Low-stress-sensitive manganese-zinc ferrite and sintering method thereof

Abstract

The application provides a low stress-sensitive manganese-zinc ferrite and a sintering method thereof. The sintering method comprises the following steps: (1) pressing manganese-zinc ferrite powder into a shape to obtain a sintering blank; (2) performing multi-stage sintering on the sintering blank, and then cooling to obtain the low stress-sensitive manganese-zinc ferrite; wherein the multi-stage sintering process comprises a first-stage sintering, a second-stage sintering, a third-stage sintering and a fourth-stage sintering with a gradient increase in temperature. The application adopts the multi-stage sintering mode of the first-stage sintering, the second-stage sintering, the third-stage sintering and the fourth-stage sintering with a gradient increase in temperature, and a low stress-sensitive, wide-frequency high-resistance high-conductivity manganese-zinc ferrite is prepared, and the inductance drop ratio of the manganese-zinc ferrite under the same stress is smaller than that of a traditional manganese-zinc ferrite.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic materials, and particularly relates to a low-stress-sensitive manganese-zinc ferrite and a sintering method thereof. Background Art

[0002] In recent years, with the onset of the Third Industrial Revolution and the advancement of science and technology, humanity has gradually entered the electronic information age. Electronic products have become indispensable for work, leisure, entertainment, learning, video conferencing, and other activities. While these products bring convenience, they also contribute to a certain degree of environmental pollution—electromagnetic interference. High-permeability manganese-zinc ferrite is widely used in signal transmission and electromagnetic interference mitigation technologies, gaining popularity due to its high permeability, low price, and compact size. However, due to its low resistivity, high-permeability manganese-zinc ferrite material struggles to meet withstand voltage requirements. This requires spray coating, as well as assembly and winding by downstream customers. These subsequent operations on the core cause stress, resulting in a reduction in core inductance. This stress is particularly pronounced in large-size products.

[0003] At present, patent CN101870578A discloses a manganese-zinc ferrite material with high magnetic permeability of 12000μi and wide temperature, which achieves the high magnetic permeability and wide temperature performance of manganese-zinc ferrite material with magnetic permeability μi=12000 by limiting the content of iron oxide to 53-58mol%, the content of zinc oxide to 20-28mol%, and the rest to manganese oxide; patent CN103011791A discloses a manganese-zinc ferrite material with high magnetic permeability of 12000μi by limiting the content of iron oxide to 51-5 4 mol%, the zinc oxide content is limited to 23-27 mol%, and the balance is manganese oxide, achieving high magnetic permeability of the manganese-zinc ferrite material; CN105541316A discloses a manganese-zinc ferrite material for anti-EMI use and a preparation method thereof. By limiting the iron oxide content to 50.5-52.5 mol%, the zinc oxide content to 18.5-20.5 mol%, and the balance to manganese oxide, a manganese-zinc ferrite material for anti-EMI use with a magnetic permeability greater than 12000 is prepared. However, the above-mentioned prior art does not explore the impact of the sintering process on the stress sensitivity of the magnetic core.

[0004] Therefore, developing a sintering method for low-stress-sensitivity manganese-zinc ferrite so that the inductance drop of the magnetic core is smaller than that of traditional manganese-zinc ferrite under the same stress is a technical problem that needs to be solved urgently. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention provides a low-stress-sensitive manganese-zinc ferrite and a sintering method thereof. By employing a multi-stage sintering process with a gradient temperature increase, comprising primary, secondary, tertiary, and quaternary sintering steps, the present invention produces a low-stress-sensitive manganese-zinc ferrite with broadband high impedance and high conductivity. Compared to conventional manganese-zinc ferrites subjected to the same stress, this ferrite exhibits a smaller inductance drop, higher impedance, and superior performance.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a sintering method for low stress-sensitive manganese-zinc ferrite, the sintering method comprising the following steps:

[0008] (1) pressing the manganese zinc ferrite powder into a shape to obtain a blank to be sintered;

[0009] (2) sintering the blank to be sintered in multiple stages and then cooling it to obtain the low stress-sensitive manganese-zinc ferrite;

[0010] The multi-stage sintering process includes primary sintering, secondary sintering, tertiary sintering and fourth stage sintering with the temperature increasing in a gradient.

[0011] The present invention adopts a multi-stage sintering method of primary sintering, secondary sintering, tertiary sintering and quadruple sintering with a temperature gradient increase to prepare a manganese-zinc ferrite with low stress sensitivity, wide bandwidth, high impedance and high conductivity. When subjected to the same stress, the inductance drop ratio of the manganese-zinc ferrite is smaller than that of traditional manganese-zinc ferrite.

[0012] As a preferred technical solution of the present invention, the initial magnetic permeability of the manganese-zinc ferrite powder in step (1) is ≥10,000, for example, it can be 10,000, 12,000 or 15,000.

[0013] Preferably, the blank to be sintered is a standard sample ring blank with a size of 50 mm×20 mm×25 mm.

[0014] It should be noted that large-sized manganese zinc ferrite is more susceptible to stress, but the technical solution provided by the present invention can effectively circumvent this problem and obtain a wide-band, high-impedance and high-conductivity manganese zinc ferrite material.

[0015] As a preferred technical solution of the present invention, the temperature of the primary sintering is 120-220°C, for example, it can be 120°C, 140°C, 160°C, 180°C, 200°C or 220°C.

[0016] Preferably, the primary sintering time is 3-5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0017] The present invention performs primary sintering at 120-220° C. for 3-5 hours, which can fully remove moisture from the blank.

[0018] Preferably, during the primary sintering process, oxygen-containing gas is introduced, and the flow rate of the oxygen-containing gas is 20-40m 3 / h, for example, it can be 20m 3 / h、25m 3 / h、30m 3 / h、35m 3 / h or 40m 3 / h, etc. Exemplarily, the oxygen-containing gas may be air.

[0019] As a preferred technical solution of the present invention, the temperature of the secondary sintering is 500-700°C, for example, it can be 500°C, 550°C, 600°C, 650°C or 700°C.

[0020] Preferably, the secondary sintering time is 2-3 hours, for example, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours.

[0021] The present invention performs secondary sintering at 500-700° C. for 2-3 hours, which helps to achieve the volatilization of PVA (polyvinyl alcohol) at a low melting point position.

[0022] Preferably, during the secondary sintering process, oxygen-containing gas is introduced, and the flow rate of the oxygen-containing gas is 30-40m 3 / h, for example, 30m 3 / h、32m 3 / h、34m 3 / h、36m 3 / h、38m 3 / h or 40m 3 / h, etc. Exemplarily, the oxygen-containing gas may be air.

[0023] As a preferred technical solution of the present invention, the temperature of the three-stage sintering is 900-1200°C, for example, it can be 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C or 1200°C, preferably 1050-1150°C.

[0024] Preferably, the three-stage sintering time is 3-5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0025] The present invention performs three-stage sintering at 900-1200° C. for 3-5 hours, which helps to remove acid ions (such as sulfate ions) in the green part.

[0026] Preferably, during the three-stage sintering process, oxygen-containing gas is introduced, and the flow rate of the oxygen-containing gas is 30-35m 3 / h, for example, 30m 3 / h、31m 3 / h、32m 3 / h、33m 3 / h、34m 3 / h or 35m 3 / h, etc. Exemplarily, the oxygen-containing gas may be air.

[0027] As a preferred technical solution of the present invention, the temperature of the four-stage sintering is 1300-1420°C, for example, it can be 1300°C, 1320°C, 1340°C, 1360°C, 1380°C, 1400°C or 1420°C.

[0028] Preferably, the time for the four-stage sintering is 6-10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0029] The present invention performs four-stage sintering at 1300-1420° C. for 6-10 hours, which can promote grain growth and increase density.

[0030] Preferably, the four-stage sintering is performed in a protective atmosphere, and the gas in the protective atmosphere includes nitrogen.

[0031] Preferably, the gas in the protective atmosphere further comprises oxygen, and the content of the oxygen is ≤21 vol%, for example, it can be 21 vol%, 20 vol%, 15 vol%, 10 vol%, 5 vol% or 1 vol%, etc., preferably 11-20 vol%.

[0032] In the present invention, the green body is preferably subjected to four-stage sintering under the condition that the oxygen content is less than 11-20 vol%, which helps to reduce the volatilization of zinc oxide.

[0033] As a preferred technical solution of the present invention, the cooling process in step (2) is carried out in an atmosphere of balanced oxygen partial pressure.

[0034] Preferably, the cooling rate of step (2) is 0-3°C / min, for example, 0, 1°C / min, 2°C / min or 3°C / min.

[0035] As a preferred technical solution of the present invention, the sintering method includes the following steps:

[0036] (1) pressing a manganese-zinc ferrite powder having an initial magnetic permeability of ≥10,000 to obtain a sintered blank having a size of 50 mm × 20 mm × 25 mm, wherein the sintered blank is a standard sample ring blank;

[0037] (2) The blank to be sintered is subjected to primary sintering at 120-220°C for 3-5 hours, and the flow rate during the primary sintering is 20-40m 3 / h of oxygen-containing gas, and then heated to 500-700℃ at a heating rate of 0-2℃ / min (for example, 0, 1℃ / min or 2℃ / min, etc.) for 2-3h of secondary sintering, and the flow rate during the secondary sintering process is 30-40m 3 / h of oxygen-containing gas, and then heated to 900-1200℃ at a heating rate of 1-2℃ / min (for example, 1, 1.5℃ / min or 2℃ / min, etc.) for 3-5h of three-stage sintering, and the flow rate during the three-stage sintering is 30-35m 3 / h of oxygen-containing gas, then heating to 1300-1420°C at a heating rate of 0-2°C / min (for example, 0, 1°C / min or 2°C / min, etc.), and performing four-stage sintering in a protective atmosphere, wherein the four-stage sintering time is 6-10h;

[0038] Wherein, the gas in the protective atmosphere includes nitrogen and oxygen, and the content of the oxygen is ≤21 vol%;

[0039] (3) Cooling the sintered blank to 40-60°C (for example, 40°C, 50°C, or 60°C), wherein the cooling is carried out in an atmosphere of balanced oxygen partial pressure, and the cooling rate is 0-3°C / min (for example, 0, 1°C / min, 2°C / min, or 3°C / min), to obtain low stress-sensitive manganese-zinc ferrite.

[0040] In a second aspect, the present invention provides a low stress-sensitive manganese-zinc ferrite prepared by the sintering method as described in the first aspect.

[0041] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The present invention adopts a multi-stage sintering method of primary sintering, secondary sintering, tertiary sintering and quadruple sintering with a temperature gradient increase to prepare a manganese-zinc ferrite with low stress sensitivity, wide bandwidth, high impedance and high conductivity. When subjected to the same stress, the inductance drop ratio of the manganese-zinc ferrite is smaller than that of traditional manganese-zinc ferrite. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] Example 1

[0046] This embodiment provides a sintering method for low-stress-sensitive manganese-zinc ferrite, the sintering method comprising the following steps:

[0047] (1) pressing a manganese-zinc ferrite powder having an initial magnetic permeability of 10,000 to obtain a sintered blank having a size of 50 mm × 20 mm × 25 mm, wherein the sintered blank is a standard sample ring blank;

[0048] (2) The blank to be sintered is subjected to primary sintering at 210°C for 3 hours, and the flow rate during the primary sintering is 30m 3 / h of air, the exhaust frequency is 35Hz, and then the temperature is raised to 530℃ at a heating rate of 1℃ / min for 3h of secondary sintering, and the flow rate during the secondary sintering process is 36m 3 / h of air, the exhaust frequency is 40Hz, and then the temperature is raised to 1100℃ at a heating rate of 2℃ / min for 5h of three-stage sintering, and the flow rate during the three-stage sintering is 32m 3 / h of air, with an exhaust frequency of 40 Hz, and then heating to 1410°C at a heating rate of 1°C / min, and performing four-stage sintering in a protective atmosphere, wherein the four-stage sintering time is 8 hours;

[0049] Wherein, the gas in the protective atmosphere includes nitrogen and oxygen, and the content of the oxygen is 15 vol%;

[0050] (3) Cooling the sintered blank to 50° C. in an atmosphere of balanced oxygen partial pressure at a cooling rate of 3° C. / min to obtain low stress-sensitive manganese-zinc ferrite.

[0051] Example 2

[0052] This embodiment provides a sintering method for low-stress-sensitive manganese-zinc ferrite, the sintering method comprising the following steps:

[0053] (1) pressing a manganese-zinc ferrite powder having an initial magnetic permeability of 10,000 to obtain a sintered blank having a size of 50 mm × 20 mm × 25 mm, wherein the sintered blank is a standard sample ring blank;

[0054] (2) The blank to be sintered is subjected to primary sintering at 160°C for 5 hours, and the flow rate during the primary sintering is 30m 3 / h of air, the exhaust frequency is 35Hz, and then the temperature is raised to 530℃ at a heating rate of 2℃ / min for 3h of secondary sintering, and the flow rate during the secondary sintering process is 36m 3 / h of air, the exhaust frequency is 40Hz, and then the temperature is raised to 900℃ at a heating rate of 1℃ / min for 5h of three-stage sintering, and the flow rate during the three-stage sintering is 32m 3 / h of air, with an exhaust frequency of 40 Hz, and then heating to 1410°C at a heating rate of 2°C / min, and performing four-stage sintering in a protective atmosphere, wherein the four-stage sintering time is 8 hours;

[0055] Wherein, the gas in the protective atmosphere includes nitrogen and oxygen, and the content of the oxygen is 15 vol%;

[0056] (3) Cooling the sintered blank to 50° C. in an atmosphere of balanced oxygen partial pressure at a cooling rate of 3° C. / min to obtain low stress-sensitive manganese-zinc ferrite.

[0057] Example 3

[0058] This embodiment provides a sintering method for low-stress-sensitive manganese-zinc ferrite, the sintering method comprising the following steps:

[0059] (1) pressing a manganese-zinc ferrite powder having an initial magnetic permeability of 10,000 to obtain a sintered blank having a size of 50 mm × 20 mm × 25 mm, wherein the sintered blank is a standard sample ring blank;

[0060] (2) The blank to be sintered is subjected to primary sintering at 160°C for 5 hours, and the flow rate during the primary sintering is 30m 3 / h of air, the exhaust frequency is 35Hz, and then the temperature is raised to 700℃ at a heating rate of 1.5℃ / min for 2h of secondary sintering, and the flow rate during the secondary sintering process is 36m 3 / h of air, the exhaust frequency is 40Hz, and then the temperature is raised to 900℃ at a heating rate of 1.5℃ / min for 5h of three-stage sintering, and the flow rate during the three-stage sintering is 32m 3 / h of air, with an exhaust frequency of 40 Hz, and then heating to 1410°C at a heating rate of 1.5°C / min, and performing four-stage sintering in a protective atmosphere, wherein the four-stage sintering time is 8 hours;

[0061] Wherein, the gas in the protective atmosphere includes nitrogen and oxygen, and the content of the oxygen is 15 vol%;

[0062] (3) Cooling the sintered blank to 50° C. in an atmosphere of balanced oxygen partial pressure at a cooling rate of 3° C. / min to obtain low stress-sensitive manganese-zinc ferrite.

[0063] Example 4

[0064] This embodiment provides a sintering method for low-stress-sensitive manganese-zinc ferrite, the sintering method comprising the following steps:

[0065] (1) pressing a manganese-zinc ferrite powder having an initial magnetic permeability of 10,000 to obtain a sintered blank having a size of 50 mm × 20 mm × 25 mm, wherein the sintered blank is a standard sample ring blank;

[0066] (2) The blank to be sintered is subjected to primary sintering at 160°C for 5 hours, and the flow rate during the primary sintering is 30m 3 / h of air, the exhaust frequency is 35Hz, and then the temperature is raised to 530℃ at a heating rate of 2℃ / min for 3h of secondary sintering, and the flow rate during the secondary sintering process is 36m 3 / h of air, the exhaust frequency is 40Hz, and then the temperature is raised to 1200℃ at a heating rate of 2℃ / min for 3h of three-stage sintering, and the flow rate during the three-stage sintering is 32m 3 / h of air, with an exhaust frequency of 40 Hz, and then heating to 1410°C at a heating rate of 2°C / min, and performing four-stage sintering in a protective atmosphere, wherein the four-stage sintering time is 8 hours;

[0067] Wherein, the gas in the protective atmosphere includes nitrogen and oxygen, and the content of the oxygen is 15 vol%;

[0068] (3) Cooling the sintered blank to 50° C. in an atmosphere of balanced oxygen partial pressure at a cooling rate of 3° C. / min to obtain low stress-sensitive manganese-zinc ferrite.

[0069] Example 5

[0070] The difference between this embodiment and embodiment 1 is that the primary sintering time is 2 hours.

[0071] The remaining sintering methods and parameters remained the same as in Example 1.

[0072] Example 6

[0073] The difference between this embodiment and embodiment 1 is that the secondary sintering time is 1.5 hours.

[0074] The remaining sintering methods and parameters remained the same as in Example 1.

[0075] Example 7

[0076] The difference between this embodiment and embodiment 1 is that the time for the three-stage sintering is 2.5 hours.

[0077] The remaining sintering methods and parameters remained the same as in Example 1.

[0078] Example 8

[0079] The difference between this embodiment and embodiment 1 is that the temperature of the fourth-stage sintering is 1280°C.

[0080] The remaining sintering methods and parameters remained the same as in Example 1.

[0081] Example 9

[0082] The difference between this embodiment and embodiment 1 is that the temperature of the fourth-stage sintering is 1450°C.

[0083] The remaining sintering methods and parameters remained the same as in Example 1.

[0084] Example 10

[0085] The difference between this embodiment and embodiment 1 is that during the four-stage sintering process, the oxygen content is 25 vol%.

[0086] The remaining sintering methods and parameters remained the same as in Example 1.

[0087] Performance Testing

[0088] The manganese-zinc ferrite material prepared by the sintering method in the above embodiment was subjected to a magnetic permeability test and a stress sensitivity test.

[0089] The magnetic permeability test conditions are: 0.25V, 25°C; the stress sensitivity test formula is μi(10KHz / 10MPa) / μi(10MPa / 0MPa).

[0090] The test results are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] analyze:

[0095] It can be seen from the above table that the sintering method provided by the present invention can prepare a manganese-zinc ferrite with low stress sensitivity, broadband high impedance and high conductivity.

[0096] It can be seen from Example 1 and Examples 8-9 that if the temperature of the four-stage sintering is too low, it is not conducive to the improvement of magnetic permeability; if the temperature of the four-stage sintering is too high, it is not conducive to the improvement of stress sensitivity.

[0097] It can be seen from Examples 1 and 10 that if the oxygen content is too high during the four-stage sintering process, it is not conducive to improving the stress sensitivity.

[0098] The applicant declares that the present invention is illustrated by the above-described embodiments, but the present invention is not limited to these embodiments. This does not mean that the present invention must rely on these embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for raw materials in the present invention, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A sintering method for low stress-sensitive manganese-zinc ferrite, characterized in that: The sintering method comprises the following steps: (1) Pressing and molding manganese-zinc ferrite powder with an initial magnetic permeability of ≥10,000 to obtain a sintered blank with a size of 50 mm × 20 mm × 25 mm, wherein the sintered blank is a standard sample ring blank; (2) The blank to be sintered is subjected to primary sintering at 120-220°C for 3-5h, and during the primary sintering, an oxygen-containing gas with a flow rate of 20-40m³ / h is introduced, and then the temperature is raised to 500-700°C at a heating rate of 0-2°C / min for 2-3h of secondary sintering, and during the secondary sintering, an oxygen-containing gas with a flow rate of 30-40m³ / h is introduced, and then the temperature is raised to 900-1200°C at a heating rate of 1-2°C / min for 3-5h of tertiary sintering, and during the tertiary sintering, an oxygen-containing gas with a flow rate of 30-35m³ / h is introduced, and then the temperature is raised to 1300-1420°C at a heating rate of 0-2°C / min, and a fourth sintering is carried out in a protective atmosphere, and the time of the fourth sintering is 6-10h; Wherein, the gas in the protective atmosphere includes nitrogen and oxygen, and the content of the oxygen is ≤21vol%; (3) Cooling the sintered blank to 40-60° C. in an atmosphere of balanced oxygen partial pressure at a cooling rate of 0-3° C. / min to obtain low stress-sensitive manganese-zinc ferrite.

2. The sintering method according to claim 1, characterized in that The temperature of the three-stage sintering is 1050-1150°C.

3. A low stress-sensitive manganese-zinc ferrite prepared by the sintering method according to any one of claims 1 to 2.

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