High-impedance high-permeability MnZn ferrite material and manufacturing method thereof

Abstract

The invention relates to the technical field of MnZn ferrite materials, and discloses a high-impedance and high-permeability MnZn ferrite material and a manufacturing method thereof.The material comprises main components and auxiliary components, the main components comprise 52.0-53.0 mol% of Fe2O3, 20-22 mol% of ZnO and the balance MnO, the auxiliary components comprise Ca2CO3, Nb2O5, SiO2, Bi2O3 and MoO3, the auxiliary components are calculated according to the weight percentage relative to the total amount of Fe2O3, MnO and ZnO, and the total amount of Fe2O3, Nb2O5, SiO2, Bi2O3 and MoO3 is 10-20 mol%. The manufacturing method comprises the following steps: burdening, pre-sintering, secondary sanding, granulating and forming, sintering and testing. Through reasonable doping, sanding and sintering processes, the magnetic conductivity of the material is improved, the frequency characteristic of the material is improved, the MnZn ferrite material suitable for existing mass production can be prepared at low cost, and the prepared material has high impedance and high magnetic conductivity in a wide frequency range.

Description

Technical Field

[0001] The invention relates to the field of MnZn ferrite materials, and in particular to a high-impedance and high-permeability MnZn ferrite material and a manufacturing method thereof. Background Art

[0002] The main application areas of high permeability ferrite materials include common mode filters, broadband transformers, and communication equipment and signal transmission equipment such as electromagnetic compatibility and anti-electromagnetic interference (EMI). In addition to considering the frequency characteristics of magnetic permeability, the device impedance must also be considered during application. The core impedance will affect the impedance matching of the circuit. If the impedance does not match, the circuit will not reach the maximum power output state, thereby reducing the utilization rate of electric energy. Only the optimal impedance value can maximize the output power, transmission efficiency and energy conversion of the circuit system. With the rapid development of electronic information technology, electronic devices are increasingly integrated, high-frequency and miniaturized, and various electromagnetic interference problems are becoming more and more serious. The simple pursuit of high permeability can no longer meet the requirements of electronic development. The research on high permeability MnZn ferrite materials has shifted to comprehensive performance, and the requirements for the performance of high permeability MnZn ferrite materials are becoming more and more stringent.

[0003] In addition to high magnetic permeability, the current high permeability MnZn ferrite also requires high impedance. The high impedance characteristic improves the material's ability to resist electromagnetic interference, so that the material can be used in a wider frequency range. However, the ferrite materials in the existing technology are difficult to fully meet such usage requirements. The products have problems such as poor stability, insufficient initial magnetic permeability, low high-frequency impedance, low pass rate, etc. Therefore, the development of a new ferrite material is a technical problem that needs to be solved urgently.

[0004] Patent No. CN1677579B discloses a broadband manganese-zinc high-permeability soft ferrite material. The material disclosed in the patent has a high initial permeability, but does not exhibit its impedance characteristics.

[0005] Therefore, a new technical solution is needed to solve the above technical problems. Summary of the invention

[0006] The purpose of the present invention is to provide a high-impedance and high-permeability MnZn ferrite material and a method for manufacturing the same. By reasonable doping, sanding and sintering processes, the material's magnetic permeability is increased, the material's frequency characteristics are improved, and a MnZn ferrite material suitable for existing large-scale production can be obtained at low cost. The obtained material has high impedance and high permeability in a wider frequency range.

[0007] The technical solution adopted by the present invention is:

[0008] A high-impedance and high-permeability MnZn ferrite material comprises a main component and an auxiliary component, wherein the main component comprises 52.0-53.0 mol% of Fe2O3, 20-22 mol% of ZnO, and the remainder is MnO, and the auxiliary component comprises 0.01-0.05 wt% of Ca2CO3, 0.01-0.03 wt% of Nb2O5, 0.002-0.006 wt% of SiO2, 0.01-0.5 wt% of Bi2O3, and 0.1-0.4 wt% of MoO3, and the auxiliary component is calculated in weight percentage relative to the total amount of Fe2O3, MnO, and ZnO.

[0009] Preferably, the main components are: 52.5 mol% Fe2O3, 21.5 mol% ZnO, and 26.0 mol% MnO.

[0010] By adopting the above materials, the prepared MnZn ferrite material has both high magnetic permeability and high impedance, thereby improving the material's ability to resist electromagnetic interference.

[0011] Preferably, a method for manufacturing a high impedance and high permeability MnZn ferrite material comprises the following steps:

[0012] Step 1: Ingredients: Mix Fe2O3, MnO and ZnO in proportion and put them into a ball mill, and mix them thoroughly to obtain powder;

[0013] Step 2: Pre-burning: pre-burn the powder obtained in step 1 for 1-1.5 hours;

[0014] Step 3: Secondary sand grinding: Add auxiliary components Ca2CO3, Nb2O5, SiO2, Bi2O3, MoO3 to the pre-burned material in proportion, then add deionized water for sand grinding for 1-2.5 hours, and then dry to obtain powder;

[0015] Step 4: Granulation and molding: add 10% of 8% polyvinyl alcohol aqueous solution to the powder obtained by secondary sand grinding, mix for 10-30 minutes, granulate after mixing evenly to obtain granules, and mold the granules into standard sample ring blanks;

[0016] Step 5: Sintering: The obtained green sample is sintered in air at a maximum temperature of 1350-1550°C, with a heating rate of 1.43-2.22°C / min, and kept at the sintering temperature, with an oxygen concentration Po2 of 5.00-5.80%, and then cooled at a rate of 2.43-2.63°C / min under a balanced oxygen concentration, cooled to 1000°C, and then cooled to room temperature in nitrogen at a cooling rate of 2.57-4.00°C / min;

[0017] Step 6: Test: Use instruments to test the impedance and magnetic permeability of the sintered sample ring.

[0018] Preferably, the mixing and crushing time of the ingredients in step 1 is 10-50 minutes.

[0019] Preferably, the pre-sintering temperature of the powder in step 2 is 890-1100°C.

[0020] Preferably, in step 4, the standard sample ring blank is a standard sample ring blank of H25*15*7.5 mm and has a density of 2.40-2.52 g / cm3.

[0021] Preferably, the sintering holding time in step 5 is 4-5 hours.

[0022] By adopting the above process, the MnZn ferrite material obtained has good stability, high initial magnetic permeability, strong high-frequency impedance and high qualified rate.

[0023] 1. The process of the present invention controls the addition range of the main component and the auxiliary component, so that the MnZn ferrite material obtained has both high magnetic permeability and high impedance, thereby improving the material's anti-electromagnetic interference ability. The magnetic permeability and impedance are tested at room temperature. The magnetic permeability is 7000-13000 at a frequency of 10KHz, the magnetic permeability is ≥9500 at a frequency of 200KHz, the impedance is ≥2000Ω at a frequency of 500KHz, and the impedance is ≥2500Ω at a frequency of 1M.

[0024] 2. The present invention promotes grain growth by adding the auxiliary component Bi2O3, thereby improving the magnetic permeability, adds the auxiliary component MoO3 to prevent abnormal grain growth and crystallization, adds the auxiliary components Ca2CO3 and SiO2 to form a CaSiO3 insulating layer in the grain boundary layer, thereby improving the resistivity and impedance, and adds the auxiliary component Nb2O5 to increase the grain boundary resistance, thereby improving the impedance.

[0025] 3. The process of the present invention controls the addition range of the main components and the auxiliary components to obtain the MnZn ferrite material with good stability, high initial magnetic permeability, strong high-frequency impedance, high qualified rate, and low cost in the production process. The obtained ferrite material can overcome the shortcomings of conventional ferrite materials and has the characteristics of high magnetic permeability and high impedance. DETAILED DESCRIPTION

[0026] The present invention provides a method for manufacturing a high-impedance and high-permeability MnZn ferrite material, comprising the following steps:

[0027] Step 1: Using commercially available Fe2O3 with a purity of ≥99.3%, MnO with a Mn content of ≥76.6%, and ZnO with a purity of ≥99.7% as the main components, Fe2O3, MnO, and ZnO are placed in a ball mill and mixed evenly according to the amounts shown in Table 1. The mixing and crushing time is 35 minutes, and the mixed powder is pre-calcined at 900°C for 1 hour;

[0028] Step 2: Based on the total weight of the pre-sintered powder, the additives: Ca2CO3, Nb2O5, SiO2, Bi2O3 and MoO3 shown in Table 1, as well as deionized water, a dispersant and a defoaming agent are added, and the sand grinding time is 2 hours, and then the powder is dried;

[0029] Step 3: Based on the total weight of the ball-milled powder, 10 wt% of a polyvinyl alcohol solution with a concentration of 8 wt% is added to the powder, the mixture is mixed and granulated, and the granulated material is pressed into a green sample ring using a 40-ton dry powder press;

[0030] Step 4: The obtained green sample was sintered in air at a maximum temperature of 1390°C, with a heating rate of 1.43°C / min, and kept at the sintering temperature for 5 hours, with an oxygen concentration Po2 of 5.80%, and then cooled at a rate of 2.43°C / min at a balanced oxygen concentration to 1000°C, and then cooled to room temperature in nitrogen at a cooling rate of 2.57°C / min;

[0031] Step 5: Use the American Agilent E4980A inductance meter to test the impedance and magnetic permeability of the sintered sample ring.

[0032] The above steps refer to the addition dosage in Table 1, and 17 groups of experiments are carried out:

[0033] Table 1:

[0034]

[0035] Through the above process, the magnetic permeability test results at different frequencies are shown in Table 2:

[0036] Table 2:

[0037] Frequency f(Hz) 10K 100K 200K 300K 400K 500K 1 10601 11145 9582 6937 4711 3190 2 9426 9900 9487 7962 6206 4608 3 8671 9074 8900 7520 5894 4436 4 8317 8622 8449 7032 5461 4152 5 7116 7313 7275 7049 6501 5897 6 7059 7273 7279 6963 6419 5817 7 6959 7023 6990 6783 6240 5619 8 9064 9566 9291 8003 6666 5287 9 7787 8205 8159 7363 6350 5267 10 7946 8373 8296 7442 6364 5202 11 9287 9818 9723 8668 7058 5601 12 8497 8976 8901 7942 6621 5172 13 7020 7168 7277 7084 6608 5930 14 6848 6988 7035 6835 6448 5926 15 7173 7276 7333 7076 6591 5943 16 7883 8271 8283 7590 6493 5272 17 9583 10047 9790 8864 7432 6125

[0038] Through the above process, the impedance (Ω) test results at different frequencies (test conditions 10Ts, 0.3V) are shown in Table 3:

[0039] Table 3:

[0040] Frequency f(Hz) 100K 500K 800K 1M 2M 1 514 1632 1743 1769 1764 2 449 1679 1868 1912 1929 3 405 1556 1736 1794 1856 4 384 1427 1595 1664 1783 5 338 1672 2352 2576 2276 6 334 1646 2309 2536 2273 7 328 1620 2240 2454 2249 8 439 1823 2103 2077 1907 9 404 1788 2216 2244 1986 10 400 1748 2113 2121 1915 11 443 1912 2206 2161 1918 12 433 1879 2190 2162 1902 13 325 1645 2299 2578 2471 14 315 1603 2362 2732 2657 15 326 1635 2331 2630 2430 16 427 1878 2290 2312 1979 17 456 2085 2534 2569 2161

[0041] The above experimental data show that by using appropriate main components and auxiliary components, the impedance and permeability of the material have been greatly improved. Example 17 has a starting permeability of more than 9500 and has a great advantage in impedance at 500kHz to 2MHz.

[0042] The process of the present invention controls the addition range of the main component and the auxiliary component, and the obtained MnZn ferrite material has both high magnetic permeability and high impedance, thereby improving the anti-electromagnetic interference ability of the material. The magnetic permeability and impedance are tested at room temperature, and the magnetic permeability is 7000-13000 at a frequency of 10KHz, the magnetic permeability is ≥9500 at a frequency of 200KHz, the impedance is ≥2000Ω at a frequency of 500KHz, and the impedance is ≥2500Ω at a frequency of 1M. The present invention promotes grain growth by adding the auxiliary component Bi2O3, thereby improving the magnetic permeability, adds the auxiliary component MoO3, prevents abnormal growth of grains from causing crystallization, adds the auxiliary components Ca2CO3 and SiO2, forms a CaSiO3 insulating layer in the grain boundary layer, thereby improving the resistivity and impedance, and adds the auxiliary component Nb2O5 to increase the grain boundary resistance, thereby improving the impedance.

[0043] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art. The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiments according to the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

[0044] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by those skilled in the art should be included in the protection scope determined by the claims of the present invention.

Claims

1. A high impedance and high permeability MnZn ferrite material, characterized in that: It includes main components and auxiliary components. The main component is composed of 52.0-53.0 mol% Fe2O3, 20-22 mol% ZnO, and the balance is MnO. The auxiliary component is composed of 0.01-0.05wt% Ca2CO3, 0.01-0.03wt% Nb2O5, 0.002-0.006wt% SiO2, 0.01-0.5wt% Bi2O3, and 0.1-0.4wt% MoO3. The auxiliary components are calculated in weight percentage relative to the total amount of Fe2O3, MnO, and ZnO.

2. The high impedance and high permeability MnZn ferrite material according to claim 1, characterized in that: The main components are preferably: 52.5 mol% Fe2O3, 21.5 mol% ZnO, and 26.0 mol% MnO.

3. A method for manufacturing a high impedance and high permeability MnZn ferrite material, characterized in that: The following steps are involved: Step 1: Ingredients: Mix Fe2O3, MnO and ZnO in proportion and put them into a ball mill, and mix them thoroughly to obtain powder; Step 2: Pre-burning: pre-burn the powder obtained in step 1 for 1-1.5 hours; Step 3: Secondary sand grinding: Add auxiliary components Ca2CO3, Nb2O5, SiO2, Bi2O3, and MoO3 to the pre-burned material in proportion, then add deionized water and sand grind together. The sand grinding time is 1-2.5 hours, and then dry to obtain powder; Step 4: Granulation and molding: add 10% of 8% polyvinyl alcohol aqueous solution to the powder obtained by secondary sand grinding, mix for 10-30 minutes, granulate after mixing evenly to obtain granules, and mold the granules into standard sample ring blanks; Step 5: Sintering: The obtained green sample is sintered in air at a maximum temperature of 1350-1550°C, with a heating rate of 1.43-2.22°C / min, and kept at the sintering temperature, with an oxygen concentration Po2 of 5.00-5.80%, and then cooled at a rate of 2.43-2.63°C / min under a balanced oxygen concentration, cooled to 1000°C, and then cooled to room temperature in nitrogen at a cooling rate of 2.57-4.00°C / min; Step 6: Test: Use instruments to test the impedance and magnetic permeability of the sintered sample ring.

4. The method for manufacturing a high impedance and high permeability MnZn ferrite material according to claim 3, characterized in that: The time for mixing and crushing the ingredients in step 1 is 10-50 minutes.

5. The method for manufacturing a high impedance and high permeability MnZn ferrite material according to claim 3, characterized in that: In step 2, the powder pre-sintering temperature is 890-1100°C.

6. The method for manufacturing a high impedance and high permeability MnZn ferrite material according to claim 3, characterized in that: In step 4, the standard sample ring blank is a standard sample ring blank with a size of H25*15*7.5 mm and a density of 2.40-2.52 g / cm3.

7. The method for manufacturing a high impedance and high permeability MnZn ferrite material according to claim 3, characterized in that: The sintering holding time in step 5 is 4-5 hours.

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