CN-118047601-B - Broadband high TcHigh-conductivity manganese zinc ferrite and preparation method thereof

Abstract

A broadband high T c high-conductivity Mn-Zn ferrite and a preparation method belong to the technical field of ferrite material preparation. The method adopts high specific surface area raw materials, increases the powder contact area in the ball milling process, is favorable for improving the reactivity and reducing the sintering temperature, adopts an iron-rich and zinc-deficient system in the main formula of the MnZn ferrite, enhances the super-exchange effect, is favorable for realizing the Curie temperature of the material, introduces a combined additive in the secondary ball milling, regulates and controls the grain growth mechanism in the sintering process by means of the dual effect of fluxing and crystal inhibition, compensates the magnetocrystalline anisotropy constant of the MnZn ferrite by means of Co 2 O 3 , improves the initial magnetic conductivity, introduces CaSiO 3 to enable the material to be enriched in the grain boundary in the sintering process, improves the resistivity of the grain boundary, improves the frequency characteristic of the magnetic conductivity, precisely controls the oxygen partial pressure in the heat preservation and cooling stage in the sintering process, influences the generation amount of Fe 2+ ions, improves the resistivity of the sample, and simultaneously is favorable for grain growth and material densification by virtue of the proper sintering temperature and heat preservation time.

Inventors

• YU ZHONG
• LAN ZHONGWEN
• YU YONG
• JIN HAIYANG
• ZHANG KAI
• WU CHUANJIAN
• ZHOU XIAOJUN
• SUN KE
• CHEN CHUANGXIN
• LI QIFAN
• JIANG XIAONA

Assignees

• 电子科技大学
• 乳源东阳光磁性材料有限公司

Dates

Publication Date

20260508

Application Date

20240306

Claims (5)

1. 1. The preparation method of the broadband high-T c high-conductivity manganese zinc ferrite is characterized by comprising the following steps of: Step 1, batching: taking Fe 2 O 3 , znO and MnO as raw materials, calculating and weighing the raw materials according to a main formula of '51.8-54.0 mol% of Fe 2 O 3 and 16.5-18.0 mol% of ZnO, and the balance of MnO'; Step 2, ball milling for the first time: Performing primary ball milling on the raw materials weighed in the step 1 for 1-2 hours to obtain a primary ball grinding material; Step3, presintering: Drying and sieving the primary ball milling material obtained in the step 2, and presintering the material in an air atmosphere for 3-4 h; step 4, doping: taking the mass of the pre-sintered material obtained in the step 3 as a reference, adding "0.01~0.02wt％Co 2 O 3 、0.01~0.02wt％Nb 2 O 5 、0.03~0.05wt％Bi 2 O 3 、0.02~0.04wt％MoO 3 and 0.01-0.03wt% of CaSiO 3 ' into the pre-sintered material as additives; Step 5, performing secondary ball milling; performing secondary ball milling on the mixed powder obtained in the step 4 for 2-4 hours; step 6, granulating and molding: Adding PVA adhesive into the secondary ball milling material obtained in the step 5, uniformly mixing, granulating, and pressing on a press to obtain a green blank; Step 7, sintering: And (3) sintering the green part obtained in the step (6) in stages, and then cooling to obtain the manganese zinc ferrite, wherein the process of sintering in stages is as follows: the first stage, namely heating the mixture from 50 ℃ to 500-600 ℃ and ensuring that the oxygen partial pressure is 21%; The second stage, continuously heating to 700-850 ℃ and enabling the oxygen partial pressure to be 21%; the third stage, continuously heating to the sintering temperature of 1300-1450 ℃ and the oxygen partial pressure of 21%; and a fourth step of keeping the sintering temperature unchanged and preserving the temperature for 6-8 hours, wherein the oxygen partial pressure is kept at 21% in the first 5-6 hours and kept at 12% in the second 2-3 hours.
2. 2. The preparation method of the broadband high-T c high-conductivity manganese-zinc ferrite according to claim 1, wherein in the step 7, the temperature-reducing stage is that the sintering temperature is reduced to 1300 ℃, the oxygen partial pressure is gradually reduced to 5%, then the temperature is continuously reduced to 1100-1300 ℃, the oxygen partial pressure is gradually reduced to 1%, the temperature is continuously reduced to 950-1100 ℃, the oxygen partial pressure is gradually reduced to 0.1%, the oxygen partial pressure is pure nitrogen atmosphere after the temperature is continuously reduced to 850 ℃, and the temperature is reduced to 50 ℃ under the pure nitrogen atmosphere.
3. 3. The method for preparing broadband high-T c high-conductivity Mn-Zn ferrite according to claim 1, wherein in the step2, the ball milling rotation speed is 230-260 r/min.
4. 4. The method for preparing broadband high-T c high-conductivity Mn-Zn ferrite according to claim 1, wherein in step 3, the pre-sintering temperature is 800-900 ℃.
5. 5. The method for preparing broadband high-T c high-conductivity Mn-Zn ferrite according to claim 1, wherein in step 5, the ball milling rotation speed is 240-270 r/min.

Description

Broadband high-T c high-conductivity manganese zinc ferrite and preparation method thereof Technical Field The invention belongs to the technical field of ferrite material preparation, and particularly relates to a MnZn ferrite material with broadband, high Curie temperature and high magnetic conductivity and a preparation method thereof. Background Since the nations propose the strategic emerging industry to accelerate the cultivation and development, the overall strategic emerging industry in China presents a continuously and rapidly growing trend, and remarkable effects are achieved. In the fields of various communication, electronics, instruments, military, medical treatment, automobiles, new energy sources, industrial control and the like, a filter is required to cut off and attenuate an interference signal in a control circuit so as to achieve the purposes of reducing noise and inhibiting electromagnetic interference, and the filter plays an important role in the stability of electronic products. Common mode filter inductance modules are indispensable key elements, and along with the development of the modern electronic industry to miniaturization, high frequency, high reliability and the like, the miniaturization of filter inductances is also urgent. The development of industry puts higher demands on the high permeability MnZn ferrite, a key core material for use in filter inductor devices, which is directly related to the inductive performance. Compared with other soft magnetic materials, the MnZn ferrite has the advantage of relatively higher magnetic permeability, so that higher inductance can be generated under the condition of the same device geometric dimension and winding turns, higher impedance value is obtained, the filtering effect is enhanced, and the miniaturization of the device is facilitated. However, simply pursuing high permeability cannot meet the future development requirements, and high curie temperature, a wide application temperature range and high saturation induction are required to meet the multi-scene requirements of the device. At the same time, the material is required to be designed to have certain EMI characteristics, namely magnetic permeability frequency stability. Therefore, it is also desirable to have a high cutoff frequency and excellent permeability frequency characteristics. Aiming at the research of a broadband high-T c high-cutoff frequency high-conductivity MnZn ferrite material, the Chinese patent publication No. CN 111056830A discloses a wide-temperature broadband high-impedance high-permeability manganese zinc ferrite and a preparation method thereof, wherein the functional components comprise 56.0-60.0mol% of Fe 2O3 and equal mole percent of MnO and ZnO calculated by respective oxides. The auxiliary component accounts for 5-10% of the total mass of the functional component. The auxiliary components comprise TiO 2、NiO、MoO3、SiO2 and Bi 2O3. The preparation method of the oxide ceramic has the advantages that the high specific surface area raw material and the optimized oxide ceramic preparation method are utilized, the high impedance and inductance stability are achieved under the condition of keeping the relatively high initial permeability and Curie temperature, meanwhile, the high temperature change resistance performance is achieved, and the applicable working conditions are widened. The initial magnetic permeability of the embodiment is 11800 (1.0 KHz,0.3V and 23+/-3 ℃), the Curie temperature is 133 ℃, the saturation magnetic induction intensity is 410mT (H=1194A/m and 25 ℃), the density is 4.75g/cm 3, meanwhile, the impedance value is greatly improved, the magnetic permeability stability in a wide temperature range is good, and the comprehensive performance is comprehensive. Unfortunately, both its curie temperature and saturation induction are low. The main component of the MnZn soft magnetic ferrite disclosed in China patent publication No. CN 112723873A is 52.5-53.9mol% of Fe 2O3, 21.3-23.30mol% of ZnO and the balance of MnO. The additive comprises 400-1000 ppm of nano CaCO 3, 100-600 ppm of nano Bi 2O3, 100-350 ppm of nano Nb 2O5, 20-150 ppm of nano SiO 2 and 100-500 ppm of nano MoO 3. The MnZn ferrite with wide frequency band, high magnetic conductivity and high impedance is prepared by doping proper main components and nano additives and comprehensively adopting the processes of grinding by a bead mill and oxygen-enriched sintering. Under the conditions of 8mV and 10KHz, the magnetic permeability mu i is more than or equal to 15000, when the magnetic permeability mu i is more than or equal to 10000, and when the magnetic permeability mu i is more than or equal to 5000, the impedance coefficient has larger advantages, and the comprehensive performance is better. But its curie temperature is low, only 130 ℃, which greatly limits the application scenarios. The invention discloses a manganese zinc ferrite material with broadband high T c and high magn