A wide-temperature low-power high-Bs Mn-Zn ferrite material, its preparation method and application

Abstract

The present invention discloses a wide-temperature low-power high-Bs manganese-zinc ferrite material, its preparation method and application, belonging to the technical field of magnetic materials. The raw materials include a main component and an auxiliary component; calculated by mole fraction of 100%, the main component includes 56.18-56.48% of Fe2O3, 6.00-6.25% of ZnO, 2-4% of NiO, and the rest is MnO; the auxiliary component includes CaCO3, Nb2O5, Co3O4 and NiO. The preparation method includes the following steps: mixing and ball-milling the main component and then pre-sintering, then mixing the obtained pre-sintered material with the auxiliary component and continuing ball-milling, and then pressing the obtained powder into a mold and sintering to obtain the wide-temperature low-power high-Bs manganese-zinc ferrite material. The preparation method provided by the present invention adopts the ferrite oxide ceramic process, with relatively low cost and high efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of magnetic materials, and particularly relates to a wide-temperature, low-power, high-Bs manganese-zinc ferrite material, a preparation method thereof, and an application thereof. Background Art

[0002] The wide-temperature, low-power, high-Bs manganese-zinc ferrite material is a new material mainly developed for consumer electronics. In the power supply systems of consumer electronic devices, such as mobile phone chargers, computer power adapters, televisions, routers, monitors, etc., the most common circuit topology is the forward converter, and the core device is the main transformer made of a ferrite core. At this time, the core is in the class-II magnetic working state. As shown in Figure 1 , it works in the first quadrant (uniaxial magnetization) of the magnetization curve, and the working state of the core is similar to the discontinuous state of the flyback core current. The core works between the saturation magnetic induction Bs and the remanent magnetic induction Br, and ΔB = Bm - Br.

[0003] According to the formula: V = KBfAN, where K is the waveform factor, B is the working magnetic induction intensity, f is the switching frequency, A is the cross-sectional area of the core, and N is the number of turns of the winding. Obviously, on the premise of keeping the output voltage V unchanged, increasing the saturation magnetic induction intensity can effectively reduce the size of the material, achieve the purpose of miniaturization, and ensure the normal operation of electronic devices under complex conditions such as high temperature.

[0004] There is relatively little research on wide-temperature, low-power, high-Bs magnetic materials. In the prior art, CN202311068066.X of Shandong Kaitong Company discloses a manganese-zinc ferrite core with wide temperature, high direct current, and low power consumption and a preparation method thereof. Under the conditions of 100 kHz and 200 mT, the power consumption at 25 °C - 100 °C is 285 - 350 mW / cm 3 , and under the condition of 100 kHz, the saturation magnetic flux density at 100 °C ≥ 550 mT. The material prepared by this technology has good loss and Bs effects, but its process adopts a method close to chemical coprecipitation, and this process can only be tested in the laboratory at present and cannot be mass-produced.

[0005] Therefore, how to provide a wide-temperature, low-power, high-Bs manganese-zinc ferrite material with simple preparation and capable of mass production is a technical problem that those skilled in the art need to solve urgently. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a wide-temperature, low-power, high-Bs manganese-zinc ferrite material, a preparation method thereof, and an application thereof.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A manganese-zinc ferrite material with wide temperature range, low power consumption and high Bs, comprising a main component and an auxiliary component;

[0009] Calculated on a molar fraction of 100%, the main component comprises Fe 2 O 3 56.18 - 56.48%, ZnO 6.00 - 6.25%, NiO 2 - 4%, and the balance is MnO;

[0010] The auxiliary component comprises CaCO 3 , Nb 2 O 5 , Co 3 O 4 and NiO.

[0011] Preferably, calculated on the total weight of the main component, the auxiliary component comprises the following raw materials: CaCO 3 200 - 400 ppm, Nb 2 O 5 200 - 300 ppm, Co 2 O 3 3500 - 5000 ppm, NiO 500 - 1000 ppm.

[0012] Beneficial effects: In the present invention, NiO is introduced into the conventional ternary system of manganese-zinc ferrite to form a quaternary system, and the addition of NiO is carried out in both the main formula and the auxiliary component by means of two additions. The magnetocrystalline anisotropy constant K 1 and the saturation magnetostriction coefficient λ s are reduced, the saturation magnetization intensity Ms is increased, the internal and external stresses of the material are reduced, and a precise and uniform microstructure is formed, so that a magnetic material with high initial permeability, high saturation magnetic flux density, high surface resistivity and ultra-low power consumption can be obtained. In the auxiliary component of the present invention, Co 2 O 3 is added, so that the magnetocrystalline anisotropy constant K 1 = 0 near room temperature, and the power consumption at room temperature is reduced. In the auxiliary component, NiO is introduced again, so that the magnetocrystalline anisotropy constant K 1 = 0 near high temperature, and the power consumption at 100 °C at high temperature is reduced.

[0013] A preparation method of a manganese-zinc ferrite material with wide temperature range, low power consumption and high Bs, comprising the following steps:

[0014] Mix and ball-mill the main component and then pre-burn, then mix the obtained pre-burned material with the auxiliary component and continue ball-milling, and then obtain powder through spray drying, and obtain the manganese-zinc ferrite material with wide temperature range, low power consumption and high Bs through pressing and sintering.

[0015] Preferably, the temperature of the pre-sintering is 1030 - 1060 °C and the time is 30 - 40 min.

[0016] Preferably, the sintering is specifically as follows: Heating stage: heating from 25 °C to 1150 °C, heating in air for 6 hours; heating from 1150 °C to 1350 °C at a heating rate of 4 °C / min and under a full nitrogen atmosphere.

[0017] Insulation stage: the insulation temperature is 1350 °C, the oxygen content is 4 - 5%, and the insulation time is 4 hours.

[0018] Cooling stage: cooling from 1350 °C to 25 °C at a cooling rate of 2 °C / min and in a slightly oxidizing atmosphere.

[0019] Among them, the slightly oxidizing atmosphere is:

[0020] During the cooling process of ferrite sintering, when the oxygen atmosphere follows the equilibrium atmosphere Morin formula logO 2 % = a - b / T, no chemical reaction occurs in the magnetic core. Among them, a and b are empirical constants. For MnZn ferrite, a is usually about 7, the b value is about 14540, and T is the sintering Kelvin temperature.

[0021] When in the cooling stage of sintering, the equilibrium oxygen content is calculated using the above a and b values at most temperature points. In this preferred embodiment, in the temperature range of 1250 - 1050 during cooling, the a value is 7.5. At this time, due to the too high oxygen content, the magnetic core will undergo an oxidation reaction, and Fe 2+ is converted to Fe 3+ .

[0022] Beneficial effects: Through the Morineav's MnZn ferrite equilibrium oxygen partial pressure phase diagram, the present invention determines the oxidation degree and the oxygen content at each temperature point based on the Fe 2+ content in the ferrite (controlling the valley point of material power consumption), draws the basic temperature curve and equilibrium atmosphere curve, and performs a slightly oxidizing treatment on the cooling section on the basis of equilibrium to improve the magnetic core density and further reduce the loss. In addition, due to the use of a multi-Fe 2 O 3 and less ZnO formula, the density of the soft magnetic ferrite magnetic core is smaller than that of the conventional multi-zinc formula. Therefore, densification sintering is required in the sintering process.

[0023] Preferably, the spinel synthesis degree of the pre-sintered material is 30 - 40%.

[0024] Preferably, the pressing and forming is to mix the obtained powder with 2‰ of zinc stearate and then press and form to obtain a green compact with a density of 3 g / cm 3 ³.

[0025] Preferably, the average particle size of the slurry obtained after ball milling is 1.0 μm.

[0026] Preferably, the continued ball milling includes primary ball milling and secondary ball milling;

[0027] The average particle size of the slurry obtained after the primary ball milling is 1.2 - 1.5 μm;

[0028] The average particle size of the slurry obtained after the secondary ball milling is 0.8 - 0.9 μm.

[0029] Application of a wide - temperature, low - power - consumption, high - Bs manganese - zinc ferrite material in a mobile phone charger.

[0030] The wide - temperature, low - power - consumption, high - Bs manganese - zinc ferrite material provided by the present invention acts as a boost inductor in a mobile phone charger. Since a boost circuit is used in the mobile phone charger, the core device, the boost inductor, fails due to a decrease in inductance caused by a large amount of DC components. Therefore, a material with a relatively large ΔB is required to prevent the inductance from decreasing and failing.

[0031] Compared with the prior art, the present invention has the following advantages and technical effects:

[0032] The material of the present invention is only realized by the ferrite oxide ceramic process. This magnetic material has the characteristics of wide temperature, low loss, and high Bs. Compared with the existing conventional wide - temperature, low - loss materials, the saturation magnetic flux density Bs is increased by 10%, and the cost is relatively low and the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0034] Figure 1 It is in the magnetic working state of type II. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] To make the above - mentioned objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0037] The embodiment of the present invention discloses a wide - temperature, low - power - consumption, high - Bs manganese - zinc ferrite material, including a main component and an auxiliary component;

[0038] The main component includes Fe at 100% molar fraction 2 O 3 56.18 - 56.48%, ZnO 6.00 - 6.25%, NiO 2 - 4%, and the balance is MnO;

[0039] The auxiliary components include CaCO 3 , Nb 2 O 5 , Co 3 O 4 and NiO.

[0040] In a preferred embodiment, calculated based on the total weight of the main component, the auxiliary components include the following raw materials: CaCO 3 200 - 400 ppm, Nb 2 O 5 200 - 300 ppm, Co 2 O 3 3500 - 5000 ppm, NiO 500 - 1000 ppm.

[0041] The embodiment of the present invention also discloses a preparation method of a wide - temperature, low - power - consumption, high - Bs manganese - zinc ferrite material, comprising the following steps:

[0042] Mix and ball - mill the main component and then pre - sinter, then mix the obtained pre - sintered material with the auxiliary components and continue ball - milling, and then obtain powder through spray - drying, and obtain the wide - temperature, low - power - consumption, high - Bs manganese - zinc ferrite material through pressing and sintering.

[0043] In a preferred embodiment, the temperature of the pre - sintering is 1030 - 1060 °C and the time is 30 - 40 min.

[0044] In a preferred embodiment, the sintering specifically is: Heating stage: heating from 25 °C to 1150 °C, heating in air for 6 hours; heating from 1150 °C to 1350 °C at a heating rate of 4 °C / min and in a full - nitrogen atmosphere;

[0045] Insulation stage: insulation temperature 1350 °C, oxygen content 4 - 5%, insulation for 4 hours;

[0046] Cooling stage: cooling from 1350 °C to 25 °C at a cooling rate of 2 °C / min and in a slightly oxidizing atmosphere.

[0047] Among them, the slightly oxidizing atmosphere is:

[0048] During the cooling process of ferrite sintering, when the oxygen atmosphere follows the equilibrium atmosphere Morin - Liu formula logO 2When % = a - b / T, no chemical reaction occurs in the magnetic core. Here, a and b are empirical constants. For manganese-zinc ferrite, a is approximately 7 and b is approximately 14540, and T is the sintering Kelvin temperature.

[0049] During the sintering cooling stage, the equilibrium oxygen content is calculated using the above a and b values at most temperature points. In this preferred embodiment, in the temperature range of 1250 - 1050 during cooling, the value of a is 7.5. At this time, due to the excessive oxygen content, the magnetic core will undergo an oxidation reaction, and Fe 2+ is converted to Fe 3+ .

[0050] In a preferred embodiment, the degree of spinel synthesis of the pre-sintered material is 50 - 60%.

[0051] In a preferred embodiment, the pressing and forming is to mix the obtained powder with 2‰ zinc stearate and then press and form it to obtain a green compact with a density of 3 g / cm 3 of the green compact.

[0052] In a preferred embodiment, the average particle size of the slurry obtained after ball milling is 1.0 μm.

[0053] In a preferred embodiment, the continued ball milling includes primary ball milling and secondary ball milling;

[0054] The average particle size of the slurry obtained after the primary ball milling is 1.2 - 1.5 μm;

[0055] The average particle size of the slurry obtained after the secondary ball milling is 0.8 - 0.9 μm.

[0056] The embodiment of the present invention also discloses an application of a wide-temperature low-power high-Bs manganese-zinc ferrite material in a mobile phone charger.

[0057] The wide-temperature low-power high-Bs manganese-zinc ferrite material provided by the present invention serves as a boost inductor in a mobile phone charger. Since the boost circuit is used in the mobile phone charger, the core device boost inductor fails due to a large DC component, resulting in a decrease in inductance. Therefore, a material with a relatively large ΔB is required to prevent the inductance from decreasing and failing.

[0058] Unless otherwise specified, the raw materials in the embodiments of the present invention are all obtained through commercial channels.

[0059] The room temperature or normal temperature in the embodiments of the present invention both refer to 25 ± 3°C.

[0060] The partial oxidation atmosphere in the embodiments of the present invention is:

[0061] During the sintering and cooling process of the ferrite, the oxygen atmosphere follows the equilibrium atmosphere formula (Morin Liu formula): logO 2% = a - b / T. Where a and b are empirical constants. For manganese-zinc ferrite, a is approximately 7 and b is approximately 14540, and T is the sintering Kelvin temperature.

[0062] Example 1

[0063] A preparation method of a wide-temperature low-power high-Bs manganese-zinc ferrite material, comprising the following steps:

[0064] 1) Mix 56.18 mol% of Fe 2 O 3 , 35.82 mol% of MnO, 6 mol% of ZnO, and 2 mol% of NiO, and then ball-mill. During the ball-milling process, the ratio of material to water is 1:1.1, the ratio of material to balls is 1:3 (the balls are steel balls with ф = 3 mm), the ball-milling time is 20 min, and the average particle size of the slurry is 1.0 μm. After ball-milling, spray drying is carried out to obtain powder. The obtained powder is pre-sintered in a natural gas 500-type rotary kiln at 1040 °C in an air atmosphere for 0.8 h. During the pre-sintering process, the feeding rate is 2 - 3 kg / hour, and the rotation speed is 2 N / minute, to obtain a pre-sintered material with a spinel synthesis degree of 50 - 60%;

[0065] (2) Mix the pre-sintered material obtained in step (1) with auxiliary components to obtain a mixed powder. The obtained mixed powder is ball-milled once to obtain a slurry with an average particle size between 1.20 - 1.5 μm, and then transferred to another sand mill for secondary ball-milling to obtain a slurry with an average particle size between 0.80 - 0.9 μm. Then, a PVA solution (concentration 8%) accounting for 10% of the mass of the mixed powder is added, stirred for 120 min, and then spray-dried to obtain powder.

[0066] Among them, the auxiliary components are CaCO 3 , Nb 2 O 5 , Co 2 O 3 and NiO. Calculated based on the total weight of the main components, the content of each substance is: CaCO 3 300 ppm, Nb 2 O 5 300 ppm, Co 2 O 3 3500 ppm, NiO 500 ppm;

[0067] During the first ball-milling process, the ratio of material to water is 1:1, the ratio of material to balls is 1:5 (the balls are steel balls with ф = 6.35 mm), and the sand-milling time is 60 min;

[0068] During the second ball-milling process, the ratio of material to water for ball-milling is 1:1, the ratio of material to balls is 1:4, the balls are steel balls with ф = 6.35 mm, and the sand-milling time is 30 min;

[0069] (3) Mix the powder obtained in step (2) with 2‰ zinc stearate and press it into a mold to obtain a standard green compact with a density of 3 g / cm 3 , and then sinter it under a specific curve. After cooling, a wide-temperature, low-power, high-Bs manganese-zinc ferrite material is obtained;

[0070] Among them, the sintering curve is as follows: Heating stage: Heat from 25 °C to 1150 °C and heat in air for 6 hours; Heat from 1150 °C to 1350 °C at a heating rate of 4 °C / min and carry out in a full-nitrogen atmosphere;

[0071] Insulation stage: Insulation temperature 1350 °C, oxygen content 4 - 5%, insulation for 4 hours;

[0072] Cooling stage: Cool from 1350 °C to 25 °C at a cooling rate of 2 °C / min and carry out in a slightly oxidizing atmosphere.

[0073] Example 2

[0074] A preparation method of a wide-temperature, low-power, high-Bs manganese-zinc ferrite material, which is different from Example 1 in that in step (1), 56.38 mol% of Fe 2 O 3 , 34.52 mol% of MnO, 6.10 mol% of ZnO and 3 mol% of NiO are mixed and ball-milled;

[0075] In step (2), calculated based on the total weight of the main components, the contents of the auxiliary components in the mixed powder are: CaCO 3 200 ppm, Nb 2 O 5 300 ppm, Co 2 O 3 3500 ppm, NiO 1000 ppm.

[0076] Comparative Example 1

[0077] A preparation method of a wide-temperature, low-power, high-Bs manganese-zinc ferrite material, which is different from Example 1 in that in step (1), 56.18 mol% of Fe 2 O 3 , 37.82 mol% of MnO, 6 mol% of ZnO and 2 mol% of NiO are mixed and ball-milled;

[0078] In step (2), calculated based on the total weight of the main components, the contents of the auxiliary components in the mixed powder are: CaCO 3 200 ppm, Nb 2 O 5 300 ppm, NiO 1000 ppm.

[0079] Comparative Example 2

[0080] A method for preparing a magnetic material, which is different from that of Example 1 in that the sintering curve in step (3) is as follows:

[0081] Cool the temperature according to the equilibrium atmosphere formula, and the other steps are the same as those in Example 1.

[0082] Comparative Example 3

[0083] A method for preparing a wide-temperature, low-power, high-Bs Mn-Zn ferrite material, which is different from that of Example 1 in that in step (1), 56.18 mol% of Fe 2 O 3 , 37.82 mol% of ZnO, 5.5 mol% of NiO and 0.5 mol% of MnO are mixed and then ball-milled;

[0084] Technical effects:

[0085] The magnetic materials obtained in Examples 1-3 and Comparative Examples 1-2 were tested. The permeability was measured using an E4980A LCR bridge, and the power consumption and saturation magnetic flux density were tested using an SY8218 B-H loop tester. The results are shown in Table 1:

[0086] Table 1

[0087]

[0088] It can be seen that the materials obtained in Examples 1-2 of the present invention, under the conditions of 100 kHz and 200 mT, the power consumption at 25 °C ≤ 250 mW / cm 3 , and the power consumption at 100 °C ≤ 290 mW / cm 3 ; under the conditions of 1194 A / m and 50 Hz, the saturation magnetic flux density at 25 °C ≥ 600 mT, the saturation magnetic flux density at 100 °C ≥ 490 mT, and the initial permeability is 3000. Compared with the materials of the prior art, the materials of the present invention are only realized by the ferrite oxide ceramic process, and the prepared materials have lower wide-temperature power consumption and higher saturation magnetic flux density.

[0089] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A wide temperature, low power consumption, high Bs manganese-zinc ferrite material, characterized in that: Includes main ingredients and auxiliary ingredients; Taking the total molar fraction as 100%, the main components include 56.18-56.48% of Fe2O3, 6.00-6.25% of ZnO, 2-4% of NiO, and the rest is MnO; The auxiliary components are CaCO3, Nb2O5, Co2O3 and NiO; Calculated based on the total weight of the main components, the auxiliary components are the following raw materials: CaCO3 200-400ppm, Nb2O5 200-300ppm, Co2O3 3500-5000ppm, NiO 500-1000ppm.

2. The method for preparing a wide temperature, low power consumption, high Bs manganese-zinc ferrite material according to claim 1, characterized in that: The following steps are involved: The main components are mixed and ball-milled and then pre-fired, and then the pre-fired material is mixed with the auxiliary components and ball-milled, and then spray-dried to obtain powder, and then pressed and sintered to obtain the wide temperature, low power consumption and high Bs manganese-zinc ferrite material; The pre-burning temperature is 1030-1060°C and the time is 30-40min; The sintering is specifically as follows: a heating stage: heating from 25°C to 1150°C in air for 6 hours; heating from 1150°C to 1350°C at a heating rate of 4°C / min in a full nitrogen atmosphere; Insulation stage: Insulation temperature 1350℃, oxygen content 4-5%, insulation for 4 hours; Cooling stage: cooling from 1350°C to 25°C at a cooling rate of 2°C / min in a sluggish oxidizing atmosphere.

3. The method for preparing a wide temperature, low power consumption, high Bs manganese-zinc ferrite material according to claim 2, characterized in that: The spinel synthesis degree of the pre-sintered material is 50-60%.

4. The method for preparing a wide temperature, low power consumption, high Bs manganese-zinc ferrite material according to claim 2, characterized in that: The pressing molding is to mix the obtained powder with 2‰ zinc stearate and then press the mixture to obtain a density of 3g / cm 3 of the green body.

5. The method for preparing a wide temperature, low power consumption, high Bs manganese-zinc ferrite material according to claim 2, characterized in that: The average particle size of the slurry obtained after ball milling is 1.0 μm.

6. The method for preparing a wide temperature, low power consumption, high Bs manganese-zinc ferrite material according to claim 2, characterized in that: The continuous ball milling includes primary ball milling and secondary ball milling; The average particle size of the slurry obtained after the first ball milling is 1.2-1.5 μm; The average particle size of the slurry obtained after the secondary ball milling is 0.8-0.9 μm.

7. Application of the wide temperature, low power consumption and high Bs manganese-zinc ferrite material as claimed in claim 1 in a mobile phone charger.

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