MnZn FERRITE MATERIAL WITH WIDE TEMPERATURE RANGE AND LOW CONSUMPTION, AND PREPARATION METHOD THEREOF

Abstract

The MnZn ferrite material includes principal components and auxiliary components, where the principal components include: 52.5 mol % to 53.8 mol % of Fe.sub.2O.sub.3, 8.8 mol % to 12 mol % of ZnO, and the balance of MnO; the auxiliary components include: 0.35 wt % to 0.5 wt % of Co.sub.2O.sub.3, 0.03 wt % to 0.08 wt % of CaSiO.sub.3, 0.01 wt % to 0.04 wt % of Nb.sub.2O.sub.5, and 0.05 wt % to 0.12 wt % of TiO.sub.2 and RE elemental components; the RE elemental components include one or more from the group consisting of 0 wt % to 0.04 wt % of Gd.sub.2O.sub.3, 0 wt % to 0.02 wt % of HO.sub.2O.sub.3, and 0 wt % to 0.03 wt % of Ce.sub.2O.sub.3; the auxiliary components are all represented by a mass percentage relative to a total mass of the Fe.sub.2O.sub.3, the MnO, and the ZnO.

Claims

1. A MnZn ferrite material with a wide temperature range and low consumption, comprising principal components and auxiliary components, wherein the principal components comprise: 52.5 mol % to 53.8 mol % of Fe.sub.2O.sub.3, 8.8 mol % to 12 mol % of ZnO, and the balance of MnO; the auxiliary components comprise: 0.35 wt % to 0.5 wt % of CO.sub.2O.sub.3, 0.03 wt % to 0.08 wt % of CaSiO.sub.3, 0.01 wt % to 0.04 wt % of Nb.sub.2O.sub.5, and 0.05 wt % to 0.12 wt % of TiO.sub.2 and RE elemental components; the RE elemental components comprise one or more selected from the group consisting of 0 wt % to 0.04 wt % of Gd.sub.2O.sub.3, 0 wt % to 0.02 wt % of HO.sub.2O.sub.3, and 0 wt % to 0.03 wt % of Ce.sub.2O.sub.3; and the auxiliary components are represented by a mass percentage relative to a total mass of the Fe.sub.2O.sub.3, the MnO, and the ZnO.

2. A preparation method of the MnZn ferrite material according to claim 1, comprising the following steps: (1) preparing the principal components Fe.sub.2O.sub.3, MnO, and ZnO according to a proportion of the principal components, mixing the principal components through one-time grinding to obtain a uniform mixed powder, and conducting pre-sintering to obtain at least two MnZn ferrite pre-sintered materials with a spinel structure and an activity span by changing pre-sintering conditions; (2) thoroughly mixing the at least two MnZn ferrite pre-sintered materials obtained under different pre-sintering conditions in a specified ratio to obtain a mixed material; (3) adding the auxiliary components designed according to a proportion of the auxiliary component to the mixed material, and further grinding to a particle size D50 of 1.2 μm to 1.6 μm to obtain a slurry; (4) drying the slurry obtained from the grinding, adding 15% PVA, and conducting granulation; sieving a granulation powder to remove unevenly-granulated particles, and drying the granulation powder at 100° C. to 150° C. for 10 min to 20 min to obtain a powder with prominent flowability and filling property; and pressing the powder into a green body ring having a size of 25*15*8 mm under a pressure of 300 MPa to 350 MPa; and (5) subjecting the green body ring obtained in step (4) to sintering in a bell furnace to obtain a MnZn ferrite sample ring.

3. The preparation method according to claim 2, wherein in step (1), the pre-sintering is conducted for 2 h to 3 h at 700° C. and 1,000° C. and an oxygen content controlled at 5 vol % to 20 vol % by controlling a ratio of air to nitrogen and adopts furnace cooling.

4. The preparation method according to claim 2, wherein in step (2), the at least two MnZn ferrite pre-sintered materials obtained under 2 to 4 pre-sintering temperatures are mixed.

5. The preparation method according to claim 2, wherein in step (2), the at least two MnZn ferrite pre-sintered materials are mixed by a V-shaped powder mixer or a five-axis powder mixer.

6. The preparation method according to claim 2, wherein in step (2), after a solvent is added, the pre-sintered materials are mixed; and the solvent is deionized water or ethanol.

7. The preparation method according to claim 6, wherein in step (2), a dispersant is added along with the solvent.

8. The preparation method according to claim 2, wherein in step (4), a mold equipped with a vibration device is used in the pressing, and slight high-frequency vibration is provided to make the powder densely packed and filled in a cavity of the mold, wherein the powder has a high tap density in the cavity of the mold.

9. The preparation method according to claim 2, wherein in step (5), the sintering is conducted at a holding temperature of 1,200° C. to 1,300° C., a holding time of 4 h to 8 h, and an oxygen content of 3.5 vol % to 4.6 vol %.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is an image illustrating a metallographic structure of Comparative Example 7* of the present disclosure; and

[0028] FIG. 2 is an image illustrating a metallographic structure of Example 14 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The technical solutions in the examples of the present disclosure are clearly and completely described below with reference to the accompanying drawings in the examples of the present disclosure. Apparently, the described examples are merely a part rather than all of the examples of the present disclosure. All other examples obtained by a person of ordinary skill in the art based on the examples of the present disclosure without creative efforts shall fall within the protection scope of the present disclosure.

Examples 1 to 5 and Comparative Examples 6* to 8*

[0030] A MnZn power ferrite material was prepared by the following specific steps:

[0031] (1) Commercially-available Fe.sub.2O.sub.3 (purity ≥99.3%), MnO (Mn content ≥71%), and ZnO (purity ≥99.7%) were prepared according to the principal formula: Fe.sub.2O.sub.3: 52.5 mol %, ZnO: 8.8 mol %, and MnO: the balance.

[0032] The prepared raw materials were placed in a sand mill, deionized water was added at a ratio of 1:1, then 2 ml of ethylene glycol (EG) was added as a dispersant, and a resulting mixture was mixed for 15 min and then dried.

[0033] A dried powder was divided into two parts, one part was subjected to pre-sintering for 2 h at 700° C. under an air atmosphere (with an oxygen content of 20 vol %) in an electric resistance furnace, and the other part was subjected to pre-sintering for 2 h at 900° C. under the air atmosphere (with an oxygen content of 20 vol %) in an electric resistance furnace.

[0034] (2) Pre-sintered powders were mixed according to a ratio shown in Table 1 by a V-shaped powder mixer for 2 h.

[0035] (3) The following impurities were added to a mixed pre-sintered material: CaSiO.sub.3: 500 ppm, Nb.sub.2O.sub.5: 200 ppm, CO.sub.2O.sub.3: 4,000 ppm, TiO.sub.2: 800 ppm, and Gd.sub.2O.sub.3: 350 ppm, and a resulting mixture was subjected to secondary sanding for 60 min to control a particle size D50 at 1.2 μm to 1.5 μm, during which deionized water was added in a deionized water-raw material ratio of 5:4; and a slurry obtained from the secondary sanding was dried to completely remove moisture.

[0036] (4) A dried powder was crushed and sieved through a 40-mesh sieve, 15% PVA was added, and granulation was conducted; and a granulation product was dried at 130° C. for 15 min, and then bidirectionally pressed by a 16-ton pressing machine into a green body ring with an inner diameter of 15 mm, an outer diameter of 25 mm, a height of 8 mm, and a density of about 3.1 g/cm.sup.3. The 16-ton pressing machine was equipped with a vibration device, and slight high-frequency vibration was provided to make the powder densely packed and filled in a cavity of the mold, such that the powder had a high tap density in the cavity of the mold.

[0037] (5) Finally, the green body ring was subjected to sintering for 6 h at 1,280° C. and an oxygen partial pressure of 3.8 vol %, then cooled to 120° C. at an equilibrium oxygen partial pressure, and taken out.

[0038] A sample ring obtained in the above step was tested for power consumption Pcv and saturation magnetic flux density Bs on the SY8218 instrument of Iwatsu, Japan. Test conditions were as follows: Pcv was tested at 100 kHz and 200 mT; and Bs was tested at 1 kHz and 1,194 A/m. Results were recorded in Table 1.

TABLE-US-00001 TABLE 1 Pcv/25° C. Pcv/100° C. Pcv/120° C. Pcv/140° C. Bs(mT) Bs(mT) No. Ratio of pre-sintered materials ui kW/m.sup.3 kW/m.sup.3 kW/m.sup.3 kW/m.sup.3 /25° C. /100° C. 1 700° C. (90%) + 900° C. (10%) 3236 244 305 331 372 537 413 2 700° C. (80%) + 900° C. (20%) 3327 233 287 326 358 543 421 3 700° C. (70%) + 900° C. (30%) 3512 235 266 305 343 542 415 4 700° C. (60%) + 900° C. (40%) 3267 323 322 345 378 538 415 5 700° C. (50%) + 900° C. (50%) 3234 346 355 374 403 531 412  6* 700° C. (100%) 3237 342 345 362 393 533 415  7* 800° C. (100%) 3244 267 286 322 369 542 417  8* 900° C. (100%) 3256 287 312 346 380 537 418 Notes: The number with * represents a comparative example. Among the examples shown in Table 1, 1 to 5 represent the examples of the present disclosure, and 6* to 8* represent the comparative examples.

[0039] According to the data in Table 1:

[0040] Among Examples 1 to 5, when an amount of the low-activity pre-sintered material accounts for 30% in a total amount of a mixed pre-sintered material, a resulting product has the best performance; and when an amount of the low-activity pre-sintered material and an amount of the high-activity pre-sintered material each account for 50% in a total amount of a mixed pre-sintered material, a resulting product has the worst performance, which is even worse than that of a product obtained from a pre-sintered material obtained under a single temperature.

[0041] From the comparison of Examples 6* to 8*, it can be known that a suitable single pre-sintering temperature for a powder is 800° C., but the overall consumption, especially the consumption in a high-temperature range, is worse than that of Example 3. An image illustrating a metallographic structure of Comparative Example 7* is shown in FIG. 1.

Examples 9 to 17 and Comparative Example 18*

[0042] A MnZn power ferrite material was prepared by the following specific steps:

[0043] (1) In Examples 9 to 17, commercially-available Fe.sub.2O.sub.3 (purity ≥99.3%), MnO (Mn content ≥71%), and ZnO (purity ≥99.7%) were prepared according to the principal formula: Fe.sub.2O.sub.3: 52.98 mol %, ZnO: 10.3 mol %, and MnO: the balance. In Comparative Example 18*, the raw materials were prepared according to the principal formula: Fe.sub.2O.sub.3: 53.8 mol %, ZnO: 12 mol %, and MnO: the balance.

[0044] (2) The prepared raw materials were placed in a sand mill, deionized water was added at a ratio of 1:1, then 2 ml of EG was added as a dispersant, and a resulting mixture was mixed for 15 min and then dried.

[0045] (3) A dried powder was divided into two parts, one part was subjected to pre-sintering for 2 h at 800° C. under an air atmosphere in an electric resistance furnace, and the other part was subjected to pre-sintering for 2 h at 900° C. under the air atmosphere in an electric resistance furnace, where the air atmosphere had an oxygen content of 20 vol % in Examples 9 to 13 and Comparative Example 18*, an oxygen content of 15 vol % in Examples 14 and 15, and an oxygen content of 5 vol % in Examples 16 and 17. Pre-sintered powders were mixed according to a ratio shown in Table 2 by a V-shaped powder mixer for 2 h.

[0046] (4) The following impurities were added to a mixed pre-sintered material: CaSiO.sub.3: 500 ppm, Nb.sub.2O.sub.5: 200 ppm, CO.sub.2O.sub.3: 4,000 ppm, TiO.sub.2: 650 ppm, and HO.sub.2O.sub.3: 150 ppm, and a resulting mixture was subjected to secondary sanding for 60 min to control a particle size D50 at 1.2 μm to 1.5 μm, during which deionized water was added in a deionized water-raw material ratio of 5:4; and a slurry obtained from the secondary sanding was dried to completely remove moisture.

[0047] (5) A dried powder was crushed and sieved through a 40-mesh sieve, 15% PVA was added, and granulation was conducted; and a granulation product was dried at 130° C. for 15 min, and then bidirectionally pressed by a 16-ton pressing machine into a green body ring with an inner diameter of 15 mm, an outer diameter of 25 mm, a height of 8 mm, and a density of about 3.1 g/cm.sup.3. The 16-ton pressing machine was equipped with a vibration device, and slight high-frequency vibration was provided to make the powder densely packed and filled in a cavity of the mold, such that the powder had a high tap density in the cavity of the mold.

[0048] (6) Finally, the green body ring was subjected to sintering for 6 h at 1,280° C. and an oxygen partial pressure of 3.8 vol %, then cooled to 120° C. at an equilibrium oxygen partial pressure, and taken out.

[0049] A sample ring obtained in the above step was tested for power consumption Pcv and saturation magnetic flux density Bs on the SY8218 instrument of Iwatsu, Japan. Test conditions were as follows: Pcv was tested at 100 kHz and 200 mT; and Bs was tested at 1 kHz and 1,194 A/m. Results were recorded in Table 2.

TABLE-US-00002 TABLE 2 Pcv/25° C. Pcv/100° C. Pcv/120° C. Pcv/140° C. Bs(mT) Bs(mT) No. Ratio of pre-sintered materials ui kW/m.sup.3 kW/m.sup.3 kW/m.sup.3 kW/m.sup.3 /25° C. /100° C.  9 800° C. (90%) + 900° C. (10%) 3321 237 292 327 367 539 416 10 800° C. (80%) + 900° C. (20%) 3352 234 282 318 347 542 420 11 800° C. (70%) + 900° C. (30%) 3512 241 260 298 339 542 419 12 800° C. (60%) + 900° C. (40%) 3340 317 320 335 373 535 413 13 800° C. (50%) + 900° C. (50%) 3289 334 359 385 408 536 410 14 800° C. (80%) + 900° C. (20%) 3443 223 262 310 337 538 419 15 800° C. (70%) + 900° C. (30%) 3525 221 250 284 323 541 421 16 800° C. (80%) + 900° C. (20%) 3352 235 273 321 342 532 415 17 800° C. (70%) + 900° C. (30%) 3427 230 261 290 331 542 420  18* 800° C. (70%) + 900° C. (30%) 3587 243 282 325 351 544 423

[0050] According to the data in Table 2:

[0051] In Examples 9 to 13, a temperature span of the pre-sintered materials is reduced, but a regularity is consistent with that in Table 1. It can be seen from Examples 14 and 15 that reducing an oxygen content in the pre-sintering atmosphere helps to further reduce the consumption, but if an oxygen content is too low (Examples 16 and 17), a pre-sintering reaction is inadequate and abnormal growth easily occurs during the subsequent sintering process, resulting in increased consumption. In Comparative Example 18*, a proportion of Fe.sub.2O.sub.3 in the principal formula is increased, which increases the amount of Fe.sup.2+ and decreases the electrical resistivity, thereby causing increased consumption in a high-temperature range. An image illustrating a metallographic structure of Example 14 is shown in FIG. 2. By adopting the new process of the present disclosure, a grain size is more homogeneous, a particle size is controlled at about 10 μm to 20 μm, and the grains grown later play a role of filling pores in a matrix.

[0052] Although the examples of the present disclosure have been illustrated and described, it should be understood that those of ordinary skill in the art may make various changes, modifications, replacements and variations to the above examples without departing from the principle and spirit of the present disclosure, and the scope of the present disclosure is limited by the appended claims and legal equivalents thereof.