Manganese zinc ferrite material and preparation method thereof

Abstract

The invention provides a manganese zinc ferrite material and a preparation method thereof, and belongs to the technical field of electronic component materials. The grain size is controlled through low-temperature sintering, the fluxing substance CuO is used as a main formula, air hole discharge is promoted, the density is improved, and therefore the characteristics that the grain is small and the grain structure is compact are achieved, and medium-high frequency power consumption is reduced. Compared with the prior art, the power consumption of about 300 kHz can be reduced by about 10%, and the power consumption of about 500 kHz can be reduced by about 30%.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic component materials, and particularly relates to a manganese-zinc ferrite material and a preparation method thereof. Background Art

[0002] For power manganese-zinc ferrite materials, low power loss is the performance that manufacturers are most concerned about. Traditional ferrite materials are widely used in inductors and transformers in the low-frequency band. However, with the development of the third-generation semiconductor SiC and GaN technologies, the frequency of power devices and the conversion efficiency are gradually improving. The conventional frequency of traditional materials is around 100kHz, and a small number of devices have high-frequency requirements, which are mainly divided into medium and high frequencies (300kHz~1MHz) and ultra-high frequencies (1MHz~3MHZ). However, with the progress of the semiconductor industry, some conventional 100kHz demands cannot meet the needs of miniaturization and will gradually increase to 300kHz~1MHz. At present, 300kHz~1MHz is not only common in DC-DC converters, but is also gradually used in AC-DC converters, wireless charging, inverters, motor drives and other scenarios. Therefore, the demand for soft ferrites in this frequency band is growing rapidly.

[0003] The power consumption is mainly divided into hysteresis loss, eddy current loss and residual loss. To improve the power consumption characteristics of medium and high frequencies of 300kHz to 1MHz, it is mainly to reduce eddy current loss and maintain hysteresis loss. From the eddy current formula, we can know that:

[0004]

[0005] Where d is the thickness of the thin-sheet core material, and for ferrite materials, it is the grain size. ρ is the resistivity. It can be seen that the larger the grain size, the greater the eddy current loss; the larger the resistivity, the smaller the eddy current loss. Therefore, to reduce the eddy current loss of ferrite, the grain size must be reduced and the resistivity must be increased at the same time. In addition, at medium and high frequencies of 300kHz to 1MHz, the eddy current loss is somewhat different from the low-frequency eddy current loss. Due to the high frequency, eddy currents may pass through multiple grains, forming transcrystalline eddy currents, further increasing power consumption. The reason for the eddy current passing through the grains is currently generally believed to be the orientation of the grains and the electromagnetic discontinuity of the boundaries. Therefore, while reducing the grain size, attention should also be paid to the consistency of the grains. In the sintering of soft ferrites, the grain size is usually reduced by lowering the sintering temperature. However, the unevenness of the particles will lead to inconsistent growth of the grains when the sintering temperature is low, which will lead to an increase in transgranular eddy currents and fail to effectively reduce power consumption. Moreover, when the sintering temperature is low, the reduction in density will also lead to a deterioration in the overall magnetic properties of the core, so simply lowering the sintering temperature will not reduce power consumption. In soft ferrite materials, resistance is generally increased by doping Si, Ca, etc., but these dopings are unevenly distributed on the grain boundaries, which will also lead to an increase in transgranular eddy currents, ultimately leading to an increase in high-frequency power consumption. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a manganese-zinc ferrite material and a preparation method thereof. The manganese-zinc ferrite material provided by the present invention has low power consumption in medium and high frequency bands.

[0007] In order to achieve the above object, the present invention provides the following scheme:

[0008] The present invention provides a manganese-zinc ferrite material, the preparation raw materials include a main component and an auxiliary component;

[0009] Taking the total molar amount of the main component as 100%, the main component includes: Fe2O3 52-55.5mol%, ZnO2 5.5-9.5mol%, CuO 0.1-0.5mol%, and the balance is Mn3O4;

[0010] In terms of percentage of the total mass of the main component, the auxiliary components include: CaO 0.03-0.2%, SiO2 0.005-0.03%, Nb2O5 0.01-0.2%, Co2O3 0.1-0.6%, TiO2 0.05-0.2%, SnO2 0.05-0.3%, ZrO2 0.01-0.2%, V2O5 0.03-0.2%, MoO3 0.05-0.2%, HfO2 0.05-0.2%; the density of the manganese-zinc ferrite material is 4.85-5.0 g / cm 3 .

[0011] Preferably, the initial magnetic permeability of the manganese-zinc ferrite material is 2900-3500.

[0012] The present invention provides a method for preparing the manganese-zinc ferrite material described in the above scheme, comprising the following steps:

[0013] sand-grinding the main component to obtain abrasive;

[0014] Pre-burning the abrasive material to obtain a pre-burned material;

[0015] Mixing and sand-grinding the pre-sintered material and the auxiliary components to obtain a mixed sand-grinding material;

[0016] The mixed sand and abrasive material and the binder are mixed and molded to obtain a blank;

[0017] The blank is sintered to obtain the manganese-zinc ferrite material; the sintering temperature is 1150-1250°C.

[0018] Preferably, the sintering process includes:

[0019] In air, heat up to 200°C at a rate of 2-5°C / min, and then heat up to 300°C at a rate of 0.5-1°C / min;

[0020] The temperature is raised to 1100°C at a heating rate of 0.5-3°C / min, and the oxygen content of the sintering atmosphere at 1100°C is 0.0-3.0%, and then the temperature is raised to 1150-1250°C at a heating rate of 2-10°C / min, and the oxygen content of the sintering atmosphere at 1150-1250°C is 0.5-5.0%, and the holding time at 1150-1250°C is 150-300 minutes;

[0021] The temperature is lowered to 1000° C. at a cooling rate of 0.3 to 1.5° C. / min, wherein during the cooling to 1000° C., the oxygen content of the sintering atmosphere at 1100° C. is 0.5 to 1.0%, the oxygen content of the sintering atmosphere at 1050° C. is 0.1 to 0.3%, and the oxygen content of the sintering atmosphere at 1000° C. is 0.02 to 0.05%;

[0022] The temperature is lowered to 200°C at a rate of 3-10°C / min, and the oxygen content of the sintering atmosphere at 200°C is ≤50ppm.

[0023] Preferably, the pre-burning temperature is 840-940° C., and the holding time is 0.5-3 h.

[0024] Preferably, the D50 particle size of the mixed abrasive is 1.0 μm.

[0025] Preferably, the binder comprises a polyvinyl alcohol aqueous solution.

[0026] Preferably, the blank is an annular blank.

[0027] Preferably, the density of the blank is 3.0-3.15 g / cm 3 .

[0028] Preferably, the main component is sand-milled at a rotation speed of 270 r / min for a time of 30 to 60 min.

[0029] The present invention provides a manganese-zinc ferrite material, wherein the raw materials for preparing the material include a main component and an auxiliary component; taking the total molar amount of the main component as 100%, the main component includes: Fe2O3 52-55.5mol%, ZnO 2 5.5-9.5%, CuO 0.1-0.5%, and the balance Mn3O4; taking the total molar amount of the main component as 100%, the auxiliary component includes: CaO 0.03~0.2%,SiO20.005~0.03%,Nb2O50.01~0.2%,Co2O30.1~0.6%,TiO20.05~0.2%,SnO20.05~0.3%,ZrO20.01~0.2%,V2O50.03~0.2%,MoO30.05~0.2%,HfO20.05~0.2%,The density of the manganese-zinc ferrite material is 4.85~5.0g / cm 3 . Doping CuO into the main formula to form a quaternary formula: To reduce medium and high frequency power consumption, the grain size must be reduced, and the increase in hysteresis loss caused by reducing the grain size must be compensated from other aspects. The present invention controls the grain size by using low-temperature sintering, and uses the fluxing material CuO as the main formula to promote the discharge of pores and increase the density, thereby achieving the characteristics of small grains and dense grain structure, reducing medium and high frequency power consumption. Compared with the prior art, the present invention can reduce the power consumption of 300kHz by about 10% and 500kHz by about 30%.

[0030] The present invention provides a method for preparing the manganese-zinc ferrite material described in the above scheme. In manganese-zinc ferrite, the conventional sintering temperature is around 1300-1400°C. Reducing the medium and high frequency power consumption requires that the temperature be further reduced, so that the grain size can be reduced to achieve the purpose of reducing eddy current loss. Therefore, the present invention uses an ultra-low sintering temperature (1150-1250°C), and adds a fluxing material CuO to form a quaternary main formula, forming a dense grain structure sintered at low temperature, reducing the medium and high frequency power consumption, and the grain boundary uniformity is good. Increase the cooling time: During the sintering and heat preservation stage of MnZn ferrite, the doped Ca, Si and other impurities are dissolved into the interior of the MnZn spinel. During the cooling stage, these impurities will move and segregate to the grain boundaries. After cooling, a high-resistance insulating layer is formed at the grain boundaries, thereby improving the grain boundary resistance, reducing the high-frequency power consumption characteristics of the material, and the grain boundary uniformity is good. Prolong the densification time during the sintering process: If the densification time is short, the lattice structure of the initially generated compound is incomplete, and there are many defects and pores. When the frequency is high, eddy currents may pass through these defects and pores to form transcrystalline eddy currents, resulting in increased power consumption. Therefore, to reduce the power consumption of medium and high frequencies, it is necessary to extend the densification time (sintering temperature 300-1100°C stage). During densification, the pores are gradually discharged by reducing the oxygen content, thereby gradually discharging the pores of the material, forming a ferrite core with a dense grain structure and uniform size. In addition, the present invention can promote the consistency of grain growth by low-temperature sintering and extending the densification time.

[0031] The method provided by the present invention reduces the power consumption of manganese-zinc ferrite materials in medium and high frequency bands. With the development of emerging technologies such as artificial intelligence, the Internet of Things, and 5G communications, the demand for this material will become increasingly greater, promoting the development of related industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 This is the SEM image of the manganese-zinc ferrite material obtained in Example 1;

[0034] Figure 2 This is the SEM image of the manganese-zinc ferrite material obtained in Comparative Example 1. DETAILED DESCRIPTION

[0035] The present invention provides a manganese-zinc ferrite material, wherein the raw materials for preparing the material include a main component and an auxiliary component; taking the total molar amount of the main component as 100%, the main component includes: Fe2O3 52-55.5mol%, ZnO2 5.5-9.5mol%, CuO 0.1-0.5mol%, and the remainder Mn3O4;

[0036] Calculated as a percentage of the total mass of the main components, the auxiliary components include: CaO 0.03-0.2%, SiO2 0.005-0.03%, Nb2O5 0.01-0.2%, Co2O3 0.1-0.6%, TiO2 0.05-0.2%, SnO2 0.05-0.3%, ZrO2 0.01-0.2%, V2O5 0.03-0.2%, MoO3 0.05-0.2%, and HfO2 0.05-0.2%.

[0037] Taking the total molar amount of the main component as 100%, the main component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 52 to 55.5 mol% of Fe2O3. In an embodiment of the present invention, it can specifically be 52 mol%, 52.1 mol%, 53 mol%, 54 mol%, 55 mol% or 55.5 mol%.

[0038] Taking the total molar amount of the main component as 100%, the main component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 5.5-9.5 mol% of ZnO2. In an embodiment of the present invention, it can specifically be 5.5 mol%, 6.0 mol%, 6.5 mol%, 7.0 mol%, 7.5 mol%, 8.0 mol%, 9.0 mol% or 9.5 mol%.

[0039] Taking the total molar amount of the main component as 100%, the main component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.1-0.5 mol% of CuO. In an embodiment of the present invention, it can specifically be 0.1 mol%, 0.2 mol%, 0.3 mol%, 0.4 mol% or 0.5 mol%.

[0040] Taking the total molar amount of the main component as 100%, the main component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes the balance of Mn3O4.

[0041] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.03-0.2% CaO. In an embodiment of the present invention, it can specifically be 0.03%, 0.05%, 0.1%, 0.15% or 0.2%.

[0042] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.005-0.03% SiO2. In the embodiments of the present invention, it can specifically be 0.005%, 0.01%, 0.02% or 0.03%.

[0043] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.01-0.2% Nb2O5. In an embodiment of the present invention, it can specifically be 0.01%, 0.03%, 0.05%, 0.1%, 0.15% or 0.2%.

[0044] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.1-0.6% Co2O3. In an embodiment of the present invention, it can specifically be 0.1%, 0.2%, 0.3%, 0.4%, 0.5% or 0.6%.

[0045] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.05-0.2% TiO2. In an embodiment of the present invention, it can specifically be 0.05%, 0.08%, 0.1%, 0.15% or 0.2%.

[0046] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.05-0.3% SnO2. In an embodiment of the present invention, it can specifically be 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25% or 0.3%.

[0047] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.01-0.2% ZrO2. In an embodiment of the present invention, it can specifically be 0.01%, 0.04%, 0.1%, 0.12%, 0.14%, 0.16% or 0.2%.

[0048] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.03-0.2% of V2O5. In an embodiment of the present invention, it can specifically be 0.03%, 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.2%.

[0049] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.05-0.2% MoO3. In an embodiment of the present invention, it can specifically be 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.2%.

[0050] Calculated as a percentage of the total mass of the main component, the auxiliary component in the raw material for preparing the manganese-zinc ferrite material provided by the present invention includes 0.05-0.2% HfO2. In an embodiment of the present invention, it can specifically be 0.05%, 0.08%, 0.1%, 0.12%, 0.15% or 0.2%.

[0051] In the present invention, the initial magnetic permeability of the manganese-zinc ferrite material is preferably 2900-3500, and in the embodiments of the present invention, it can be 2900, 3000, 3002, 3050, 3063, 3100, 3200, 3205, 3300, 3400 or 3500; the density is 4.85-5.0 g / cm 3 In the embodiment of the present invention, it can be 4.85 g / cm 3 , 4.90g / cm 3 , 4.92g / cm 3 , 4.94g / cm 3 , 4.97g / cm 3 or 4.98g / cm 3 .

[0052] In the present invention, the grain size of the manganese-zinc ferrite material is preferably 10 to 13 μm.

[0053] Doping CuO into the main formula to form a quaternary formula: To reduce medium and high frequency power consumption, the grain size must be reduced, and the increase in hysteresis loss caused by reducing the grain size must be compensated from other aspects. The present invention controls the grain size by using low-temperature sintering, and uses the fluxing material CuO as the main formula to promote the discharge of pores and increase the density, thereby achieving the characteristics of small grains and dense grain structure, reducing medium and high frequency power consumption. Compared with the prior art, the present invention can reduce the power consumption of 300kHz by about 10% and 500kHz by about 30%.

[0054] The present invention provides a method for preparing the manganese-zinc ferrite material described in the above scheme, comprising the following steps:

[0055] sand-grinding the main component to obtain abrasive;

[0056] Pre-burning the abrasive material to obtain a pre-burned material;

[0057] Mixing and sand-grinding the pre-sintered material and the auxiliary components to obtain a mixed sand-grinding material;

[0058] The mixed sand and abrasive material and the binder are mixed and molded to obtain a blank;

[0059] The blank is sintered to obtain the manganese-zinc ferrite material.

[0060] Unless otherwise specified, the raw materials and equipment used in the present invention are commercially available products.

[0061] The invention sand-grinds the main component to obtain sand-grinding material.

[0062] In the present invention, the solvent for sand-grinding the main component preferably includes water; the mass ratio of water to the main component is preferably 1:1.

[0063] In the present invention, the rotation speed of sand-grinding the main component is preferably 270 r / min; the time of sand-grinding the main component is preferably 30 to 60 min, and in the embodiments of the present invention, it can be specifically 30 min, 40 min, 50 min or 60 min.

[0064] After the sand grinding is completed, the present invention also preferably includes drying and grinding the obtained sand grinding slurry, and then passing it through a 100 mesh sieve to obtain the sand grinding material.

[0065] After obtaining the abrasive material, the present invention pre-burns the abrasive material to obtain a pre-burned material.

[0066] In the present invention, the pre-firing temperature is preferably 840-940°C, and in an embodiment of the present invention, it can be 840°C, 850°C, 860°C, 880°C, 900°C, 920°C or 940°C; the pre-firing holding time is preferably 0.5-3h, and in an embodiment of the present invention, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h.

[0067] After the pre-calcination is completed, the present invention also preferably includes cooling the obtained material.

[0068] After obtaining the pre-sintered material, the present invention mixes and sand-grinds the pre-sintered material and the auxiliary components to obtain a mixed sand-grinded material.

[0069] In the present invention, the solvent of the mixed sand milling preferably includes water; the mass ratio of the water to the total mass of the pre-sintered material and the auxiliary components is preferably 1:1. In the present invention, the rotation speed of the mixed sand milling is preferably 270r / min; the time of the mixed sand milling is preferably 1 to 3h, and in the embodiments of the present invention, it can be specifically 1h, 2h or 3h.

[0070] After the mixed sand grinding is completed, the present invention preferably dries the obtained mixed sand grinding slurry to obtain a mixed sand grinding material.

[0071] In the present invention, the D50 particle size of the mixed abrasive is preferably 1.0 μm.

[0072] After obtaining the mixed sand and abrasive, the present invention mixes the mixed sand and abrasive with a binder and performs molding to obtain a blank.

[0073] In the present invention, the shaping preferably includes granulation and pressing; the granulation preferably includes spray granulation.

[0074] In the present invention, the binder preferably includes a polyvinyl alcohol (PVA) aqueous solution; the mass concentration of the polyvinyl alcohol aqueous solution is preferably 0.05-0.4%, and in the embodiments of the present invention, it can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35% or 0.4%; the mass of the binder is preferably 20% of the mass of the mixed sand and abrasive.

[0075] In the present invention, the blank is preferably an annular blank; the outer diameter of the blank is preferably 25 mm, the inner diameter is preferably 15 mm, and the height is preferably 8 mm. The present invention has no special requirements on the pressure and time of the pressing, as long as it can be pressed into an annular blank. In the present invention, the density of the blank is preferably 3.0 to 3.15 g / cm 3 In the embodiment of the present invention, it can be 3.0g / cm 3 、3.1g / cm 3 or 3.15g / cm 3 .

[0076] After obtaining the blank, the present invention sintered the blank to obtain the manganese-zinc ferrite material; the sintering temperature is 1150-1250°C.

[0077] In the present invention, the sintering process preferably includes:

[0078] In air, heat up to 200°C at a rate of 2-5°C / min, and then heat up to 300°C at a rate of 0.5-1°C / min;

[0079] The temperature is raised to 1100°C at a heating rate of 0.5-3°C / min, and the oxygen content of the sintering atmosphere at 1100°C is 0.0-3.0%, and then the temperature is raised to 1150-1250°C at a heating rate of 2-10°C / min, and the oxygen content of the sintering atmosphere at 1150-1250°C is 0.5-5.0%, and the holding time at 1150-1250°C is 150-300 minutes;

[0080] The temperature is lowered to 1000° C. at a cooling rate of 0.3 to 1.5° C. / min, wherein during the cooling to 1000° C., the oxygen content of the sintering atmosphere at 1100° C. is 0.5 to 1.0%, the oxygen content of the sintering atmosphere at 1050° C. is 0.1 to 0.3%, and the oxygen content of the sintering atmosphere at 1000° C. is 0.02 to 0.05%;

[0081] The temperature is lowered to 200°C at a rate of 3-10°C / min, and the oxygen content of the sintering atmosphere at 200°C is ≤50ppm.

[0082] The present invention heats the temperature from room temperature to 200°C in air at a heating rate of 2-5°C / min. In an embodiment of the present invention, the heating rate can specifically be 2°C / min, 2.5°C / min, 3°C / min, 4°C / min or 5°C / min.

[0083] Then the temperature is raised to 300° C. at a heating rate of 0.5-1° C. / min. In the embodiment of the present invention, the heating rate may be 0.5° C. / min, 0.6° C. / min, 0.8° C. / min or 1° C. / min.

[0084] The PVA aqueous solution added in the granulation process of the present invention will decompose and volatilize at 200-300°C. If the temperature is raised too quickly at this stage, the PVA aqueous solution will volatilize violently, which may easily cause cracking of the blank. Therefore, the temperature needs to be raised slowly at 200-300°C to ensure that the PVA aqueous solution has sufficient time to volatilize.

[0085] The present invention heats up to 1100°C at a heating rate of 0.5-3°C / min, and the oxygen content of the sintering atmosphere at 1100°C is 0.0-3.0%. In an embodiment of the present invention, the heating rate can be 0.5°C / min, 0.6°C / min, 1°C / min, 2°C / min or 3°C / min, and the oxygen content of the sintering atmosphere at 1100°C can be 0%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5% or 3%.

[0086] Then, the temperature is raised to 1150-1250°C at a heating rate of 2-10°C / min. In an embodiment of the present invention, the temperature may be 1150°C, 1200°C or 1250°C, and the heating rate may be 2°C / min, 3°C / min, 5°C / min, 8°C / min or 10°C / min. Meanwhile, the oxygen content of the sintering atmosphere at 1150-1250°C is 0.5-5.0%, and the holding time at 1150-1250°C is 150-300min. In an embodiment of the present invention, the oxygen content of the sintering atmosphere at 1150-1250°C may be 0.5%, 1%, 2%, 3%, 4% or 5%, and the holding time at 1150-1250°C may be 150min, 180min, 200min, 220min, 250min or 300min.

[0087] In the medium and high frequency bands, eddy current loss is the main component of power consumption. Due to the high frequency, the uneven grain boundaries will also cause transcrystalline eddy currents. Therefore, the densification time should not be too short. The heating rate of about 0.5-3℃ / min can ensure a more uniform grain structure. At the same time, reducing the oxygen content of the sintering atmosphere is conducive to promoting the removal of pores and promoting the microscopic densification of the material. By reducing the oxygen content of the sintering atmosphere to 0.5-5.0% and combining it with a holding time of 150-300 minutes, the material magnetic permeability can be controlled at 2900-3500 and the density can be controlled at 4.85-5.0g / cm 3 The material has good power consumption characteristics at 300kHz~1MHz.

[0088] The present invention cools the temperature to 1000°C at a cooling rate of 0.3-1.5°C / min. In the process of cooling to 1000°C, the oxygen content of the sintering atmosphere at 1100°C is 0.5-1.0%, the oxygen content of the sintering atmosphere at 1050°C is 0.1-0.3%, and the oxygen content of the sintering atmosphere at 1000°C is 0.02-0.05%. In an embodiment of the present invention, the cooling rate can be 0.3°C / min, 0.5°C / min, 1.0°C / min, 1.2°C / min or 1.5°C / min, the oxygen content of the sintering atmosphere at 1100°C can be 0.5%, 0.8% or 1.0%, the oxygen content of the sintering atmosphere at 1050°C can be 0.1%, 0.2% or 0.3%, and the oxygen content of the sintering atmosphere at 1000°C can be 0.02%, 0.025%, 0.03%, 0.04% or 0.05%.

[0089] The present invention adopts a slow cooling method during the cooling process to 1000°C after the insulation is completed, thereby ensuring that impurities such as Ca and Si have sufficient time to move and segregate to the grain boundaries, thereby increasing the thickness of the grain boundary layer of the material and improving the high-frequency power consumption characteristics of the material; the present invention reduces the oxygen content of the sintering atmosphere at 1050°C and 1000°C to avoid the formation of a heterogeneous structure during the insulation stage, thereby avoiding the deterioration of material performance.

[0090] The present invention cools the temperature to 200°C at a cooling rate of 3 to 10°C / min, and the oxygen content of the sintering atmosphere at 200°C is ≤50ppm. In an embodiment of the present invention, the cooling rate can be 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min or 10°C / min.

[0091] Usually, the sintering temperature of ferrite is between 1300 and 1400°C. This sintering temperature can ensure the density and magnetic permeability, so the power consumption at 100kHz is low. However, the medium and high frequencies of 300kHz to 1MHz require a smaller grain size, so it is necessary to rely on the coordination between doping and sintering temperature so that the material can ensure a smaller grain size and higher resistance while maintaining a higher density and magnetic permeability. Low-melting-point substances will enter the grain boundaries at the same time, increase the grain boundary resistance, and reduce eddy current losses. In addition, CuO and V2O5 and other dopants such as SiO2 and CaO will increase the grain boundary resistance and reduce eddy current losses. In addition, low-temperature sintering ensures that the material has a smaller grain size, so the eddy current loss of manganese-zinc ferrite material is lower at high frequencies. The present invention uses fluxing agent CuO, combined with V2O5 (melting point 690°C) and MoO3 (795°C), so that the manganese-zinc ferrite material can obtain a higher sintering density (4.85 to 5.0 g / cm2) at a lower sintering temperature (1150 to 1250°C). 3 ), so that the manganese-zinc ferrite material has fewer internal pores and defects, the resistance to the movement of the magnetic domain wall is small, and the hysteresis loss of the manganese-zinc ferrite material is low, which ensures the low loss characteristics of the manganese-zinc ferrite material at medium frequency and the overall loss is relatively low.

[0092] The method provided by the present invention reduces the power consumption of manganese-zinc ferrite materials in medium and high frequency bands. With the development of emerging technologies such as artificial intelligence, the Internet of Things, and 5G communications, the demand for this material will become increasingly greater, promoting the development of related industries.

[0093] In order to further illustrate the present invention, a manganese-zinc ferrite material and a preparation method thereof provided by the present invention are described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0094] Example 1

[0095] Taking the total molar amount of the main components as 100%, the main components are: Fe2O3 52.1mol%, ZnO2 9.0mol%, CuO 0.2mol%, and the balance is Mn3O4;

[0096] In terms of percentage of the total mass of the main component, the auxiliary components are: CaO 0.03%, SiO2 0.005%, Nb2O5 0.05%, Co2O3 0.3%, TiO2 0.05%, SnO2 0.05%, ZrO2: 0.01%, V2O5 0.05%, MoO3 0.07%, HfO2 0.05%;

[0097] According to the above-mentioned component ratio, iron red Fe2O3, CuO, Mn3O4 and ZnO are accurately weighed, mixed and placed in a sand mill, and an appropriate amount of water (the mass ratio of water to the main component = 1:1) is added, and then the sand mill is used for mixing, the sand mill speed is 270r / min, and the mixing is performed for 60min. After the mixing is completed, the obtained sand abrasive slurry is placed in an oven for drying to obtain a sand abrasive;

[0098] The sand abrasive is ground into fine powder, passed through a 100-mesh screen, and then placed in a muffle furnace for pre-calcination at a temperature of 860° C. for a holding time of 2.5 h. After being fully cooled, a pre-calcined material is obtained;

[0099] The pre-sintered material is returned to the sand mill, and auxiliary components and an appropriate amount of water (the mass ratio of water to the total mass of the pre-sintered material and the auxiliary components = 1:1) are added to the sand mill. The speed of the sand mill is 270 r / min, and the sand milling time is 2 h. After drying, a mixed sand abrasive is obtained, and the D50 particle size of the mixed sand abrasive is 1.0 μm;

[0100] The mixed abrasive material and a binder polyvinyl alcohol aqueous solution (the mass concentration of the polyvinyl alcohol aqueous solution is 0.1%) are mixed, and spray granulation is performed, the mass of the polyvinyl alcohol aqueous solution is 20% of the mass of the mixed abrasive material, to obtain a granular material;

[0101] The granules were pressed to obtain a sample ring blank with an outer diameter of 25 mm, an inner diameter of 15 mm, and a height of 8 mm. The density of the blank was 3.10 g / cm 3 ;

[0102] The blank is sintered in an atmosphere protection bell furnace, and the sintering steps are as follows:

[0103] In air, the temperature was raised from room temperature to 200°C at a rate of 2.5°C / min, and then raised to 300°C at a rate of 1°C / min;

[0104] The temperature was raised to 1100°C at a heating rate of 0.6°C / min, and the oxygen content of the sintering atmosphere was reduced to 0.05% at 1100°C. The temperature was then raised to 1250°C at a heating rate of 5°C / min, and the oxygen content of the sintering atmosphere was increased to 4% at 1250°C. The temperature was kept at 1250°C for 300 minutes.

[0105] After the heat preservation is completed, the temperature is lowered to 1000°C at a cooling rate of 1°C / min. During the cooling process to 1000°C, the oxygen content of the sintering atmosphere is reduced. The oxygen content of the sintering atmosphere at 1100°C is 0.5%, the oxygen content of the sintering atmosphere at 1050°C is 0.2%, and the oxygen content of the sintering atmosphere at 1000°C is 0.025%;

[0106] The temperature was lowered to 200°C at a cooling rate of 3°C / min, and at the same time, the oxygen content of the sintering atmosphere was reduced. The oxygen content of the sintering atmosphere at 200°C was ≤50ppm.

[0107] After sintering, the manganese-zinc ferrite material is obtained.

[0108] Example 2

[0109] The preparation steps are the same as those in Example 1, except that the ratio of the main component to the auxiliary component is different. Specifically, based on the total molar amount of the main component as 100%, the main component is: Fe2O3 52.1 mol%, ZnO2 9.0 mol%, CuO 0.3 mol%, and the balance is Mn3O4;

[0110] Calculated as a percentage of the total mass of the main component, the auxiliary components are: CaO 0.05%, SiO2 0.005%, Nb2O5 0.05%, Co2O3 0.3%, TiO2 0.05%, SnO2 0.05%, ZrO2 0.01%, V2O5 0.05%, MoO3 0.05%, and HfO2 0.05%.

[0111] Example 3

[0112] The preparation steps are the same as those in Example 1, except that the ratio of the main component to the auxiliary component is different. Specifically, based on the total molar amount of the main component as 100%, the main component is: Fe2O3 52.1 mol%, ZnO2 9.0 mol%, CuO 0.2 mol%, and the balance is Mn3O4;

[0113] Calculated as a percentage of the total mass of the main component, the auxiliary components are: CaO 0.05%, SiO2 0.005%, Nb2O5 0.03%, Co2O3 0.5%, TiO2 0.1%, SnO2 0.05%, ZrO2 0.01%, V2O5 0.05%, MoO3 0.05%, and HfO2 0.05%.

[0114] Comparative Example 1

[0115] The preparation steps are the same as those in Example 1, except that Fe2O3 52.1 mol%, ZnO 2 9.0%, and the balance is Mn3O4;

[0116] The auxiliary components are as follows according to mass percentage: CaO: 0.06%, SiO2: 0.005%, Nb2O5 0.03%, Co2O3 0.3%, TiO2 0.05%, SnO2 0.05%, ZrO2 0.01%, V2O5: 0.05%;

[0117] The pressed blank is sintered in an atmosphere-protected bell furnace. The sintering steps are as follows:

[0118] In air, the temperature was raised to 200°C at a rate of 2.5°C / min, and then raised to 300°C at a rate of 1°C / min;

[0119] The temperature is raised to 1100° C. at a heating rate of 1.5° C. / min. During the process of lowering the temperature to 1100° C., the oxygen content of the sintering atmosphere is reduced, and the oxygen content of the sintering atmosphere at 1100° C. is 0.05%. The temperature is then raised to 1330° C. at a heating rate of 5° C. / min. The oxygen content of the sintering atmosphere is increased, and the oxygen content of the sintering atmosphere at 1330° C. is 5%. The temperature is kept at 1330° C. for 300 minutes.

[0120] After the heat preservation is completed, the temperature is lowered to 1000°C at a cooling rate of 1°C / min, and the oxygen content of the sintering atmosphere is reduced at the same time. The oxygen content of the sintering atmosphere at 1100°C is 0.8%, the oxygen content of the sintering atmosphere at 1050°C is 0.5%, and the oxygen content of the sintering atmosphere at 1000°C is 0.025%;

[0121] The temperature was lowered to 200°C at a cooling rate of 5°C / min, and the oxygen content of the sintering atmosphere was reduced at the same time. The oxygen content of the sintering atmosphere at 200°C was ≤50ppm.

[0122] The properties of the manganese-zinc ferrite materials of Examples 1 to 3 and Comparative Example 1 are shown in Table 1.

[0123] Table 1 Manganese-zinc ferrite material properties of Examples 1 to 3 and Comparative Example 1

[0124]

[0125] It can be seen from Table 1 that, compared with the comparative example, the power consumption of the manganese-zinc ferrite materials of Examples 1 to 3 at 300kHz to 1MHz is significantly reduced.

[0126] Figure 1 This is the SEM image of the manganese-zinc ferrite material obtained in Example 1; Figure 2 This is the SEM image of the manganese-zinc ferrite material obtained in Comparative Example 1. Figures 1-2 It can be seen that the manganese-zinc ferrite material obtained in Example 1 has smaller grains and a more uniform grain structure, so its power consumption at 300kHz to 1MHz is lower.

[0127] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A manganese-zinc ferrite material, characterized in that: The raw materials for preparation include a main component and an auxiliary component; taking the total molar amount of the main component as 100%, the main component includes: Fe2O3 52-55.5mol%, ZnO2 5.5-9.5mol%, CuO 0.1-0.5mol%, and the balance is Mn3O4; In terms of percentage of the total mass of the main component, the auxiliary components include: CaO 0.03-0.2%, SiO2 0.005-0.03%, Nb2O5 0.01-0.2%, Co2O3 0.1-0.6%, TiO2 0.05-0.2%, SnO2 0.05-0.3%, ZrO2 0.01-0.2%, V2O5 0.03-0.2%, MoO3 0.05-0.2%, HfO2 0.05-0.2%; the density of the manganese-zinc ferrite material is 4.85-5.0 g / cm 3 .

2. The manganese-zinc ferrite material according to claim 1, characterized in that: The initial magnetic permeability of the manganese-zinc ferrite material is 2900-3500.

3. The method for preparing the manganese-zinc ferrite material according to claim 1 or 2, characterized in that: The following steps are involved: sand-grinding the main component to obtain abrasive; Pre-burning the abrasive material to obtain a pre-burned material; Mixing and sand-grinding the pre-sintered material and the auxiliary components to obtain a mixed sand-grinding material; The mixed sand and abrasive material and the binder are mixed and molded to obtain a blank; The blank is sintered to obtain the manganese-zinc ferrite material; the sintering temperature is 1150-1250°C.

4. The preparation method according to claim 3, characterized in that: The sintering process includes: In air, heat up to 200°C at a rate of 2-5°C / min, and then heat up to 300°C at a rate of 0.5-1°C / min; The temperature is raised to 1100°C at a heating rate of 0.5-3°C / min, and the oxygen content of the sintering atmosphere at 1100°C is 0.0-3.0%, and then the temperature is raised to 1150-1250°C at a heating rate of 2-10°C / min, and the oxygen content of the sintering atmosphere at 1150-1250°C is 0.5-5.0%, and the holding time at 1150-1250°C is 150-300 minutes; The temperature is lowered to 1000° C. at a cooling rate of 0.3 to 1.5° C. / min, wherein during the cooling to 1000° C., the oxygen content of the sintering atmosphere at 1100° C. is 0.5 to 1.0%, the oxygen content of the sintering atmosphere at 1050° C. is 0.1 to 0.3%, and the oxygen content of the sintering atmosphere at 1000° C. is 0.02 to 0.05%; The temperature is lowered to 200°C at a rate of 3-10°C / min, and the oxygen content of the sintering atmosphere at 200°C is ≤50ppm.

5. The preparation method according to claim 3, characterized in that: The pre-burning temperature is 840-940° C., and the heat preservation time is 0.5-3 hours.

6. The preparation method according to claim 3, 4 or 5, characterized in that: The D50 particle size of the mixed sand abrasive is 1.0 μm.

7. The preparation method according to claim 3, characterized in that: The binder includes a polyvinyl alcohol aqueous solution.

8. The preparation method according to claim 3, characterized in that: The blank is an annular blank.

9. The preparation method according to claim 3 or 8, characterized in that: The density of the blank is 3.0-3.15 g / cm 3 .

10. The preparation method according to claim 3 or 4, characterized in that: The main component is sand-milled at a rotation speed of 270 r / min for a time of 30 to 60 min.

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