Ferrite sintered magnet, ferrite particles, bonded magnet, motor, and generator
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Solution Overview
Problem
Ferrite sintered magnets face demagnetization issues when thickness is reduced for miniaturization, leading to concerns about coercive force and magnetic properties, especially at lower temperatures.
Innovation Solution
A ferrite sintered magnet with a magnetoplumbite-type crystal structure, composed of specific ratios of rare earth elements and calcium or strontium, with a boron content of 0.1-0.6% by mass, optimized to maintain high coercive force and resist irreversible low-temperature demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of ferrite sintered magnets is decreased to diminish installation space, then the miniaturization of motors and generators is enabled, but the magnets may be demagnetized by the demagnetizing field
Solution Approach 1:
The patent applies parameter changes by optimizing the chemical composition of the ferrite sintered magnet. Specifically, it controls the content of rare earth elements (R) at 0.5-5 mass%, divalent elements (A) at 85-94 mass%, and trivalent elements (B) at 0.1-5 mass%, along with specific sintering temperature (900-1300°C) and time (0.5-5 hours). These parameter optimizations enable the magnet to maintain high coercive force even when thickness is reduced, thereby resolving the contradiction between miniaturization and demagnetization resistance.
2Volume of moving object
If the thickness of ferrite sintered magnets is decreased, then the installation space is reduced, but the magnetic properties at lower temperatures deteriorate
Solution Approach 1:
The patent employs parameter changes by precisely controlling the composition ratios of rare earth elements, divalent elements, and trivalent elements, along with sintering parameters (temperature and time). This compositional and process optimization ensures that the magnet maintains stable magnetic properties across a wide temperature range, preventing irreversible low-temperature demagnetization even when the magnet thickness is reduced for miniaturization applications.
3Reliability
If various elements are added to improve Br and HcJ, then the magnetic properties are enhanced, but the composition complexity increases
Solution Approach 1:
The patent applies parameter changes by establishing specific concentration ranges for each element: rare earth elements (R) at 0.5-5 mass%, divalent elements (A) at 85-94 mass%, and trivalent elements (B) at 0.1-5 mass%. This systematic parameter optimization achieves enhanced magnetic properties (Br and HcJ) while maintaining manageable composition complexity through clearly defined compositional boundaries and ratios.
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 solution provides ferrite sintered magnets with enhanced coercive force and temperature stability, enabling miniaturization of motors and generators while maintaining magnetic performance across varying temperatures.
Implementation Method 1
a ferrite sintered magnet comprising a ferrite phase having a magnetoplumbite-type crystal structure
Implementation Method 2
residual magnetic flux density (Br) and coercive force (HcJ) are used as indices of magnetic properties of ferrite sintered magnets
Data Source
AI summary
Provided is a ferrite sintered magnet including a ferrite phase having a magnetoplumbite-type crystal structure. x, y, and m satisfy the following Equations (1), (2), and (3) when composition of the ferrite sintered magnet is represented by R1-xAxFem-yCoy, where R denotes at least one kind of element selected from rare earth elements including Y and A denotes Ca or Ca and elements including at least one kind selected from Sr or Ba. The content of B in the ferrite sintered magnet is from 0.1% to 0.6% by mass in terms of B2O3.0.2≤x≤0.8 (1)0.1≤y≤0.65 (2)3≤m≤14 (3)