Ferrite Sintered Magnet Composition Stabilizing Magnetic Properties
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Solution Overview
Problem
Ferrite sintered magnets face challenges in achieving stable high magnetic properties due to their dependence on sintering temperature, and existing methods to enhance residual magnetic flux density (Br) and coercive force (HcJ) are not consistently effective across different compositions and temperature ranges.
Innovation Solution
A ferrite sintered magnet with a hexagonal structure, comprising specific atomic ratios of Ca, Sr, Fe, Co, and rare-earth elements like La, with controlled crystal grain size variation and optional inclusion of B, Al, and Ba, to minimize sintering temperature dependence and stabilize magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the composition of ferrite magnets is changed to improve Br and HcJ, then magnetic properties are enhanced, but the complexity of finding optimal combinations increases and stability across different sintering temperatures is not guaranteed
Solution Approach 1:
The invention changes the chemical composition parameters of ferrite magnets by incorporating specific rare-earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, or Lu) at controlled atomic ratios (0.360≤w≤0.420) along with Sr (0.110≤x≤0.173) and Co (0.208≤m≤0.269). This systematic parameter adjustment achieves high and stable magnetic properties (Br≥3.80 mT, HcJ≥400 kA/m) while reducing sensitivity to sintering temperature variations.
2Manufacturing precision
If the sintering temperature range is narrowed to obtain stable magnetic properties, then manufacturing precision is improved, but manufacturing management becomes difficult
Solution Approach 1:
The invention modifies the chemical composition parameters to inherently reduce sintering temperature sensitivity. By optimizing the atomic ratios of rare-earth elements, Sr, Fe, and Co, the patent achieves a composition that maintains stable magnetic properties across a broader sintering temperature range (1050-1250°C), thereby improving manufacturing precision without compromising ease of manufacture.
3Reliability
If existing element combinations are used to improve Br and HcJ, then magnetic properties are enhanced, but consistent effectiveness across different compositions and temperature ranges is not achieved
Solution Approach 1:
The invention creates a composite ferrite magnet material combining multiple elements (Ca, Sr, Fe, Co, and rare-earth elements) in specific proportions. This composite composition (Ca1-w-xRwSrxFezCom) achieves consistent magnetic property improvement (Br≥3.80 mT, HcJ≥400 kA/m) across different sintering temperatures and compositional variations, demonstrating enhanced adaptability.
Data Source
AI summary
The present invention provides a ferrite sintered magnet comprising ferrite crystal grains having a hexagonal structure, wherein the ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1). In formula (1), R is at least one element selected from the group consisting of Bi and rare-earth elements, and R comprises at least La. In formula (1), w, x, z and m satisfy formulae (2) to (5). The above-mentioned ferrite sintered magnet further has a coefficient of variation of a size of the crystal grains in a section parallel to a c axis of less than 45%.Ca1-w-xRwSrxFezCom (1)0.360≤w≤0.420 (2)0.110≤x≤0.173 (3)8.51≤z≤9.71 (4)0.208≤m≤0.269 (5)