Rare Earth Magnet Composition for Edge Anti-Demagnetization
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Solution Overview
Problem
Existing rare earth permanent magnets, such as R-Fe-B magnets, face challenges in maintaining high coercive force and anti-demagnetization ability, especially in high-temperature environments, with existing methods not fully addressing the need for improved stability and reliability.
Innovation Solution
A rare earth permanent magnet with a specific composition and structure, incorporating light and heavy rare earth elements (Nd, Dy, and Tb), featuring symmetrical edge and middle portions with varying weight percentages of Dy and Tb, is prepared through a method involving surface attachments and heat treatment, resulting in enhanced coercive force distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements (Dy, Tb) are added to R-Fe-B permanent magnets to improve coercive force and anti-demagnetization ability, then the magnet's stability and reliability improve, but the cost and complexity of the material composition increase
Solution Approach 1:
The patent applies local quality by creating distinct regions within the magnet with different rare earth compositions. The edge portions contain heavy rare earth elements (Dy, Tb) to provide high coercive force and anti-demagnetization ability, while the middle portion uses light rare earth elements (Nd, Pr) to maintain high remanence. This spatial differentiation of material properties resolves the contradiction by providing enhanced reliability only where needed (at edges) rather than uniformly throughout the entire magnet, thus reducing overall material complexity.
2Reliability
If heavy rare earth elements are uniformly distributed throughout the magnet to maximize coercive force, then anti-demagnetization ability improves, but the remanence and overall magnetic performance decreases
Solution Approach 1:
The patent implements local quality by concentrating heavy rare earth elements (Dy, Tb) specifically in the edge portions of the magnet where they are needed for high coercive force and anti-demagnetization protection. The middle portion retains light rare earth elements (Nd, Pr) that provide high remanence. This localized distribution resolves the contradiction by ensuring high coercive force at critical edge regions without sacrificing the high remanence properties in the central region, thereby maintaining overall magnetic performance.
3Reliability
If the magnet structure is divided into multiple portions with different compositions, then anti-demagnetization performance improves, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the magnet into distinct edge portions and a middle portion with different rare earth compositions. The edge portions contain heavy rare earths (Dy, Tb) for high coercive force, while the middle portion contains light rare earths (Nd, Pr) for high remanence. This segmentation resolves the contradiction by creating functionally optimized regions that improve anti-demagnetization performance while maintaining a relatively simple overall structure that can be manufactured using conventional sintering processes.
4Reliability
If Dy content is increased to enhance coercive force at edge portions, then anti-demagnetization ability improves, but the cost of rare earth materials increases
Solution Approach 1:
The patent applies local quality by restricting heavy rare earth elements (Dy, Tb) to only the edge portions of the magnet where they are most needed for coercive force and anti-demagnetization protection. The middle portion uses lighter, less expensive rare earth elements (Nd, Pr). This localized approach resolves the contradiction by minimizing the total quantity of expensive heavy rare earth materials required while still achieving high coercive force at the critical edge regions, thereby reducing overall material cost.
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
The magnet exhibits excellent anti-demagnetization performance and high coercive force, suitable for embedded motors, with minimal demagnetization even at elevated temperatures, ensuring motor stability and reliability.
Implementation Method 1
The edge portion has an outer edge and an inner edge, wherein the outer edge is far away from the middle portion, the inner edge is close to the middle portion; along the direction from the outer edge of the edge portion towards the central axis of the middle portion, the weight percentage of Dy gradually increases, while the weight percentage of Tb gradually decreases
Data Source
Figure 1
AI summary
The present disclosure discloses a rare earth permanent magnet, its preparation method and motors. The rare earth permanent magnet comprises a light rare earth element and a heavy rare earth element. The light rare earth element must contain Nd and the heavy rare earth element must contain Dy and Tb; along the width direction, the rare earth permanent magnet has two edge portions and one middle portion; along the direction from the outer edge of the edge portion towards the central axis of the middle portion, the weight percentage of Dy gradually increases, while the weight percentage of Tb gradually decreases; the average coercive force of the edge portion is more than that of the middle portion. The rare earth permanent magnet of the present disclosure has a good anti-demagnetization performance