CN114685153A

CN114685153A - Wide-temperature wide-band MnZn power ferrite material and preparation method thereof

Info

Publication number: CN114685153A
Application number: CN202210326133.2A
Authority: CN
Inventors: 余忠; 易耀华; 王宏; 邬传健; 窦海之; 孙科; 杨仕机; 兰中文; 蒋晓娜; 余勇
Original assignee: Sunshine Electronic Technology Co ltd; University of Electronic Science and Technology of China
Current assignee: Sunshine Electronic Technology Co ltd; University of Electronic Science and Technology of China
Priority date: 2022-03-30
Filing date: 2022-03-30
Publication date: 2022-07-01
Anticipated expiration: 2042-03-30
Also published as: CN114685153B

Abstract

A wide-temperature broadband MnZn power ferrite material relates to the technical field of ferrite material preparation. The wide-temperature broadband MnZn power ferrite material comprises a main component and an additive, and is characterized in that the main component comprises 51.5-53.0 mol% of Fe₂O₃And ZnO of 10.0-12.0 mol%, the rest is MnO; the additive comprises 0.02-0.08 wt% of CaCO based on the weight of the pre-sintered main component₃、0.01～0.05wt％Nb₂O₅、0.01～0.05wt％ZrO₂、0.3～0.5wt％Co₂O₃0.01 to 0.02 wt% of NiO and 0.001 to 0.012 wt% of BTO-based PTC dielectric ceramic powder. The invention improves the stability of magnetic conductivity, and particularly reduces the loss in a wide temperature range of 25-140 ℃ and a wide frequency range of 100-300kHz at the same time.

Description

Wide-temperature wide-band MnZn power ferrite material and preparation method thereof

Technical Field

The invention relates to the technical field of ferrite material preparation.

Background

In recent years, a number of emerging industries such as 5G communication, new energy vehicles, high-density assembled flat panel displays and the like appear in China. Emerging industries have put higher requirements on the aspects of volume, weight, reliability and the like of an electronic complete machine system, and the requirements are not only small size, but also high-temperature reliability and strong electromagnetic compatibility. An increase in the switching frequency leads to an increase in the losses of the magnetic element and also to an increase in the drive losses, which directly reduces the efficiency of the switching power supply. In general, the loss and volume of the magnetic element account for most of the total loss and volume of the switching power supply, and the volume, weight and efficiency of the magnetic element become bottlenecks which limit the miniaturization and high efficiency of the switching power supply. Based on the fact that the switching power supply puts forward higher and higher requirements on the size, power loss and reliability of a magnetic element, the MnZn power ferrite material serving as the core of the switching power supply cannot meet the requirement of development of electronic equipment when the high permeability is simply pursued, and the requirements on the application of specific frequency and the wide-temperature and wide-frequency characteristics are met.

Chinese patent publication No. CN 112979301A, discloses a high-frequency high-temperature low-loss MnZn power ferrite material and a preparation method thereof, and the main component of the MnZn power ferrite material comprises Fe₂O₃53.5-56.5 mol%, MnO32.5-35.5 mol%, ZnO9.0-12.0 mol%; the additive comprises 0.06-0.12 wt% of CaCO₃、0.01～0.04wt％V₂O₅、0.10～0.40wt％TiO₂、0.02～0.08wt％SnO₂、0.20～0.55wt％Co₂O₃、0.01～0.06wt％BaTiO₃(BTO)、0.1～0.3wt％CaCu₃Ti₄O₁₂(CCTO). The application frequency of the MnZn power ferrite prepared by jointly doping the BTO and CCTO with high resistance is MHz level. For another example, the Chinese patent publication No. CN 108530050A discloses a wide-temperature range low-loss high-impedance MnZn soft magnetic ferrite material and a preparation method thereof, wherein the main material comprises Fe₂O₃52.0-55.0 mol% of ZnO9.5-12.5 mol% of MnO and 0.03-0.05 wt% of CaO as an auxiliary material, wherein the balance is MnO; the additive comprises 0.001-0.05 wt% of nano BaTiO₃、0.001～0.05wt％Bi₂O₃、0.001～0.035wt％CaO、0.001～0.02wt％Nb₂O₅、0.003～0.2wt％HfO₂、0.08～0.3wt％Co₂O₃. The characteristic of high resistivity of BTO is still only utilized, the contact with the particle material is increased through the nano BTO powder, the grain boundary resistivity of MnZn ferrite is increased, and the prepared material has the performance of only 100kHz 200mT, so that the application of the material is limited.

In the research of low-Loss MnZn power Ferrite material, the microwave Magnetic material and the integrated circuit center of the northeast university of America disclose a method for reducing the eddy current Loss of MnZn power Ferrite (Andalib P, Chen Y, Harris V G. Current Core Loss supression and High Permeability by Introduction of High purity Insulating Magnetic Inclusions to MnZn Ferrite [ J]IEEE Magnetics Letters,2018,9:1-5.) which exploits the non-magnetic and high resistivity properties of BTO by coupling with yttrium iron garnet ferrite YIGThe mixed doping is carried out, the eddy current loss is obviously reduced, and the loss of the prepared MnZn power ferrite is 195mW/cm³(500kHz 30mT, 25 ℃). China university of electronic technology has published a high frequency MnZn power ferrite material (Wu G H, Yu Z, Sun K, et al. ultra-low core wires at high frequencies and temperatures in MnZn ferrite with Nano-BaTiO3 additives-scientific direct [ J]Journal of Alloys and Compounds,821.) that utilizes dielectric material BTO to suppress high frequency and high temperature magnetic losses of MnZn ferrite, the performance indexes of the prepared MnZn power ferrite are: under the condition of 3MHz and 30mT, the loss at 25 ℃ and 100 ℃ is 320mW/cm respectively³And 890mW/cm³。

China university of science and technology discloses a method for normal temperature Curie point ceramic PTC (Songjia beam, normal temperature PTC thermal control material and thermal control method research thereof [ D)]2016.) having the formula 0.7mol BaCO₃+0.3molSrCO₃+1.01molTiO₂+0.001～0.004molY₂O₃+0.005molAl₂O₃+0.024molSiO₂. The preparation process comprises the following steps: mixing BaCO₃、SrCO₃、TiO₂And Y₂O₃Weighing according to the set mol percentage, pre-sintering at 1150 ℃ after one-time grinding to obtain BaTiO₃A main crystalline phase; the two-grinding ingredient is prepared by mixing Al according to a set molar ratio₂O₃、SiO₂Adding into the pre-sintered material, granulating, molding, and air sintering at 1350 deg.C to obtain BaTiO with Curie temperature of more than 45 deg.C₃A base ceramic PTC material. Nanjing university of science and technology discloses a formula of low Curie point ceramic PTC (Zhang hong Liang positive temperature coefficient heat-sensitive material preparation and research [ D)]2019.), the formula is shown as follows: 65 mol% BaCO₃+35mol％SrCO₃+100mol％TiO₂+xmol％Nb₂O₅+ymol％Ce₂O₃+1mol％TiO₂+0.5mol％Al₂O₃+2.4mol％SiO₂Wherein x is 0.2 and y is 0.2-0.3. Preparing BaTiO with Curie temperature of 50-90 DEG C₃Based on PTC ceramic materials. Huazhong university of science and technology also discloses a method for sintering PTC ceramic at low temperature (Kongming Ri, Jiangsheng, Tuwenfang, BaO-B)₂O₃-SiO₂SiO in glass additive₂Effect on Low temperature sintering PTCR ceramic Properties [ J]Material report, 2009,23(12):68-70+74.), formulated as follows: (Ba)_0.75Sr_0.25)Ti_1.02O₃+ 0.6% (mole fraction) Y₂O₃The preparation process comprises the following steps: the main formula is BaCO₃、SrCO₃、TiO₂And Y₂O₃Weighing according to the set mol percentage, pre-burning at 1150 ℃ after first grinding; the 3 percent of glass additive BaB is added into the mixture of the two mills₂O₄Adding the mixture into a pre-sintering material, drying, granulating and forming a secondary grinding material, and sintering in air at 970-1250 ℃ to obtain BaTiO with the Curie temperature of about 97 DEG C₃A base ceramic PTC material.

The materials of the existing patents related to the barium titanate PTC ceramic, such as a PTC thermistor ceramic material and a preparation method and application thereof disclosed in Chinese patent publication No. CN 112694325A, and a barium titanate PTC thermistor ceramic material and application thereof in a lithium battery disclosed in patent publication No. CN113651612A, are all composed of barium titanate-based ceramic powder and additives, are mainly applied to PTC thermistor elements, and effectively block thermal runaway generated by electronic circuits by utilizing PTC effect of which the resistivity is sharply increased along with temperature rise, so that the current-limiting and thermal-protecting effects are realized, and the safety and reliability of electronic equipment are improved.

In summary, the prior patents and studies, BaTiO₃Added as an additive to MnZn power ferrite, only utilizes the high resistivity characteristic of BTO, and BaTiO₃The base PTC ceramic is generally used for a thermosensitive element to play a role in current limiting and thermal protection, and the improvement research on the wide-temperature and wide-frequency characteristics of MnZn power ferrite by utilizing the PTC effect of BTO base dielectric ceramic is not carried out at present.

Disclosure of Invention

The invention aims to solve the technical problem of solving the key technical problem that the resistivity of MnZn ferrite is sharply reduced along with the rise of temperature, and provides a wide-temperature broadband MnZn power ferrite material and a preparation method thereof.

The technical scheme adopted by the invention for solving the technical problems is that the wide-temperature wide-band MnZn power ferrite material comprises main components and additives and is characterized in that,

the main component comprises 51.5 to 53.0 mol% Fe₂O₃And 10.0-12.0 mol% ZnO, and the balance MnO;

based on the weight of the pre-sintered main component, the additive comprises: 0.02 to 0.08 wt% of CaCO₃、0.01～0.05wt％Nb₂O₅、0.01～0.05wt％ZrO₂、0.3～0.5wt％Co₂O₃0.01 to 0.02 wt% of NiO and 0.001 to 0.012 wt% of BTO-based PTC dielectric ceramic powder.

Furthermore, the content of the BTO-based PTC dielectric ceramic is 0.002-0.004 wt%.

Further, in the main component, Fe₂O₃52.5 mol% and 11.5 mol% of ZnO;

the additive comprises the following components: 0.02 to 0.08 wt% of CaCO₃、0.01～0.05wt％Nb₂O₅、0.01～0.05wt％ZrO₂、0.3～0.5wt％Co₂O₃0.01 to 0.02 wt% of NiO and 0.001 to 0.012 wt% of BTO-based PTC dielectric ceramic powder.

The invention also provides a preparation method of the wide-temperature broadband MnZn power ferrite material, which comprises the following steps:

(1) preparation of BTO dielectric ceramic powder

By high temperature solid phase method with BaCO₃、SrCO₃And TiO₂As a raw material, xmol% BaCO as a main component₃：ymol％SrCO₃：zmol％TiO₂Weighing the raw materials according to the proportion, wherein x is 30-40, y is 10-20, and z is 45-55; after primary ball milling, preserving heat for 0.5-1 h at 1000-1200 ℃ to finish pre-sintering to obtain BaTiO₃Pre-sintering a main crystal phase;

with BaTiO₃Taking the main crystal phase pre-sintering material as the reference of the molar ratio, and adding 0.1-0.3 mol% of Y₂O₃、0.1～0.3mol％Al₂O₃、1～5molSiO₂Adding to BaTiO₃Carrying out secondary ball milling on the main crystal phase pre-sintered material, granulating, sintering in air at 1300-1400 ℃ for 2-5 h, and grinding to obtain BTO-based PTC dielectric ceramic powder with the particle size of 0.5-1 mu m;

with BaTiO₃The main crystal phase pre-sintering material is taken as a molar ratio reference and is based on BaTiO₃(abbreviated as BTO) main crystal phase pre-sintering material is a denominator calculated by molar ratio, for example, 100mol of BTO main crystal phase pre-sintering material is added with Y₂O₃0.1～0.3mol，SiO₂1 to 5mol, based on the molar ratio of the BTO main crystal phase pre-sintered material, Y₂O₃In an amount of 0.1 to 0.3 mol%, SiO₂1 to 5 mol%.

(2) Preparation of MnZn ferrite pre-sintering material

Fe in an amount of 51.5 to 53.0 mol% based on the main component₂O₃Weighing the main component raw materials according to the proportion of ZnO accounting for 10.0-12.0 mol% and MnO accounting for the rest, performing primary ball milling, and pre-sintering at the temperature of 860-920 ℃ for 1-3 h to obtain a MnZn power ferrite pre-sintered material;

(3) doping treatment

Taking the weight of the MnZn power ferrite pre-sintering material obtained in the step 2) as a reference standard, adding the following additives: 0.02 to 0.08 wt% of CaCO₃、0.01～0.05wt％Nb₂O₅、0.01～0.05wt％ZrO₂、0.3～0.5wt％Co₂O₃0.01-0.02 wt% of NiO, 0.001-0.012 wt% of BTO-based PTC dielectric ceramic powder, and performing secondary ball milling;

"the weight of MnZn power ferrite is used as a reference" means that the weight of the main component is used as a denominator and the additive is used as a numerator, and for example, the weight of the main component is 100g, the weight of the BTO-based PTC dielectric ceramic powder is 0.004g, and the BTO ratio is 0.004 wt% based on the weight of the main component.

(4) Sample shaping

Drying the ball-milled material obtained by the secondary ball milling, granulating, and forming a green body;

(5) sintering

And (3) placing the molded green part in an atmosphere sintering device for staged sintering treatment:

the first stage is as follows: heating from 50 ℃ to 800-950 ℃, wherein the oxygen partial pressure is 21%;

and a second stage: continuously heating to 950-1250 ℃ with oxygen partial pressure of 0.05-1%;

and a third stage: preserving the heat for 6-10 h at the sintering temperature of 1250-1320 ℃, and controlling the oxygen partial pressure to be 2-5%; then increasing the sintering temperature by 20-100 ℃, preserving the heat for 1-3 hours, and controlling the oxygen partial pressure to be 1-4%;

a fourth stage: and (5) cooling. The temperature rate is controlled to be-0-3 ℃/min, and the temperature reduction oxygen partial pressure is less than 1%.

The range denoted by "-" in the present invention includes numerical values at both ends of the range, e.g. "SiO₂The range defined as 1 to 5 mol% includes 1 mol% and 5 mol%.

Compared with the prior art, the invention has the following beneficial effects:

(1) the MnZn power ferrite material provided by the invention has magnetic conductivity mu_i＝3300±15％(25～140℃，f＝10kHz)，B_s> 530mT (25 ℃, f 1kHz, H1194A/m). The requirements of high magnetic conductivity and high saturation magnetic induction intensity of the broadband switching power supply can be met.

(2) By BaTiO₃The PTC effect of the base dielectric ceramic improves the stability of magnetic conductivity, particularly reduces the loss in a wide temperature range of 25-140 ℃ and a wide frequency range of 100-300kHz, and improves the reliability of an electronic system.

Drawings

Fig. 1 is a temperature characteristic diagram of resistivity of a general BTO-based ceramic (left).

FIG. 2 is a temperature characteristic diagram of resistivity of BTO-based dielectric ceramics (right) used in the present invention.

FIG. 3 is a graph showing the temperature characteristics of loss of comparative example 1 and examples 1 and 2 at 100kHz-200 mT.

FIG. 4 is a graph showing the loss temperature characteristics of comparative example 1 and examples 1 and 2 at 200kHz-125 mT.

FIG. 5 is a graph showing the loss temperature characteristics of comparative example 1 and examples 1 and 2 at 300kHz-100 mT.

FIG. 6 is a graph showing the loss ratios of comparative example 1 and example 1 to example 2 at 300kHz-100 mT.

Fig. 7 is a graph showing the initial permeability temperature characteristics of comparative example 1 and examples 1 and 2.

Fig. 8 is a graph of resistance separation for comparative example 1 and examples 1 and 2.

FIG. 9 is a SEM micrograph of comparative example 1 and examples 1 and 2.

Detailed Description

The wide-temperature broadband MnZn power ferrite material comprises a main component and an additive, wherein the main component comprises 51.5-53.0 mol% of Fe₂O₃And ZnO of 10.0-12.0 mol%, the rest is MnO;

Further, in the main component, Fe₂O₃52.5 mol% and 11.5 mol% of ZnO;

The invention also provides a preparation method of the wide-temperature broadband MnZn power ferrite, which comprises the following preparation steps:

(1)BaTiO₃preparation of base PTC dielectric ceramic powder

By high temperature solid phase method with BaCO₃、SrCO₃And TiO₂As a raw material, BaCO was contained in an amount of 35 mol% based on the main component₃：15mol％SrCO₃：50mol％TiO₂Weighing the raw materials in proportion; after one grinding, the temperature is kept at 1150 ℃ for 0.5h to finish pre-sintering to obtain BaTiO₃A main crystalline phase; grinding the mixture twice to obtain 0.25 mol% of Y₂O₃、0.25mol％Al₂O₃、1.2mol％SiO₂Adding into pre-sintered material, granulating, molding, and air sintering at 1350 deg.C for 2 hr to obtain BaTiO with PTC effect₃A base dielectric ceramic. Finally grinding itObtaining BaTiO with the grain diameter of 0.5-1 mu m₃Based PTC dielectric ceramic powder.

(2) Preparation of MnZn ferrite pre-sintering material

With Fe₂O₃ZnO and MnO as raw materials, 52.5 mol% Fe as a main component₂O₃And ZnO of 11.5mol percent, and MnO in balance;

performing primary ball milling on the powder in a planetary ball mill for 2 hours (h is hour);

and after drying and sieving the obtained ball-milled material, presintering for 2 hours at the temperature of 900 ℃ to obtain the MnZn power ferrite presintering material.

(3) Doping treatment

Taking the MnZn power ferrite pre-sintering material obtained in the step 2) as a reference standard, carrying out the embodiment, wherein the additive content is shown in the following table:

carrying out secondary ball milling on the pre-sintered material and each group of additives in a planetary ball mill for 3 hours;

(4) sample shaping

Drying the ball milling material obtained by the secondary ball milling, and adding 12 wt% of PVA organic binder according to the weight percentage for granulation;

and pressing the obtained granulated material into a required sample green body according to the required sample shape, wherein the forming pressure is 6 MPa.

(5) Sintering of the sample

And placing the formed green part in an atmosphere sintering device for staged sintering treatment.

The first stage is as follows: and (5) a glue discharging stage. Heating from 50 ℃ to 900 ℃, wherein the oxygen partial pressure is 21%;

and a second stage: and (3) a densification stage. Continuously heating to 1250 ℃, wherein the oxygen partial pressure is 0.05%;

and a third stage: and (5) a heat preservation stage. Firstly, heat preservation is carried out for 6 hours at the sintering temperature of 1250 ℃, and the oxygen partial pressure is controlled to be 3 percent;

then preserving the heat for 1h at 1285 ℃, and controlling the oxygen partial pressure to be 2.5%;

a fourth stage: and (5) cooling. The temperature rate is controlled to be-2 ℃/min, and the temperature reduction oxygen partial pressure is 0.05 percent.

(6) Testing

The inductance L of the MnZn power ferrite sample is tested by adopting a homonymy TH2826 precision LCR tester and converted into initial permeability; the basic magnetic properties of the sample were tested using a Kawasaki SY 8232B-H analyzer.

Experiment and data

Basic properties of the examples and comparative examples:

fig. 1 and 2 show that the curie temperature of the BTO dielectric ceramic having the PTC effect is about 80 ℃, and the resistivity thereof sharply increases in an order of magnitude after exceeding the curie temperature, whereas the resistivity of the general BTO ceramic maintains the same order of magnitude as the temperature increases, and gradually decreases after exceeding 80 ℃.

Fig. 3 to 5 show that the losses of the MnZn power ferrite of the examples and the comparative examples are not much different at normal temperature, but the losses of the high temperature zone and the high frequency zone are obviously improved.

Fig. 6 shows that the embodiment has reduced proportion of ferrite eddy current loss and improved broadband performance after adding BTO dielectric ceramic with PTC effect.

FIG. 7 shows μ for an example_ithe-T curve is smoother than that of the comparative example, and has better wide-temperature and wide-frequency characteristics.

FIG. 8 shows that the grain boundary resistance of the high-temperature section of the embodiment is increased, so that the decrease rate of the resistivity of the ferrite along with the increase of the temperature can be reduced, and the high-temperature loss can be reduced.

FIG. 9 shows that the crystal grains of the example are finer, more compact and more uniform than those of the comparative example.

Claims

1. The wide-temperature broadband MnZn power ferrite material comprises a main component and an additive, and is characterized in that the main component comprises 51.5-53.0 mol% of Fe₂O₃And ZnO of 10.0-12.0 mol%, the rest is MnO;

the additive comprises 0.02-0.08 wt% of CaCO based on the weight of the pre-sintered main component₃、0.01～0.05wt％Nb₂O₅、0.01～0.05wt％ZrO₂、0.3～0.5wt％Co₂O₃0.01 to 0.02 wt% of NiO and 0.001 to 0.012 wt% of BTO-based PTC dielectric ceramic powder.

2. The wide-temperature broadband MnZn power ferrite material as claimed in claim 1, wherein the BTO-based PTC dielectric ceramic is contained in an amount of 0.002-0.004 wt%.

3. The wide-temperature broadband MnZn power ferrite material as claimed in claim 1, wherein,

in the main component, Fe₂O₃52.5mol percent of ZnO, 11.5mol percent of ZnO and the balance of MnO;

the additive comprises the following components in percentage by weight:

0.02wt％CaCO₃、

0.02wt％Nb₂O₅、

0.01wt％ZrO₂、

0.3wt％Co₂O₃、

0.01wt％NiO；

0.004 wt% of a BTO-based PTC dielectric ceramic.

4. The preparation method of the wide-temperature broadband MnZn power ferrite material is characterized by comprising the following steps of:

(1) preparation of BTO dielectric ceramic powder

By high temperature solid phase method with BaCO₃、SrCO₃And TiO₂As raw material, BaCO according to molar ratio₃:SrCO₃:TiO₂Weighing raw materials according to the proportion of x to y to z, wherein x is 30-40, y is 10-20, and z is 45-55; aAfter secondary ball milling, preserving heat for 0.5-1 h at 1000-1200 ℃ to finish pre-sintering to obtain a BTO main crystal phase pre-sintered material;

taking BTO main crystal phase pre-sintering material as a molar ratio reference, and adding 0.1-0.3 mol% of Y₂O₃、0.1～0.3mol％Al₂O₃、1～5mol％SiO₂Adding the mixture into a pre-sintered material of a BTO main crystal phase for secondary ball milling, granulating and sintering the mixture for 2 to 5 hours at 1300 to 1400 ℃ in air to obtain BaTiO with PTC effect₃A base dielectric ceramic; finally grinding the ceramic powder to obtain BTO-based PTC dielectric ceramic powder with the particle size of 0.5-1 mu m;

(2) preparation of MnZn ferrite pre-sintering material

With Fe₂O₃ZnO and MnO as raw materials, based on 51.5-53.0 mol% Fe₂O₃Weighing the raw materials according to the proportion of ZnO accounting for 10.0-12.0 mol% and MnO in balance, carrying out primary ball milling, drying, and presintering at 860-920 ℃ for 1-3 h to obtain a ferrite presintering material;

(3) doping treatment

Taking the ferrite pre-sintering material obtained in the step 2) as a weight reference standard, adding the following additives: 0.02 to 0.08 wt% of CaCO₃、0.01～0.05wt％Nb₂O₅、0.01～0.05wt％ZrO₂、0.3～0.5wt％Co₂O₃0.01-0.02 wt% of NiO, 0.001-0.012 wt% of BTO-based PTC dielectric ceramic powder, and performing secondary ball milling;

(4) pressing and forming;

(5) and (4) sintering at high temperature.

5. The preparation method of the wide-temperature broadband MnZn power ferrite material according to claim 4, wherein in the step (5), the sintering temperature is 1250-1320 ℃, and the heat preservation time is 6-10 h; the sintering oxygen partial pressure is controlled to be 2-5%.

6. The method for preparing a wide-temperature broadband MnZn power ferrite material according to claim 4, wherein in the step (5), the sintering temperature is 1320 ℃, and the heat preservation time is 7 h; the sintering oxygen partial pressure was controlled to 3%.