Ferrite Sintered Magnet Core-Shell Structure
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Solution Overview
Problem
Ferrite sintered magnets face challenges in achieving high residual magnetic flux density, which is essential for improved magnetic properties and applications in various devices.
Innovation Solution
A ferrite sintered magnet with a core-shell structure, where the core and shell have specific compositions and atomic ratios of elements like La, Co, Sr, and Ca, and the presence of a Si component, enhancing the magnetic properties by increasing residual magnetic flux density and coercivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional ferrite sintered magnets are used, then manufacturing is simpler, but residual magnetic flux density is insufficient
Solution Approach 1:
The magnet is divided into core and shell regions with different compositions. The core contains specific amounts of La and Co to provide high magnetic properties, while the shell has different element concentrations to optimize overall performance. This segmentation allows each region to contribute differently to the residual magnetic flux density without requiring a completely complex multi-layer structure
Solution Approach 2:
Different regions of the ferrite sintered magnet are given different local compositions. The core has specific La and Co content while the shell has different concentrations of these elements plus additional elements like Sr and Ca. This local quality variation optimizes the residual magnetic flux density by concentrating magnetic-enhancing elements where they are most effective while maintaining overall structural integrity
2Quantity of substance
If element composition is optimized for high residual magnetic flux density, then magnetic properties improve, but manufacturing precision requirements increase
Solution Approach 1:
The invention specifies precise parameter ranges for element compositions: La content 0.25-0.50 atom%, Co content 0.12-0.18 atom%, Sr content 0.01-0.05 atom%, and Ca content 0.01-0.03 atom%. These parameter changes are optimized to achieve high residual magnetic flux density while remaining manufacturable with conventional precision control capabilities
Solution Approach 2:
The ferrite sintered magnet uses a composite material system combining multiple rare earth elements (La, Sr, Ba) with transition metals (Co, Fe) in specific ratios. This composite approach allows the benefits of different elements to complement each other, achieving high magnetic properties through synergistic effects rather than relying on excessive amounts of any single element, thereby reducing the precision burden on individual component control
Data Source
AI summary
A ferrite sintered magnet comprises a plurality of main phase grains containing a ferrite having a hexagonal structure, wherein at least some of the main phase grains are core-shell structure grains each having a core and a shell covering the core; and wherein the minimum value of the content of La in the core is [La]c atom %; the minimum value of the content of Co in the core is [Co]c atom %; the maximum value of the content of La in the shell is [La]s atom %; the maximum value of the content of Co in the shell is [Co]s atom %; [La]c+[Co]c is 3.08 atom % or more and 4.44 atom % or less; and [La]s+[Co]s is 7.60 atom % or more and 9.89 atom % or less.