Rare Earth Permanent Magnet, Its Preparation Method And Motors
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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, featuring symmetrical edge and middle portions with varying dysprosium and terbium distributions, is prepared by attaching these elements to a sintered neodymium-iron-boron magnet and undergoing controlled heat treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If grain boundary diffusion agents containing heavy rare earths are used to improve coercive force, then coercive force increases, but the anti-demagnetization ability at high temperature still needs improvement
Solution Approach 1:
The patent applies local quality by creating distinct regions with different rare earth element compositions: edge portions containing heavy rare earths (Dy, Tb) for high coercive force, and a middle portion with light rare earths (Nd, Pr) for high remanence. This spatial differentiation of material properties resolves the contradiction by optimizing each region for its specific function while maintaining overall magnetic performance and high-temperature stability.
Solution Approach 2:
The patent employs composite materials by combining multiple rare earth elements (Nd, Pr, Dy, Tb) in a single magnet structure with different R2Fe14B phases distributed throughout. The composite structure integrates high-coercivity regions (edge portions with heavy rare earths) and high-remanence regions (middle portion with light rare earths), achieving both improved coercive force and enhanced anti-demagnetization ability at high temperatures.
2Reliability
If heavy rare earth elements are added to improve anti-demagnetization performance, then anti-demagnetization ability improves, but the complexity of the preparation process increases
Solution Approach 1:
The patent applies preliminary action by pre-coating the magnet edges with grain boundary diffusion agents containing heavy rare earth elements before the main sintering process. This preliminary coating ensures that the edge portions receive the necessary heavy rare earth concentration during diffusion, simplifying the overall process by eliminating the need for separate post-processing steps to achieve the desired compositional gradient.
Solution Approach 2:
The patent replaces complex mechanical mixing or multi-step deposition processes with a grain boundary diffusion mechanism. By applying grain boundary diffusion agents to the magnet edges and conducting a controlled heat treatment, the heavy rare earth elements automatically diffuse into the magnet structure, creating the desired compositional gradient through thermal diffusion rather than mechanical means.
3Ease of manufacture
If uniform rare earth distribution is used to simplify manufacturing, then manufacturing is easier, but the coercive force and anti-demagnetization ability are insufficient
Solution Approach 1:
The patent applies local quality by creating distinct regions with different rare earth element compositions: edge portions containing heavy rare earths (Dy, Tb) for high coercive force, and a middle portion with light rare earths (Nd, Pr) for high remanence. This spatial differentiation of material properties resolves the contradiction by optimizing each region for its specific function while maintaining overall magnetic performance and high-temperature stability.
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 enhanced anti-demagnetization performance and high coercive force, suitable for embedded motors, with minimal demagnetization even at elevated temperatures.
Implementation Method 1
coating the edges of neodymium-iron-boron magnets with grain boundary diffusion agents containing heavy rare earths or light rare earths, or grain boundary diffusion agents without rare earths; and then conducting heat treatment
Implementation Method 2
conducting heat treatment
Data Source
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.