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High-surface magnetic flux density dry-pressed permanent ferrite magnet and preparation method thereof

A technology of permanent ferrite and dry pressing, which is applied in the manufacture of inductors/transformers/magnets, the magnetism of inorganic materials, and electrical components, etc. It can solve the problems of reducing production efficiency, reducing friction, and increasing the difficulty of crushing, so as to reduce production Cost and energy consumption, increase the surface magnetic flux density, and the effect of improving the magnetic performance of the product

Inactive Publication Date: 2019-01-04
HUNAN AEROSPACE MAGNET & MAGNETO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] CN101599333A discloses a method for manufacturing anisotropic multi-pole magnetic rings by dry pressing. However, the wet crushed magnetic powder is dried before pre-pressing and pre-magnetizing, although a certain amount of Binder and lubricant, but the lubricating effect on dry powder is limited. Due to the large frictional resistance between particles of dry powder, it is difficult to rotate and orient powder particles under the magnetic field during pre-compression and pre-magnetization. The magnetization effect is poor, it is difficult to prepare high-performance products with a surface magnetic flux density greater than 1900Gs, and the above-mentioned problem (1) cannot be handled well
[0007] CN105622082A discloses a method for preparing permanent ferrite anisotropic dry-pressed powder. The method pre-presses and pre-magnetizes the slurry after wet ball milling. During the pre-magnetization process, the water medium between the magnetic powder particles plays a very important role. Good lubricating effect greatly reduces the friction between particles, and the effect of pre-magnetization is better. However, the operation steps after pre-magnetization are to crush and then dry, and to crush the pre-magnetized green body in the state of water. One is , which increases the difficulty of crushing and reduces production efficiency. Second, it is easy to destroy the magnetic domain orientation effect brought about by pre-magnetization, failing to deal with the above-mentioned (2) problem, and it is difficult to prepare high-performance products.
[0008] CN108147803A discloses a method for preparing a dry-formed strontium ferrite magnet. It also pre-presses and pre-magnetizes the slurry after wet ball milling, and takes the operation steps of drying and then crushing the pre-magnetized green body. Although in To a certain extent, the orientation effect of pre-magnetization is solidified, but its effect is very limited, and the above-mentioned (2) problem cannot be solved well. Therefore, when the final product is pressed by dry method, a strong forming magnetic field needs to be applied. In addition, it needs to be heated to 40-200°C to improve product performance, which undoubtedly increases production costs and energy efficiency, and weakens the market competitiveness of products

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  • High-surface magnetic flux density dry-pressed permanent ferrite magnet and preparation method thereof
  • High-surface magnetic flux density dry-pressed permanent ferrite magnet and preparation method thereof
  • High-surface magnetic flux density dry-pressed permanent ferrite magnet and preparation method thereof

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Embodiment 1

[0044] (1) Add 200 kg of water to 65 kg of strontium ferrite calcined material, carry out wet ball milling until the average particle size of the powder in the slurry is 0.80 μm, then add 0.5 kg of methyl cellulose, at 29000 r / min Stir for 1 min to obtain a mixed slurry;

[0045] (2) The mixed slurry obtained in step (1) was subjected to wet press molding in a 7000 Oe magnetic field at 25 MPa until the density of the green body was 3.0 g / cm 3 Cylindrical (diameter 30 mm, thickness 15 mm), dried at 120°C for 5 h, crushed to obtain oriented pre-magnetized blocks;

[0046] (3) Add 1.3 kg camphor (100 mesh) to the oriented magnetized block obtained in step (2), mix and pulverize, and pass through a 60-mesh sieve to obtain anisotropic powder;

[0047] (4) Dry press the anisotropic powder obtained in step (3) in a 5000 Oe magnetic field at 20°C and 12 MPa until the density of the green body is 3.1 g / cm 3 Cylindrical (diameter 30 mm, thickness 15 mm), then placed in an electric kil...

Embodiment 2

[0050] (1) Mix 65kg of strontium ferrite pre-fired material with 3.25 kg of CaCO 3 , 1.95 kg Al 2 o 3 and 1.95 kg H 3 BO 3 After mixing, add 35 kg of water, perform wet ball milling until the average particle size of the powder in the slurry is 0.85 μm, then add 0.16 kg of sodium carboxymethyl cellulose, and stir for 10 minutes at 90 r / min to obtain a mixed slurry;

[0051] (2) The mixed slurry obtained in step (1) is subjected to wet press molding in a 4000Oe magnetic field at 16MPa until the density of the green body is 2.8g / cm 3 Cylindrical (diameter 40mm, thickness 20mm), dried at 100°C for 10h, crushed to obtain oriented pre-magnetized blocks;

[0052] (3) Add 0.2 kg of calcium stearate (325 mesh) and 0.4 kg of polyethylene glycol (325 mesh) to the oriented magnetized block obtained in step (2), mix and pulverize, pass through a 40-mesh sieve, and obtain each Anisotropic powder;

[0053] (4) Dry press the anisotropic powder obtained in step (3) in a magnetic field o...

Embodiment 3

[0056] (1) Mix 65 kg of strontium ferrite pre-fired material with 3.00kg of CaCO 3 and 1.85kg SiO 2 After mixing, add 65 kg of water and carry out wet ball milling until the average particle size of the powder in the slurry is 0.75 μm, then add 0.13 kg of ethyl cellulose and 0.13 kg of hydroxyalkyl cellulose, and stir at 1000 r / min 480 min to obtain mixed slurry;

[0057] (2) The mixed slurry obtained in step (1) was subjected to wet press molding at 12 MPa in a magnetic field of 10000 Oe until the density of the green body was 2.8 g / cm 3 Cylindrical (diameter 40 mm, thickness 10 mm), dried at 80°C for 12 h, crushed to obtain oriented pre-magnetized blocks;

[0058] (3) Add 0.16 kg of stearic acid amide (200 mesh) and 0.16 kg of oleic acid amide (200 mesh) to the oriented magnetized block obtained in step (2), mix and pulverize, pass through a 80-mesh sieve to obtain an isotropic heterosexual powder;

[0059] (4) Dry press the anisotropic powder obtained in step (3) in a 9...

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Abstract

The invention discloses a high-surface magnetic flux density dry-pressed permanent ferrite magnet and a preparation method thereof. The magnet is prepared according to the method comprising the following steps: (1), adding water into a permanent ferrite pre-sintered material, performing wet ball milling, then adding a cellulose ether additive, and stirring to obtain a mixed slurry; (2), in a magnetic field, performing wet pressing moulding, drying, and crushing to obtain an oriented pre-magnetized material block; (3), adding a lubricating and bonding agent, mixing, crushing, and sieving to obtain anisotropic powder; (4), in the magnetic field, performing dry pressing moulding, sintering, and grinding to obtain the magnet. The surface magnetic flux density of the dry-pressed permanent ferrite magnet can reach 1920 Gs or above, and the magnetic performance thereof is significantly better than that of the permanent ferrite magnet obtained by the conventional dry moulding technology; according to the method, the pre-magnetizing effect is maximized, the dry pressing magnetic field strength is low, no heating is required, a technology is simple, the energy consumption is low, the cost islow, and suitability for industrial production is achieved.

Description

technical field [0001] The invention relates to a permanent ferrite magnet and a preparation method thereof, in particular to a dry-pressed permanent ferrite magnet with high surface magnetic flux density and a preparation method thereof. Background technique [0002] With the acceleration of global industrialization and household intelligence and automation, the market demand for various types of motors continues to grow, and the requirements for the size and energy efficiency of motors are becoming more and more stringent, which promotes the development of motors to be miniaturized, planarized, and energy-saving. Due to its low cost, excellent magnetic properties and chemical stability, and the availability of small-sized anisotropic devices with complex shapes, dry-pressed permanent ferrite magnets are widely used in various low-end micro permanent magnet motors In China, the market demand is soaring and the prospect is bright. [0003] In order to broaden the applicatio...

Claims

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Application Information

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IPC IPC(8): C04B35/26C04B35/622C04B35/626H01F41/02H01F1/11
CPCH01F1/11H01F41/0253H01F41/0266C04B35/2683C04B35/622C04B35/62605C04B2235/6567C04B2235/6562C04B2235/3418C04B2235/3409C04B2235/3217C04B2235/3208
Inventor 姚锐刘超郑自儒陈晓宇邓雅之
Owner HUNAN AEROSPACE MAGNET & MAGNETO