Mn-Zn ferrite material and preparation method thereof

Abstract

The invention provides a Mn-Zn ferrite material and a preparation method thereof. The material is composed of a main component and an auxiliary component, and the main component is composed of the following components in molar percentage: 52-55 mol% of Fe2O3, 14-17 mol% of ZnO and the balance of Mn3O4; and the auxiliary component is prepared from the following components in percentage by weight: 200 to 500 ppm of CaCO3, 200 to 500 ppm of Bi2O3, 100 to 350 ppm of MoO3 and 1000 to 2000 ppm of CoO. The invention further discloses a preparation method of the high-temperature-resistant ceramic. The Mn-Zn ferrite material disclosed by the invention has the characteristics of high initial permeability, wide temperature, low temperature coefficient, broadband and high impedance, and can meet the use requirements of high-performance automobile electronic components.

Description

Technical Field

[0001] The invention relates to the technical field of soft ferrite materials, and in particular to a Mn-Zn ferrite material and a preparation method thereof. Background Art

[0002] With the continuous development of electronic technology, high permeability manganese-zinc ferrite is developing towards high frequency, miniaturization, and patching, and it is also necessary to ensure that the material has high permeability, low loss and anti-electromagnetic interference and other characteristics. In the automotive electronics industry, there are more and more EMC (electromagnetic compatibility) cores for vehicle use. The closer to the engine, the worse the working environment of the core. In addition, with the emergence of extreme weather in recent years, this requires the core to have good temperature stability and a higher Curie temperature in the temperature range of -20 to 140°C, and the EMC core requires a wider frequency characteristic. However, the existing high permeability materials have too large permeability changes at too high or too low temperatures, and the overall performance of the material cannot take into account the performance requirements of broadband high impedance. Secondly, as an anti-electromagnetic interference material, it is required to have a fast attenuation speed and a wide frequency band, while ensuring that there is no distortion within the working frequency range and can adapt to various environments. Therefore, the future research direction of high permeability series Mn-Zn ferrites is high permeability, broadband characteristics, wide temperature and low temperature coefficient, etc., but these aspects are often contradictory.

[0003] Chinese invention patent CN101620908A discloses a wide temperature and high permeability manganese-zinc ferrite material and its preparation method, which limits the iron oxide content to 53-55 mol%, zinc oxide 16-19 mol%, and achieves a wide temperature range of -40 to +125 ° C, but the temperature coefficient in this temperature range is high, and the overall permeability is maintained at a low level of about 5000. Patent CN109626981A discloses a wide temperature and wide frequency high permeability manganese-zinc ferrite and its preparation method, which limits the iron oxide content to 58-65 mol%, zinc oxide 10-20 mol%, and the working temperature is 0-110 ° C, but its overall temperature stability is poor, and there is no permeability characteristic in the negative temperature range. Patent CN106747396B discloses a high permeability manganese-zinc ferrite material for automotive electronics and its preparation method, which limits the iron oxide content to 52-53 mol%, zinc oxide 17-20.5 mol%, and can only achieve good temperature stability at 25-80 ° C.

[0004] Patent CN113480302A discloses a method for preparing a wide temperature range high permeability manganese zinc ferrite material, the initial permeability is only 5000-6000, and the temperature stability in a wide temperature range is poor. Patent CN113443906A discloses a high permeability low temperature coefficient manganese zinc ferrite material, which limits the iron oxide content to 51-54 mol%, zinc oxide 18.1-26 mol%, and achieves a low temperature coefficient of manganese zinc ferrite material at -55-120 ° C, but the permeability is low. Patent CN101863657B discloses a wide temperature range high permeability manganese zinc ferrite material, which limits the iron oxide content to 51-56 mol%, zinc oxide 16-26 mol%, and achieves a permeability of more than 5000 at -60-130 ° C of manganese zinc ferrite material, but the temperature coefficient is high, and there are no higher requirements for the frequency and impedance characteristics of the material. Patent CN101560091A discloses a wide temperature range, low temperature coefficient, and high Curie temperature manganese-zinc ferrite material. By limiting the iron oxide content to 52.5-55 mol% and zinc oxide to 10-18 mol%, the manganese-zinc ferrite material has a low temperature coefficient at -25 to 150°C, but its overall magnetic permeability is only about 5000.

[0005] In summary, there is currently no manganese-zinc ferrite material with wide temperature, high magnetic permeability and high impedance coefficient characteristics in the range of -20-140°C, so as to ensure the normal operation of the EMC core of automotive electronics under extreme temperature conditions. Summary of the invention

[0006] The main purpose of the present invention is to provide a Mn-Zn ferrite material and a preparation method thereof, so as to solve the problem that the soft ferrite material in the prior art cannot take into account a wide operating temperature range, high temperature stability, high operating frequency characteristics and high magnetic permeability.

[0007] In order to achieve the above object, according to one aspect of the present invention, a Mn-Zn ferrite material is provided, which is composed of a main component and an auxiliary component, wherein, by mole percentage, the main component is composed of the following components: 52-55 mol% of Fe 2 O 3 , 14-17 mol% ZnO, the rest is Mn 3 O 4 ; wherein, in terms of weight percentage of the main component, the auxiliary component is composed of the following components: 200-500 ppm of CaCO 3 , 200~500ppm Bi 2 O 3 , 100~350ppm MoO 3 , 1000~2000ppm CoO.

[0008] Furthermore, in terms of molar percentage, the main component consists of the following components: 52-53 mol% of Fe 2 O 3 , 14-15 mol% ZnO, the rest is Mn 3 O 4 Preferably, in terms of molar percentage, the main component consists of the following components: 52.7 to 52.8 mol% Fe 2 O 3 , 14.3-14.5 mol% ZnO, the rest is Mn 3 O 4 More preferably, Fe 2 O 3 The molar ratio to ZnO is (3.6~3.7):1.

[0009] Furthermore, the auxiliary component is composed of the following components, based on the weight percentage of the main component: 400-500 ppm of CaCO 3 , 400~500ppm Bi 2 O 3 , 200~300ppm MoO 3 , 1500~2000ppm CoO.

[0010] Further, in terms of molar percentage, the main components consist of the following components: 52.8 mol% of Fe 2 O 3 , 14.4 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary components are composed of the following components in terms of weight percentage of the main component: 400ppm of CaCO 3 , 400ppm Bi 2 O 3 , 200ppm MoO 3 , 2000ppm CoO; or in terms of molar percentage, the main components are composed of the following components: 52.8mol% Fe 2 O 3 , 14.4 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary components are composed of the following components in terms of weight percentage of the main component: 400ppm of CaCO 3 , 400ppm Bi 2 O 3 , 300ppm MoO 3 , 1500ppm CoO; or in terms of molar percentage, the main components are composed of the following components: 52.7mol% Fe 2 O 3, 14.3 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary components are composed of the following components in terms of weight percentage of the main component: 500ppm of CaCO 3 , 400ppm Bi 2 O 3 , 200ppm MoO 3 , 2000ppm CoO.

[0011] According to another aspect of the present invention, a preparation method of the above-mentioned Mn-Zn ferrite material of the present invention is provided, comprising the following steps: step S1: ball-milling each raw material of the main component to obtain a primary ball-milled material; step S2: pre-sintering the primary ball-milled material to obtain a pre-sintered material; step S3: mixing the pre-sintered material with each raw material of the auxiliary component and ball-milling it for a secondary time to obtain a secondary ball-milled material; step S4: mixing the secondary ball-milled material with a binder and spray-granulating it to obtain a Mn-Zn ferrite granular material; step S5: pressing and molding the Mn-Zn ferrite granular material to obtain a Mn-Zn ferrite green body; step S6: sintering the Mn-Zn ferrite green body to obtain a Mn-Zn ferrite material.

[0012] Furthermore, in step S1, the first ball milling is a wet ball milling mixing; preferably, the time of the wet ball milling mixing is 20 to 60 minutes, the frequency is 40 to 60 Hz, and the rotation speed is 200 to 300 r / min.

[0013] Furthermore, in step S2, the pre-firing temperature is 700-800°C, and the holding time is 2-4h.

[0014] Furthermore, in step S3, the secondary ball milling is secondary wet ball milling mixing; preferably, the secondary wet ball milling mixing time is 100 to 150 minutes, the frequency is 40 to 60 Hz, and the rotation speed is 200 to 300 r / min.

[0015] Furthermore, in step S4, the weight of the binder accounts for 5-15wt% of the weight of the secondary ball abrasive; preferably, the binder is glue PVA.

[0016] Further, in step S6, the sintering includes a first-stage sintering and a second-stage sintering performed sequentially, the first-stage sintering includes sintering at 1350-1400°C for 6-8h in a nitrogen atmosphere and controlling the oxygen volume content to 19-21vol%; the second-stage sintering includes sintering at 1350-1400°C for 1-2h in a nitrogen atmosphere and controlling the oxygen volume content to 3-5vol%; and then cooling at a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material.

[0017] By applying the technical solution of the present invention, on the basis of optimizing the main components of the Mn-Zn ferrite material, combining a special auxiliary component doping system, and using only a few components for synergistic effect, the material can have the following characteristics while reducing the cost:

[0018] 1. Higher initial magnetic permeability: μi ≥ 4200, up to 7000;

[0019] 2. Higher Curie temperature: Curie temperature ≥195℃;

[0020] 3. It has a low temperature coefficient of magnetic permeability in a wide temperature range of -20 to 140°C;

[0021] 4. High frequency characteristics: L(100KHz) / L(10KHz)≥90%, L(300KHz) / L(10KHz)≥89%;

[0022] 5. High impedance characteristics: Under the condition of 0.5~1MHz, the impedance coefficient is ≥22Ω / mm.

[0023] In summary, the Mn—Zn ferrite material of the present invention has high initial magnetic permeability, low temperature coefficient over a wide temperature range, and high impedance over a wide frequency band, and can meet the requirements for use of high-performance automotive electronic components. DETAILED DESCRIPTION

[0024] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0025] Unless otherwise specified, the materials used in the present invention can be easily purchased from the market, and the technical terms involved are all defined in common sense in the art.

[0026] As described in the background of the present invention, there is a problem in the prior art that soft ferrite materials cannot take into account a wide operating temperature range, high temperature stability, high operating frequency characteristics and high magnetic permeability. In order to solve the above problems, in a typical embodiment of the present invention, a Mn-Zn ferrite material is provided, which is composed of a main component and an auxiliary component, wherein, in terms of molar percentage, the main component is composed of the following components: 52-55 mol% of Fe 2 O 3 , 14-17 mol% ZnO, the rest is Mn 3 O 4 ; wherein, in terms of weight percentage of the main component, the auxiliary component is composed of the following components: 200-500 ppm of CaCO 3 , 200~500ppm Bi 2 O 3 , 100~350ppm MoO3 , 1000~2000ppm CoO.

[0027] The inventor unexpectedly found during the research that the Curie temperature directly affects the use temperature and temperature stability of the Mn-Zn ferrite material. The Curie temperature is mainly determined by the components of the ferrite. In the main formula of the Mn-Zn ferrite material provided by the present invention, by appropriately reducing the ZnO content and correspondingly increasing the Fe 2 O 3 When the content is within a specific range, the Curie temperature of the material can be ≥195°C. Among the main components of Mn-Zn ferrite materials, Fe 2 O 3 The content is greater than 50 mol%, which can generate an appropriate amount of Fe 3 O 4 It plays a positive role in compensating λs (saturation magnetostriction coefficient); the addition of a specific content of non-magnetic Zn ions can dilute the coupling effect of magnetic ions, thereby effectively improving the μi (initial magnetic permeability) value.

[0028] Among the auxiliary components of Mn-Zn ferrite materials, an appropriate amount of CaCO 3 The doping of Ca 2+ Existing in large quantities at the grain boundaries, Bi generates a non-grain boundary intermediate phase to achieve high impedance characteristics. 2 O 3 As a flux, it is beneficial to liquid phase sintering and can obtain high-density ferrite at a lower temperature. 3 Doping can be beneficial to complete grain growth, uniform grain size, small number of pores, high degree of grain densification and good microstructure.

[0029] Adding an appropriate amount of CoO to generate CoFe 2 O 4 The K1 (magnetocrystalline anisotropy constant) of CoFe is positive, which can compensate for positive and negative values, making the K1 of ferrite material close to 0 within -20 to 160°C. 2 O 4 The λs of the material is greater than zero, and the λs of the material can also approach zero, so that its μi increases, thereby achieving a higher initial magnetic permeability under a wide temperature condition, with small magnetic permeability change and high stability, and leveling the overall μi-T (initial magnetic permeability-temperature) curve of the material.

[0030] The present invention optimizes the main components of the Mn-Zn ferrite material, combines a special auxiliary component doping system, and uses only a few components for synergistic effect, which can reduce the cost while making the material have a higher initial magnetic permeability (μi ≥ 4200, up to 7000), a higher Curie temperature (≥ 195°C, can be ≥ 200°C), and a lower magnetic permeability temperature coefficient (0 to 1×10 -6 ), with high frequency characteristics (L(100KHz) / L(10KHz)≥90%, L(300KHz) / L(10KHz)≥89%), and high impedance characteristics (under the condition of 0.5~1MHz, the impedance coefficient is ≥22Ω / mm). It can even make the initial magnetic permeability μi of the material ≥7000, the Curie temperature ≥200℃, and the magnetic permeability temperature coefficient 0~1×10 in a wide temperature range of -20~140℃. -6 , and achieve high frequency characteristics (L(100KHz) / L(10KHz)≥95%, L(300KHz) / L(10KHz)≥92%, high impedance characteristics under 0.5~1MHz conditions, impedance coefficient ≥27Ω / mm.

[0031] The Mn-Zn ferrite material of the present invention has high initial magnetic permeability, wide temperature range low temperature coefficient and broadband high impedance characteristics, which can meet the use requirements of high-performance automotive electronic components, so that automotive electronic components can work normally within the temperature range of -20 to 140°C, greatly increasing the application range of electronic devices.

[0032] In a preferred embodiment, the main component is composed of the following components by molar percentage: 52-53 mol% Fe 2 O 3 , 14-15 mol% ZnO, the rest is Mn 3 O 4 The above content range can make the synergistic effect of the components in the main component of the Mn-Zn ferrite material better, thereby further improving the use temperature range and temperature stability of the Mn-Zn ferrite material, and further improving the initial magnetic permeability. Based on similar reasons, it is further preferred that, in terms of molar percentage, the main component consists of the following components: 52.7-52.8 mol% of Fe 2 O 3 , 14.3-14.5 mol% ZnO, the rest is Mn 3 O 4 More preferably, Fe 2 O 3 The molar ratio to ZnO is (3.6~3.7):1.

[0033] Accordingly, in a preferred embodiment, the auxiliary component is composed of the following components in terms of weight percentage of the main component: 400-500 ppm of CaCO 3 , 400~500ppm Bi 2 O 3 , 200~300ppm MoO 3 , 1500-2000ppm CoO. Within the above content range, the synergistic effect of each component in the auxiliary component of the Mn-Zn ferrite material can be better, thereby further improving the temperature stability of the Mn-Zn ferrite material and further improving the impedance characteristics.

[0034] Most preferably, based on similar reasons, in a preferred embodiment, the main component is composed of the following components in molar percentage: 52.8 mol% Fe 2 O 3 , 14.4 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary components are composed of the following components in terms of weight percentage of the main component: 400ppm of CaCO 3 , 400ppm Bi 2 O 3 , 200ppm MoO 3 , 2000ppm CoO; or in terms of molar percentage, the main components are composed of the following components: 52.8mol% Fe 2 O 3 , 14.4 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary components are composed of the following components in terms of weight percentage of the main component: 400ppm of CaCO 3 , 400ppm Bi 2 O 3 , 300ppm MoO 3 , 1500ppm CoO; or in terms of molar percentage, the main components are composed of the following components: 52.7mol% Fe 2 O 3 , 14.3 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary components are composed of the following components in terms of weight percentage of the main component: 500ppm of CaCO 3 , 400ppm Bi 2 O 3 , 200ppm MoO 3, 2000ppm CoO. The Mn-Zn ferrite material within the above range has the best high initial permeability, wide temperature low temperature coefficient and broadband high impedance characteristics, which can better meet the requirements of high-performance automotive electronic components.

[0035] In another typical embodiment of the present invention, a preparation method of the above-mentioned Mn-Zn ferrite material of the present invention is also provided, comprising the following steps: step S1: ball-milling each raw material of the main component to obtain a primary ball-milled material; step S2: pre-burning the primary ball-milled material to obtain a pre-burned material; step S3: mixing the pre-burned material with each raw material of the auxiliary component and ball-milling it for a second time to obtain a secondary ball-milled material; step S4: mixing the secondary ball-milled material with a binder and spray-granulating it to obtain a Mn-Zn ferrite granular material; step S5: pressing and molding the Mn-Zn ferrite granular material to obtain a Mn-Zn ferrite green body; step S6: sintering the Mn-Zn ferrite green body to obtain a Mn-Zn ferrite material.

[0036] The present invention firstly ball-mills and pre-sinters the raw materials of the main components, during which the various raw materials initially undergo solid-phase reaction. Then, the raw materials of the auxiliary components are subjected to secondary ball-milling and granulation, pressed into shape, and finally sintered to obtain the Mn-Zn ferrite material through shrinkage (densification) and crystallization. The above preparation method is simple, easy to operate, uses less raw materials, has lower cost, and is more suitable for the preparation of the high-performance Mn-Zn ferrite material of the present invention.

[0037] In order to further improve the mixing uniformity of the raw materials of the main components, in a preferred embodiment, in step S1, the first ball milling is a wet ball milling mixing; preferably, the time of the wet ball milling mixing is 20 to 60 minutes, the frequency is 40 to 60 Hz, and the rotation speed is 200 to 300 r / min.

[0038] In a preferred embodiment, in step S2, the pre-sintering temperature is 700-800°C, the holding time is 2-4h, and the heating rate is 2-5°C / min. Under the above conditions, the solid phase reaction progress of each raw material of the main component can be further improved, thereby further improving the use temperature range width, temperature stability and initial magnetic permeability of the Mn-Zn ferrite material.

[0039] In order to further improve the mixing uniformity of the main component and the auxiliary component, in a preferred embodiment, in step S3, the secondary ball milling is secondary wet ball milling mixing; preferably, the secondary wet ball milling mixing time is 100 to 150 min, the frequency is 40 to 60 Hz, and the rotation speed is 200 to 300 r / min; the SMD particle size range of the prepared secondary ball mill material is 1.0 to 1.2 μm, and the X50 particle size range is 1.3 to 1.5 μm.

[0040] In a preferred embodiment, in step S4, the weight of the binder accounts for 5-15wt% of the weight of the secondary ball mill material; preferably, the binder is glue PVA. Under the above conditions, the Mn-Zn ferrite particles can maintain better particle size uniformity, which is convenient for subsequent pressing and sintering.

[0041] In order to obtain a better sintering effect, in a preferred embodiment, in step S6, the sintering includes a first stage sintering and a second stage sintering performed in sequence, wherein the first stage sintering includes sintering at 1350-1400°C for 6-8h in a nitrogen atmosphere and controlling the oxygen volume content to be 19-21vol%; the second stage sintering includes sintering at 1350-1400°C for 1-2h in a nitrogen atmosphere and controlling the oxygen volume content to be 3-5vol%; and then cooling at a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material. Under the above conditions, the sintering process of the material can be further controlled to be more suitable, so that the Mn-Zn ferrite material has better high initial magnetic permeability, wide temperature low temperature coefficient and broadband high impedance characteristics.

[0042] Typically, but not limiting, the main component is composed of the following components in molar percentage: 52 mol%, 52.5 mol%, 52.7 mol%, 52.8 mol%, 53 mol%, 53.5 mol%, 54 mol%, 54.5 mol%, 55 mol% or any two of the above values ​​of Fe. 2 O 3 , 14mol%, 14.3mol%, 14.5mol%, 15mol%, 15.5mol%, 16mol%, 16.5mol%, 17mol% or any two of them as the boundary value of ZnO, and the rest is Mn 3 O 4 .

[0043] Typically, but not limiting, the auxiliary component is composed of the following components, based on the weight percentage of the main component: 200ppm, 300ppm, 400ppm, 500ppm or any two of the values ​​of CaCO 3 , 200ppm, 300ppm, 400ppm, 500ppm or any two of them as the boundary value Bi 2 O 3 , 100ppm, 150ppm, 200ppm, 250ppm, 300ppm, 350ppm or any two of them as the boundary value of MoO 3 , CoO with a boundary value of 1000ppm, 1200ppm, 1400ppm, 1500ppm, 1600ppm, 1800ppm, 2000ppm or any two of them.

[0044] Typically but not limiting, in step S2, the pre-firing temperature is 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C or a boundary value composed of any two of them, and the holding time is 2h, 2.5h, 3h, 3.5h, 4h or a boundary value composed of any two of them.

[0045] Typically but not limiting, in step S6, the temperature of the first stage sintering is 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C or a boundary value composed of any two of their values, and the holding time is 6h, 6.5h, 7h, 7.5h, 8h; the temperature of the second stage sintering is 1350°C, 1360°C, 1370°C, 1380°C, 1390°C, 1400°C or a boundary value composed of any two of their values, and the holding time is 1h, 1.5h, 2h or a boundary value composed of any two of their values.

[0046] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0047] The compositions of the Mn-Zn ferrite materials of the following examples and comparative examples are detailed in Table 1.

[0048] Example 1

[0049] Step S1: After weighing the raw materials of the main component, wet ball milling is performed for mixing. The ball milling time is 30 min, the frequency of the planetary ball mill is 50 Hz, and the rotation speed is 250 r / min to obtain a primary ball mill material.

[0050] Step S2: drying the primary ball mill material and pre-firing it at a temperature of 750° C. for 3 h to obtain a pre-firing material.

[0051] Step S3: adding various raw materials of auxiliary components to the pre-sintered material, and wet ball milling and mixing, the ball milling time is 150min, the frequency of the planetary ball mill is 50Hz, and the rotation speed is 250r / min, to obtain secondary ball milled material, the SMD particle size is 1.01μm, and the X50 particle size is 1.22μm.

[0052] Step S4: The secondary ball-milled material is mixed with 10 wt % of PVA, and spray-granulated, and passed through a 30-mesh sieve to obtain Mn-Zn ferrite particles.

[0053] Step S5: Press the Mn-Zn ferrite particles into a shape to obtain a Mn-Zn ferrite green body of Φ25mm×Φ15mm×8mm, with a green body density of 3.5g / cm 3 .

[0054] Step S6: Place the Mn-Zn ferrite green body in N 2 The samples were sintered at 1360 °C for 7 h under the condition of controlling the oxygen content to 21 vol%, and then heated in N 2 The sintering was carried out at 1360° C. for 1 h under the condition of controlling the oxygen content to 3 vol%, and the cooling stage was carried out under a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material.

[0055] Example 2

[0056] Step S1: After weighing the raw materials of the main component, wet ball milling is performed for mixing. The ball milling time is 30 min, the frequency of the planetary ball mill is 50 Hz, and the rotation speed is 250 r / min to obtain a primary ball mill material.

[0057] Step S2: drying the primary ball mill material and then pre-burning it at a temperature of 700° C. for 3 h to obtain a pre-burned material.

[0058] Step S3: Add various raw materials of auxiliary components to the pre-sintered material, and perform wet ball milling mixing. The ball milling time is 130 min, the frequency of the planetary ball mill is 50 Hz, and the rotation speed is 250 r / min to obtain secondary ball milled material with an SMD particle size of 1.09 μm and an X50 particle size of 1.28 μm.

[0059] Step S4: The secondary ball-milled material is mixed with 10 wt % of PVA, and spray-granulated, and passed through a 30-mesh sieve to obtain Mn-Zn ferrite particles.

[0060] Step S5: Press the Mn-Zn ferrite particles into a shape to obtain a Mn-Zn ferrite green body of Φ25mm×Φ15mm×8mm, with a green body density of 3.5g / cm 3 .

[0061] Step S6: Place the Mn-Zn ferrite green body in N 2 The samples were sintered at 1370 °C for 7 h under the condition of controlling the oxygen content to 21 vol%, and then heated in N 2 The sintering was carried out at 1370°C for 2 hours under the condition of controlling the oxygen content to 4 vol%, and the cooling stage was carried out under a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material.

[0062] Example 3

[0063] Step S1: After weighing the raw materials of the main component, wet ball milling is performed for mixing. The ball milling time is 30 min, the frequency of the planetary ball mill is 50 Hz, and the rotation speed is 250 r / min to obtain a primary ball mill material.

[0064] Step S2: drying the primary ball mill material and then pre-burning it at a temperature of 750° C. for 3 h to obtain a pre-burned material.

[0065] Step S3: adding various raw materials of auxiliary components to the pre-sintered material, and wet ball milling and mixing, the ball milling time is 150min, the frequency of the planetary ball mill is 50Hz, and the rotation speed is 250r / min, to obtain secondary ball milled material, the SMD particle size is 1.03μm, and the X50 particle size is 1.22μm.

[0066] Step S4: The secondary ball-milled material is mixed with 10 wt % of PVA, and spray-granulated, and passed through a 30-mesh sieve to obtain Mn-Zn ferrite particles.

[0067] Step S5: Press the Mn-Zn ferrite particles into a shape to obtain a Mn-Zn ferrite green body of Φ25mm×Φ15mm×8mm, with a green body density of 3.5g / cm 3 .

[0068] Step S6: Place the Mn-Zn ferrite green body in N 2 The samples were sintered at 1360 °C for 6 h under the condition of controlling the oxygen content to 21 vol%, and then heated in N 2 The sintering was carried out at 1360° C. for 2 h under the condition of controlling the oxygen content to 5 vol%, and the cooling stage was carried out under a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material.

[0069] Example 4

[0070] Step S1: After weighing the raw materials of the main component, wet ball milling is performed for mixing. The ball milling time is 30 minutes, the frequency of the planetary ball mill is 50 Hz, and the rotation speed is 250 r / min to obtain a primary ball mill material.

[0071] Step S2: drying the primary ball mill material and pre-firing it at a temperature of 800° C. for 3 h to obtain a pre-firing material.

[0072] Step S3: Add various raw materials of auxiliary components to the pre-sintered material, and perform wet ball milling mixing. The ball milling time is 130 min, the frequency of the planetary ball mill is 50 Hz, and the rotation speed is 250 r / min to obtain secondary ball milled material with an SMD particle size of 1.06 μm and an X50 particle size of 1.25 μm.

[0073] Step S4: The secondary ball-milled material is mixed with 10 wt % of PVA, and spray-granulated, and passed through a 30-mesh sieve to obtain Mn-Zn ferrite particles.

[0074] Step S5: Press the Mn-Zn ferrite particles into a shape to obtain a Mn-Zn ferrite green body of Φ25mm×Φ15mm×8mm, with a green body density of 3.5g / cm3 .

[0075] Step S6: Place the Mn-Zn ferrite green body in N 2 The samples were sintered at 1360 °C for 7 h under the condition of controlling the oxygen content to 21 vol%, and then heated in N 2 The sintering was carried out at 1360° C. for 2 h under the condition of controlling the oxygen content to 4 vol%, and the cooling stage was carried out under a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material.

[0076] Example 5

[0077] Step S1, weigh the raw materials of the main component, and then perform wet ball milling to mix them. The ball milling time is 20 minutes, the frequency of the planetary ball mill is 60 Hz, and the rotation speed is 300 r / min to obtain a primary ball mill material.

[0078] Step S2, drying the primary ball mill material and pre-burning it at a temperature of 700° C. for a heat preservation time of 4 hours to obtain a pre-burned material.

[0079] Step S3, adding various raw materials of auxiliary components to the pre-sintered material, and wet ball milling and mixing, the ball milling time is 100 min, the frequency of the planetary ball mill is 60 Hz, the rotation speed is 200 r / min, and secondary ball milling material is obtained, the SMD particle size is 1.01 μm, and the X50 particle size is 1.22 μm.

[0080] Step S4, mixing the secondary ball-milled material with 5 wt % PVA, spray granulating, and passing through a 30-mesh sieve to obtain Mn-Zn ferrite granules.

[0081] Step S6, placing the Mn-Zn ferrite green body on N 2 The samples were sintered at 1350 °C for 8 h under the condition of controlling the oxygen content to 19 vol%, and then heated in N 2 The sintering was carried out at 1350° C. for 2 h under the condition of controlling the oxygen content to be 3 vol%, and the cooling stage was carried out under a balanced oxygen partial pressure to obtain a Mn-Zn ferrite material.

[0082] Example 6

[0083] Step S1, weighing the raw materials of the main component, and then mixing them by wet ball milling, the ball milling time is 60 minutes, the frequency of the planetary ball mill is 40 Hz, and the rotation speed is 200 r / min, to obtain a primary ball mill material.

[0084] Step S2, drying the primary ball mill material and pre-firing it at a temperature of 800° C. for a heat preservation time of 2 hours to obtain a pre-firing material.

[0085] Step S3, adding various raw materials of auxiliary components to the pre-sintered material, and wet ball milling and mixing, the ball milling time is 150min, the frequency of the planetary ball mill is 40Hz, and the rotation speed is 300r / min, to obtain secondary ball milled material, the SMD particle size is 1.03μm, and the X50 particle size is 1.22μm.

[0086] Step S4, mixing the secondary ball-milled material with 15 wt % PVA, spray granulating, and passing through a 30-mesh sieve to obtain Mn-Zn ferrite granules.

[0087] Step S6, placing the Mn-Zn ferrite green body on N 2 The samples were sintered at 1400 °C for 6 h under the condition of controlling the oxygen content to 21 vol%, and then heated in N 2 The sintering was carried out at 1400°C for 1 hour under the condition of controlling the oxygen content to 5 vol%, and the cooling stage was carried out under the equilibrium oxygen partial pressure to obtain the Mn-Zn ferrite material.

[0088] Comparative Examples 1 to 12

[0089] The difference from Example 1 is that the composition of the Mn-Zn ferrite material is different, see Table 1 for details.

[0090] The performance test of the Mn-Zn ferrite materials provided in the above embodiments and comparative examples was carried out: under the test conditions of frequency f = 10KHz and voltage U = 0.25V, a 10-turn winding method was used, and the initial magnetic permeability μi was tested at different temperature points within the temperature range of -40 to 160°C, where the specific temperature coefficient αμ / μi (×10 -6 ). Under the test conditions of frequency f = 1MHz and voltage U = 0.25V, the impedance characteristics are tested. The performance test results are shown in Table 2, Table 3 and Table 4.

[0091] Table 1

[0092]

[0093] Table 2

[0094]

[0095] Table 3

[0096]

[0097]

[0098] Table 4

[0099]

[0100]

[0101] It can be seen from the above that, compared with the comparative examples, the Mn-Zn ferrite material provided by each embodiment of the present invention controls the composition and addition amount of the main component and the auxiliary component, and combines the corresponding sintering process to obtain a wide temperature, low temperature coefficient, wide frequency and high impedance Mn-Zn ferrite material. No CoO is added to the auxiliary component of Comparative Example 1, resulting in a rapid decrease in the initial magnetic permeability in the range of 25 to 100°C with increasing temperature. Comparative Examples 2 and 3 have too little CoO added, resulting in a large change in the initial magnetic permeability in the range of -20 to 140°C with temperature.

[0102] It can be seen from the above that, compared with the comparative example, the embodiments of the present invention, based on the optimization of the main components of the Mn-Zn ferrite material, combine a special auxiliary component doping system, and use only a few components for synergistic effect, which can reduce the cost while making the Mn-Zn ferrite material have high initial magnetic permeability, wide temperature range and low temperature coefficient, and wide-band high impedance characteristics, which can meet the requirements for the use of high-performance automotive electronic components.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A Mn-Zn ferrite material, It is characterized in that It consists of main components and auxiliary components. Wherein, in terms of molar percentage, the main component is composed of the following components: 52-55 mol% of Fe 2 O 3 , 14-17 mol% ZnO, the rest is Mn 3 O 4 ; Wherein, the auxiliary component is composed of the following components in terms of weight percentage of the main component: 200-500 ppm of CaCO 3 , 200~500ppm Bi 2 O 3 , 100~350ppm MoO 3 , 1000~2000ppm CoO.

2. The Mn-Zn ferrite material according to claim 1, It is characterized in that In terms of molar percentage, the main component consists of the following components: 52-53 mol% Fe 2 O 3 , 14-15 mol% ZnO, the rest is Mn 3 O 4 ; Preferably, in terms of molar percentage, the main component consists of the following components: 52.7-52.8 mol% of Fe 2 O 3 , 14.3-14.5 mol% ZnO, the rest is Mn 3 O 4 ; More preferably, Fe 2 O 3 The molar ratio to ZnO is (3.6~3.7):

1.

3. The Mn-Zn ferrite material according to claim 1 or 2, It is characterized in that The auxiliary component is composed of the following components in terms of weight percentage of the main component: 400-500 ppm of CaCO 3 , 400~500ppm Bi 2 O 3 , 200~300ppm MoO 3 , 1500~2000ppm CoO.

4. The Mn-Zn ferrite material according to any one of claims 1 to 3, It is characterized in that In terms of molar percentage, the main component consists of the following components: 52.8 mol% Fe 2 O 3 , 14.4 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary component is composed of the following components in terms of weight percentage of the main component: 400ppm of CaCO 3 , 400ppm Bi 2 O 3 , 200ppm MoO 3 , 2000ppm CoO; or In terms of molar percentage, the main component consists of the following components: 52.8 mol% Fe 2 O 3 , 14.4 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary component is composed of the following components in terms of weight percentage of the main component: 400ppm of CaCO 3 , 400ppm Bi 2 O 3 , 300ppm MoO 3 , 1500ppm CoO; or In terms of molar percentage, the main component consists of the following components: 52.7 mol% Fe 2 O 3 , 14.3 mol% ZnO, the rest Mn 3 O 4 ; and the auxiliary component is composed of the following components in terms of weight percentage of the main component: 500ppm of CaCO 3 , 400ppm Bi 2 O 3 , 200ppm MoO 3 , 2000ppm CoO.

5. The method for preparing the Mn-Zn ferrite material according to any one of claims 1 to 4, It is characterized in that The following steps are involved: Step S1: ball-milling each raw material of the main component to obtain a primary ball-milled material; Step S2: pre-sintering the primary ball-milled material to obtain a pre-sintered material; Step S3: mixing the pre-sintered material with various raw materials of auxiliary components and performing secondary ball milling to obtain secondary ball milled material; Step S4: mixing the secondary ball-milled material with a binder and spray granulating the mixture to obtain Mn-Zn ferrite particles; Step S5: pressing and molding the Mn-Zn ferrite particles to obtain a Mn-Zn ferrite green body; Step S6: sintering the Mn—Zn ferrite green body to obtain the Mn—Zn ferrite material.

6. The preparation method according to claim 5, It is characterized in that In the step S1, the first ball milling is a wet ball milling mixing; Preferably, the time of the wet ball milling mixing is 20 to 60 minutes, the frequency is 40 to 60 Hz, and the rotation speed is 200 to 300 r / min.

7. The preparation method according to claim 5 or 6, It is characterized in that In the step S2, the pre-burning temperature is 700-800°C, and the holding time is 2-4 hours.

8. The preparation method according to any one of claims 5 to 7, It is characterized in that In the step S3, the secondary ball milling is secondary wet ball milling mixing; Preferably, the secondary wet ball milling mixing time is 100 to 150 min, the frequency is 40 to 60 Hz, and the rotation speed is 200 to 300 r / min.

9. The preparation method according to any one of claims 5 to 8, It is characterized in that In the step S4, the weight of the binder accounts for 5-15wt% of the weight of the secondary ball mill; Preferably, the adhesive is glue PVA.

10. The preparation method according to any one of claims 5 to 9, It is characterized in that In the step S6, the sintering includes a first-stage sintering and a second-stage sintering performed sequentially, wherein the first-stage sintering includes sintering at 1350-1400°C for 6-8h in a nitrogen atmosphere and controlling the oxygen volume content to be 19-21vol%; the second-stage sintering includes sintering at 1350-1400°C for 1-2h in a nitrogen atmosphere and controlling the oxygen volume content to be 3-5vol%; and then cooling down at a balanced oxygen partial pressure to obtain the Mn-Zn ferrite material.

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