Ferrite Sintered Magnet Coercive Force via Rare-Earth Optimization
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Solution Overview
Problem
Ferrite magnets with high coercive force are challenging to develop, especially when combining elements with significantly different valences and ion radii, such as Co and rare-earth elements like La, which often result in insufficient coercive force.
Innovation Solution
A ferrite sintered magnet with a hexagonal structure, comprising metallic elements at a specific atomic ratio including rare-earth elements like La, with controlled ratios of Ca, Sr, Fe, and Co, and optionally incorporating Al and B, to enhance coercive force and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elements with greatly different valences and ion radii (such as Co and rare-earth elements like La) are combined, then the magnetic properties are enhanced, but the coercive force becomes insufficient
Solution Approach 1:
The patent optimizes the atomic ratios of multiple elements (Ca, Sr, R, Fe, Co, Al, B) within specific ranges to achieve high coercive force. By precisely controlling the parameters of element combinations and their proportions, the patent resolves the contradiction between enhancing magnetic properties through complex element combinations and maintaining sufficient coercive force.
Solution Approach 2:
The patent creates a composite ferrite system incorporating multiple rare-earth elements (R = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, or Y) combined with Ca, Sr, Fe, Co, Al, and B in specific ratios. This composite approach allows the material to benefit from the synergistic effects of different elements while maintaining high coercive force through optimized composition.
2Reliability
If the grain size is reduced to improve magnetic properties, then the coercive force increases, but the manufacturing precision becomes more difficult to control
Solution Approach 1:
The patent controls grain size by optimizing the atomic ratios of elements, particularly the presence of Al and B which influence grain growth during sintering. By adjusting compositional parameters within specific ranges, the patent achieves fine grain size (0.5-2.0 mm) while maintaining manufacturing control and high coercive force.
Data Source
AI summary
This ferrite sintered magnet comprises metallic elements at an atomic ratio represented by formula (1):Ca1-w-xRwSrxFezCom (1)in formula (1), R is at least one element selected from the group consisting of rare-earth elements and Bi, and R comprises at least La, in formula (1), w, x, z and m satisfy formulae (2) to (5):0.360≤w≤0.420 (2)0.110≤x≤0.173 (3)8.51≤z≤9.71 (4)0.208≤m≤0.269 (5), andin a section parallel to an axis of easy magnetization, when the number of total ferrite grains is N and the number of ferrite grains having a stacking fault is n, 0≤n/N≤0.20 is satisfied.