Bonded Magnet Ferrite Powder for Better Magnetic Field Orientation
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Solution Overview
Problem
The existing strontium ferrite particle powders for bonded magnets have difficulty achieving high residual magnetization due to the interference of plate-shaped particles during magnetic field orientation.
Innovation Solution
A method involving the mixing of a complex oxide powder of iron, strontium, lanthanum, and cobalt with iron oxide, followed by granulation and firing, to produce a ferrite powder with a specific composition and particle size distribution that facilitates high residual magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If plate-shaped particles are used in strontium ferrite powder, then the magnetic field orientation is interfered with, but the manufacturing cost is reduced compared to rare earth magnets
Solution Approach 1:
The patent changes the particle shape parameter from plate-shaped to spherical or near-spherical particles. This parameter change eliminates the interference with magnetic field orientation while maintaining the cost advantage of ferrite materials over rare earth magnets.
Solution Approach 2:
Instead of using plate-shaped particles that interfere with orientation, the patent inverts the approach by using spherical particles that facilitate orientation. This inversion resolves the contradiction by adopting the opposite particle morphology.
2Force
If ferritic sintered magnets are used, then strong magnetic force is achieved, but processing complicated shapes is difficult and productivity is reduced
Solution Approach 1:
The patent replaces the mechanical sintering process with a bonded magnet process using resin or metal matrices. This substitution eliminates the need for complex shaping and polishing operations, significantly improving productivity while maintaining strong magnetic force through optimized particle morphology.
Solution Approach 2:
The patent changes the particle shape to spherical or near-spherical forms that can be easily processed and molded into complicated shapes. This parameter change enables both strong magnetic force and high productivity by facilitating complex shape fabrication without extensive post-processing.
3Force
If rare earth magnets are used, then strong magnetic force is achieved, but the cost increases twenty times compared to ferrite magnets
Solution Approach 1:
The patent uses inexpensive ferrite particles instead of expensive rare earth magnets. By optimizing the particle morphology to spherical or near-spherical shapes with controlled size distributions, the patent achieves strong magnetic force in bonded magnets using the cheaper ferrite material, reducing cost by a factor of twenty while maintaining performance.
4Force
If rare earth magnets are used, then strong magnetic force is achieved, but rust resistance is poor
Solution Approach 1:
The patent selects ferrite material over rare earth magnets, taking advantage of ferrite's superior rust resistance. By optimizing the particle morphology and using bonded magnet technology, the patent achieves both strong magnetic force and excellent corrosion resistance, eliminating the reliability issues of rare earth magnets.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The resulting ferrite powder enables the production of bonded magnets with high residual magnetization and maximum energy product, while also minimizing low-temperature demagnetization.
Implementation Method 1
granulating the mixture to obtain a granulated mixture
Implementation Method 2
firing the granulated mixture
Implementation Method 3
pulverizing the fired substance to obtain a pulverized substance
Implementation Method 4
annealing the pulverized substance
Implementation Method 5
arranged in the magnetic field direction thereof by the magnetic field orientation thereof
Data Source
Figure 1
Figure 2~3
AI summary
There is provided a ferrite powder for bonded magnet, which can obtain a bonded magnet having a high residual magnetization Br by the magnetic field orientation thereof, and a method for producing the same. The ferrite powder for bonded magnet, which has a composition of (Sr1-xLax) · (Fe1-yCoy)nO19-x (wherein 0 < x ≦ 0.5, 0 < y ≦ 0.04, 10.0 ≦ n ≦ 12.5, -1.0 ≦ z ≦ 3.5) and an average particle diameter of 1.3 to 2.5 µm, is produced by mixing a complex oxide powder of iron, strontium, lanthanum and cobalt with iron oxide to obtain a mixture which is granulated to be fired to obtain a fired substance which is coarsely pulverized to obtain a coarsely pulverized powder which is pulverized to be annealed.