A manganese-zinc power ferrite composite material and a preparation method thereof

Abstract

The application provides a manganese-zinc power ferrite composite material and a preparation method thereof. The manganese-zinc power ferrite composite material is prepared from the following components by weight percentage: 75-90% of manganese-zinc power ferrite material and 10-25% of a binder composition; the binder composition is composed of the following components by weight percentage: 10-15% of polyformaldehyde resin, 2-5% of high-density polyethylene, 0.5-1.5% of polyethylene octene co-elastic body, 0.2-0.5% of vinyl bis-stearamide, 1-3% of zinc stearate and 1-3% of dioctyl phthalate. The application improves the injection molding performance of the manganese-zinc power ferrite composite material by regulating the composition of the binder and improving the process conditions, so as to ensure that the manganese-zinc power ferrite composite material has high magnetic induction intensity (Bs), low power loss (Pc) and good mechanical strength.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ferrite materials, and particularly relates to a manganese-zinc power ferrite composite material and a preparation method thereof. BACKGROUND

[0002] In recent years, with the vigorous development of the electric power industry, the electronic industry and the automobile industry, various parts and equipment gradually tend to be small, complex and diversified, and at the same time, the demand for small magnetic devices with high magnetic properties and complex shapes is increasing.

[0003] Powder metallurgy technology can prepare high-performance magnetic components. At present, the traditional dry pressing forming process breaks through the limitation of the existing forming process, which mainly utilizes the fluidity of the powder to perform mold filling and pressing treatment, but there are certain limitations in manufacturing external slot, horizontal hole, blind hole, external thread, concave table, key pin and surface knurling, number or identification and other complex-shaped parts. Plastic injection molding technology can mass-produce various complex-shaped products at a low price, but it cannot guarantee high magnetic properties. Injection molding technology has irreplaceable advantages in material forming due to its batch production, accurate size manufacturing and easy forming.

[0004] Manganese-zinc ferrite material has excellent properties of high frequency, high magnetic permeability, high saturation magnetic induction (Bs) and low power loss (Pc), so it can be widely used in new energy vehicles, medical treatment and communication fields. Therefore, in order to meet the diversified and high-performance requirements of future product structures, it is necessary to develop an injection molding process for manganese-zinc ferrite material.

[0005] Injection molding process can meet the high-precision requirements of the prepared magnetic devices, but the magnetic properties of the magnet are reduced due to the existence of a large amount of non-magnetic organic binder components in the raw material. Based on this, Chinese invention patent CN111370198A discloses an injection molded soft magnetic ferrite magnet, and the specific components include: 80-93% of soft magnetic ferrite magnetic powder, 0.1-1.0% of magnetic powder surface modifier, 0.1-0.5% of coupling agent, 0.2-0.8% of surface organic insulating agent, 6-19% of binder and 0.1-1.0% of flow aid, so as to prepare an injection molded soft magnetic ferrite magnet with high crushing strength, complex shape easy to form and miniaturization. However, the overall magnetic permeability of the above-mentioned magnet is low, and other magnetic properties (such as volume power consumption value or saturation magnetic induction) are not disclosed.

[0006] In summary, the present application aims to manufacture small complex magnets with high magnetic properties by using injection molding technology, while solving the technical problems of the above-mentioned raw materials caused by the addition of a large amount of organic binder, which reduces the overall performance of the magnet. SUMMARY

[0007] In order to solve the technical problems of small and complex magnetic core forming difficulty and the addition of organic binder causing the magnetic properties of the manganese-zinc power ferrite material to decline, the manganese-zinc power ferrite composite material injection molding performance is improved by regulating the composition of the binder and improving the process conditions, so as to ensure that it has high magnetic induction intensity (Bs), low power loss (Pc) and good mechanical strength.

[0008] To achieve the purpose of the application, the following technical solutions are adopted in the application:

[0009] In the first aspect, the application provides a manganese-zinc power ferrite composite material, which is prepared from the following components by weight percentage: manganese-zinc power ferrite material 75% to 90% and binder composition 10% to 25%.

[0010] The binder composition is composed of the following components by weight percentage: polyformaldehyde resin (POM) 10% to 15%, high-density polyethylene (HDPE) 2% to 5%, polyethylene octene co-elastic body (POE) 0.5% to 1.5%, ethylene bis-stearamide (EBS) 0.2% to 0.5%, zinc stearate (SA) 1% to 3%, and dioctyl phthalate (DOP) 1% to 3%.

[0011] The application regulates the formula of the binder to improve the injection molding performance, magnetic properties and mechanical strength of the manganese-zinc power ferrite composite material. First, the application selects polyformaldehyde resin (POM) as the main component of the binder, which not only has better flowability, but also has almost no branches and side groups on the POM molecular chain, and most of the carbon atoms are connected with hydrogen atoms, so that the molecular chain is very regular, and POM has high crystallinity. At the same time, the carbon-oxygen bond in the POM molecule is short, so the cohesive energy density of POM is high, and the molecular chains are closely packed. This structure helps to reduce the directionality of the chain during forming, thereby obtaining a formed blank with good isotropy. In addition, POM also has the advantages of high mechanical strength, fatigue resistance, creep resistance, wear resistance and good chemical resistance, thereby further improving the mechanical properties and practicality of the manganese-zinc power ferrite composite material.

[0012] Secondly, the application selects high-density polyethylene (HDPE) as a stabilizer, so that the material structure remains stable and uniformly dispersed during subsequent processing, especially maintaining good stability under high shear force.

[0013] In addition, the present application adopts dioctyl phthalate (DOP) as a plasticizer, which can reduce the glass transition temperature of POM, finally improve the heat distortion temperature thereof, so that the POM can keep good wetting property to the manganese-zinc power ferrite material, thereby improving the mixing property of the manganese-zinc power ferrite material and the binder composition, and finally improving the magnetic property of the manganese-zinc power ferrite composite material.

[0014] Finally, the polyformaldehyde resin component in the binder composition provided by the present application can be easily chemically decomposed in subsequent catalytic degreasing, so that the degreasing reaction rate can be accelerated, and thus the degreasing efficiency is greatly improved.

[0015] In the present application, the weight percentage of the manganese-zinc power ferrite material is 75% to 90%, for example, can be 75%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, etc.

[0016] In the present application, the weight percentage of the binder composition is 10% to 25%, for example, can be 10%, 11%, 12%, 13%, 14%, 15%, 18%, 20%, 22%, 25%, etc.

[0017] In the present application, the weight percentage of the polyformaldehyde resin is 10% to 15%, for example, can be 10%, 11%, 12%, 13%, 14%, 15%, etc. If the weight percentage is too low, the material cannot be formed by dense mixing, otherwise, the product performance will be reduced and the processing difficulty will be increased.

[0018] In the present application, the weight percentage of the high-density polyethylene is 2% to 5%, for example, can be 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, etc. If the weight percentage is too low, the stability and durability of the material will be reduced, otherwise, the dense mixing will be uneven.

[0019] In the present application, the weight percentage of the polyethylene octene co-elastic body is 0.5% to 1.5%, for example, can be 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, etc. In the present application, by adjusting the weight percentage of the polyethylene octene co-elastic body, it is controlled within the preferred content range. If the weight percentage is too low, the flexibility of the product will be insufficient, otherwise, the dimensional stability of the product will be affected.

[0020] In the present application, the weight percentage of the vinyl bis stearamide is 0.2% to 0.5%, for example, it can be 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.38%, 0.4%, 0.42%, 0.45%, 0.48%, 0.5%, etc.

[0021] In the present application, the weight percentage of the zinc stearate is 1% to 3%, for example, it can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, etc.

[0022] In the present application, by regulating the weight percentage of the vinyl bis stearamide and the zinc stearate, the content of both is controlled in the preferred content range, too low weight percentage will result in poor lubrication effect of the product, on the contrary, too much added amount will possibly form too thick coating on the surface of the mold, which will result in difficult demolding.

[0023] In the present application, the weight percentage of the dioctyl phthalate is 1% to 3%, for example, it can be 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, etc., too low weight percentage will result in poor plasticizing effect of the product, on the contrary, it will result in significant decrease of the mechanical properties such as tensile strength, hardness, etc. of the product.

[0024] Preferably, the manganese-zinc power ferrite composite material is prepared from the following weight percentage of components: manganese-zinc power ferrite material 78% to 85% and binder composition 15% to 22%.

[0025] Preferably, the binder composition is composed of the following weight percentage of components: polyformaldehyde resin 10% to 14%, high density polyethylene 2% to 3%, polyethylene octene co- elastomer 1% to 1.5%, vinyl bis stearamide 0.3% to 0.5%, zinc stearate 2% to 3%, and dioctyl phthalate 1% to 2%.

[0026] Preferably, the average particle size of the manganese-zinc power ferrite material is 1.1 to 1.4 μm, for example, it can be 1.1 μm, 1.12 μm, 1.15 μm, 1.18 μm, 1.2 μm, 1.21 μm, 1.22 μm, 1.23 μm, 1.24 μm, 1.25 μm, 1.26 μm, 1.27 μm, 1.28 μm, 1.29 μm, 1.3 μm, 1.32 μm, 1.35 μm, 1.38 μm, 1.4 μm, etc.

[0027] Preferably, the polyformaldehyde resin has a melt index of 90-150 g / 10 min, preferably 120 g / 10 min, for example 90 g / 10 min, 100 g / 10 min, 110 g / 10 min, 120 g / 10 min, 130 g / 10 min, 140 g / 10 min, 150 g / 10 min, etc.

[0028] Preferably, the high-density polyethylene has a molecular weight of 40,000-300,000, preferably 100,000, for example 40,000, 60,000, 80,000, 100,000, 200,000, 300,000, etc.

[0029] Preferably, the high-density polyethylene has a melt index of 0.1-10 g / 10 min, preferably 0.5 g / 10 min, for example 0.1 g / 10 min, 0.2 g / 10 min, 0.5 g / 10 min, 0.8 g / 10 min, 1 g / 10 min, 2 g / 10 min, 5 g / 10 min, 8 g / 10 min, 10 g / 10 min, etc.

[0030] Preferably, the polyethylene octene co-elastic body has a molecular weight of 3,000-3,500, preferably 3,500, for example 3,000, 3,100, 3,200, 3,300, 3,400, 3,500, etc.

[0031] Preferably, the polyethylene octene co-elastic body has a melt index of 0.1-3 g / 10 min, preferably 1.2 g / 10 min, for example 0.1 g / 10 min, 0.3 g / 10 min, 0.5 g / 10 min, 0.8 g / 10 min, 1 g / 10 min, 1.2 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 2.2 g / 10 min, 2.5 g / 10 min, 2.8 g / 10 min, 3 g / 10 min, etc.

[0032] In the present application, by regulating the physical property parameters of the above components, the binder composition has optimal performance, which facilitates the improvement of the injection molding performance, magnetic performance and mechanical strength of the manganese-zinc power ferrite composite material.

[0033] In a second aspect, the present application provides a method for preparing the manganese-zinc power ferrite composite material according to the first aspect, the method comprising the following steps:

[0034] The manganese-zinc power ferrite material and the binder composition are mixed and densified according to the formulation amount to obtain a first material;

[0035] The first material is subjected to extrusion and granulation treatment to obtain a second material;

[0036] The second material is subjected to injection molding treatment to obtain a green body;

[0037] The green body is subjected to debinding treatment to obtain a debound body;

[0038] The debound body is subjected to sintering treatment to obtain the manganese-zinc power ferrite composite material.

[0039] Preferably, the method for preparing the manganese-zinc power ferrite material comprises the following steps: subjecting iron oxide, manganese oxide and zinc oxide to primary ball milling treatment to obtain a primary ball mill; subjecting the primary ball mill to pre-sintering treatment to obtain a pre-sintered material; and subjecting the pre-sintered material to secondary ball milling treatment to obtain the manganese-zinc power ferrite material.

[0040] Preferably, the mass ratio of the iron oxide, the manganese oxide and the zinc oxide is 73.4:21.8:4.8.

[0041] Preferably, the pre-sintering treatment is performed at a temperature of 600-900℃, for example, 600℃, 700℃, 800℃, 900℃, etc., for a time of 2-4h, for example, 2h, 3h, 4h, etc.

[0042] Preferably, the secondary ball milling treatment is further followed by drying and sieving treatment.

[0043] Preferably, the manganese-zinc power ferrite material has a water content of ≤0.1%, for example, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc.

[0044] Preferably, the temperature for the internal mixing is 160-190℃, preferably 180-190℃, for example, 160℃, 165℃, 170℃, 175℃, 180℃, 185℃, 190℃, etc.

[0045] Preferably, the time for the internal mixing is 30-60min, preferably 30-45min, for example, 30min, 32min, 35min, 38min, 40min, 42min, 45min, 48min, 50min, 52min, 55min, 58min, 60min, etc.

[0046] In the present application, too low temperature for the internal mixing or too long time for the internal mixing can result in uneven wrapping of the magnetic powder by the binder composition, thereby reducing the mechanical strength of the manganese-zinc power ferrite composite material.

[0047] Preferably, the temperature of the granulation process is 150-170℃, preferably 150-160℃, for example 150℃, 155℃, 160℃, 165℃, 170℃, etc.

[0048] Preferably, the length of the second material is 3-5mm, for example 3mm, 3.2mm, 3.5mm, 3.8mm, 4mm, 4.2mm, 4.5mm, 4.8mm, 5mm, etc.

[0049] Preferably, the temperature of the injection molding process is 80-140℃, for example 80℃, 85℃, 90℃, 95℃, 100℃, 110℃, 120℃, 130℃, 140℃, etc.

[0050] Preferably, the temperature of the debinding process is 100-200℃, preferably 120-150℃, for example 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, etc.

[0051] Preferably, the debinding process uses oxalic acid for debinding.

[0052] In the present application, the polyformaldehyde resin in the binder composition provided by the present application is easily chemically decomposed under the action of oxalic acid, nitrogen plays a protective role in the reaction and carries away the formaldehyde gas produced in the decomposition, so that the reaction can continue to occur quickly, thereby greatly improving the debinding efficiency.

[0053] Preferably, the amount of oxalic acid is 1-5g / min, preferably 1-3g / min, for example 1g / min, 1.5g / min, 2g / min, 2.5g / min, 3g / min, 3.5g / min, 4g / min, 4.5g / min, 5g / min.

[0054] Preferably, the temperature of the sintering process is 1250-1350℃, for example 1250℃, 1260℃, 1270℃, 1280℃, 1290℃, 1300℃, 1310℃, 1320℃, 1330℃, 1340℃, 1350℃, etc.; the time is 4-12h, for example 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc.

[0055] Preferably, the volume content of oxygen during the sintering process is 2-21vol%, for example 2vol%, 3vol%, 5vol%, 8vol%, 10vol%, 12vol%, 15vol%, 18vol%, 20vol%, 21vol%, etc.

[0056] Preferably, the sintering process comprises sintering at 1280-1330 DEG C for 5-8h in the presence of 19-21vol% oxygen, then sintering at 1280-1330 DEG C for 1-4h in the presence of 2-5vol% oxygen, and finally cooling under balanced oxygen partial pressure.

[0057] Compared with the prior art, the present application has the following advantages:

[0058] The present application provides a kind of manganese zinc power ferrite composite material, first, the present application selects polyformaldehyde resin (POM) as the main component of binder, not only better fluidity, and POM molecular chain has almost no branch and side group, and most of carbon atoms are connected with hydrogen atom, so that molecular chain is very regular, so POM has higher crystallinity;At the same time, the carbon-oxygen bond in POM molecule is shorter, so the cohesive energy density of POM is high, and the molecular chain is closely gathered, this structure helps to reduce the directionality of chain in forming process, and then obtain the forming blank with good isotropy.In addition, POM also has the advantages of high mechanical strength, fatigue resistance, creep resistance, wear resistance and good chemical resistance, etc., so as to further improve the mechanical properties and practicability of manganese zinc power ferrite composite material.

[0059] Secondly, the present application selects high density polyethylene (HDPE) as stabilizer, so that the material structure remains stable and uniformly dispersed during subsequent processing, especially maintaining good stability under high shear force.

[0060] In addition, the present application uses dioctyl phthalate (DOP) as plasticizer, which can reduce the glass transition temperature of POM and finally improve its heat distortion temperature, so that POM maintains good wettability to manganese zinc power ferrite material, so as to improve the mixing property of manganese zinc power ferrite material and binder composition, and finally improve the magnetic property of manganese zinc power ferrite composite material.

[0061] Finally, the polyformaldehyde resin component in the binder composition provided by the present application can be easily chemically decomposed during subsequent catalytic degreasing, so as to accelerate the degreasing reaction rate and greatly improve the degreasing efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0062] Figure 1 The schematic diagram of the green body of the magnetic ring sample and the magnetic strip sample after injection molding provided by the present application is shown in the figure;

[0063] Figure 2 The measurement schematic diagram of the pressing strength of the magnetic strip tested by universal testing machine is shown in the figure. DETAILED DESCRIPTION

[0064] The technical solutions of the present application will be further illustrated below by combining with the drawings and specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0065] The preparation method of the manganese-zinc power ferrite soft magnetic material in the embodiments and comparative examples of the present application comprises the following steps: iron oxide, manganese oxide and zinc oxide are subjected to primary ball milling treatment according to a mass ratio of 73.4:21.8:4.8 to obtain a primary ball milling material; the primary ball milling material is subjected to pre-sintering treatment at 800℃ for 3h to obtain a pre-sintered material; the pre-sintered material is subjected to secondary ball milling, drying and sieving treatment to obtain the manganese-zinc power ferrite soft magnetic material.

[0066] In the formula, the average particle size (D50) of the manganese-zinc power ferrite soft magnetic material is measured by Fisher air permeability method, and the measuring instrument is HMK-22 average particle size instrument.

[0067] In the embodiments and comparative examples of the present application, the melt index of the polyformaldehyde resin is 120g / 10min; the molecular weight of the high-density polyethylene is 100000, and the melt index is 0.5g / 10min; the molecular weight of the polyethylene octene copolymer elastomer is 3500, and the melt index is 1.2g / 10min.

[0068] Example 1

[0069] The present embodiment provides a manganese-zinc power ferrite composite material, which is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.1μm, water content ≤0.1%) 80% and binder composition 20%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 12.5%, high-density polyethylene 2.5%, polyethylene octene copolymer elastomer 1.5%, vinyl bis-stearamide 0.5%, zinc stearate 2% and dioctyl phthalate 1%.

[0070] The present embodiment provides a preparation method of the above manganese-zinc power ferrite composite material, which comprises the following steps:

[0071] (1) Banbury mixing: the components of the binder are weighed according to the formula amount, mixed to obtain the binder composition, and mixed with the manganese-zinc power ferrite soft magnetic material; the temperature of the Banbury mixer is raised to 190℃ for preheating, and the manganese-zinc power ferrite soft magnetic material and the binder composition are added in turn after preheating; first, at a speed of 10r / min, a pre-mixed 20min, then the speed is increased to 25r / min for 10min, and then the speed is increased to 40r / min, and the Banbury mixing is kept for 40min to obtain the first material;

[0072] (2) The first material is added to a granulator, and extrusion and granulation treatment is carried out at 160°C to obtain a second material with a length of 2-3 mm;

[0073] (3) The second material is subjected to injection molding treatment, and a Φ16 mm x Φ9 mm x 8 mm magnetic ring green body and a 8 mm high magnetic strip green body as shown in the figure are prepared by a mold at 80°C; Figure 1

[0074] (4) The magnetic ring green body and the magnetic strip green body are placed in an oxalic acid debinding furnace, and debinding treatment is carried out at 130°C and an oxalic acid feeding rate of 3 g / min to obtain a debound body;

[0075] (5) The debound body is first sintered at 1290°C for 6 h in a nitrogen-oxygen mixed gas (21 vol% oxygen content), then sintered at 1290°C for 3 h in a nitrogen-oxygen mixed gas (2 vol% oxygen content), and finally cooled under balanced oxygen partial pressure to obtain a manganese-zinc power ferrite magnetic ring composite material and a manganese-zinc power ferrite magnetic strip composite material.

[0076] Example 2

[0077] The present embodiment provides a manganese-zinc power ferrite composite material, which is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.2 μm, water content ≤0.1%) 78% and binder composition 22%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 14%, high-density polyethylene 3%, polyethylene octene co-elastic body 1%, vinyl bis-stearamide 0.5%, zinc stearate 2.5%, and dioctyl phthalate 1%.

[0078] The present embodiment provides a preparation method of the above-mentioned manganese-zinc power ferrite composite material, which comprises the following steps:

[0079] (1) Banbury mixing: the components of the binder are weighed according to the formula amount, mixed to obtain a binder composition, and mixed with the manganese-zinc power ferrite soft magnetic material; the temperature of the banbury mixer is raised to 185°C for preheating, and the manganese-zinc power ferrite soft magnetic material and the binder composition are added in turn after preheating; first at a rotation speed of 10 r / min, a pre-mixed 20 min, then the rotation speed is increased to 25 r / min for 10 min, and then the rotation speed is increased to 40 r / min, and the banbury mixing is kept for 40 min to obtain a first material;

[0080] (2) The first material is added to a granulator, and extrusion and granulation treatment is carried out at 155°C to obtain a second material with a length of 2-3 mm;

[0081] ​(3) the second material is subjected to injection molding treatment, and a magnetic ring green body with a size of Φ16mmxΦ9mmx8mm and a magnetic strip green body with a height of 8mm are prepared by a mold at 80℃;

[0082] (4) the magnetic ring green body and the magnetic strip green body are placed in an oxalic acid debinding furnace, and are subjected to debinding treatment at 130℃ and an oxalic acid feeding amount of 3g / min, to obtain debinding bodies;

[0083] (5) the debinding bodies are first sintered at 1310℃ for 5h in a nitrogen-oxygen mixed gas (the volume content of oxygen is 21vol%), then sintered at 1310℃ for 4h in a nitrogen-oxygen mixed gas (the volume content of oxygen is 5vol%), and finally cooled under balanced oxygen partial pressure, to obtain a manganese-zinc power ferrite magnetic ring composite material and a manganese-zinc power ferrite magnetic strip composite material.

[0084] Example 3

[0085] The embodiment provides a manganese-zinc power ferrite composite material, which is prepared from the following components in percentage by weight: 80.5% of a manganese-zinc power ferrite soft magnetic material (the average particle size is 1.1μm, and the water content is ≤0.1%) and 19.5% of a binder composition; the binder composition is composed of the following components in percentage by weight: 13% of a polyformaldehyde resin, 2% of high-density polyethylene, 1% of a polyethylene octene co-elastic body, 0.5% of vinyl bis-stearamide, 2% of zinc stearate and 1% of dioctyl phthalate.

[0086] The embodiment provides a preparation method of the manganese-zinc power ferrite composite material, which comprises the following steps:

[0087] (1) Banbury mixing: the components of the binder are weighed according to the formula amount, mixed to obtain a binder composition, and mixed with the manganese-zinc power ferrite soft magnetic material; the temperature of the Banbury mixer is raised to 185℃ for preheating, and the manganese-zinc power ferrite soft magnetic material and the binder composition are sequentially added after preheating; first, a speed of 10r / min is used for a pre-mixing period of 20min, then the speed is increased to 25r / min for mixing for 10min, and then the speed is increased to 40r / min, and the Banbury mixing is kept for 30min, to obtain a first material;

[0088] (2) the first material is added to a granulator, and is subjected to extrusion and granulation treatment at 155℃, to obtain a second material with a length of 2-3mm;

[0089] (3) the second material is subjected to injection molding treatment, and a magnetic ring green body with a size of Φ16mmxΦ9mmx8mm and a magnetic strip green body with a height of 8mm are prepared by a mold at 80℃;

[0090] (4) placing the green magnetic ring and green magnetic strip into an oxalic acid debinding furnace, and performing debinding treatment at 130°C and an acid feeding rate of 4 g / min to obtain debinded blanks;

[0091] (5) sintering the debinded blanks in nitrogen-oxygen mixed gas (21 vol% oxygen) at 1310°C for 5 h, then in nitrogen-oxygen mixed gas (5 vol% oxygen) at 1310°C for 4 h, and finally cooling under balanced oxygen partial pressure to obtain manganese-zinc power ferrite magnetic ring composite material and manganese-zinc power ferrite magnetic strip composite material.

[0092] Example 4

[0093] The present example provides a manganese-zinc power ferrite composite material, which is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.1 μm, water content ≤0.1%) 77% and binder composition 23%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 13%, high-density polyethylene 4%, polyethylene octene co-elastic body 1.5%, vinyl bis-stearamide 0.5%, zinc stearate 2.5%, and dioctyl phthalate 1.5%.

[0094] The present example provides a preparation method of the above manganese-zinc power ferrite composite material, which comprises the following steps:

[0095] (1) Banbury mixing: weighing the components of the binder according to the formula, mixing to obtain the binder composition, and mixing with the manganese-zinc power ferrite soft magnetic material; raising the temperature of the Banbury mixer to 180°C for preheating, and then adding the manganese-zinc power ferrite soft magnetic material and the binder composition in sequence; first mixing at a rotation speed of 10 r / min for 20 min, then increasing the rotation speed to 25 r / min for 10 min, and then increasing the rotation speed to 40 r / min for 30 min of mixing and holding to obtain the first material;

[0096] (2) adding the first material into a granulator, and performing extrusion and granulation treatment at 155°C to obtain the second material with a length of 2-3 mm;

[0097] (3) performing injection molding treatment on the second material to obtain a magnetic ring green body with a diameter of Φ16 mm, a diameter of Φ9 mm, and a height of 8 mm, and a magnetic strip green body with a height of 8 mm;

[0098] (4) placing the green magnetic ring and green magnetic strip into an oxalic acid debinding furnace, and performing debinding treatment at 130°C and an acid feeding rate of 4 g / min to obtain debinded blanks;

[0099] (5) sintering the debinding blank in nitrogen-oxygen mixed gas (21 vol% oxygen) at 1290°C for 5h, then in nitrogen-oxygen mixed gas (5 vol% oxygen) at 1290°C for 4h, and finally cooling under balanced oxygen partial pressure to obtain a manganese-zinc power ferrite magnetic ring composite material and a manganese-zinc power ferrite magnetic strip composite material.

[0100] Example 5

[0101] The present example provides a manganese-zinc power ferrite composite material, which is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.2 μm, water content ≤0.1%) 80% and binder composition 20%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 12.5%, high-density polyethylene 2.2%, polyethylene octene co-elastic body 1.5%, vinyl bis-stearamide 0.3%, zinc stearate 2% and dioctyl phthalate 1.5%.

[0102] The present example provides a preparation method of the above-mentioned manganese-zinc power ferrite composite material, which comprises the following steps:

[0103] (1) Banbury mixing: weigh the components of the binder according to the formula, mix to obtain the binder composition, and mix with the manganese-zinc power ferrite soft magnetic material; raise the temperature of the Banbury mixer to 220°C for preheating, and then add the manganese-zinc power ferrite soft magnetic material and the binder composition in sequence; first at a rotation speed of 10 r / min, pre-mix for 20 min, then increase the rotation speed to 25 r / min for 10 min, and then increase the rotation speed to 40 r / min, and Banbury mixing for 40 min, to obtain a first material;

[0104] (2) Add the first material to the granulator, and perform extrusion and granulation treatment at 160°C to obtain a second material with a length of 2-3 mm;

[0105] (3) Perform injection molding treatment on the second material, and pass through a mold at 80°C to obtain a magnetic ring green body of Φ16 mm x Φ9 mm x 8 mm and a magnetic strip green body with a height of 8 mm;

[0106] (4) Place the magnetic ring green body and the magnetic strip green body in an oxalic acid debinding furnace, and perform debinding treatment at 130°C and an acid feeding rate of 1 g / min to obtain a debinding blank;

[0107] (5) the green compact is sintered at 1290°C for 5h in nitrogen-oxygen mixed gas (21vol% oxygen), then sintered at 1290°C for 4h in nitrogen-oxygen mixed gas (5vol% oxygen), and finally cooled under balanced oxygen partial pressure to obtain the manganese-zinc power ferrite magnetic ring composite material and the manganese-zinc power ferrite magnetic strip composite material.

[0108] Example 6

[0109] The difference between this example and Example 2 is that the manganese-zinc power ferrite composite material is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.1 μm, water content ≤0.1%) 81.7% and binder composition 18.3%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 10%, high-density polyethylene 2%, polyethylene octene co-elastic body 1%, vinyl bis-stearamide 0.3%, zinc stearate 3% and dioctyl phthalate 2%, and the others are the same as in Example 2.

[0110] Example 7

[0111] The difference between this example and Example 2 is that the manganese-zinc power ferrite composite material is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.1 μm, water content ≤0.1%) 75% and binder composition 25%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 15%, high-density polyethylene 5%, polyethylene octene co-elastic body 1.5%, vinyl bis-stearamide 0.5%, zinc stearate 2% and dioctyl phthalate 1%, and the others are the same as in Example 2.

[0112] Example 8

[0113] The difference between this example and Example 2 is that the manganese-zinc power ferrite composite material is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.1 μm, water content ≤0.1%) 85% and binder composition 15%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 10%, high-density polyethylene 2%, polyethylene octene co-elastic body 0.5%, vinyl bis-stearamide 0.5%, zinc stearate 1% and dioctyl phthalate 1%, and the others are the same as in Example 2.

[0114] Example 9

[0115] The difference between this example and Example 2 is that in the preparation method, step (5) is that the green compact is directly sintered at 1290°C for 8h in nitrogen-oxygen mixed gas (21vol% oxygen), and finally cooled under balanced oxygen partial pressure, and the others are the same as in Example 2.

[0116] Comparative Example 1

[0117] The difference between this comparative example and Example 2 is that the Mn-Zn power ferrite composite material is prepared from the following components by weight percentage: Mn-Zn power ferrite soft magnetic material (average particle size 1.2 μm, water content ≤0.1%) 80% and binder composition 20%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 15%, polyethylene octene co-elastic body 1%, vinyl bis-stearamide 0.5%, zinc stearate 0.5% and dioctyl phthalate 3%; in the preparation method, the temperature of the internal mixing is reduced to 180°C, and the time of the internal mixing is adjusted to 30 min, and the others are the same as Example 2.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 2 is that the Mn-Zn power ferrite composite material is prepared from the following components by weight percentage: Mn-Zn power ferrite soft magnetic material (average particle size 1.2 μm, water content ≤0.1%) 80% and binder composition 20%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 13%, high-density polyethylene 2%, vinyl bis-stearamide 0.5%, zinc stearate 2.5% and dioctyl phthalate 2%; in the preparation method, the green compact is first sintered at 1330°C for 4 h in a nitrogen-oxygen mixed gas (oxygen content by volume 21 vol%), then sintered at 1330°C for 3 h in a nitrogen-oxygen mixed gas (oxygen content by volume 5 vol%), and finally cooled under balanced oxygen partial pressure, and the others are the same as Example 2.

[0120] Comparative Example 3

[0121] The difference between this comparative example and Example 2 is that the Mn-Zn power ferrite composite material is prepared from the following components by weight percentage: Mn-Zn power ferrite soft magnetic material (average particle size 1.2 μm, water content ≤0.1%) 82% and binder composition 18%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 14%, high-density polyethylene 2%, polyethylene octene co-elastic body 0.5%, zinc stearate 0.5% and dioctyl phthalate 1%, and the others are the same as Example 2.

[0122] Comparative Example 4

[0123] This comparative example differs from Example 2 in that the manganese zinc power ferrite composite was prepared from the following weight percent components: manganese zinc power ferrite soft magnetic material (average particle size 1.0 μm, water content < 0.1%) 81% and binder composition 19%; the binder composition was composed of the following weight percent components: polyformaldehyde resin 14%, high density polyethylene 1.5%, polyethylene octene co- elastomer 1%, vinyl bis stearamide 0.5%, and dioctyl phthalate 2%, and the remainder was the same as in Example 2.

[0124] Comparative Example 5

[0125] This comparative example differs from Example 2 in that the manganese zinc power ferrite composite was prepared from the following weight percent components: manganese zinc power ferrite soft magnetic material (average particle size 1.6 μm, water content < 0.1%) 82% and binder composition 18%; the binder composition was composed of the following weight percent components: polyformaldehyde resin 12%, high density polyethylene 2%, polyethylene octene co- elastomer 1.4%, vinyl bis stearamide 0.8%, zinc stearate 0.9%, and dioctyl phthalate 0.9%, and the remainder was the same as in Example 2.

[0126] Comparative Example 6

[0127] This comparative example differs from Example 2 in that the manganese zinc power ferrite composite was prepared from the following weight percent components: manganese zinc power ferrite soft magnetic material (average particle size 1.4 μm, water content < 0.1%) 80% and binder composition 20%; the binder composition was composed of the following weight percent components: polyformaldehyde resin 13.5%, high density polyethylene 2%, polyethylene octene co- elastomer 1.5%, vinyl bis stearamide 0.5%, zinc stearate 1%, and dioctyl phthalate 1.5%, and the remainder was the same as in Example 2.

[0128] Comparative Example 7

[0129] This comparative example differs from Example 2 in that the manganese zinc power ferrite composite was prepared from the following weight percent components: manganese zinc power ferrite soft magnetic material (average particle size 1.2 μm, water content < 0.1%) 76% and binder composition 24%; the binder composition was composed of the following weight percent components: polyformaldehyde resin 14%, high density polyethylene 3%, polyethylene octene co- elastomer 3%, vinyl bis stearamide 0.5%, zinc stearate 2.5%, and dioctyl phthalate 1%, and the remainder was the same as in Example 2.

[0130] Comparative Example 8

[0131] The difference between the present comparative example and Example 2 is that the manganese-zinc power ferrite composite material is prepared from the following components by weight percentage: manganese-zinc power ferrite soft magnetic material (average particle size 1.2 μm, water content ≤0.1%) 73% and binder composition 27%; the binder composition is composed of the following components by weight percentage: polyformaldehyde resin 14%, high-density polyethylene 8%, polyethylene octene co-elastic body 1%, vinyl bis-stearamide 0.5%, zinc stearate 2.5% and dioctyl phthalate 1%, and the others are the same as in Example 2.

[0132] Test conditions

[0133] The manganese-zinc power ferrite magnetic ring composite materials and manganese-zinc power ferrite magnetic strip composite materials provided by Examples 1 to 9 and Comparative Examples 1 to 8 are subjected to performance testing, and the testing methods are as follows:

[0134] The Φ16 mm x Φ9 mm x 8 mm magnetic ring composite materials can be measured for magnetic properties such as permeability, saturation magnetic induction (Bs) and power loss (Pc) by means of impedance analyzer, SY8218 and SY8258 instruments, and the pressing strength of the magnetic strip composite materials is evaluated by means of a universal testing machine, and the measurement schematic diagram is shown in Figure 2 .

[0135] The specific compositions of the manganese-zinc power ferrite magnetic ring composite materials and manganese-zinc power ferrite magnetic strip composite materials provided by the examples and comparative examples are shown in Table 1:

[0136] Table 1

[0137]

[0138]

[0139] The performance data of the Φ16 mm x Φ9 mm x 8 mm magnetic ring composite materials and the magnetic strip composite materials with a height of 8 mm prepared by the examples and comparative examples are shown in Table 2.

[0140] Table 2

[0141]

[0142] As can be seen from Table 2, compared with the comparative examples, the manganese-zinc power ferrite composite materials provided by the examples in the present application have improved injection molding performance by regulating the composition of the binder and improving the process conditions, thereby ensuring that they have high magnetic induction (Bs), low power loss (Pc) and good mechanical strength.

[0143] Example 5 Due to the high temperature of the internal mixer, part of the polyoxymethylene resin (POM) is oxidized and decomposed at high temperature, resulting in poor mixing effect of the material, and the actual sintering density is only 4.4 g / cm 3 And there are many pores inside, and the overall porosity of the product is large, resulting in a large power loss and a low saturation magnetic induction intensity of the manganese-zinc power ferrite magnetic ring composite material.

[0144] Compared with Example 2, in Example 9, step (5) is a one-time calcination treatment by directly sintering at 1290℃ for 8h in a nitrogen-oxygen mixed gas (21vol% oxygen content), and the comprehensive performance of the manganese-zinc power ferrite composite material prepared finally is poor.

[0145] Comparative Example 1 shows that due to the absence of a high-density polyethylene component in the binder composition, the magnetic properties and mechanical strength of the product are both reduced.

[0146] Comparative Example 2 shows that due to the absence of a polyethylene octene elastomer component in the binder composition, the overall pressure strength of the material is low, and no connection points are formed in the molecular structure of the composite material, so that the system cannot disperse and buffer the pressure well under the action of pressure, and therefore the pressure strength of the product is low.

[0147] Comparative Example 4 shows that the present application uses an ultra-fine manganese-zinc power ferrite soft magnetic material feeding system, but because it does not add a stearic acid component, the distribution uniformity of the powder particles is poor, resulting in poor compatibility between the manganese-zinc power ferrite soft magnetic material powder and the binder composition, and the comprehensive performance of the product is poor.

[0148] Comparative Examples 5 and 6, and Comparative Examples 7 and 8 show that due to the content of part of the components in the binder composition not being within the preferred range, the comprehensive performance of the magnetic ring composite material and the magnetic strip composite material prepared is unbalanced.

[0149] The applicant declares that the above examples illustrate the process of the present application, but the present application is not limited to the above process steps, i.e. it does not mean that the present application must rely on the above process steps to be implemented. It should be understood by those skilled in the art that any improvement on the present application, equivalent replacement of the materials selected by the present application, addition of auxiliary ingredients, selection of specific methods, etc. all fall within the scope of protection and disclosure of the present application.

Claims

1. A Mn-Zn power ferrite composite material having high magnetic induction, low power loss and good mechanical strength, characterized by, The manganese-zinc power ferrite composite material is prepared from components with the following weight percentages: manganese-zinc power ferrite material 75%-90% and binder composition 10%-25%; ​ The binder composition is composed of components with the following weight percentages: polyformaldehyde resin 10%-15%, high-density polyethylene 2%-5%, polyethylene octene co-elastic body 0.5%-1.5%, vinyl bis-stearamide 0.2%-0.5%, zinc stearate 1%-3% and dioctyl phthalate 1%-3%.

2. The Mn-Zn power ferrite composite of claim 1, wherein, The manganese-zinc power ferrite composite material is prepared from components with the following weight percentages: manganese-zinc power ferrite material 75%-90% and binder composition 10%-25%; 3. The Mn-Zn power ferrite composite of claim 2, wherein, The binder composition is composed of components with the following weight percentages: polyformaldehyde resin 10%-15%, high-density polyethylene 2%-5%, polyethylene octene co-elastic body 0.5%-1.5%, vinyl bis-stearamide 0.2%-0.5%, zinc stearate 1%-3% and dioctyl phthalate 1%-3%.

4. The Mn-Zn power ferrite composite of claim 1, wherein, The average particle size of the manganese-zinc power ferrite material is 1.1-1.4 μm.

5. The Mn-Zn power ferrite composite of claim 1, wherein, The melt index of the polyformaldehyde resin is 90-150 g / 10 min.

6. The Mn-Zn power ferrite composite of claim 5, wherein, The melt index of the polyformaldehyde resin is 120 g / 10 min.

7. The Mn-Zn power ferrite composite of claim 1, wherein, The molecular weight of the high-density polyethylene is 40,000-300,000.

8. The Mn-Zn power ferrite composite of claim 7, wherein, The molecular weight of the high-density polyethylene is 100,000.

9. The Mn-Zn power ferrite composite of claim 1, wherein, The melt index of the high-density polyethylene is 0.1-10 g / 10 min.

10. The Mn-Zn power ferrite composite of claim 9, wherein, The melt index of the high-density polyethylene is 0.5 g / 10 min.

11. The Mn-Zn power ferrite composite of claim 1, wherein, The molecular weight of the polyethylene octene co-elastic body is 3,000-3,500.

12. The Mn-Zn power ferrite composite of claim 11, wherein, The molecular weight of the polyethylene octene co-elastic body is 3,500.

13. The Mn-Zn power ferrite composite of claim 1, wherein, The melt index of the polyethylene octene co-elastic body is 0.1-3 g / 10 min.

14. The Mn-Zn power ferrite composite of claim 13, wherein, The melt index of the polyethylene octene co-elastic body is 1.2 g / 10 min.

15. A method of producing the manganese-zinc power ferrite composite material according to any one of claims 1 to 14, characterized by, The method comprises the following steps: The manganese-zinc power ferrite material and the binder composition are mixed and densified according to the prescription amount to obtain a first material; The first material is extruded and granulated to obtain a second material; The second material is injection molded to obtain a green body; The green body is subjected to debinding treatment to obtain a debound body; The debound body is sintered to obtain the manganese-zinc power ferrite composite material.

16. The method of claim 15, wherein, The preparation method of the manganese-zinc power ferrite material comprises the following steps: the iron oxide, manganese oxide and zinc oxide are subjected to primary ball milling to obtain a primary ball milled material; the primary ball milled material is subjected to pre-sintering to obtain a pre-sintered material; and the pre-sintered material is subjected to secondary ball milling to obtain the manganese-zinc power ferrite material.

17. The method of claim 16, wherein, The mass ratio of the iron oxide, manganese oxide and zinc oxide is 73.4:21.8:4.

8.

18. The method of claim 16, wherein, The pre-sintering is performed at a temperature of 600-900 ℃ for 2-4 h.

19. The method of claim 16, wherein, The secondary ball milling is followed by drying and sieving.

20. The method of claim 16, wherein, The water content of the manganese-zinc power ferrite material is ≤0.1%.

21. The method of claim 15, wherein, The densification is performed at a temperature of 160-190 ℃.

22. The method of claim 21, wherein, The densification is performed at a temperature of 180-190 ℃.

23. The method of claim 15, wherein, The time of the internal mixing is 30-60 minutes.

24. The method of claim 23, wherein, The time of the internal mixing is 30-45 minutes.

25. The method of claim 15, wherein, The temperature of the granulation is 150-170℃.

26. The method of claim 25, wherein, The temperature of the granulation is 150-160℃.

27. The method of claim 15, wherein, The length of the second material is 3-5mm.

28. The method of claim 15, wherein, The temperature of the injection molding is 80-140℃.

29. The method of claim 15, wherein, The temperature of the debinding is 100-200℃.

30. The method of claim 29, wherein, The temperature of the debinding is 120-150℃.

31. The method of claim 15, wherein, The debinding uses oxalic acid.

32. The method of claim 31, wherein, The feeding amount of the oxalic acid is 1-5g / min.

33. The method of claim 32, wherein, The feeding amount of the oxalic acid is 1-3g / min.

34. The method of claim 15, wherein, The temperature of the sintering is 1250-1350℃, and the time is 4-12h.

35. The method of claim 15, wherein, The volume content of oxygen during the sintering is 2-21vol%.

36. The method of claim 15, wherein, The sintering process includes first sintering at 1280-1330℃ for 5-8h under the condition of 19-21vol% oxygen, then sintering at 1280-1330℃ for 1-4h under the condition of 2-5vol% oxygen, and finally cooling under the balanced oxygen partial pressure.

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