A low-loss soft magnetic ferrite material and a method for producing the same

Abstract

The application discloses a kind of low-loss soft magnetic ferrite material and preparation method thereof, the present application is by introducing lithium oxide in pre-sintering mixture, improve the microstructure of soft magnetic ferrite material, reduce the grain size, further reduce the loss of soft magnetic ferrite material;Meanwhile, the present application also adds MoO3, ZrO2 And CaCO3 Additive, the addition MoO3 can slow down the shrinkage rate of blank, improve sintering density, ZrO2 And CaCO3 It has high resistivity, can control the growth process of grain, refine grain, can improve the resistivity of grain boundary to inhibit high-frequency loss;The present application can refine grain and make grain become uniform through the interaction of multiple additives, with the effect of lower high-frequency loss.

Description

Technical Field

[0001] This invention relates to the field of ferrite material preparation technology, specifically to a low-loss soft magnetic ferrite material and its preparation method. Background Technology

[0002] Soft magnetic ferrite materials are ferrimagnetic oxides with Fe2O3 as the main component, produced by powder metallurgy. When magnetized, their coercivity (Hc) is no greater than 1000 A / m. Soft magnetic ferrite materials come in various types, such as Mn-Zn, Cu-Zn, and Ni-Zn, each with its specific applications. For example, Mn-Zn ferrites have low resistivity and are commonly used at frequencies below 100 kHz; while Cu-Zn and Ni-Zn ferrites have lower losses in the radio frequency band and are therefore often used in radio antenna coils and intermediate frequency transformers.

[0003] Soft magnetic ferrite materials possess many excellent properties, such as high permeability, high resistivity, low loss, and the wear resistance of ceramics. These properties make them widely used in the electronics field, including electron beam deflection coils in televisions, flyback transformers, chokes in radios, intermediate frequency transformers, inductors, switching power supplies, communication equipment, filters, computers, and electronic ballasts. With the widespread application of electronic technology, especially the popularization of digital circuits and switching power supplies, electromagnetic interference (EMI) has become increasingly important, and soft magnetic ferrites are playing an increasingly vital role in solving EMI problems.

[0004] Soft ferrite materials and their fabricated cores are widely used in high-frequency power electronics due to their high resistivity, high frequency, and low power loss. Low-power-loss cores can reduce the temperature rise of electronic devices and improve their energy conversion efficiency. Meanwhile, to reduce the size of electronic devices, the operating frequency of ferrite cores is increasing, with some cores exceeding 1MHz. Currently, to obtain high-frequency, low-power-loss soft ferrite cores, research is needed on the formulation design, fabrication process optimization, and structural design of traditional ferrite materials.

[0005] Chinese patent document CN112661502 A discloses a high-frequency, high-magnetic-field, low-loss manganese-zinc ferrite material. The preparation method of the high-frequency, high-magnetic-field, low-loss manganese-zinc ferrite material includes the following steps: (1) Batching and sand milling: Weigh the main components according to the proportion, perform wet mixing and sand milling, and obtain primary sand milling material after one drying; (2) Pre-firing: Pre-firing the primary sand milling material to obtain pre-firing material; (3) Secondary sand milling: Additives are added to the pre-firing material, and secondary wet sand milling is performed. After secondary drying, secondary sand milling material is obtained; (4) Granulation and molding: A binder is added to the secondary sand milling material, and after granulation, the particles are pressed into a blank; (5) Sintering: The blank is placed under the condition of controlling the oxygen partial pressure to be 3-5 vo1% and sintered at 1200-1250℃ to obtain the high-frequency, high-magnetic-field, low-loss manganese-zinc ferrite material; however, the loss of the ferrite material prepared is still relatively high. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a low-loss soft magnetic ferrite material and its preparation method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0009] S1, Configuration containing Fe 3+ Mn 2+ and Li + A mixed solution of soluble salts;

[0010] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, and then add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system is 9-12. Then carry out a hydrothermal reaction under N2 atmosphere. After the reaction is completed, filter, wash, dry and calcine to obtain a pre-calcined mixture.

[0011] S3. Add MoO3, ZrO2 and CaCO3 to the pre-calcined mixture, mix evenly, add binder, granulate and press to obtain blank material;

[0012] S4. The blank is sintered and then cooled under balanced oxygen partial pressure to obtain low-loss soft magnetic ferrite material.

[0013] Specifically, in step S1, Fe 3+ The concentration is 1.0-1.2 mol / L, and in some embodiments of the present invention, it can be selected as 1.0 mol / L, 1.1 mol / L, or 1.2 mol / L; Mn 2+The concentration is 0.25-0.35 mol / L, for example, 0.25 mol / L, 0.28 mol / L, 0.30 mol / L, 0.32 mol / L, and 0.35 mol / L; Li + The concentration is 0.18-0.22 mol / L, for example, 0.18 mol / L, 0.20 mol / L, 0.22 mol / L can be selected; but it is not limited to the listed values, other unlisted values ​​within the range are also applicable.

[0014] Specifically, Fe 3+ Mn 2+ and Li + The soluble salt can be selected from nitrates, sulfates or chlorides.

[0015] Specifically, in step S2, the molar ratio of sodium hydroxide to sodium carbonate in the mixed alkaline solution is 2-3:1. In some embodiments of the present invention, it can be selected as 2:1, 2.5:1, or 3:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] Specifically, in step S2, the temperature of the hydrothermal reaction is 60-80℃. In some embodiments of the present invention, it can be selected as 60℃, 65℃, 70℃, 75℃, or 80℃. The time of the hydrothermal reaction is 12-24h. For example, it can be selected as 12h, 15h, 18h, 21h, or 24h. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0017] Specifically, in step S2, the calcination temperature is 950-1100℃. In some embodiments of the present invention, it can be selected as 950℃, 980℃, 1000℃, 1050℃, 1080℃, or 1100℃. The calcination time is 3-5h. In some embodiments of the present invention, it can be selected as 3h, 3.5h, 4h, 4.5h, or 5h. However, it is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0018] Specifically, in step S3, based on a pre-calcined mixture mass of 100 wt%, the amount of MoO3 added is 0.06-0.15 wt%, for example, 0.06 wt%, 0.08 wt%, 0.10 wt%, 0.12 wt%, or 0.15 wt%; the amount of ZrO2 added is 0.02-0.04 wt%, for example, 0.02 wt%, 0.03 wt%, or 0.04 wt%; the amount of CaCO3 added is 0.05-0.09 wt%, for example, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, or 0.09 wt%; but is not limited to the listed values, other unlisted values ​​within the range are also applicable.

[0019] Specifically, in step S3, the binder is selected from polyvinyl alcohol or polyvinyl butyral resin, and the amount of binder added is 1-1.5 wt% of the total weight of the material. For example, it can be selected as 1 wt%, 1.2 wt%, or 1.5 wt%, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Specifically, in step S4, the sintering method includes: sintering at 1250-1300℃ for 3-5 hours under a nitrogen atmosphere with an oxygen content of 19-21 vol%, and then sintering at 1250-1300℃ for 1-2 hours under a nitrogen atmosphere with an oxygen content of 3-5 vol%.

[0021] Specifically, in step S4, the cooling conditions are: cooling in a nitrogen atmosphere with an oxygen volume content of 0.08%-0.1%.

[0022] The present invention also provides a low-loss soft magnetic ferrite material prepared by the above preparation method.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) Compared with the traditional method of directly mixing and calcining iron oxide and manganese oxide powder materials, the present invention uses a hydrothermal method to prepare layered ferrite precursors, which avoids the problems of uneven mixing of raw materials and low activity, improves the uniformity of the internal structure of soft magnetic ferrite materials, and reduces the coercivity and magnetic loss of soft magnetic ferrite materials.

[0025] (2) This invention improves the microstructure of soft magnetic ferrite materials by introducing lithium oxide into the pre-calcined mixture, reduces grain size, and further reduces the loss of soft magnetic ferrite materials. At the same time, this invention also adds MoO3, ZrO2 and CaCO3 additives. The addition of MoO3 can slow down the shrinkage rate of the blank and increase the sintering density. ZrO2 and CaCO3 have high resistivity, which can regulate the grain growth process and refine the grains. They can suppress high-frequency loss by increasing the resistivity of the grain boundaries. Through the interaction of multiple additives, this invention can refine the grains and make the grains more uniform, resulting in lower high-frequency loss. Attached Figure Description

[0026] Figure 1 Power loss diagrams for different ferrite materials. Detailed Implementation

[0027] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0028] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0029] Example 1

[0030] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0031] S1. Add ferric nitrate, manganese nitrate, and lithium chloride to deionized water and stir until homogeneous to obtain a soluble salt mixture solution, in which Fe... 3+ The concentration of Mn is 1 mol / L. 2+ The concentration was 0.25 mol / L, Li + The concentration was 0.18 mol / L;

[0032] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 2 mol / L and the concentration of sodium carbonate is 1 mol / L. Then, add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system reaches 10. Then, carry out a hydrothermal reaction under N2 atmosphere at a temperature of 60℃ for 24 hours. After the reaction is completed, filter the product, wash it with deionized water, dry it in a vacuum drying oven at 60℃ for 5 hours, and then calcine it in a muffle furnace at 950℃ for 5 hours to obtain a pre-calcined mixture.

[0033] S3. Based on 100wt% of the pre-calcined mixture, add 0.10wt% MoO3, 0.03wt% ZrO2 and 0.06wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0034] S4. The blank is sintered by means of: sintering at 1280°C for 3 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1280°C for 2 hours under nitrogen atmosphere with oxygen content controlled at 4 vol%, and then cooling to room temperature in nitrogen atmosphere with oxygen content of 0.08% by volume to obtain low-loss soft magnetic ferrite material.

[0035] Example 2

[0036] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0037] S1. Add ferric nitrate, manganese nitrate, and lithium chloride to deionized water and stir until homogeneous to obtain a soluble salt mixture solution, in which Fe... 3+ The concentration of Mn is 1 mol / L. 2+ The concentration was 0.35 mol / L, Li +The concentration was 0.20 mol / L;

[0038] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 2 mol / L and the concentration of sodium carbonate is 1 mol / L. Then, add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system reaches 12. Then, carry out a hydrothermal reaction under N2 atmosphere at a temperature of 80℃ for 12 hours. After the reaction is completed, filter the product, wash it with deionized water, dry it in a vacuum drying oven at 60℃ for 5 hours, and then calcine it in a muffle furnace at 1000℃ for 4 hours to obtain a pre-calcined mixture.

[0039] S3. Based on 100wt% of the pre-calcined mixture, add 0.06wt% MoO3, 0.02wt% ZrO2 and 0.05wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1.2% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0040] S4. The blank is sintered by means of: sintering at 1250°C for 5 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1250°C for 2 hours under nitrogen atmosphere with oxygen content controlled at 3 vol%, and then cooling to room temperature in nitrogen atmosphere with oxygen content of 0.08% by volume to obtain low-loss soft magnetic ferrite material.

[0041] Example 3

[0042] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0043] S1. Add ferric nitrate, manganese nitrate, and lithium chloride to deionized water and stir until homogeneous to obtain a soluble salt mixture solution, in which Fe... 3+ The concentration was 1.1 mol / L, Mn 2+ The concentration was 0.30 mol / L, Li + The concentration was 0.18 mol / L;

[0044] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 2 mol / L and the concentration of sodium carbonate is 1 mol / L. Then, add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system reaches 9. Then, carry out a hydrothermal reaction under N2 atmosphere at a temperature of 60℃ for 24 hours. After the reaction is completed, filter the product, wash it with deionized water, dry it in a vacuum drying oven at 60℃ for 5 hours, and then calcine it in a muffle furnace at 1100℃ for 3 hours to obtain a pre-calcined mixture.

[0045] S3. Based on 100wt% of the pre-calcined mixture, add 0.15wt% MoO3, 0.02wt% ZrO2 and 0.07wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1.2% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0046] S4. The blank material is sintered by means of: sintering at 1300℃ for 5 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1300℃ for 2 hours under nitrogen atmosphere with oxygen content controlled at 3 vol%, and then cooling to room temperature in nitrogen atmosphere with oxygen content of 0.08% by volume to obtain low-loss soft magnetic ferrite material.

[0047] Example 4

[0048] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0049] S1. Add ferric nitrate, manganese nitrate, and lithium chloride to deionized water and stir until homogeneous to obtain a soluble salt mixture solution, in which Fe... 3+ The concentration was 1.2 mol / L, Mn 2+ The concentration was 0.25 mol / L, Li + The concentration was 0.22 mol / L;

[0050] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 3 mol / L and the concentration of sodium carbonate is 1 mol / L. Then, add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system reaches 11. Then, carry out a hydrothermal reaction under N2 atmosphere at a temperature of 60℃ for 24 hours. After the reaction is completed, filter the product, wash it with deionized water, dry it in a vacuum drying oven at 60℃ for 5 hours, and then calcine it in a muffle furnace at 1100℃ for 3 hours to obtain a pre-calcined mixture.

[0051] S3. Based on 100wt% of the pre-calcined mixture, add 0.10wt% MoO3, 0.04wt% ZrO2 and 0.09wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1.2% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0052] S4. The blank material is sintered by means of: sintering at 1300℃ for 4 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1300℃ for 1.5 hours under nitrogen atmosphere with oxygen content controlled at 3 vol%, and then cooling to room temperature in nitrogen atmosphere with oxygen content of 0.08% by volume to obtain low-loss soft magnetic ferrite material.

[0053] Comparative Example 1

[0054] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0055] S1. Mix iron oxide, manganese oxide and lithium oxide evenly to obtain a mixture. The molar ratio of Fe, Mn and Li in the mixture is 1:0.25:0.18. Then, calcine the mixture in a muffle furnace at 950℃ for 5 hours to obtain a pre-calcined mixture.

[0056] S2. Based on 100wt% of the pre-calcined mixture, add 0.10wt% MoO3, 0.03wt% ZrO2 and 0.06wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0057] S3. The blank material is sintered. The sintering method is as follows: sintering at 1280℃ for 3 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1280℃ for 2 hours under nitrogen atmosphere with oxygen content controlled at 4 vol%, and then cooling to room temperature in a nitrogen atmosphere with oxygen volume content of 0.08% to obtain low-loss soft magnetic ferrite material.

[0058] Comparative Example 2

[0059] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0060] S1. Add ferric nitrate and manganese nitrate to deionized water and stir until homogeneous to obtain a soluble salt mixture solution, in which Fe... 3+ The concentration of Mn is 1 mol / L. 2+ The concentration was 0.25 mol / L;

[0061] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 2 mol / L and the concentration of sodium carbonate is 1 mol / L. Then, add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system reaches 10. Then, carry out a hydrothermal reaction under N2 atmosphere at a temperature of 60℃ for 24 hours. After the reaction is completed, filter the product, wash it with deionized water, dry it in a vacuum drying oven at 60℃ for 5 hours, and then calcine it in a muffle furnace at 950℃ for 5 hours to obtain a pre-calcined mixture.

[0062] S3. Based on 100wt% of the pre-calcined mixture, add 0.10wt% MoO3, 0.03wt% ZrO2 and 0.06wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0063] S4. The blank is sintered by means of: sintering at 1280°C for 3 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1280°C for 2 hours under nitrogen atmosphere with oxygen content controlled at 4 vol%, and then cooling to room temperature in nitrogen atmosphere with oxygen content of 0.08% by volume to obtain low-loss soft magnetic ferrite material.

[0064] Comparative Example 3

[0065] A method for preparing a low-loss soft magnetic ferrite material includes the following steps:

[0066] S1. Add ferric nitrate, manganese nitrate, and zinc nitrate to deionized water and stir until homogeneous to obtain a soluble salt mixture solution, in which Fe... 3+ The concentration of Mn is 1 mol / L. 2+ The concentration of Zn is 0.25 mol / L. 2+ The concentration was 0.18 mol / L;

[0067] S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, wherein the concentration of sodium hydroxide is 2 mol / L and the concentration of sodium carbonate is 1 mol / L. Then, add the mixed alkaline solution dropwise to the soluble salt mixture. Stop adding the mixed alkaline solution when the pH of the system reaches 10. Then, carry out a hydrothermal reaction under N2 atmosphere at a temperature of 60℃ for 24 hours. After the reaction is completed, filter the product, wash it with deionized water, dry it in a vacuum drying oven at 60℃ for 5 hours, and then calcine it in a muffle furnace at 950℃ for 5 hours to obtain a pre-calcined mixture.

[0068] S3. Based on 100wt% of the pre-calcined mixture, add 0.10wt% MoO3, 0.03wt% ZrO2 and 0.06wt% CaCO3 to the pre-calcined mixture, mix evenly, add 1% of the total weight of the material as binder polyvinyl alcohol, granulate and press to obtain the blank.

[0069] S4. The blank is sintered by means of: sintering at 1280°C for 3 hours under nitrogen atmosphere with oxygen content controlled at 21 vol%, then sintering at 1280°C for 2 hours under nitrogen atmosphere with oxygen content controlled at 4 vol%, and then cooling to room temperature in nitrogen atmosphere with oxygen content of 0.08% by volume to obtain low-loss soft magnetic ferrite material.

[0070] The low-loss soft magnetic ferrite materials prepared in Examples 1-4 and Comparative Examples 1-3 were subjected to power loss tests. The test conditions were: test frequency 1MHz, magnetic flux density 50mT, and temperature 100℃; the average value was taken from three tests. The experimental results are as follows: Figure 1 As shown, by comparing the data of Example 1 and Comparative Examples 1-3, the ferrite material prepared by the method of the present invention can significantly reduce power loss.

[0071] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a low-loss soft magnetic ferrite material, characterized in that, Includes the following steps: S1, Configuration containing Fe 3+ Mn 2+ and Li + A mixed solution of soluble salts; S2. Prepare a mixed alkaline solution of sodium hydroxide and sodium carbonate, and then add the mixed alkaline solution dropwise to the soluble salt mixture. When the pH of the system is 9-12, stop adding the mixed alkaline solution. Then carry out a hydrothermal reaction under N2 atmosphere. After the reaction is completed, filter, wash, dry and calcine to obtain a pre-calcined mixture. S3. Add MoO3, ZrO2 and CaCO3 to the pre-calcined mixture, mix evenly, add binder, granulate and press to obtain blank material; S4. The blank is sintered and then cooled under balanced oxygen partial pressure to obtain low-loss soft magnetic ferrite material. In step S1, Fe 3+ The concentration is 1.0-1.2 mol / L, Mn 2+ The concentration is 0.25-0.35 mol / L, Li + The concentration is 0.18-0.22 mol / L.

2. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S2, the molar ratio of sodium hydroxide to sodium carbonate in the mixed alkaline solution is 2-3:

1.

3. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S2, the hydrothermal reaction temperature is 60-80℃, and the hydrothermal reaction time is 12-24h.

4. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S2, the roasting temperature is 950-1100℃ and the roasting time is 3-5h.

5. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S3, based on the mass of the pre-calcined mixture as 100 wt%, the amount of MoO3 added is 0.06-0.15 wt%, the amount of ZrO2 added is 0.02-0.04 wt%, and the amount of CaCO3 added is 0.05-0.09 wt%.

6. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S3, the binder is selected from polyvinyl alcohol or polyvinyl butyral resin, and the amount of binder added is 1-1.5 wt% of the total weight of the material.

7. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S4, the sintering method includes: sintering at 1250-1300℃ for 3-5 hours under a nitrogen atmosphere with an oxygen content of 19-21 vol%, and then sintering at 1250-1300℃ for 1-2 hours under a nitrogen atmosphere with an oxygen content of 3-5 vol%.

8. The method for preparing low-loss soft magnetic ferrite material according to claim 1, characterized in that, In step S4, the cooling conditions are: cooling in a nitrogen atmosphere with an oxygen volume content of 0.08%-0.1%.

9. The low-loss soft magnetic ferrite material prepared by the preparation method according to any one of claims 1-8.

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