Core-Shell Rare Earth Magnet With Lower Heavy Rare Earth Use
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Solution Overview
Problem
The high cost and scarcity of heavy rare earth elements pose a challenge in maintaining enhanced coercive force in rare earth magnets, as they are expensive and their price is expected to rise further, necessitating a reduction in their usage while preserving coercive force.
Innovation Solution
A rare earth magnet with a core/shell structure is developed, where the molar ratio of heavy rare earth elements is higher in the shell part than in the core part, and a modifier containing both a heavy rare earth element and Ce is used to diffuse and penetrate into the magnet precursor, optimizing the distribution of elements to enhance coercive force without excessive use of expensive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy rare earth elements are used to enhance coercive force, then coercive force is improved, but cost increases and scarcity becomes a problem
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where heavy rare earth elements (R2) are concentrated in the shell part surrounding the core part. This localized distribution ensures that the expensive heavy rare earth elements are placed only where they are most effective for enhancing coercive force, rather than being uniformly distributed throughout the entire magnet. The shell part contains the heavy rare earth elements that contribute to high coercive force, while the core part uses lighter rare earth elements, thus reducing overall cost while maintaining performance.
2Strength
If heavy rare earth elements are used to enhance coercive force, then coercive force is improved, but the price expected to rise further
Solution Approach 1:
The patent employs parameter changes by precisely controlling the composition ratios and distribution of rare earth elements. Specifically, it defines the shell part composition with R2 content and the ratio of R2 at 4g sites versus 4f sites, creating a optimized configuration that achieves high coercive force with minimized heavy rare earth element usage. This parameter optimization allows the magnet to maintain high performance while reducing dependence on expensive and scarce heavy rare earth elements.
3Adaptability or versatility
If a plurality of types of rare earth elements are selected as R1, then function optimization is achieved, but complexity of composition arrangement increases
Solution Approach 1:
The patent applies segmentation by dividing the magnet into distinct core and shell regions with different compositional characteristics. The core part contains a specific rare earth element composition, while the shell part contains another composition with heavy rare earth elements. This segmentation simplifies the overall design by creating two distinct zones with clear functional assignments, making it easier to control and reproduce the desired magnetic properties without dealing with complex uniform multi-element arrangements.
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
This approach allows for a higher coercive force than predicted by the content ratio of heavy rare earth elements, reducing the amount needed while maintaining performance, thus addressing the cost and scarcity issues.
Implementation Method 1
allowing a modifier containing both a heavy rare earth element and Ce to diffuse and penetrate into a rare earth magnet precursor
Data Source
AI summary
A rare earth magnet in which the amount used of a heavy rare earth element is more reduced while maintaining enhancement of the coercive force, and a producing method thereof are provided. The rare earth magnet of the present disclosure has a main phase 10 and a grain boundary phase 20. The main phase 10 has a composition represented by R12T14B. The main phase 10 has a core part 12 and a shell part 14. Denoting the abundances of R2 and Ce (R2 is heavy rare earth element) occupying 4f site of the shell part 14 as R24f and Ce4f, respectively, and denoting the abundances of R2 and Ce occupying 4g site of the shell part 14 as R24g and Ce4g, respectively, the rare earth magnet satisfies 0.44≤R24g/(R24f+R24g)≤0.70 and 0.04≤(Ce4f+Ce4g)/(R24f+R24g). The rare earth magnet-producing method of the present disclosure uses a modifier containing at least R2 and Ce.