Manganese zinc ferrite as well as preparation method and application thereof

Abstract

The invention discloses manganese zinc ferrite as well as a preparation method and application thereof. The manganese zinc ferrite comprises a main component and an additive, the manganese zinc ferrite also comprises SiO2, and the SiO2 is at least coated on the surface of the main component; the main component comprises the following components in percentage by weight: 53.2 mol%-54.4 mol% of Fe2O3, 5.5 mol%-6 mol% of ZnO and the balance of MnO; the additive is prepared from the following components in parts by weight: 1500 ppm to 3000 ppm of Co2O3, 1000 ppm to 1600 ppm of calcium citrate, 100 ppm to 300 ppm of Nb2O5, 1500 ppm to 2000 ppm of TiO2, and 300 ppm to 600 ppm of ZrO2. The low-loss high-frequency manganese zinc ferrite material is obtained by regulating and controlling the main components, the sintering process and the types and contents of the additives and coating the silicon dioxide.

Description

Technical Field

[0001] The present invention belongs to the technical field of soft magnetic ferrites, and specifically relates to a manganese-zinc ferrite, a preparation method thereof, and uses thereof. Background Art

[0002] Existing manganese-zinc ferrite (MnZn ferrite) materials, as the basic materials for contemporary electronics industry and information industry, are widely used in the fields of electronics and communication. With the development of electronic components towards humanization, miniaturization, and high output power, the operating frequency of MnZn ferrite cores gradually shifts from low frequency to high frequency, and the operating conditions develop from small current to large current. When the operating frequency shifts to high frequency, the loss of traditional MnZn ferrites will increase sharply, unable to meet the usage requirements, and it is necessary to reduce the high-frequency loss.

[0003] The main reason for the sharp increase in the high-frequency loss of traditional MnZn ferrites is that as the frequency increases, the eddy current loss of the manganese-zinc ferrite increases sharply. High-frequency manganese-zinc ferrites generally add additives such as SiO 2 / CaO to form a high-resistance layer at the grain boundaries to reduce the eddy current loss.

[0004] CN115536380A discloses a high saturation magnetic flux density and low loss manganese-zinc ferrite material, belonging to the technical field of manganese-zinc ferrite materials, which consists of a main component and a secondary component; the main component includes Fe 2 O 3 , ZnO, MnO; the secondary component, calculated based on the total mass of the main component of 100 wt%, includes the following components: SiO 2 is 0 to 0.01 wt%, CaCO 3 is 0.08 to 0.18 wt%, Nb 2 O 5 is 0.01 to 0.03 wt%, ZrO 2 is 0.01 to 0.03 wt%, V 2 O 5 is 0.015 to 0.03 wt%, TiO 2 is 0.05 to 0.10 wt%. The manganese-zinc ferrite material prepared by this patent by controlling the composition and content of the main component and the secondary component of the manganese-zinc ferrite material and optimizing the sintering process has a dB above 0.40 T at 100 °C, and the power consumption P cv is less than 300 kwm -3 at 100 kHz and 200 mT. However, its sintering temperature is high (1250 °C), the grain size is large, and the overall resistance is low, which will result in high high-frequency loss and cannot meet the high-frequency usage requirements.

[0005] The traditional doping method is to grind ferrite and additives together in a ball mill to achieve the purpose of mixing. The uniformity of this mixing method is poor, and the finally sintered high-resistance layer is uneven and discontinuous.

[0006] Therefore, it is necessary to provide a manganese-zinc ferrite and a preparation method thereof to improve the uniformity of the high-resistance layer, so as to obtain a high-frequency manganese-zinc ferrite material with excellent performance and low loss. Summary of the Invention

[0007] Aiming at the above problems existing in the prior art, the purpose of the present invention is to provide a manganese-zinc ferrite, a preparation method and a use thereof. By regulating the main components, sintering process, types and contents of additives, and coating the main components with silicon dioxide, the present invention optimizes the uniformity of the grain boundary resistance layer and obtains a high-frequency manganese-zinc ferrite material with low loss.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a manganese-zinc ferrite, which comprises main components and additives, and also comprises SiO 2 , and the SiO 2 is at least coated on the surface of the main components;

[0010] Based on the total molar amount of the main components being 100 mol%, the main components include:

[0011] Fe 2 O 3 53.2 mol% to 54.4 mol%

[0012] ZnO 5.5 mol% to 6 mol%

[0013] MnO the balance;

[0014] Based on the total mass of the manganese-zinc ferrite, the additives include:

[0015]

[0016] In the manganese-zinc ferrite of the present invention, the content of Fe 2 O 3 is 53.2 mol% to 54.4 mol%, such as 53.2 mol%, 53.5 mol%, 53.8 mol%, 54.0 mol%, 54.2 mol% or 54.4 mol% etc.

[0017] In the Mn-Zn ferrite of the present invention, the content of ZnO is 5.5 mol% to 6 mol%, such as 5.5 mol%, 5.6 mol%, 5.8 mol%, 5.9 mol% or 6 mol%, etc.

[0018] In the Mn-Zn ferrite of the present invention, Co 2 O 3 has a content of 1500 ppm to 3000 ppm, such as 1500 ppm, 1600 ppm, 1700 ppm, 1800 ppm, 2000 ppm, 2200 ppm, 2400 ppm, 2600 ppm, 2700 ppm, 2800 ppm, 2900 ppm or 3000 ppm, etc.

[0019] In the Mn-Zn ferrite of the present invention, the content of calcium citrate is 1000 ppm to 1600 ppm, such as 1000 ppm, 1100 ppm, 1200 ppm, 1300 ppm, 1400 ppm, 1500 ppm or 1600 ppm, etc.

[0020] In the Mn-Zn ferrite of the present invention, Nb 2 O 5 has a content of 100 ppm to 300 ppm, such as 100 ppm, 120 ppm, 130 ppm, 140 ppm, 150 ppm, 165 ppm, 175 ppm, 185 ppm, 200 ppm, 220 ppm, 230 ppm, 245 ppm, 260 ppm, 280 ppm or 300 ppm, etc.

[0021] In the Mn-Zn ferrite of the present invention, TiO 2 has a content of 1500 ppm to 2000 ppm, such as 1500 ppm, 1600 ppm, 1650 ppm, 1800 ppm, 1900 ppm or 2000 ppm, etc.

[0022] In the Mn-Zn ferrite of the present invention, ZrO 2 has a content of 300 ppm to 600 ppm, such as 300 ppm, 320 ppm, 340 ppm, 350 ppm, 360 ppm, 380 ppm, 400 ppm, 425 ppm, 450 ppm, 470 ppm, 480 ppm, 500 ppm, 525 ppm, 550 ppm, 580 ppm or 600 ppm, etc.

[0023] The present invention reduces the overall loss of the material through the combined action of appropriate main components and additives. Among them, SiO 2Coating the main components can improve the adsorption capacity of the material surface, enhance the synergistic cooperation between the main components and the additives, and can also reduce the agglomeration oxidation of the ferrite, improving the stability and compatibility. Compared with other calcium sources (such as calcium carbonate), calcium citrate can better adsorb on the surface of SiO 2 modified by intermolecular forces, and utilize the synergistic effect of Si-Ca to promote the formation of a uniform high-resistance grain boundary after sintering, reducing the eddy current loss of the material.

[0024] The manganese-zinc ferrite of the present invention is a low-loss high-frequency manganese-zinc ferrite, and its Pcv ≤ 100 mw / cm at 25°C under 1 MHz 50 mT 3 , and Pcv ≤ 110 mw / cm at 100°C 3 .

[0025] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

[0026] Preferably, based on the total mass of the manganese-zinc ferrite, the content of SiO 2 is 100 ppm to 150 ppm, such as 100 ppm, 120 ppm, 130 ppm, 140 ppm or 150 ppm, etc.

[0027] In a second aspect, the present invention provides a method for preparing the manganese-zinc ferrite as described in the first aspect, and the preparation method includes the following steps:

[0028] (1) Using Fe 2 O 3 , MnO and ZnO as the main components, ball milling and then pre-sintering to obtain a pre-sintered material;

[0029] (2) Mixing the pre-sintered material with a mixed solution of ammonia, alcohol and water, and then adding a silicon source, and reacting to obtain a manganese-zinc ferrite coated with silica;

[0030] (3) After mixing and ball milling the manganese-zinc ferrite coated with silica with an additive, mixing the ball-milled material with polyvinyl alcohol and granulating, and pressing it into a blank,

[0031] wherein, the additive includes Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 , and ZrO mixed;

[0032] (4) Sintering the blank to obtain the manganese-zinc ferrite.

[0033] In the method of the present invention, in step (2), by treating the pre-sintered material with a mixed solution of ammonia, alcohol and water, good dispersion uniformity can be ensured, the coating uniformity of silicon dioxide can be improved, and agglomeration can be avoided. SiO 2 Coating the pre-sintered material can increase the surface energy of the ferrite, better adsorb other additives, and improve the dispersion of the additives. Moreover, pre-coating with SiO 2 can react with Ca during subsequent sintering to form a continuous and uniform high-resistance layer.

[0034] Preferably, the ball milling time in step (1) is 1 h to 4 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h or 4 h, etc.

[0035] Preferably, the ball milling in step (1) is wet ball milling, and after ball milling, drying is carried out. The drying method can be drying by baking.

[0036] Preferably, the pre-sintering temperature in step (1) is 800 °C to 850 °C, such as 800 °C, 815 °C, 820 °C, 825 °C, 830 °C, 835 °C, 840 °C, 845 °C or 850 °C, etc.

[0037] Preferably, the pre-sintering time in step (1) is 3 h to 6 h, such as 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h, etc.

[0038] Preferably, the pre-sintering atmosphere in step (1) is air.

[0039] Preferably, after the pre-sintering in step (1), secondary ball milling is carried out.

[0040] Preferably, the time of the secondary ball milling is 2 h to 3 h, such as 2 h, 2.2 h, 2.5 h, 2.7 h or 3 h, etc.

[0041] Preferably, the particle size D50 of the material obtained after the secondary ball milling is 1 μm to 1.2 μm, such as 1 μm, 1.05 μm, 1.1 μm, 1.15 μm or 1.2 μm, etc.

[0042] Preferably, the secondary ball milling is wet ball milling, and after the secondary ball milling, drying is carried out. The drying method can be drying by baking.

[0043] As a preferred technical solution of the method for preparing the manganese-zinc ferrite of the present invention, in step (2), the mass ratio of the pre-sintered material to the mixed solution of ammonia, alcohol and water is (5 - 10):100, such as 5:100, 5.5:100, 6:100, 6.5:100, 7:100, 7.5:100, 8:100, 8.5:100, 9:100, 9.5:100 or 10:100, etc.

[0044] Preferably, in the mixed solution of ammonia, alcohol and water in step (2), the mass percentages of ammonia, alcohol and water are 0.5% - 3%, 70% - 80%, and 20% - 27% respectively. Among them, the selection range of ammonia is "0.5% - 3%", such as 0.5%, 1%, 1.5%, 2%, 2.5% or 3%, etc.; the selection range of alcohol is "70% - 80%", such as 70%, 72%, 74%, 75%, 76%, 78% or 80%, etc.; the selection range of water is "20% - 27%", such as 20%, 21%, 22%, 23%, 24%, 25%, 26% or 27%, etc. It should be noted that the mass percentage here refers to the active ingredient. For example, for ammonia water, the active ingredient therein is NH 3 .

[0045] The present invention does not specifically limit the types of ammonia and alcohol. Exemplarily, ammonia can be sourced from ammonia water, and alcohol can be sourced from ethanol.

[0046] Preferably, in step (2), before adding the mixed solution of ammonia, alcohol and water to the pre-fired material, the pre-fired material is first added to a citric acid solution, ultrasonicated and then dried. Through this step, the dispersion uniformity can be further improved.

[0047] Preferably, the concentration of the citric acid solution is 0.01M - 0.03M, such as 0.01M, 0.02M or 0.03M, etc.

[0048] Preferably, the time of the ultrasonic treatment is 15min - 30min, such as 15min, 17min, 18min, 20min, 22min, 25min, 27min or 30min, etc.

[0049] Preferably, in step (2), the silicon source is added under stirring conditions.

[0050] Preferably, the silicon source in step (2) includes tetraethyl orthosilicate.

[0051] Preferably, the reaction in step (2) is carried out under water bath heating, and the heating temperature is 80°C - 120°C, such as 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C or 120°C, etc.

[0052] Preferably, the reaction time in step (2) is 6h - 10h, such as 6h, 7h, 7.5h, 8h, 8.5h, 9h or 10h, etc.

[0053] Preferably, after the reaction in step (2), the liquid is removed to obtain manganese-zinc ferrite coated with silica. The present invention does not limit the method for removing the liquid. For example, the liquid can be removed by centrifugation.

[0054] As a preferred technical solution of the method for preparing the manganese-zinc ferrite of the present invention, the ball milling time in step (3) is 1 h to 2 h, such as 1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.

[0055] Preferably, the particle size D50 of the material obtained after ball milling in step (3) is 0.7 μm to 0.8 μm, such as 0.7 μm, 0.72 μm, 0.73 μm, 0.74 μm, 0.75 μm, 0.77 μm, 0.78 μm or 0.8 μm, etc.

[0056] Preferably, in step (3), based on the mass of the manganese-zinc ferrite being 100%, the dosage of the polyvinyl alcohol is 5% to 15%, such as 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc.

[0057] Preferably, the ball milling in step (3) is wet ball milling, and after ball milling, drying is carried out. The drying method can be drying by baking.

[0058] Preferably, in step (3), after the ball milled material is mixed with polyvinyl alcohol and granulated, sieving is carried out. The mesh number of the sieve used for sieving is 60 mesh. The purpose of this step is to remove the over-large agglomerated particles generated during granulation and remove the unevenly granulated particles.

[0059] The present invention does not limit the shape of the blank obtained in step (3). For example, it can be an annular blank.

[0060] As a preferred technical solution of the method for preparing the manganese-zinc ferrite of the present invention, the sintering temperature in step (4) is 1000 °C to 1110 °C, such as 1000 °C, 1030 °C, 1050 °C, 1070 °C, 1080 °C or 1100 °C, etc. The sintering temperature here should not be too high. If the temperature is too high, it will cause the crystal grains to be too large and lead to an increase in high-frequency loss.

[0061] Preferably, the heat preservation time for sintering in step (4) is 5 h to 10 h, such as 5 h, 6 h, 6.5 h, 7 h, 7.5 h, 8 h, 8.5 h, 9 h or 10 h, etc.

[0062] Preferably, the sintering in step (4) is carried out in an oxygen-containing atmosphere.

[0063] Preferably, the oxygen-containing atmosphere includes a protective gas and oxygen.

[0064] Preferably, the protective gas includes at least one of helium, neon or nitrogen.

[0065] In a third aspect, the present invention provides a use of the manganese-zinc ferrite as described in the first aspect, and the manganese-zinc ferrite is used in the field of electronics or communication.

[0066] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges not listed. Due to space limitations and for the sake of simplicity, the present invention does not exhaustively list the specific point values included in the ranges.

[0067] Compared with the prior art, the present invention has the following beneficial effects:

[0068] (1) In the present invention, the overall loss of the material is reduced through the combined action of appropriate main components and additives. Among them, by coating the main components with SiO 2 , the adsorption capacity on the surface of the material can be improved, and the synergistic cooperation between the main components and the additives can be enhanced. Compared with other calcium sources (such as calcium carbonate), calcium citrate can be better adsorbed on the surface modified by SiO 2 through intermolecular forces. Utilizing the synergistic effect of Si-Ca, it promotes the formation of a uniform high-resistance grain boundary after sintering and reduces the eddy current loss of the material.

[0069] (2) The manganese-zinc ferrite of the present invention is a low-loss high-frequency manganese-zinc ferrite, and its Pcv ≤ 100 mw / cm at 25 °C under 1 MHz 50 mT 3 , and Pcv ≤ 110 mw / cm at 100 °C 3 . Detailed Embodiments

[0070] The technical solutions of the present invention will be further described below through specific embodiments.

[0071] The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0072] In the embodiments of the present invention, the ball milling involved is wet ball milling, that is, the solvent is included in the process of ball milling. However, the present invention is not limited thereto, and the method of dry ball milling is also applicable to the present invention.

[0073] Example 1

[0074] This example provides a low-loss high-frequency manganese-zinc ferrite, which includes main components and additives. SiO 2 is also included in the manganese-zinc ferrite, and the SiO 2 coats at least the surface of the main components. Based on the total mass of the manganese-zinc ferrite, the content of SiO 2 is 100 ppm.

[0075] Based on the total molar amount of the main components being 100 mol%, the main components include: 53.2 mol% of Fe 2 O 3 , 5.5 mol% of ZnO, with the balance being MnO;

[0076] Based on the total mass of the manganese-zinc ferrite, the additives include: Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 , and their mass fractions are 2000 ppm, 1000 ppm, 100 ppm, 1500 ppm, and 300 ppm respectively.

[0077] The method for preparing the manganese-zinc ferrite provided in this example includes the following steps:

[0078] (1) Using Fe 2 O 3 , MnO, and ZnO powders as the main components, mix them in a ball mill for 3 h according to the proportional requirements, then dry and perform pre-sintering. Among them, the pre-sintering temperature is 800 °C, the pre-sintering time is 3 h, and the pre-sintering atmosphere is air;

[0079] Use a ball mill to perform secondary ball milling on the material obtained by pre-sintering and then dry it to obtain a pre-sintered material. Among them, the secondary ball milling time is 3 h, and the particle size D50 of the material after secondary ball milling is 1.2 μm.

[0080] (2) Add the pre-sintered material to a 0.03 M citric acid solution, perform ultrasonic treatment for 30 min, dry it, and then add it to a mixed solution of ammonia water, ethanol, and water (where the mass percentages of the active ingredients NH 3 , ethanol, and water are 1.5%, 75%, and 23.5% respectively) to obtain a suspension. Among them, the mass ratio of the pre-sintered material to the mixed solution of ammonia water, ethanol, and water is 10:100;

[0081] Add tetraethyl orthosilicate to the suspension under stirring conditions, heat it in a water bath to 100 °C, continuously stir for 10 h, centrifuge the reaction solution, and remove the liquid part to obtain manganese-zinc ferrite coated with silica.

[0082] (3) Mix the manganese-zinc ferrite coated with silica with the additives (Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2)Mix, perform ball milling using a ball mill and then dry. The ball milling time is 1 h, the particle size D50 of the milled material is 0.75 μm. Add 10% (based on the mass of the manganese-zinc ferrite) of PVA for granulation. After passing through a 60-mesh sieve, remove the unevenly granulated particles and press them into a blank sample ring.

[0083] (4) Sinter the blank sample ring in an oxygen-containing atmosphere. The oxygen-containing atmosphere is composed of nitrogen and oxygen. The sintering temperature is 1110 °C, and the holding time for sintering is 7 h to obtain a sample ring with dimensions of 12.5 mm × 7.5 mm × 7 mm. Among them, the outer diameter of the sample ring is 12.5 mm, the inner diameter is 7.5 mm, and the height is 7 mm.

[0084] Example 2

[0085] This example provides a low-loss high-frequency manganese-zinc ferrite, which includes a main component and an additive. The manganese-zinc ferrite also includes SiO 2 , and the SiO 2 at least coats the surface of the main component. Based on the total mass of the manganese-zinc ferrite, the content of the SiO 2 is 150 ppm.

[0086] Based on the total molar amount of the main component being 100 mol%, the main component includes: 54 mol% of Fe 2 O 3 , 5.8 mol% of ZnO, and the balance is MnO;

[0087] Based on the total mass of the manganese-zinc ferrite, the additive includes: Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO, and their mass fractions are 1500 ppm, 1300 ppm, 200 ppm, 1800 ppm, and 500 ppm respectively.

[0088] The preparation method of the manganese-zinc ferrite provided in this example includes the following steps:

[0089] (1) Use Fe 2 O 3 , MnO and ZnO powders as the main components, mix them in a ball mill for 3 h according to the proportional requirements, then dry and perform pre-sintering. Among them, the pre-sintering temperature is 850 °C, the pre-sintering time is 6 h, and the pre-sintering atmosphere is air;

[0090] Use a ball mill to perform secondary ball milling on the material obtained from pre-sintering and then dry to obtain a pre-sintered material. Among them, the secondary ball milling time is 3 h, and the particle size D50 of the material after secondary ball milling is 1.2 μm.

[0091] (2) Add the pre-sintered material into a 0.02 M citric acid solution, ultrasonically treat for 15 min, and then add it into a mixed solution of ammonia water, ethanol and water (where the mass percentages of the active ingredients NH 3 , ethanol and water are 1.5%, 75% and 23.5% respectively) to obtain a suspension. The mass ratio of the pre-sintered material to the mixed solution of ammonia water, ethanol and water is 5:100;

[0092] Add tetraethyl orthosilicate to the suspension under stirring conditions, heat it in a water bath to 100 °C, continuously stir for 10 h, centrifuge the reaction solution, and remove the liquid part to obtain manganese-zinc ferrite coated with silica.

[0093] (3) Mix the manganese-zinc ferrite coated with silica with additives (Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 ), use a ball mill to ball mill and dry. The ball milling time is 2 h, the particle size D50 of the ball milled material is 0.7 μm. After passing through a 60-mesh sieve, add 10% (based on the mass of the manganese-zinc ferrite) PVA for granulation, sieve, remove unevenly granulated particles, and press them into a blank sample ring.

[0094] (4) Sinter the blank sample ring in an oxygen-containing atmosphere. The oxygen-containing atmosphere is composed of nitrogen and oxygen. The sintering temperature is 1110 °C, and the holding time for sintering is 7 h to obtain a sample ring of 12.5 mm × 7.5 mm × 7 mm.

[0095] Example 3

[0096] This example provides a low-loss high-frequency manganese-zinc ferrite, which includes a main component and additives. The manganese-zinc ferrite also includes SiO 2 , and the SiO 2 is at least coated on the surface of the main component. Based on the total mass of the manganese-zinc ferrite, the content of the SiO 2 is 150 ppm.

[0097] Based on the total molar amount of the main component being 100 mol%, the main component includes: 54.4 mol% of Fe 2 O 3 , 6 mol% of ZnO, and the balance is MnO;

[0098] Based on the total mass of the manganese-zinc ferrite, the additives include: Co 2 O 3 , calcium citrate, Nb2 O 5 、TiO 2 and ZrO 2 , with mass fractions of 3000 ppm, 1600 ppm, 300 ppm, 2000 ppm, and 600 ppm, respectively.

[0099] The method for preparing the manganese-zinc ferrite provided in this embodiment includes the following steps:

[0100] (1) Using Fe 2 O 3 , MnO, and ZnO powders as the main components, mix them in a ball mill for 3 h according to the proportional requirements, then dry and perform pre-sintering. Among them, the pre-sintering temperature is 850 °C, the pre-sintering time is 6 h, and the pre-sintering atmosphere is air;

[0101] Use a ball mill to perform secondary ball milling on the material obtained by pre-sintering and dry it to obtain a pre-sintered material. Among them, the secondary ball milling time is 3 h, and the particle size D50 of the material after secondary ball milling is 1.2 μm.

[0102] (2) Add the pre-sintered material to a 0.03 M citric acid solution, perform ultrasonic treatment for 20 min, dry it, and then add it to a mixed solution of ammonia water, ethanol, and water (where the mass percentages of the active ingredients NH 3 , ethanol, and water are 1.5%, 75%, and 23.5%, respectively) to obtain a suspension. Among them, the mass ratio of the pre-sintered material to the mixed solution of ammonia water, ethanol, and water is 10:100;

[0103] Add tetraethyl orthosilicate to the suspension under stirring conditions, heat it in a water bath to 100 °C, and continuously stir for 10 h. After centrifuging the reaction solution, remove the liquid part to obtain manganese-zinc ferrite coated with silica.

[0104] (3) Mix the manganese-zinc ferrite coated with silica with additives (Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 ), use a ball mill to perform ball milling and dry it. The ball milling time is 2 h, the particle size D50 of the material after ball milling is 0.7 μm, add 10% (based on the mass of the manganese-zinc ferrite) PVA for granulation, remove unevenly granulated particles after passing through a 60-mesh sieve, and press it into a blank sample ring.

[0105] (4) Sinter the blank sample ring in an oxygen-containing atmosphere. The oxygen-containing atmosphere is composed of nitrogen and oxygen. The sintering temperature is 1110 °C, and the sintering holding time is 7 h to obtain a sample ring of 12.5 mm × 7.5 mm × 7 mm.

[0106] Example 4

[0107] This example provides a high-frequency Mn-Zn ferrite with low loss, which includes a main component and additives. The Mn-Zn ferrite also includes SiO 2 , and the SiO 2 is at least coated on the surface of the main component. Based on the total mass of the Mn-Zn ferrite, the content of the SiO 2 is 120 ppm.

[0108] Based on the total molar amount of the main component being 100 mol%, the main component includes: 53.5 mol% of Fe 2 O 3 , 5.7 mol% of ZnO, and the balance is MnO;

[0109] Based on the total mass of the Mn-Zn ferrite, the additives include: Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 , and ZrO 2 , and their mass fractions are 2500 ppm, 1400 ppm, 150 ppm, 1700 ppm, and 400 ppm respectively.

[0110] The preparation method of the Mn-Zn ferrite provided in this example includes the following steps:

[0111] (1) Using Fe 2 O 3 , MnO, and ZnO powders as the main components, mix them in a ball mill for 2 h according to the proportional requirements, then dry and perform pre-sintering. Among them, the pre-sintering temperature is 820 °C, the pre-sintering time is 4.5 h, and the pre-sintering atmosphere is air;

[0112] Use a ball mill to perform secondary ball milling on the material obtained by pre-sintering and dry it to obtain a pre-sintered material. Among them, the secondary ball milling time is 2 h, and the particle size D50 of the material after secondary ball milling is 1.1 μm.

[0113] (2) Add the pre-sintered material to a 0.01 M citric acid solution, perform ultrasonic treatment for 30 min, dry it, and then add it to a mixed solution of ammonia water, ethanol, and water (where the mass percentages of the active ingredients NH 3 , ethanol, and water are 1.0%, 77%, and 22.0% respectively) to obtain a suspension. Among them, the mass ratio of the pre-sintered material to the mixed solution of ammonia water, ethanol, and water is 8:100;

[0114] The suspension was added with tetraethyl orthosilicate under stirring conditions, heated in a water bath to 110 °C, and continuously stirred for 8 h. After centrifuging the reaction solution, the liquid part was removed to obtain manganese-zinc ferrite coated with silica.

[0115] (3) The manganese-zinc ferrite coated with silica was mixed with additives (Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 ), ball milled and dried using a ball mill. The ball milling time was 1.5 h, the particle size D50 of the ball milled material was 0.72 μm. After passing through a 60-mesh sieve, 8% (based on the mass of the manganese-zinc ferrite) PVA was added for granulation, sieved, unevenly granulated particles were removed, and a blank sample ring was pressed.

[0116] (4) The blank sample ring was sintered in an oxygen-containing atmosphere composed of nitrogen and oxygen. The sintering temperature was 1050 °C, and the holding time for sintering was 10 h to obtain a sample ring of 12.5 mm × 7.5 mm × 7 mm.

[0117] Example 5

[0118] This example provides a low-loss high-frequency manganese-zinc ferrite. The difference in its preparation method from that of Example 1 is that in step (2), the pre-sintered material was not added to the citric acid solution for ultrasonic treatment.

[0119] Example 6

[0120] This example provides a low-loss high-frequency manganese-zinc ferrite. The difference from Example 1 is that the addition amount of tetraethyl orthosilicate in the preparation method was changed, so that based on the total mass of the manganese-zinc ferrite, the content of SiO 2 was 90 ppm.

[0121] Example 7

[0122] This example provides a low-loss high-frequency manganese-zinc ferrite. The difference from Example 1 is that the addition amount of tetraethyl orthosilicate in the preparation method was changed, so that based on the total mass of the manganese-zinc ferrite, the content of SiO 2 was 170 ppm.

[0123] Comparative Example 1

[0124] This comparative example provides a manganese-zinc ferrite. The difference from Example 1 is that SiO2 exists in the manganese-zinc ferrite in the form of an additive rather than in the form of a coating layer.

[0125] The preparation method of the manganese-zinc ferrite provided in this comparative example includes the following steps:

[0126] (1) Using Fe 2 O 3 , MnO and ZnO powders as the main components, mix them in a ball mill for 3 h according to the proportional requirements, then dry and perform pre-sintering. Among them, the pre-sintering temperature is 800 °C, the pre-sintering time is 3 h, and the pre-sintering atmosphere is air;

[0127] Use a ball mill to perform secondary ball milling on the material obtained by pre-sintering and dry it to obtain a pre-sintered material. Among them, the secondary ball milling time is 3 h, and the particle size D50 of the material after secondary ball milling is 1.2 μm.

[0128] (2) Mix the manganese-zinc ferrite with additives (SiO 2 , Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 ), use a ball mill to perform ball milling and dry it. The ball milling time is 1 h, the particle size D50 of the material after ball milling is 0.75 μm. After passing through a 60-mesh sieve, add 10% (based on the mass of the manganese-zinc ferrite) PVA for granulation, sieve, remove unevenly granulated particles, and press them into a blank sample ring.

[0129] (4) Sinter the blank sample ring in an oxygen-containing atmosphere. The oxygen-containing atmosphere is composed of nitrogen and oxygen. The sintering temperature is 1110 °C, and the holding time for sintering is 7 h to obtain a sample ring of 12.5 mm × 7.5 mm × 7 mm.

[0130] Comparative Example 2

[0131] This comparative example provides a manganese-zinc ferrite. The difference in its preparation method from that of Example 1 is that calcium carbonate is used to replace calcium citrate.

[0132] Comparative Example 3

[0133] This comparative example provides a manganese-zinc ferrite. The difference from Example 1 is that step (2) is not carried out in the preparation method, so that the manganese-zinc ferrite does not contain SiO 2 .

[0134] Comparative Example 4

[0135] This comparative example provides a manganese-zinc ferrite. The difference from Example 1 is that based on the total mass of the manganese-zinc ferrite, the additives include: Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO2 , with mass fractions of 2500 ppm, 1700 ppm, 400 ppm, 2500 ppm, and 700 ppm respectively.

[0136] Comparative Example 5

[0137] This comparative example provides a manganese-zinc ferrite, which is different from Example 1 in that, based on the total molar amount of the main components being 100 mol%, the main components include: 53 mol% of Fe 2 O 3 , 5.4 mol% of ZnO, with the balance being MnO; based on the total mass of the manganese-zinc ferrite, the additives include: Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 , with mass fractions of 2500 ppm, 1700 ppm, 400 ppm, 2500 ppm, and 700 ppm respectively.

[0138] Comparative Example 6

[0139] This comparative example provides a manganese-zinc ferrite, which is different from Example 1 in that, based on the total molar amount of the main components being 100 mol%, the main components include: 54.8 mol% of Fe 2 O 3 , 6.2 mol% of ZnO, with the balance being MnO; based on the total mass of the manganese-zinc ferrite, the additives include: Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 and ZrO 2 , with mass fractions of 2500 ppm, 1700 ppm, 400 ppm, 2500 ppm, and 700 ppm respectively.

[0140] Comparative Example 7

[0141] This comparative example provides a manganese-zinc ferrite, which is different from Example 1 in that the sintering temperature is 1150 °C.

[0142] Performance test:

[0143] The sample rings were tested using a SY-8218 loss test device, and the test coil was a double-strand 3-turn coil with a wire diameter of 0.4 mm.

[0144] The test conditions were as follows: test frequency: 1 MHz; test B value: 50 mT; test temperature: 25 °C / 100 °C.

[0145] The results are shown in Table 1.

[0146] Table 1 Test data table of sample rings

[0147]

[0148]

[0149] As can be seen from Table 1, by using a combination of a main component and an additive with appropriate contents and types, and coating the main component with silica, the present invention can obtain a low-loss high-frequency manganese-zinc ferrite with excellent performance.

[0150] By comparing Example 1 with Example 5, it can be seen that pretreating the pre-sintered material with a citric acid solution can improve the performance of the finally prepared ferrite.

[0151] By comparing Example 1 with Examples 6-7, it can be seen that the coating amount of silica has a preferred range of 100 ppm to 150 ppm, and within this range, it is more beneficial to improve the performance of the ferrite.

[0152] By comparing Example 1 with Comparative Example 1 and Comparative Example 3, it can be seen that if SiO 2 is used as an additive instead of coating the main component in a coated form, it will result in a worse overall loss of the sample ring than that of Example 1. The manganese-zinc ferrite in Comparative Example 3 does not contain silica, and its effect is worse than that of Example 1 and Comparative Example 1.

[0153] By comparing Example 1 with Comparative Example 2, it can be seen that if calcium citrate in the additive is replaced with CaCO 3 , it will result in a worse overall loss of the sample ring than that of Example 1.

[0154] By comparing Example 1 with Comparative Examples 4-6, it can be seen that the contents of each component in the additive and the content of the main component need to be controlled within appropriate ranges, otherwise the loss of the sample ring will be worse than that of Example 1.

[0155] By comparing Example 1 with Comparative Example 7, it can be seen that the sintering temperature needs to be controlled within an appropriate range, otherwise the loss of the sample ring will be worse than that of Example 1.

[0156] The applicant declares that the present invention uses the above examples to illustrate the detailed method of the present invention, but the present invention is not limited to the above detailed method, that is, it does not mean that the present invention must rely on the above detailed method to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A manganese-zinc ferrite, characterized in that The manganese-zinc ferrite includes a main component and an additive, and SiO is also included in the manganese-zinc ferrite 2 , and the SiO 2 is at least coated on the surface of the main component; based on the total molar amount of the main components being 100 mol%, the main components include: Fe 2 O 3 53.2 mol% to 54.4 mol% ZnO 5.5 mol% - 6 mol% MnO the balance; based on the total mass of the manganese-zinc ferrite, the additives include:

2. The manganese-zinc ferrite according to claim 1, characterized in that Based on the total mass of the manganese-zinc ferrite, the content of SiO 2 is 100 ppm to 150 ppm.

3. A method for preparing the manganese-zinc ferrite according to claim 1 or 2, characterized in that the preparation method comprises the following steps: (1) Using Fe 2 O 3 , MnO and ZnO as main components, after ball milling, pre-sintering is carried out to obtain a pre-sintered material; (2) Mix the pre-sintered material with a mixed solution of ammonia, alcohol and water, and then add a silicon source, and after reaction, obtain manganese-zinc ferrite coated with silica; (3) Mix the manganese-zinc ferrite coated with silica with an additive and ball-mill, then mix the ball-milled material with polyvinyl alcohol and granulate, and press into a blank, Among them, the additive includes Co 2 O 3 , calcium citrate, Nb 2 O 5 , TiO 2 , and ZrO are mixed; (4) Sinter the blank to obtain the manganese-zinc ferrite.

4. The method for preparing the manganese-zinc ferrite according to claim 3, characterized in that the time of ball-milling in step (1) is 1 h - 4 h; Preferably, the temperature of pre-sintering in step (1) is 800 °C - 850 °C; Preferably, the time of pre-sintering in step (1) is 3 h - 6 h; Preferably, the atmosphere of pre-sintering in step (1) is air.

5. The method for preparing the manganese-zinc ferrite according to claim 3 or 4, characterized in that after pre-sintering in step (1), secondary ball-milling is carried out; Preferably, the time of the secondary ball-milling is 2 h - 3 h; Preferably, the particle size D50 of the material obtained after the secondary ball-milling is 1 μm - 1.2 μm.

6. The method for preparing the manganese-zinc ferrite according to any one of claims 3 - 5, characterized in that in step (2), the mass ratio of the pre-sintered material to the mixed solution of ammonia, alcohol and water is (5 - 10):100; Preferably, in the mixed solution of ammonia, alcohol and water in step (2), the mass percentages of ammonia, alcohol and water are 0.5% - 3%, 70% - 80%, 20% - 27% respectively; Preferably, in step (2), before adding the pre-sintered material to the mixed solution of ammonia, alcohol and water, the pre-sintered material is first added to a citric acid solution, ultrasonically treated and then dried; Preferably, the concentration of the citric acid solution is 0.01 M - 0.03 M; Preferably, the time of the ultrasonic treatment is 15 min - 30 min.

7. The method for preparing the manganese-zinc ferrite according to any one of claims 3 - 6, characterized in that the silicon source is added in step (2) under stirring conditions; Preferably, the silicon source in step (2) includes tetraethyl orthosilicate; Preferably, the reaction in step (2) is carried out under water bath heating, and the heating temperature is 80 °C - 120 °C; Preferably, the reaction time in step (2) is 6 h - 10 h; Preferably, after the reaction in step (2), the liquid is removed to obtain manganese-zinc ferrite coated with silica.

8. The method for preparing the manganese-zinc ferrite according to any one of claims 3 - 7, characterized in that the time of ball-milling in step (3) is 1 h - 2 h; Preferably, the D50 of the material obtained after ball milling in step (3) is 0.7 μm to 0.8 μm; Preferably, in step (3), based on the mass of the manganese zinc ferrite being 100%, the dosage of the polyvinyl alcohol is 5% to 15%; Preferably, in step (3), after the ball mill material and polyvinyl alcohol are mixed and granulated after ball milling, sieving is performed, and the mesh number of the sieve used for sieving is 60 mesh.

9. The method for preparing manganese zinc ferrite according to any one of claims 3 - 8, characterized in that, the sintering temperature in step (4) is 1000 °C to 1110 °C; Preferably, the heat preservation time of the sintering in step (4) is 5 h to 10 h; Preferably, the sintering in step (4) is carried out in an oxygen-containing atmosphere; Preferably, the oxygen-containing atmosphere includes a protective gas and oxygen; Preferably, the protective gas includes at least one of helium, neon or nitrogen.

10. The use of a manganese zinc ferrite according to claim 1 or 2, characterized in that, the manganese zinc ferrite is used in the electronic or communication field.

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