NICKEL-MAGNESIUM-ZINC-COPPER FERRITE AND PREPARATION METHOD THEREFOR AND MAGNETIC DEVICE THEREOF

Abstract

A nickel-magnesium-zinc-copper ferrite, a preparation method therefor and a magnetic device thereof are provided. The nickel-magnesium-zinc-copper ferrite includes major components, the major components include, by mass fraction, 66.95% to 71.8% of Fe.sub.2O.sub.3, 15.6% to 19.7% of ZnO, 2.1% to 4.2% of NiO, 2.1% to 5.0% of MnO, 2.0% to 4.9% of CuO and 1.82% to 2.98% of MgO; and auxiliary additives including CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3. The preparation method includes weighing the major components according to proportion and wet-grinding same to obtain a first mixture; drying and pre-sintering the first mixture to obtain a pre-sintered material; weighing the auxiliary additives according to proportion, wet-grinding the auxiliary additives with the pre-sintered material and drying same to obtain a second mixture; and, powdering, shaping, and sintering the second mixture in sequence to obtain the nickel-magnesium-zinc-copper ferrite. The nickel-magnesium-zinc-copper ferrite can be applied in a magnetic device.

Claims

1. A nickel-magnesium-zinc-copper ferrite, comprising: major components, wherein by mass fraction, the major components comprise 66.95% to 71.8% of Fe.sub.2O.sub.3, 15.6% to 19.7% of ZnO, 2.1% to 4.2% of NiO, 2.1% to 5.0% of MnO, 2.0% to 4.9% of CuO and 1.82% to 2.98% of MgO; and auxiliary additives, wherein by mass fraction, the auxiliary additives comprise CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3, a mass of CaCO.sub.3 ranges from 0.1% to 0.3% of that of the major components, a mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.4% of that of the major components, a mass of MoO.sub.3 ranges from 0.01% to 0.39% of that of the major components, and a mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.29% of that of the major components.

2. The nickel-magnesium-zinc-copper ferrite of claim 1, wherein the major components comprise, by mass fraction, 68.2% to 70.9% of Fe.sub.2O.sub.3, 16.1% to 19.1% of ZnO, 2.2% to 3.5% of NiO, 2.7% to 5.0% of MnO, 3.5% to 4.9% of CuO, and 1.95% to 2.35% of MgO.

3. The nickel-magnesium-zinc-copper ferrite of claim 1, wherein a mass of CaCO.sub.3 ranges from 0.15% to 0.3% of that of the major components; and/or, a mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.3% of that of the major components; and/or, a mass of MoO.sub.3 ranges from 0.05% to 0.3% of that of the major components; and/or, a mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.2% of that of the major components.

4. A method for preparing nickel-magnesium-zinc-copper ferrite of claim 1, comprising following steps: weighing the major components according to proportion and wet-grinding same to obtain a first mixture; drying and pre-sintering the first mixture to obtain a pre-sintered material; weighing the auxiliary additives according to proportion, wet-grinding the auxiliary additives with the pre-sintered material and drying same to obtain a second mixture; and, powdering, shaping, and sintering the second mixture in sequence to obtain nickel-magnesium-zinc-copper ferrite.

5. The method for preparing the nickel-magnesium-zinc-copper ferrite of claim 4, wherein in the step of weighing the major components and wet-grinding, a weight ratio of the major components, a grinding ball, and a solvent is 1:(4.5 to 6):(0.6 to 1.2).

6. The method for preparing the nickel-magnesium-zinc-copper ferrite of claim 4, wherein in the step of weighing the auxiliary additives according proportion and wet-grinding the auxiliary additives with the pre-sintered material, a weight ratio of a sum of the auxiliary additives and the pre-sintered material, a grinding ball, and a solvent is 1:(4 to 7):(1 to 1.2).

7. The method for preparing the nickel-magnesium-zinc-copper ferrite of claim 4, wherein a particle size of the second mixture is in a range of 0.5 m to 1.6 m.

8. The method for preparing the nickel-magnesium-zinc-copper ferrite of claim 4, wherein the step of sintering is a segmented heating sintering process.

9. The method for preparing the nickel-magnesium-zinc-copper ferrite of claim 4, wherein in the step of shaping, pressure of shaping is in a range of 3 MPa to 10 MPa.

10. A magnetic device, comprising the nickel-magnesium-zinc-copper ferrite of claim 1.

Description

DETAILED DESCRIPTION

[0017] The following will provide a clear and complete description of the technical solution in the embodiments of the present disclosure, in communication with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all of them. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary skill in this art without creative labor fall within the scope of protection of the present disclosure.

[0018] In order to facilitate understanding of the present disclosure, a more detailed description of the present disclosure will be provided below. However, it should be understood that the present disclosure can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosed content of the present disclosure more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used in this article have the same meanings as those commonly understood by those skilled in the art of the present disclosure. The terms used in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term and/or used in this article includes any and all combinations of one or more related listed items.

[0020] The present disclosure provides a nickel-magnesium-zinc-copper ferrite. The nickel-magnesium-zinc-copper ferrite includes major components and auxiliary additives. By mass fraction, the major components include 66.95% to 71.8% of Fe.sub.2O.sub.3, 15.6% to 19.7% of ZnO, 2.1% to 4.2% of NiO, 2.1% to 5.0% of MnO, 2.0% to 4.9% of CuO and 1.82% to 2.98% of MgO. By mass fraction, the auxiliary additives include CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3, a mass of CaCO.sub.3 ranges from 0.1% to 0.3% of that of the major component, a mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.4% of that of the major component, a mass of MoO.sub.3 ranges from 0.01% to 0.39% of that of the major component, and a mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.29% of that of the major component.

[0021] In the nickel-magnesium-zinc-copper ferrite of the present disclosure, an account of NiO is reduced, which is cooperated with Fe.sub.2O.sub.3, ZnO, MgO, MnO, and CuO, with specific amounts and CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3, and Co.sub.2O.sub.3 with specific proportions are added as the auxiliary additives, facilitating improving a microstructure of nickel-magnesium-zinc-copper ferrite. That is, the nickel-magnesium-zinc-copper ferrite is densified, and a spinel lattice structure of the nickel-magnesium-zinc-copper ferrite is maintained, resulting in avoiding lattice distortion, thus the nickel-magnesium-zinc-copper ferrite maintains a high permeability over a wide frequency range from 1 kHz to 1000 KHz, while having a high Curie temperature of at least 160 C. and high impedance, and a product cost is greatly reduced.

[0022] In order to further adjust magnetic permeability and Curie temperature, the account of Fe.sub.2O.sub.3 is slightly excessed, and Zn in ZnO can be inhibited to volatilize by cooperation between Fe.sub.2O.sub.3, ZnO, MgO, MnO, and CuO. In some embodiment, the major components include, by the mass fraction, 68.2% to 70.9% Fe.sub.2O.sub.3, 16.1% to 19.1% of ZnO, 2.2% to 3.5% of NiO, 2.7% to 5.0% of MnO, 3.5% to 4.9% of CuO, and 1.95% to 2.35% of MgO.

[0023] A composition of CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3, and Co.sub.2O.sub.3 is the auxiliary additives, which is cooperated with Fe.sub.2O.sub.3, ZnO, MgO, MnO, and CuO of the major components, resulting in stability improving an electromagnetic property of nickel-magnesium-zinc-copper ferrite.

[0024] By further precisely adjusting of proportion between CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3, and Co.sub.2O.sub.3, it facilitates obtaining nickel-magnesium-zinc-copper ferrite with better performance.

[0025] The account of CaCO.sub.3 can be adjusted slightly to further improve a solid-phase reaction, facilitating further making the nickel-magnesium-zinc-copper ferrite densify, resulting in increasing the density of the nickel-magnesium-zinc-copper ferrite, and facilitating synergistically adjusting grain size of the nickel-magnesium-zinc-copper ferrite, resulting in improving a performance of the nickel-magnesium-zinc-copper ferrite. In some embodiments, the mass of CaCO.sub.3 ranges from 0.15% to 0.3% of that of the major components.

[0026] Bi.sub.2O.sub.3 and MoO.sub.3 with lower melting point can form a liquid phase during a process of preparing the nickel-magnesium-zinc-copper ferrite, facilitating promoting the solid-phase reaction. In the major components with slightly excessive Fe.sub.2O.sub.3, the account of MoO.sub.3 can be slightly adjusted, facilitate further promoting grow of grain of the nickel-magnesium-zinc-copper ferrite, facilitating improving primary magnetic permeability, and synergistically reducing additive amount of Bi.sub.2O.sub.3. In some embodiments, the mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.3% of that of the major component. In some embodiments, the mass of MoO.sub.3 ranges from 0.05% to 0.3% of that of the major components.

[0027] Co.sub.2O.sub.3 can be substituted with the major components and dissolved in the spinel lattice. The account of Co.sub.2O.sub.3 can be slightly adjusted, facilitating further improving micro structure of the nickel-magnesium-zinc-copper ferrite, resulting in improving stop frequency, improving resistivity, reducing losses, enhancing high-frequency impedance performance, and maintaining magnetic permeability. In some embodiments, the mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.2% of that of the major components.

[0028] In some embodiments, in the nickel-magnesium-zinc-copper ferrite, the major components include, by the mass fraction, 68.2% to 70.9% of Fe.sub.2O.sub.3, 16.1% to 19.1% of ZnO, from 2.2% to 3.5% of NiO, 2.7% to 5.0% of MnO, 3.5% to 4.9% of CuO and 1.95% to 2.35% of MgO. The auxiliary additives include CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3, the mass of CaCO.sub.3 ranges from 0.15% to 0.3% of that of the major component, the mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.3% of that of the major component, the mass of MoO.sub.3 ranges from 0.05% to 0.3% of that of the major component, and the mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.2% of that of the major component.

[0029] The present disclosure further provides a method for preparing the nickel-magnesium-zinc-copper ferrite. The method of preparing the nickel-magnesium-zinc-copper ferrite includes following steps:

[0030] S1, weighing the major components according to proportion and wet-grinding same to obtain a first mixture; S2, drying and pre-sintering the first mixture to obtain a pre-sintered material; S3, weighing the auxiliary additives according to the proportion, wet-grinding the auxiliary additives with the pre-sintered material, drying same to obtain a second mixture; and S4, powdering, shaping, and sintering the second mixture in sequence to obtain the nickel-magnesium-zinc-copper ferrite.

[0031] In the step S1, in order to adjust moisture content of the first mixture, the first mixture is mixed evenly, and breathability of the first mixture is improved, thereby improving sintering efficiency of the nickel-magnesium-zinc-copper ferrite. In the step of weighing the major component according to the proportion and wet-grinding, a weight ratio of the major component, a grinding ball, and a solvent is 1:(4.5 to 6):(0.6 to 1.2). In some embodiments, the solvent is water.

[0032] In order to evenly mix the major component and the solvent, in some embodiments, time of a wet-grinding process is in a range of 1 h to 3 h.

[0033] In the step S2, an influence of the solvent in the first mixture for sintering technology can be reduced by drying. By a pre-sintering process, a microstructure of nickel-magnesium-zinc-copper ferrite is improved, so as to ensure a volume stability of the nickel-magnesium-zinc-copper ferrite and accuracy of external dimensions of the nickel-magnesium-zinc-copper ferrite, resulting in improving the performance of the nickel-magnesium-zinc-copper ferrite.

[0034] The temperature of the step of pre-sintering is in a range of 920 C. to 1000 C., and the time of the step of pre-sintering is in a range of 6 h to 10 h.

[0035] In the step S3, in order to achieve a suitable particle size distribution, good flowability, and a certain loose packing density for the second mixture, it benefits for subsequent powdering and shaping, so as to obtain the nickel-magnesium-zinc-copper ferrite with high quality. In addition, in the step of weighing the auxiliary additives according the proportion and wet-grinding the auxiliary additives with the pre-sintering material, a weight ratio of a sum of the auxiliary additive and the pre-sintering material, the grinding ball, and a solvent is 1:(4 to 7):(1 to 1.2). In some embodiments, the time of the wet-grinding process is in a range of 2 h to 6 h.

[0036] Furthermore, considering efficiency of a subsequent powdering process, in some embodiments, a particle size of the second mixture is in a range of 0.5 m to 1.6 m.

[0037] In the step S4, the second mixture is selected by the powdering process, granulated powder with uniform particle size and good activity is prepared, thereby ensuring the granulated power to distribute more evenly during a process of shaping, and ensuring consistency and density of a formed billet.

[0038] In order to further ensure a compression performance and billet strength in the shaping process, in some embodiments, the powdering technology is a spraying powdering method.

[0039] A preparing step of the spraying powdering includes: mixing binder, defoamer and the second mixture for 1 h to 3 h, and obtaining the granulated powder via a spraying powdering process. The mass of the binder ranges from 5% to 15% of the mass of the second mixture. The mass of the defoamer ranges from 0.03% to 0.3% of the mass of the second mixture. In some embodiments, the binder is a polyvinyl alcohol solution with 8% to 10% concentration. In some embodiments, the defoamer is capryl alcohol.

[0040] In order to facilitate demolding of a shaped billet, in some embodiments, a lubricant is added to the granulated powder, which is mixed and pressed into the billet. The mass of the lubricant ranges from 0.01% to 0.1% of the mass of granulated powder. In some embodiments, the lubricant is zinc stearate.

[0041] In an embodiment, a pressure of shaping process is in a range of 3 MPa to 10 MPa.

[0042] The step of sintering can be a once heating sintering process or a segmented heating sintering process. In some embodiments, the step of sintering is the segmented heating sintering process. In some embodiments, the segmented heating sintering process includes a first heating stage, a second heating stage, an insulation stage, a temperature-reducing stage, and a cooling process. The temperature of the first heating stage is in a range of 800 C. to 1000 C., and the time of the first heating stage is in a range of 5 h to 10 h. The temperature of the second heating stage is in a range of 1180 C. to 1220 C., and the time of the second heating stage is in a range of 1.5 h to 3 h. The temperature of the insulation stage is the same as the temperature of the second heating stage, and the time of the insulation stage is in a range of 3 h to 6 h. The temperature of the temperature-reducing stage is in a range of 130 C. to 200 C., and the time of the temperature-reducing stage is in a range of 7 h to 10 h. The cooling process is cooling the sintered billet into a room temperature.

[0043] The present disclosure further provides a use of the nickel magnesium zinc copper ferrite in a magnetic device.

[0044] The nickel-magnesium-zinc-copper ferrite is used in the magnetic device, which can satisfy a performance requirement of broadband high impedance, high Curie temperature and so on, for the nickel-magnesium-zinc-copper ferrite in fields such as modern medical, automotive, photovoltaic, network communication, aerospace and so on. Therefore, a market requirement for the nickel-magnesium-zinc-copper ferrite in applications such as inductive filters, photovoltaic energy storage transformers, and medical devices further increases. In addition, the nickel-magnesium-zinc-copper ferrite can significantly reduce a production cost, thereby increasing a market competitiveness of the nickel-magnesium-zinc-copper ferrite in the magnetic device.

[0045] In the following, the nickel-magnesium-zinc-copper ferrite, the method thereof and the use thereof are further described by the following specific embodiments.

Example 1

[0046] 68.6 weight percent of Fe.sub.2O.sub.3, 18.65 weight percent of ZnO, 3.4 weight percent of NiO, 2.7 weight percent of MnO, 4.6 weight percent of CuO and 2.05 weight percent of MgO were weighed to form major components. The major components, a grinding ball, and water were mixed and wet-grinded for 1 h to obtain a first mixture, in which a weight ratio of the major components, the grinding ball, and the water was 1:4.5:0.8.

[0047] The first mixture was dried and pre-sintered at 950 C. for 6 h, and insulated for 4 hours to obtain a pre-sintered material.

[0048] CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3 were weighed as auxiliary additives, in which the mass of CaCO.sub.3 was 0.15% of that of the major components, the mass of Bi.sub.2O.sub.3 is 0.15% of that of the major components, the mass of MoO.sub.3 was 0.08% of that of the major components, and the mass of Co.sub.2O.sub.3 was 0.05% of that of the major components. A pre-sintered material with the auxiliary additive, a grinding ball and water were mixed and wet-grinded in a weight ratio of 1:4:1 for 3 hours, which was dried to obtain a second mixture with an average particle size of 1.2 m.

[0049] Polyvinyl alcohol solution (mass fraction thereof is 5%) and n-capryl alcohol were added to the second mixture, which was stirred for 2 hours to obtain a granulated power. The mass of the polyvinyl alcohol solution was 5% of that of the second mixture. The mass of the n-capryl alcohol was 0.1% of that of the second mixture. Zinc stearate was added to the granulated powder, which was stirred evenly and pressed into a billet under a pressure of shaping of 5 MPa. An additive amount of the zinc stearate was 0.1% of the mass of the granulated power. The billet was placed into push plate kiln for segmented heating sintering, which includes following steps: the temperature of the billet was increased from a room temperature to 900 C. within 8 hours, the temperature was continuously increased at 1205 C. within 2 hours and insulated for 3 hours, the temperature was reduced to 150 C. within 10 hours, the billet was cooled to the room temperature, and a ring-shaped nickel-magnesium-zinc-copper ferrite with an outer size of 25 mm, an inner size of 15 mm and a height of 7 mm was obtained.

Example 2

[0050] 70.1 weight percent of Fe.sub.2O.sub.3, 16.65 weight percent of ZnO, 2.8 weight percent of NiO, 3.5 weight percent of MnO, 4.6 weight percent of CuO and 2.35 weight percent of MgO were weighed to form major components. The major components, a grinding ball, and water were mixed and wet-grinded for 1 hour to obtain a first mixture, in which a weight ratio of the major components, the grinding ball, and the water was 1:5:1.2.

[0051] The first mixture was dried and pre-sintered at 980 C. for 8 hours, and insulated for 4 hours to obtain a pre-sintered material.

[0052] CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3 were weighed as auxiliary additives, in which the mass of CaCO.sub.3 was 0.15% of that of the major components, the mass of Bi.sub.2O.sub.3 was 0.15% of that of the major components, the mass of MoO.sub.3 was from to 0.1% of that of the major components, and the mass of Co.sub.2O.sub.3 was from 0.05% of that of the major components. A pre-sintered material with the auxiliary additive, a grinding ball and water were mixed and wet-grinded in a weight ratio of 1:5:1.2 for 4 hours, which was dried to obtain a second mixture with an average particle size of 1.1 m.

[0053] Polyvinyl alcohol solution (mass fraction thereof is 10%) and n-capryl alcohol were added to the second mixture, which was quickly stirred for 2 hours to obtain a granulated power. The mass of the polyvinyl alcohol solution was 10% of that of the second mixture. The mass of the n-capryl alcohol was 0.1% of that of the second mixture. Zinc stearate was added to the granulated powder, which was stirred evenly and pressed into a billet under a pressure of shaping of 5 MPa. An additive amount of the zinc stearate was 0.1% of the mass of the granulated power. The billet was placed into a push plate kiln for segmented heating sintering, which includes following steps: the temperature of the billet was increased from a room temperature to 900 C. within 8 hours, the temperature was continuously increased at 1205 C. within 2 hours and insulated for 3 hours, the temperature was reduced to 150 C. within 10 hours, the billet was cooled into the room temperature, and a ring-shaped nickel-magnesium-zinc-copper ferrite with an outer size of 25 mm, an inner size of 15 mm and height of 7 mm was obtained.

Example 3

[0054] 69.5 weight percent of Fe.sub.2O.sub.3, 16.1 weight percent of ZnO, 2.2 weight percent of NiO, 4.6 weight percent of MnO, 4.75 weight percent of CuO and 2.85 weight percent of MgO were weighed to form major components. The major components, a grinding ball, and water were mixed and wet-grinded for 1 hour to obtain a first mixture, in which a weight ratio of the major components, the grinding ball, and the water was 1:5:1.2.

[0055] The first mixture was dried and pre-sintered at 980 C. for 8 hours, and insulated for 4 hours to obtain a pre-sintered material.

[0056] CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3 were weighed as auxiliary additives, in which the mass of CaCO.sub.3 was 0.2% of that of the major components, the mass of Bi.sub.2O.sub.3 was 0.15% of that of the major components, the mass of MoO.sub.3 was 0.15% of that of the major components, and the mass of Co.sub.2O.sub.3 was 0.1% of that of the major components. A pre-sintered material with the auxiliary additive, a grinding ball and water were mixed and wet-grinded in a weight ratio of 1:5:1.2 for 4 hours, which was dried to obtain a second mixture with an average particle size of 1.1 m.

[0057] Polyvinyl alcohol solution (mass fraction thereof is 7%) and n-capryl alcohol were added to the second mixture, which was quickly stirred for 2 hours to obtain a granulated power. The mass of the polyvinyl alcohol solution was 10% of that of the second mixture. The mass of the capryl alcohol was 0.12% of that of the second mixture. Zinc stearate was added to the granulated powder, which was stirred evenly and pressed into a billet under a pressure of shaping of 5.5 MPa. An additive amount of the zinc stearate was 0.2% of the mass of the granulated power. The billet was placed into push plate kiln for segmented heating sintering, which includes following steps: the temperature of the billet was increased from a room temperature to 920 C. within 9 hours, the temperature was continuously increased at 1190 C. within 3 hours and insulated for 2 hours, the temperature was reduced to 150 C. within 10 hours, the billet was cooled into the room temperature, and a ring-shaped nickel-magnesium-zinc-copper ferrite with an outer size of 25 mm, an inner size of 15 mm and height of 7 mm was obtained.

Example 4

[0058] 68.6 weight percent of Fe.sub.2O.sub.3, 17.65 weight percent of ZnO, 3.1 weight percent of NiO, 3.7 weight percent of MnO, 4.6 weight percent of CuO and 2.35 weight percent of MgO were weighed to form major components. The major components, a grinding ball, and water were mixed and wet-grinded for 1 hour to obtain a first mixture, in which a weight ratio of the major components, the grinding ball, and the water was 1:5:1.2.

[0059] The first mixture was dried and pre-sintered at 980 C. for 8 hours, and insulated for 4 hours to obtain a pre-sintered material.

[0060] CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3 were weighed as auxiliary additives, in which the mass of CaCO.sub.3 was 0.15% of that of the major components, the mass of Bi.sub.2O.sub.3 was 0.1% of that of the major components, the mass of MoO.sub.3 was 0.2% of that of the major components, and the mass of Co.sub.2O.sub.3 was 0.2% of that of the major component, a pre-sintered material with the auxiliary additive, a grinding ball and water were mixed and wet-grinded in a weight ratio of 1:5:1.2 for 4 hours, which was dried to obtain a second mixture with an average particle size of 1.1 m.

[0061] Polyvinyl alcohol solution (mass fraction thereof is 10%) and n-capryl alcohol were added to the second mixture, which was quickly stirred for 3 hours to obtain a granulated power. The mass of the polyvinyl alcohol solution was 10% of that of the second mixture. The mass of the capryl alcohol was 0.1% of that of the second mixture. Zinc stearate was added to the granulated powder, which was stirred evenly and pressed into a billet under a pressure of shaping of 5 MPa. An additive amount of the zinc stearate was 0.1% of the mass of the granulated power. The billet was placed into push plate kiln for segmented heating sintering, which includes following steps: the temperature of the billet was increased from a room temperature to 950 C. within 6 hours, the temperature was continuously increased at 1195 C. within 2 hours and insulated for 3 hours, the temperature was reduced to 150 C. within 10 hours, the billet was cooled into the room temperature, and a ring-shaped nickel-magnesium-zinc-copper ferrite with an outer size of 25 mm, an inner size of 15 mm and height of 7 mm was obtained.

Comparative Example 1

[0062] The comparative example 1 is substantially the same as the example 1, except that, in the comparative example 1, no auxiliary additive was added, pre-sintered material directly was dry-grinded until an average particle size of the pre-sintered material is 1.1 m, powdering, shaping, and sintering was processed.

Comparative Example 2

[0063] The comparative example 2 is substantially the same as the example 2, except that, in the comparative example 2, in an auxiliary additive, a mass of Co.sub.2O.sub.3 is 0.4% of that of major components.

Comparative Example 3

[0064] The comparative example 3 is substantially the same as the example 3, except that, in the comparative example 3, in an auxiliary additive, the mass of MoO.sub.3 is 0.4% of that of a major component.

Comparative Example 4

[0065] The comparative example 4 is substantially the same as the example 4, except that, in the comparative example 4, in an auxiliary additive, a mass of CaCO.sub.3 was 0.4% of that of major components.

Comparative Example 5

[0066] The comparative example 5 is substantially the same as the example 4, except that, in the comparative example 5, Co.sub.2O.sub.3 was not added in auxiliary additives.

Comparative Example 6

[0067] The comparative example 6 is substantially the same as the example 4, except that, in the comparative example 6, no MoO.sub.3 was added in auxiliary additives.

Comparative Example 7

[0068] The comparative example 7 is substantially the same as the example 4, except that, in the comparative example 7, CaCO.sub.3 was not added in auxiliary additives.

Comparative Example 8

[0069] The comparative example 8 is substantially the same as the example 4, except that, in the comparative example 8, in major components, Fe.sub.2O.sub.3 was 64.91 weight percent, ZnO was 19.37 weight percent, NiO was 3.1 weight percent, MnO was 4.2 weight percent, CuO was 6.37 weight percent and MgO is 2.05 weight percent.

Comparative Example 9

[0070] The comparative example 9 is substantially the same as the example 4, except that, in the comparative example 9, in major components, ZnO was 20 weight percent and Fe.sub.2O.sub.3 was 70.95 weight percent.

Comparative Example 10

[0071] The comparative example 10 is substantially the same as the example 4, except that, in the comparative example 10, in major components, MnO was 1.2 weight percent and Fe.sub.2O.sub.3 was 71.1 weight percent.

Comparative Example 11

[0072] The comparative example 11 is substantially the same as the example 4, except that, in the comparative example 11, in major components, Fe.sub.2O.sub.3 was 70.6 weight percent, ZnO was 17.65 weight percent, NiO was 3.45 weight percent, MnO was 3.7 weight percent and CuO was 4.6 weight percent.

[0073] The magnets obtained from the examples 1 to 4 and the comparative example 1 to 11 were tested for the quality. The result was shown in Table 1.

[0074] In a condition of temperature (T) is 25 C. and voltage (u) is 0.25 v, AgClient E4980A was used to test the primary magnetic permeability (i) under frequency conditions of 1 KHz, 100 KHz, 200 KHz, and 1000 KHz and high-low-temperature-controllable oven was used to test Curie temperature (Tc). SM-8220 testing instrument was used for testing surface resistance. Impedance testing was conducted by HP4291B at frequencies of 1 MHz, 25 MHz, 100 MHz, and 200 MHz.

TABLE-US-00001 TABLE 1 Primary magnetic permeability Curie Surface of different frequencies (.sub.i) Impedance () temperature resistance 1K 100K 200K 1000K 1M 25M 100M 200M ( C.) ( .Math. m) Hz Hz Hz Hz Hz Hz Hz Hz Example 1 165 1.2 10.sup.7 1045 1022 1016 1012 11.01 74.51 179 389 Example 2 177 4.8 10.sup.7 1240 1185 1152 1072 11.91 75.8 176 381 Example 3 165 3.2 10.sup.7 993 975 962 932 11.12 76.4 181 393 Example 4 180 5.2 10.sup.7 1092 1026 1004 942 10.86 79.1 192 401 Comparative 120 4.1 10.sup.7 1290 1023 984 876 12.45 74.6 169 366 example 1 Comparative 260 4.2 10.sup.7 285 259 256 261 3.65 81.3 212 448 example 2 Comparative 105 6.5 10.sup.7 790 743 675 612 8.76 71.9 161 375 example 3 Comparative 137 8.1 10.sup.7 852 841 817 804 9.28 73.4 165 381 example 4 Comparative 110 6.3 10.sup.5 1490 1380 1260 1030 15.61 69.2 146 246 example 5 Comparative 160 7.6 10.sup.7 569 557 549 541 7.28 78.7 187 382 example 6 Comparative 148 3.6 10.sup.5 921 916 908 902 9.76 75.2 172 374 example 7 Comparative 155 3.2 10.sup.3 522 510 507 496 6.54 78.7 196 412 example 8 Comparative 90 2.1 10.sup.6 1153 1047 986 725 11.51 67.6 141 195 example 9 Comparative 142 2.9 10.sup.5 905 864 812 734 9.34 65.5 170 351 example 10 Comparative 167 5.2 10.sup.7 812 809 802 792 8.95 79.9 189 387 example 11

[0075] According to the table 1, in the nickel-magnesium-zinc-copper ferrite, an account of NiO was reduced, which was cooperated with specific amounts of Fe.sub.2O.sub.3, ZnO, MgO, MnO, and CuO, and specific proportions of CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3, and Co.sub.2O.sub.3 were added as the auxiliary additives, such that the nickel-magnesium-zinc-copper ferrite could maintain a high permeability over a wide frequency range of 1 KHz to 1000 KHz, and have a high Curie temperature of at least 160 C. and high impedance of at least 105 .Math.m (DC 500 V, distance 10 mm).

[0076] Since the comparative example 1 had no auxiliary additive to coordinate to a major component, the Curie temperature was reduced to 120 C. In the comparative example 2, the account of Co.sub.2O.sub.3 excessed 0.29%, causing lattice distortion and resulting in a decrease in the primary magnetic permeability. In the comparative example 3, the account of MoO.sub.3 excessed 0.39%, causing discontinuous growth of some grains, increasing grain boundary stress, and increasing porosity, and resulting in a decrease in density, the magnetic permeability, and the Curie temperature. In the comparative example 4, the account of CaCO.sub.3 excessed 0.3%, resulting in a significant decrease in magnetic performance. In the comparative example 5, Co.sub.2O.sub.3 was not added, resulting in increased losses, decreased resistivity, and decreased high-frequency impedance performance. In the comparative 6, MoO.sub.3 was not added, resulting in a decrease in initial magnetic permeability. In the comparative example 7, CaCO.sub.3 was not added, resulting in a decrease in density and a significant decrease in magnetic properties. In the comparative example 8, the account of Fe.sub.2O.sub.3 was less than 68.2 weight percent and the account of CuO was greater than 4.9 weight percent, resulting in an increase in zinc volatilization and causing a phenomenon of zinc removal, thereby reducing electrical resistivity and magnetic permeability. In the comparative example 9, the account of ZnO was greater than 19.7 weight percent, resulting in a decrease in Curie temperature. The account of MnO in comparative example 10 is less than 2.1 weight percent, resulting in a decrease in the magnetic permeability and the Curie temperature. In the comparative example 11, MgO was not added, resulting in a decrease in the magnetic permeability.

Example 5

[0077] The example 5 is substantially the same as the example 2, except that, in the comparative example 5, in major components, Fe.sub.2O.sub.3 was 66.96 weight percent, ZnO was 19.7 weight percent, NiO was 4.12 weight percent, MnO was 4.3 weight percent, CuO was 3.1 weight percent and MgO was 1.82 weight percent.

Example 6

[0078] The example 6 is substantially the same as the example 2, except that, in the example 6, in major components, Fe.sub.2O.sub.3 was 71.8 weight percent, ZnO was 15.6 weight percent, NiO was 3.5 weight percent, MnO was 4.12 weight percent, CuO was 2 weight percent and MgO was 2.98 weight percent.

Example 7

[0079] The example 7 is substantially the same as the example 2, except that, in the example 7, in major components, Fe.sub.2O.sub.3 was 70.9 weight percent, ZnO was 17.95 weight percent, NiO was 2.1 weight percent, MnO was 2.1 weight percent, CuO was 4.9 weight percent and MgO was 2.05 weight percent.

Example 8

[0080] The example 8 is substantially the same as the example 2, except that, in the example 8, in major components, Fe.sub.2O.sub.3 was 68.2 weight percent, ZnO was 19.1 weight percent, NiO was 3.25 weight percent, MnO was 4 weight percent, CuO was 3.5 weight percent and MgO was 1.95 weight percent.

[0081] The magnets obtained in the examples 5 to 8 were tested for the quality, and the result was shown in table 2.

TABLE-US-00002 TABLE 2 Primary magnetic permeability Curie Surface in different frequencies (.sub.i) Impedance () temperature resistance 1K 100K 200K 1000K 1M 25M 100M 200M ( C.) ( .Math. m) Hz Hz Hz Hz Hz Hz Hz Hz Example 5 160 7.9 10.sup.5 954 948 936 921 10.98 70.3 173 374 Example 6 180 9.8 10.sup.5 1320 1165 987 839 12.35 72.6 169 367 Example 7 162 5.7 10.sup.6 1265 1241 1206 1165 12.04 73.7 171 372 Example 8 165 3.2 10.sup.7 1105 1087 1065 1032 11.03 75.1 175 379

[0082] Comparing the example 2 with the examples 5 to 8, by mass fraction, when the major components include, by mass fraction, 68.2% to 70.9% of Fe.sub.2O.sub.3, 16.1% to 19.1% of ZnO, 2.2% to 3.5% of NiO, 2.7% to 5% of MnO, 3.5% to 4.9% of CuO and 1.95% to 2.35% of MgO, a performance of nickel-magnesium-zinc-copper ferrite is better.

Example 9

[0083] The example 9 is substantially the same as the example 2, except that, in the example 9, in auxiliary additives, a mass of CaCO.sub.3 was 0.1% of that of major components, a mass of Bi.sub.2O.sub.3 was 0.4% of that of the major components, a mass of MoO.sub.3 is 0.05% of that of the major components, a mass of Co.sub.2O.sub.3 was 0.29% of that of the major components.

Example 10

[0084] The example 10 is substantially the same as the example 2, except that, in the example 10, in auxiliary additives, a mass of CaCO.sub.3 was 0.1% of that of major components, a mass of Bi.sub.2O.sub.3 was 0.1% of that of the major components, a mass of MoO.sub.3 was 0.39% of that of the major components, and a mass of Co.sub.2O.sub.3 was 0.01% of that of the major components.

Example 11

[0085] The example 11 is substantially the same as the example 2, except that, in the example 11, in auxiliary additives, a mass of CaCO.sub.3 was 0.3% of that of major components, a mass of Bi.sub.2O.sub.3 was 0.25% of that of the major components, a mass of MoO.sub.3 was 0.01% of that of the major components, and a mass of Co.sub.2O.sub.3 was 0.15% of that of the major components.

Example 12

[0086] The example 12 is substantially the same as the example 2, except that, in the example 12, in auxiliary additives, a mass of CaCO.sub.3 was 0.1% of that of major components, a mass of Bi.sub.2O.sub.3 is 0.2% of that of the major components, a mass of MoO.sub.3 was 0.3% of that of the major components, a mass of Co.sub.2O.sub.3 was 0.01% of that of the major components.

[0087] The magnets obtained in examples 9 to 12 were tested for the quality, and the result was shown in table 3.

TABLE-US-00003 TABLE 3 Primary magnetic permeability Curie Surface of different frequencies (.sub.i) Impedance () temperature resistance 1K 100K 200K 1000K 1M 25M 100M 200M ( C.) ( .Math. m) Hz Hz Hz Hz Hz Hz Hz Hz Example 9 169 5.9 10.sup.6 1065 1047 1024 1002 10.99 76.1 178 387 Example 10 171 9.8 10.sup.6 1354 1312 1256 1181 13.02 71.2 164 365 Example 11 162 5.7 10.sup.6 963 958 941 911 10.91 72.7 173 375 Example 12 167 3.2 10.sup.6 1280 1242 1203 1126 12.87 70.4 163 362

[0088] Comparing the examples 9 to 12 with the example 2, when the auxiliary additives include CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3, a mass of CaCO.sub.3 ranges from 0.15% to 0.3% of that of the major components, a mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.3% of that of the major components, a mass of MoO.sub.3 ranges from 0.05% to 0.3% of that of the major components, and a mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.2% of that of the major components, and the performance of the nickel-magnesium-zinc-copper ferrite is better.

[0089] Furthermore, comparing the examples 5 to 12 with the comparative examples 1, 2 and 4, the major components include, by the mass fraction, 68.2% to 70.9% of Fe.sub.2O.sub.3, 16.1% to 19.1% of ZnO, 2.2% to 3.5% of NiO, 2.7% to 5.0% of MnO, 3.5% to 4.9% of CuO and 1.95% to 2.35% of MgO, and the auxiliary additives include CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3 and Co.sub.2O.sub.3, the mass of CaCO.sub.3 ranges from 0.15% to 0.3% of that of the major components, the mass of Bi.sub.2O.sub.3 ranges from 0.1% to 0.3% of that of the major components, the mass of MoO.sub.3 ranges from 0.05% to 0.3% of that of the major components, and the mass of Co.sub.2O.sub.3 ranges from 0.01% to 0.2% of that of the major components, the performance of the nickel-magnesium-zinc-copper ferrite is best.

[0090] In the nickel-magnesium-zinc-copper ferrite of the present disclosure, the account of NiO was reduced, which cooperates with specific amounts of Fe.sub.2O.sub.3, ZnO, MgO, MnO, and CuO, and specific proportions of CaCO.sub.3, Bi.sub.2O.sub.3, MoO.sub.3, and Co.sub.2O.sub.3 were added as the auxiliary additives, facilitating improving a microstructure of nickel-magnesium-zinc-copper ferrite. Moreover, the nickel-magnesium-zinc-copper ferrite is densified, and a spinel lattice structure of the nickel-magnesium-zinc-copper ferrite is maintained, resulting in avoiding lattice distortion, thus the nickel-magnesium-zinc-copper ferrite maintains the high permeability over the wide frequency in a range from 1 KHz to 1000 KHz, while having the high Curie temperature of at least 160 C. and the high impedance, and a product cost is significantly reduced.

[0091] Therefore, the nickel-magnesium-zinc-copper ferrite can meet broadband high impedance, high Curie temperature and other performance requirements in fields of modern medical, automotive, photovoltaic, network communication, aerospace and other fields. It not only improves market demand of nickel-magnesium-zinc-copper ferrite in inductive filters, photovoltaic energy storage transformers, medical devices and other application fields, but also further enhances market competitiveness of the nickel-magnesium-zinc-copper ferrite.

[0092] The various technical features of the above embodiments can be combined in any way. In order to make the description concise, not all possible combinations of the various technical features in the above embodiments have been described. However, as long as there is no contradiction in the combination of these technical features, they should be considered within the scope of the specification.

[0093] The above embodiments only express several embodiments of the present disclosure, and their descriptions are more specific and detailed, but should not be understood as limiting the scope of the disclosure. It should be pointed out that for ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the disclosure, which are within the scope of protection of the disclosure. Therefore, the scope of protection of the present disclosure should be based on the attached claims.