1, comprises the following steps:
s10, 50mol% Fe 2 O 3 30mol% of MnO and 20mol% of ZnO are taken as raw powder, deionized water is taken as grinding aid, and dispersing agent is added for ball milling to form mixed slurry;
preferably, the dispersing agent is polyacrylamide, and the adding amount is 0.3-0.5% of the weight of the original powder;
preferably, zirconia ceramic balls are used for ball milling, the ball-material ratio is 1.2:1, the rotating speed is 150-180 r/min during ball milling, and the ball milling time is 3-6 hours.
S20, filtering, drying, crushing and sieving the mixed slurry prepared in the step S10 to prepare ferrite mixed powder;
s30, pre-sintering the ferrite mixed powder prepared in the step S20, wherein the sintering temperature is 900-960 ℃ and the sintering time is 2-4 hours; presintering is the most important process, and the manganese zinc ferrite powder undergoes a series of physical and chemical changes in the presintering process, so that the performance of the final magnetic core product is decisively influenced.
The aim of presintering is to enable each raw material of ferrite to generate a certain degree of solid phase reaction and achieve a certain ferrite generation rate. The presintering has the following functions:
1) Eliminating the generation of ZnFe 2 O 4 Adverse effect of abnormal swelling at the time. When MnZn ferrite is prepared, if the raw material mixture is directly molded and sintered, uniform and compact ferrite is difficult to obtain, and even the magnetic core is cracked when serious. The reason for this is that ZnFe is generated 2 O 4 The volume of the material expands during the reaction, and the stress formed thereby causes cracking of the core. Most of ZnFe after presintering 2 O 4 The formation reaction is completed and the effect of abnormal swelling can be substantially eliminated.
2) Improving the matching property of each component in the powder. When the presintering temperature of the mixed powder reaches about 750 ℃, znO+Fe occurs 2 O 3 →ZnFe 2 O 4 Reacting to form ZnFe 2 O 4 Mn at about 850 DEG C 3 O 4 +Fe 2 O 3 →MnFe 2 O 4 +Mn 2 O 3 ZnFe at about 950 DEG C 2 O 4 Start and MnFe 2 O 4 Generating a small amount of MnZnFe 2 O 4 . On the one hand, the powder composition after burn-in changes compared with the powder not burned-in, and the powder composition after burn-in mainly comprises: znFe (ZnFe) 2 O 4 、MnFe 2 O 4 、α-Fe 2 O 3 、Mn 2 O 3 A small amount of MnZnFe 2 O 4 The physical and chemical properties of the powder components are closer, the dispersion characteristics are more similar, and the dispersion effect in the ball milling process is enhanced; on the other hand, after presintering, the particle size distribution of ferrite powder is more uniform during gel casting. When the presintering temperature is low, the reaction is insufficient, the component change is small, and the improvement effect is not obvious.
As shown in fig. 2, fig. 2 (a) shows the particle size of the powder without calcination, fig. 2 (b) shows the particle size distribution of the powder after calcination at 850 ℃, and fig. 2 (c) shows the particle size of the powder after calcination at 930 ℃. It can be seen that the particle size distribution of the powder after presintering is more concentrated and uniform, and the powder particle size matching can be better performed, but when the presintering temperature is lower, the reaction is insufficient, the particle size distribution improvement effect is general, and the particle size distribution is more dispersed. The reasonable particle size distribution of the powder can improve the solid phase content of the prepared ferrite slurry, reduce the viscosity and shearing stress of the slurry, improve the filling capacity of the slurry, further improve the compactness of ferrite green bodies, reduce the drying shrinkage and sintering shrinkage of gel casting ferrite blanks, and obtain blanks with high density, high strength and good uniformity;
however, as the sintering temperature is further increased, more solid solution MnZnFe is formed 2 O 4 Particle size and ZnFe 2 O 4 、MnFe 2 O 4、 α-Fe 2 O 3 、Mn 2 O 3 The difference is large, so that the dispersibility of the slurry is poor, the solid phase content is reduced, and the optimal pre-sintering temperature of the powder is 900-960 DEG C℃。
3) The sintering shrinkage rate of the product is reduced, and the fluidity is improved. Ferrite is generated by solid phase reaction, so that powder is shrunk, the shrinkage rate and deformation of the product are small, meanwhile, the loose density of the presintered powder is increased, and the fluidity is good.
4) The presintering can remove the raw materials to react at the temperature of about 850 ℃:3Mn 2 O 3 →2Mn 3 O 4 +1/2O 2 The gas generated by thermal decomposition removes acid radicals and nonmetallic impurities, eliminates part of composition variation and promotes homogenization of components.
S40, crushing and sieving the presintered ferrite powder for multiple times to obtain presintered ferrite powder for gel casting;
s50, deionized water is adopted as a solution, a dispersing agent, an organic monomer and a crosslinking agent are added for dispersion, and then a pH adjusting solution is added for adjusting the pH value to 9-11, so as to prepare a premix;
zeta potential is an important parameter reflecting the colloidal behaviour of particles, and small changes in the charged groups on the surface of the particles will cause changes in the Zeta potential of the particles. The dispersing agent can effectively characterize mutual rejection energy of particles in slurry under different pH values, so that the action effect of the dispersing agent can be characterized by Zeta potential measurement. According to colloid chemistry, the interaction force between particles in the liquid phase is van der Waals force, which makes the particles mutually attract to agglomerate, and electric double layer repulsive force, which hinders the agglomeration. DLVO theory considers that the stability of particles in liquid phase depends on the total potential energy of the particles, potential energy barriers near an equipotential point are small, and sedimentation is easy. The pH value is regulated to be far away from the equipotential point, the Zeta potential absolute value is large, the repulsive power is increased, and particles are dispersed in a liquid phase, so that the viscosity is low. Therefore, for the premix liquid required by ferrite slurry, the optimal pH value range is 9-11, and when the pH value is not in the range, the Zeta potential absolute value of the slurry is smaller, and the dispersion effect is poor.
Preferably, the deionized water is added in an amount of 11.2-19.8% of the weight of the original powder. The correct proportion of the material and water can ensure that the slurry with high solid phase content is obtained.
Preferably, the dispersing agent is polyacrylamide, and the adding amount is 0.75-0.98% of the weight of the original powder. Too little amount is added, so that the dispersing effect is not obvious, and the powder is agglomerated; too much amount of the mixture affects ball milling efficiency, resulting in suspension or flocculation of slurry and affecting ceramic strength. When the added dispersing agent reaches a proper value, the dispersing agent can be coated on the surface of the particles, so that a good dispersing effect is achieved.
Preferably, the organic monomer is acrylamide, and the compounding amount is 1.8% -2.2% of the weight of the original powder. The gel casting process is used as a colloid ceramic forming technology, and the gel reaction is utilized to form a polymer network to wrap ceramic powder, the polymer network is solidified and sintered to form a high-strength ceramic material, and an organic monomer is an important material for forming the polymer network.
Preferably, the cross-linking agent is N, N' -methylene bisacrylamide, and the compounding amount is 2.8-3.9% of the weight percentage of the organic monomer. The cross-linking agent and the organic monomer act together to form a polymer network.
Preferably, the pH regulating liquid is tetramethyl ammonium hydroxide, and the adding amount is 0.2-0.31% of the weight of the powder.
Preferably, the dispersing mode can adopt common ultrasonic dispersing, and the time can be set between 10 and 15 minutes.
S60, adding the pre-mixed solution prepared in the S50 into the presintered ferrite powder prepared in the S40, and performing ball milling to prepare ferrite slurry with solid phase content of more than or equal to 56vol%.
Preferably, a nylon ball milling tank is adopted, the pre-mixed liquid is added into the presintered ferrite powder in turn for four times, the ball milling rotating speed is 155-175r/min, and the four times of ball milling time is 1-2 hours, 3-5 hours and 7-10 hours respectively. The ball milling efficiency is low when the rotating speed is too low, the powder and the grinding balls are easy to centrifugally move when the rotating speed is too high, and the ball milling effect cannot be achieved.
Preferably, in the step S60, n-butanol is added in the ball milling process as a defoaming agent, and the adding amount is 0.4-0.6% of the volume percentage of deionized water.
The beneficial effects of this application are:
1. by pre-sintering ferrite powderAnd a certain content of ZnFe is generated 2 O 4 And MnZn ferrite, can eliminate ZnFe in the sintering process of the gel casting green compact in the later period 2 O 4 The method has the advantages that the adverse effect of abnormal expansion during production is achieved, the particle size matching degree of powder components is effectively improved, ferrite slurry with solid phase content more than or equal to 56vol%, slurry viscosity less than 989cp, shearing stress less than 1888MPa and zeta potential absolute value more than 36mV can be prepared, the solid phase content of the slurry is improved, the material density is further improved, the fluidity and the filling capacity of the slurry are enhanced, the reduction of the drying shrinkage rate and the sintering shrinkage rate of a green body is facilitated, blanks with high density, high strength and good uniformity are obtained, and the preparation of manganese-zinc ferrite cores with complex shapes by gel casting is facilitated;
2. by controlling the pH value of the slurry, the Zeta potential value of the slurry is increased, and the dispersibility of the slurry is enhanced while the high solid content is maintained;
3. the method has simple flow and easy operation, and is suitable for industrialized popularization and application.
Drawings
Fig. 1 is a process flow diagram of a method for preparing a high solids content soft magnetic manganese zinc ferrite slurry for gel casting in an embodiment of the present application.
Fig. 2 (a) is a particle size distribution diagram of a powder not subjected to calcination, fig. 2 (b) is a particle size distribution diagram of a powder subjected to calcination at 850 ℃, and fig. 2 (c) is a particle size distribution diagram of a powder subjected to calcination obtained at a temperature of 930 ℃.
Detailed Description
The technical features and advantages of the present application will be described in more detail below with reference to examples and comparative examples so that the advantages and features of the present application can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present invention.
In each of the examples and comparative examples, the ferrite slurry prepared was tested for viscosity and shear stress by using an NDJ-9T digital rotary viscometer manufactured by Shanghai Fang Rui instruments, inc., a MA160-1CN type solid phase content detector of Sidoris SARTORIUS, and a STABINO ZETA type nano particle size and Zeta potential analyzer of Germany Mickey company (Microtrac).
In each of the examples and comparative examples, a blank was gel-cast using the prepared ferrite slurry, and the linear shrinkage of the green body and the firing linear shrinkage were measured using a vernier caliper.
The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
S10, taking Fe 2 O 3 、Mn 3 O 4 Adding 10.12g of dispersing agent into a 5L ball milling tank, adding 1000ml of deionized water, then adding the mixture for ball milling, and ball milling for 3 hours after 5.5kg of zirconia grinding balls with diameters of phi 3mm and phi 15mm are filled in the tank, thereby obtaining primary ball milling slurry;
s20, filtering the slurry in the S10, drying the slurry in a drying oven at 60 ℃ for 24 hours, and crushing and sieving the slurry to obtain ferrite mixed powder;
s30, placing the ferrite mixed powder prepared in the S20 into a corundum sintering boat, and pre-sintering ferrite powder at 960 ℃;
s40, crushing and sieving the presintered ferrite powder to obtain presintered manganese-zinc ferrite powder for gel casting;
s50, deionized water is adopted as a solution, a dispersing agent, an organic monomer and a crosslinking agent are added, ultrasonic dispersion is carried out for 15min, and then pH value is adjusted to 9.3 by adding a pH adjusting solution, so as to prepare a premix;
wherein, the addition amount of each material is as follows:
dispersing agent: 24.60g of polyacrylamide;
organic monomer: acrylamide, 59.97g;
deionized water: 440.88g;
crosslinking agent: n, N-methylenebisacrylamide, 1.93g
pH adjusting solution: tetramethyl ammonium hydroxide, 7.06g;
s60, sequentially pouring the premix prepared in the step S50 into a 5L ball milling tank, controlling the rotating speed to 170r/min, adding 2.5mL of n-butyl alcohol as a defoaming agent, adding the pre-sintered manganese-zinc ferrite powder prepared in the step S40, and performing ball milling to prepare manganese-zinc ferrite slurry for gel casting;
and S70, pouring the Mn-Zn ferrite slurry prepared in the step S60 into a 2L beaker, placing the beaker in a vacuum stirring deaerator for deaeration for 10min, adding 5% Ammonium Persulfate (APS) as an initiator while stirring after deaeration is completed, and then pouring the mixture into a 180 mm-180 mm die for molding to prepare a ferrite green body.
In the embodiment, the manganese zinc ferrite slurry prepared after ball milling for 24 hours in the step S60 has the viscosity of 853.78cp, the shearing stress of 1599.7MPa (rotating speed of 12 rpm), the Zeta potential absolute value of 38.8mV and the solid phase volume fraction of the slurry measured as 56vol%; the ferrite green body produced in S70 had a linear shrinkage of 3.45% and a firing linear shrinkage of 18.5%.
Example 2
S10, taking Fe 2 O 3 、Mn 3 O 4 And 3.21kg of ZnO mixture, adding 13.48g of dispersing agent into a 5L-sized ball milling tank, adding 1000ml of deionized water, then adding the mixture for ball milling, and ball milling for 3 hours by filling 5.5kg of zirconia grinding balls with diameters of phi 3mm and phi 15mm into the tank to obtain primary ball milling slurry;
s20, filtering the slurry prepared in the S10, drying the slurry in a drying oven at 60 ℃ for 24 hours, and crushing and sieving the slurry to prepare ferrite mixed powder;
s30, placing the ferrite powder prepared in the S20 into a corundum sintering boat, and pre-sintering the ferrite powder at 930 ℃;
s40, crushing and sieving the presintered ferrite powder to obtain presintered manganese-zinc ferrite powder for gel casting;
s50, deionized water is used as a solvent, a dispersing agent, an organic monomer and a crosslinking agent are added in sequence, ultrasonic dispersion is carried out for 15min, and then PH value is adjusted to 10.1 by adding PH adjusting solution, so as to prepare a premix;
the amounts of the materials added were as follows:
dispersing agent: 28.71g of polyacrylamide;
organic monomer: 60.99g of acrylamide;
deionized water: 382.02g;
crosslinking agent: n, N-methylenebisacrylamide, 1.89g
pH adjusting solution: tetramethyl ammonium hydroxide, 7.38g;
s60, sequentially pouring the prepared premix into a 5L ball milling tank, controlling the rotating speed to be 170r/min, adding 2.0mL of n-butyl alcohol as a defoaming agent, adding the pre-sintered manganese-zinc ferrite powder prepared in the S40, and performing ball milling to prepare manganese-zinc ferrite slurry for gel casting;
and S70, pouring the manganese zinc ferrite slurry prepared in the step S60 into a 2L beaker, placing the beaker in a vacuum stirring deaerator for deaeration for 15min, adding 5% Ammonium Persulfate (APS) as an initiator while stirring after deaeration is completed, and then pouring the mixture into a 180 mm-180 mm die for molding to prepare a ferrite green body.
In the embodiment, the manganese zinc ferrite slurry prepared after ball milling for 24 hours in the step S60 has the viscosity of 785.70cp, the shearing stress of 1348.2MPa (rotating speed of 12 rpm), the Zeta potential absolute value of 41.3mV and the solid phase volume fraction of the slurry of 62vol percent; the gel molded green body obtained in S70 had a linear shrinkage of 1.6% and a firing linear shrinkage of 15.6%, and it was found that the shrinkage of the green body prepared in this example was significantly reduced relative to the green body and firing linear shrinkage of the green body prepared in comparative example 1 without presintering the powder gel molded.
Example 3
S10, taking Fe 2 O 3 、Mn 3 O 4 And 3.01kg of ZnO mixture, adding 11.43g of dispersing agent into a 5L-sized ball milling tank, adding 1000ml of deionized water, then adding the mixture for ball milling, and ball milling for 3 hours by filling 5.5kg of zirconia grinding balls with diameters of phi 3mm and phi 15mm into the tank to obtain primary ball milling slurry;
s20, filtering the slurry prepared in the step S10, drying the slurry in a drying oven at 60 ℃ for 24 hours, and crushing and sieving the slurry to prepare ferrite mixed powder;
s30, placing the ferrite powder prepared in the S20 into a corundum sintering boat, and pre-sintering the ferrite powder at 900 ℃;
s40, crushing and sieving the presintered ferrite powder to obtain presintered manganese-zinc ferrite powder for gel casting;
s50, deionized water is used as a solvent, a dispersing agent, an organic monomer and a crosslinking agent are added in sequence, ultrasonic dispersion is carried out for 15min, and then PH value is adjusted to 10.7 by adding PH adjusting solution, so as to prepare a premix;
the addition amounts of the various materials are as follows:
dispersing agent: 26.59g of polyacrylamide;
organic monomer: 58.22g of acrylamide;
deionized water: 420.23g;
crosslinking agent: n, N-methylenebisacrylamide, 1.86g
pH adjusting solution: tetramethyl ammonium hydroxide, 8.02g;
s60, sequentially pouring the premix prepared in the S50 into a 5L ball milling tank, controlling the rotating speed to 170r/min, adding 2.4mL of n-butyl alcohol as a defoaming agent, adding the pre-sintered manganese-zinc ferrite powder prepared in the S40, and performing ball milling to prepare manganese-zinc ferrite slurry for gel casting;
and S70, pouring the manganese zinc ferrite slurry prepared in the step S60 into a 2L beaker, placing the beaker in a vacuum stirring deaerator for deaeration for 10min, adding 4% Ammonium Persulfate (APS) as an initiator while stirring after deaeration is completed, and then pouring the mixture into a 180 mm-180 mm die for molding to prepare a ferrite green body.
In the embodiment, the manganese zinc ferrite slurry prepared after ball milling for 24 hours in the step S60 has the viscosity of 988.12cp, the shearing stress of 1887.2MPa (rotating speed of 12 rpm), the Zeta potential absolute value of 36.1mV and the solid phase volume fraction of the slurry of 58vol percent; the gel-molded green body obtained in S70 had a linear shrinkage of 2.64% and a firing linear shrinkage of 17.3%.
Comparative example 1
S10, taking Fe 2 O 3 、Mn 3 O 4 And ZnO mixture 2.65kg, adding 9.84g of dispersing agent into a 5L ball milling tank, adding 1000ml of deionized water, then adding the mixture for ball milling,the tank is filled with 5.5kg of zirconia grinding balls with the diameter phi 3mm and 15mm, and ball milling is carried out for 3 hours to obtain primary ball milling slurry;
s20, filtering the slurry in the S10, drying the slurry in a drying oven at 60 ℃ for 24 hours, crushing the slurry, and sieving the crushed slurry to obtain ferrite mixed powder;
s30, sequentially adding a dispersing agent, an organic monomer, deionized water and a crosslinking agent, performing ultrasonic dispersion for 15min, and then adding a PH regulating solution to regulate the PH value to 9.6 to prepare a premix;
the addition amounts of the various materials are as follows:
dispersing agent: 24.63g of polyacrylamide;
organic monomer: acrylamide, 55.11g;
deionized water: 490.08g;
crosslinking agent: n, N-methylenebisacrylamide, 1.91g
pH adjusting solution: tetramethyl ammonium hydroxide, 7.04 g;
s40, sequentially pouring the premix prepared in the S30 into a 5L ball milling tank, controlling the rotating speed to 170r/min, adding 2.2mL of a defoaming agent, sequentially adding the manganese zinc ferrite mixed powder prepared in the S20, and performing ball milling to prepare sizing agent for gel casting;
s50, pouring the slurry prepared in the S40 into a 2L beaker, placing the beaker in a vacuum stirring deaeration machine for deaeration for 15min, adding 4% of initiator while stirring after deaeration is completed, and then pouring the slurry into a 180 mm-180 mm die for molding to prepare the gel casting green compact.
In this comparative example, the slurry for gel casting prepared after ball milling for 24 hours in S40 had a viscosity of 2442cp, a shear stress of 4192MPa (rotation speed of 12 rpm), a Zeta potential absolute value of 32.2mV, and a solid phase volume fraction of 51vol% of the slurry was measured; the ferrite green body obtained in S50 had a linear shrinkage of 4.44% and a firing linear shrinkage of 19.8%.
The gel casting slurries and green performance parameters prepared in the examples and comparative examples are shown in the following table:
table 1 performance parameters of each sample
From the table, the solid phase content of the slurry is improved by the pre-sintering treatment of the Mn-Zn ferrite powder, the viscosity and the shearing stress of the slurry are greatly reduced, and the increase of the Zeta potential absolute value also shows that the dispersion effect of the slurry is better; in the process of preparing the green body from the slurry through gel casting, the drying shrinkage and sintering shrinkage of the green body are reduced, and the improvement of the forming quality of the green body is facilitated.
The foregoing description is only exemplary embodiments of the present application and is not intended to limit the scope of the present application, and all equivalent structures or equivalent processes using the descriptions and the drawings of the present application, or direct or indirect application in other related technical fields are included in the scope of the present application.
Claims (10)
1. A high solid content soft magnetic Mn-Zn ferrite slurry for gel casting is characterized in that the solid content of the slurry is more than or equal to 56vol%.
2. The high solid content soft magnetic manganese zinc ferrite slurry for gelcasting according to claim 1, wherein the slurry has a viscosity of < 989cp, a shear stress of < 1888mpa, and a zeta potential absolute value of > 36mV.
3. A method for preparing the high solid content soft magnetic manganese zinc ferrite slurry for gel casting, which is characterized by comprising the following steps of:
s10, 50mol% Fe 2 O 3 30mol% of MnO and 20mol% of ZnO are taken as raw powder, deionized water is taken as grinding aid, and dispersing agent is added for ball milling to form mixed slurry;
s20, filtering, drying, crushing and sieving the mixed slurry to obtain ferrite mixed powder;
s30, pre-sintering ferrite mixed powder at 900-960 ℃ for 2-4 hours;
s40, crushing and sieving the presintered ferrite powder to obtain presintered ferrite powder for gel casting;
s50, deionized water is adopted as a solution, a dispersing agent, an organic monomer and a crosslinking agent are added for dispersion, and then a pH adjusting solution is added for adjusting the pH value to 9-11, so as to prepare a premix;
s60, adding the pre-mixed solution prepared in the S50 into the presintered ferrite powder prepared in the S40, and performing ball milling to prepare ferrite slurry with solid phase content of more than or equal to 56vol%.
4. The method for preparing the high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 3, wherein the dispersant is polyacrylamide and the adding amount is 0.3-0.5% of the weight of the original powder.
5. The method for preparing the high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 4, wherein in the step S10, zirconia ceramic balls are used for ball milling, the ball-material ratio is 1.2:1, the ball milling rotating speed is 150r/min-180r/min, and the ball milling time is 3-6 hours.
6. The method for preparing high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 3, wherein the deionized water is added in an amount of 11.2% -19.8% of the weight of the original powder in step S50.
7. The method for preparing high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 6, wherein the dispersant in the step S50 is polyacrylamide, and the amount of the dispersant is 0.75-0.98% of the weight of the original powder.
8. The method for preparing high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 7, wherein the organic monomer is acrylamide, and the adding amount is 1.8% -2.2% of the weight of the original powder; the cross-linking agent is N, N' -methylene bisacrylamide, and the adding amount is 2.8-3.9% of the weight percentage of the organic monomer.
9. The method for preparing high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 8, wherein the pH adjusting liquid in step S50 is tetramethylammonium hydroxide, and the blending amount is 0.2% -0.31% of the powder by weight.
10. The method for preparing the high solid content soft magnetic manganese zinc ferrite slurry for gel casting according to claim 3, wherein in the step S60, a nylon ball milling tank is adopted, the pre-mixed solution is added into the presintered ferrite powder in turn for four times, the ball milling speed is 155-175r/min, and the four times of ball milling time is 1-2 hours, 3-5 hours and 7-10 hours respectively; n-butanol is added in the ball milling process as a defoaming agent, and the adding amount is 0.4-0.6% of the volume percentage of deionized water.
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