Ferrite Sintered Magnet Core-Shell Structure
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Solution Overview
Problem
Ferrite sintered magnets with varying compositions at the center and grain boundary of main phase particles impair magnetic characteristics, and existing methods that concentrate La or Co near grain boundaries do not effectively enhance residual magnetic flux density and coercive force.
Innovation Solution
A ferrite sintered magnet with a hexagonal structure, where core-shell structured particles are fewer than main phase particles, and the Sr content is higher in the core than the shell, and Ca content is higher in the shell than the core, with specific atomic ratios and the inclusion of a Si component, to optimize magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high concentration of La or Co is present in the vicinity of grain boundary, then a magnetic phase having high anisotropy is formed near the grain boundary, but the residual magnetic flux density and coercive force are not effectively enhanced
Solution Approach 1:
The patent applies local quality by creating distinct compositional zones within main phase particles: the core region contains specific elements (La, Co) while the shell region has different composition. This spatial differentiation of composition allows optimization of magnetic properties in different regions without uniform distribution, resolving the contradiction between achieving high magnetic characteristics and controlling composition effectively.
Solution Approach 2:
The patent segments the main phase particles into core-shell structures, dividing each particle into distinct regions with different compositions. The core contains elements for high anisotropy while the shell has optimized composition for overall magnetic performance. This segmentation allows independent optimization of different functional regions, effectively enhancing both residual magnetic flux density and coercive force.
2Adaptability or versatility
If main phase particles having different compositions in the vicinity of the center and grain boundary are used, then composition variation is achieved, but the magnetic characteristics of the entire ferrite sintered magnet are impaired
Solution Approach 1:
The patent employs composite materials by creating core-shell structured particles where the core and shell have different compositions optimized for specific functions. The core contains elements for high anisotropy while the shell provides optimized magnetic properties. This composite structure at the particle level maintains overall magnetic characteristics while allowing necessary composition variation, resolving the contradiction between adaptability and reliability.
3Manufacturing precision
If core-shell structured particles are increased, then compositional control is improved, but the number of main phase particles with optimal uniform composition decreases
Solution Approach 1:
The patent applies parameter changes by precisely controlling the atomic ratios of elements in the core and shell regions. Specific ranges are defined for La content (0.25<w<0.5), Sr content (0.01<x<0.35), and other elements, with additional constraints on their relationships (w/m=1.0-2.1, m/z=0.017-0.055). This parametric control optimizes magnetic characteristics while managing the core-shell structure proportion, resolving the contradiction between manufacturing precision and reliability.
Data Source
AI summary
There is provided a ferrite sintered magnet having a high residual magnetic flux density.A ferrite sintered magnet 2 includes a plurality of main phase particles 5 including ferrite having a hexagonal structure, the number of core-shell structured particles 5A having a core 7 and a shell 9 covering the core 7, among the main phase particles 5, is smaller than the number of the main phase particles 5 other than the core-shell structured particles 5A.