Low-cost injection ferrite magnetic powder and manufacturing method thereof

Abstract

The invention discloses low-cost injection ferrite magnetic powder and a manufacturing method thereof, and particularly relates to the field of magnetic materials, the molecular general formula is as follows: BaO.nFe2O3, n represents a molar ratio and satisfies n = 5.3-5.7, barium carbonate is adopted to completely replace strontium carbonate, the price of barium carbonate is only 1 / 3-1 / 4 of that of strontium carbonate, meanwhile, FeC l2 is adopted as a fluxing agent to replace SrC l2 in the prior art, and the price of FeC l2 is only 1 / 9-1 / 10 of that of SrC l2. And the material cost is reduced by 30%.

Description

Technical Field

[0001] The invention relates to the field of magnetic materials, in particular to low-cost injected ferrite magnetic powder and a manufacturing method thereof. Background Art

[0002] Strontium ferrite is the most widely used permanent magnet ferrite material at present. It can be divided into sintered permanent magnet ferrite and bonded permanent magnet ferrite according to its use. Among them, bonded permanent magnet ferrite is a composite of permanent magnet ferrite powder and a binder. It has the characteristics of high product dimensional accuracy, good mechanical properties, uniform performance of each part of the magnet, and easy radial magnetization and multi-pole magnetization of the magnet. Bonded ferrite can be divided into extrusion molded magnets, injection molded magnets, and calendering molded magnets according to different molding methods. Among them, injection molded magnets have a large degree of freedom in product design and high product dimensional accuracy. It is suitable for manufacturing electronic parts with complex shapes, and its application field has become increasingly wide in recent years. In the prior art, injection ferrite magnetic powder is generally obtained by mixing strontium carbonate and iron red and pre-burning to obtain pre-burned material, and the pre-burned material is coarsely ground, finely ground, dried, vibrated, and tempered to obtain injection ferrite magnetic powder. At the same time, the prior art adds SrCl2 as a flux during the mixing process of raw materials.

[0003] Patent CN200410034695.1 discloses a ferrite magnetic powder, which is made of iron oxide red and strontium carbonate as raw materials. By controlling the particle size distribution of the ferrite magnetic powder, 15-40% of fine powder with a particle size range of 0.5-1.0μm and 60-85% of coarse powder with a particle size range of 2.5-5.0μm are mixed to prepare a bonded ferrite magnetic powder with a wider particle size distribution.

[0004] Patent CN201010225009.4 discloses a solution, by adding a certain proportion of La, Zn and Bi elements, the magnetic powder has the main phase of the following molecular formula: (M1~xLax)O·n(Fe1~yZnyBi z)2O3. Among them, M represents at least one element of strontium and barium; x, y, z, n represent the molar ratio, satisfying x=2mn(y+z), and x=0.01~0.4, 0.01≤z / y≤0.3, n=5.5~6.4, m=0.9~1.1. At the same time, chloride is added to the mixture as a flux while mixing, and the chloride includes: any one or any combination of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, strontium oxide, and barium chloride.

[0005] Patent CN201610167551.6 discloses a scheme that, by adding a certain proportion of Ba element, makes the magnetic powder have the main phase of the following molecular formula: (Sr1-xBax)O·nFe2O3, where n represents the molar ratio, and satisfies n=6.11-6.30, 0.1≤x≤0.2. In this scheme, the proportion of barium atoms replacing strontium atoms does not exceed 20%, and strontium chloride is added during the raw material mixing process.

[0006] In recent years, with the widespread application of injection molding in the field of motor rotors, in some scenarios, the requirements for magnetic properties and fluidity are not high, but the cost is extremely sensitive. Since strontium compounds are expensive, the current price of strontium carbonate is 3-4 times that of barium carbonate, and the price of strontium chloride is 5-10 times higher than other chlorides. Therefore, a cheaper production solution is needed. Summary of the invention

[0007] The object of the present invention is to provide a low-cost injected ferrite magnetic powder and a method for manufacturing the same, using barium carbonate to completely replace strontium carbonate and using FeCl2 as a flux to solve the problems raised in the above background technology.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A low-cost injection ferrite powder, characterized in that the molecular formula is as follows: BaO·nFe2O 3， , wherein n represents the molar ratio, and n satisfies n=5.3 to 5.7.

[0010] A method for manufacturing low-cost injected ferrite magnetic powder comprises the following steps:

[0011] 1) Using industrial grade iron oxide red and barium carbonate as raw materials, the ingredients are prepared according to the molecular formula BaO·nFe2O3, wherein n represents the molar ratio, and n satisfies n=5.3-5.7;

[0012] 2) The raw materials are mixed evenly, and 1.0-1.6wt% FeCl2 is added during the mixing process;

[0013] 3) pre-calcining at 1175-1225° C. to obtain a pre-calcined material;

[0014] 4) roughly crushing and grinding the pre-burned material, and obtaining fine powder after drying;

[0015] 5) performing a vibration grinding treatment on the fine powder; and performing an annealing treatment on the fine powder after the vibration grinding.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention adopts barium carbonate to completely replace strontium carbonate, and the price of barium carbonate is only 1 / 3-1 / 4 of that of strontium carbonate. Meanwhile, FeCl2 is used as flux to replace SrCl2 in the prior art, and the price of FeCl2 is only 1 / 9-1 / 10 of that of SrCl2. The material cost is reduced by 30%, and a low-cost injection ferrite magnetic powder and a manufacturing method thereof are provided. DETAILED DESCRIPTION

[0018] Example 1

[0019] The raw materials of each component are weighed according to the molecular formula BaO·nFe2O3, wherein the purity of iron oxide red is 99%, the purity of barium carbonate is 99%, n=5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, and 1.4wt% FeCl2 is added at the same time, and the mixture is evenly mixed by a strong mixer, granulated, and sintered at 1200°C for 2 hours to obtain a pre-burned material; the pre-burned material balls are roughly broken, and then ground with a ball mill for 5 hours, and dried to obtain fine powder; the fine powder is annealed at 950°C for 1 hour, and dispersed to obtain injection ferrite magnetic powder.

[0020] The compression density (CD value) of this embodiment is tested by weighing 15 grams of magnetic powder, pressing it into a Φ25mm magnetic block under a pressure of 8Mpa, and testing the density of the compact.

[0021] In this embodiment, the above-mentioned injection ferrite magnetic powder can be used to prepare a magnet by injection molding process, specifically as follows: weigh 1000g of bonded magnetic powder, 75g of nylon 6 and 10g of related additives (silane coupling agent and lubricant TAF), mix them evenly, and then use a twin-screw extruder for mixing and granulation, and the mixing temperature is 240°C; add the granules to a vertical injection molding machine, heat to 270°C, and injection mold to obtain a Φ20×10mm cylindrical magnetic block, and apply a magnetic field strength of 10000e during the injection molding process. The hysteresis loop of the cylindrical magnetic block obtained above can be measured by a B~H tester to obtain the magnet performance.

[0022] Comparative Example 1

[0023] According to the molecular formula SrO·5.8Fe2O3, the raw materials of each component are weighed, wherein the purity of iron oxide is 99% and the purity of barium carbonate is 99%. At the same time, 1.4wt% SrCl2 is added, and the mixture is evenly mixed using a strong mixer, granulated, and sintered at 1200°C for 2 hours to obtain a pre-burned material. The remaining steps are the same as in Example 1.

[0024]

[0025]

[0026] Example 2

[0027] The raw materials of each component are weighed according to the molecular formula BaO·5.6Fe2O3, wherein the purity of iron oxide red is 99%, and the purity of barium carbonate is 99%. 0.8, 1.0, 1.2, 1.4, 1.6, and 1.8 wt% FeCl2 are added respectively, and the mixture is evenly mixed with a strong mixer, granulated, and sintered at 1200°C for 2 hours to obtain a pre-burned material; the pre-burned material balls are coarsely broken, and then ground with a ball mill for 5 hours, and dried to obtain fine powder; the fine powder is annealed at 950°C for 1 hour, and dispersed to obtain injected ferrite magnetic powder.

[0028] The remaining steps are the same as those in Example 1.

[0029]

[0030] Example 3

[0031] The raw materials of each component are weighed according to the molecular formula BaO·5.6Fe2O3, wherein the purity of iron oxide red is 99%, the purity of barium carbonate is 99%, 1.4wt% FeCl2 is added, and the mixture is evenly mixed by a strong mixer, granulated, and sintered at 1150°C, 1175°C, 1200°C, 1225°C, and 1250°C for 2 hours to obtain pre-burned materials; the pre-burned balls are roughly broken, then ground by a ball mill for 5 hours, and dried to obtain fine powder; the fine powder is annealed at 950°C for 1 hour, and dispersed to obtain injection ferrite magnetic powder.

[0032] The remaining steps are the same as those in Example 1.

[0033]

[0034]

Claims

1. A low-cost injected ferrite powder, characterized in that: The molecular formula is as follows: BaO·nFe2O 3， , wherein n represents the molar ratio, and n satisfies n=5.3 to 5.

7.

2. A method for manufacturing low-cost injected ferrite powder, characterized in that: The steps include: 1) Using industrial grade iron oxide red and barium carbonate as raw materials, the ingredients are prepared according to the molecular formula BaO·nFe2O3, wherein n represents the molar ratio, and n satisfies n=5.3-5.7; 2) The raw materials are mixed evenly, and 1.0-1.6wt% FeCl2 is added during the mixing process; 3) pre-calcining at 1175-1225° C. to obtain a pre-calcined material; 4) roughly crushing and grinding the pre-burned material, and obtaining fine powder after drying; 5) performing a vibration grinding treatment on the fine powder; and performing an annealing treatment on the fine powder after the vibration grinding.

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