Rare Earth Sintered Magnet Composition for Thermal Magnetic Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing Nd—Fe—B-based sintered magnets face degradation in magnetic properties at room temperature and with temperature rise, and the use of alternative rare earth elements like Ce, La, and Sm leads to further deterioration, necessitating a solution to maintain magnetic properties while reducing the consumption of Nd and Dy.
Innovation Solution
A rare earth sintered magnet with a main phase of (Nd, La, Sm)—Fe—B and a crystalline subphase of (Nd, La, Sm)—O, where Sm is concentrated in the subphase to enhance Nd diffusion and maintain magnetic properties, and a core-shell structure with higher Nd concentration in the shell portion to improve magnetic anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If alternative rare earth elements (Ce, La, Sm) are used to substitute Nd and Dy, then cost is reduced and procurement risk is lowered, but magnetic properties are significantly degraded
Solution Approach 1:
The patent applies local quality by creating a core-shell structure where the main phase crystal grains have high Nd concentration for magnetic properties, while the grain boundary phase has high La concentration for thermal stability. This spatial differentiation allows each region to optimize its function: the core maintains magnetization while the boundary prevents degradation at high temperatures.
Solution Approach 2:
The patent uses composite materials by combining multiple rare earth elements (Nd, La, Sm) in specific phases. The main phase contains (Nd, Sm)2Fe14B for magnetic properties while the grain boundary phase contains La-rich compounds. This composite approach leverages the strengths of different elements: Nd for magnetization, Sm for coercivity, and La for thermal stability.
2Temperature
If La and Sm are added to Nd2Fe14B to prevent magnetic property degradation with temperature rise, then heat resistance is improved, but magnetic properties at room temperature deteriorate due to uniform dispersion
Solution Approach 1:
The patent segments the magnet structure into distinct phases: main phase crystal grains and grain boundary phase. By separating La and Sm into different locations (Sm in main phase, La in grain boundary), it prevents uniform dispersion and allows each element to fulfill its specific function without compromising the other.
Solution Approach 2:
The patent implements local quality by concentrating Sm in the main phase crystal grains where it enhances coercive force, while concentrating La in the grain boundary phase where it provides thermal stability. This localized distribution ensures that room temperature magnetic properties are maintained while heat resistance is improved.
3Quantity of substance
If Ce is added to the rare earth sintered magnet, then cost is reduced, but magnetization monotonically decreases as the amount of Ce added increases
Solution Approach 1:
The patent applies local quality by restricting Ce to the grain boundary phase while maintaining high Nd concentration in the main phase crystal grains. This spatial separation allows Ce to provide cost benefits and some magnetic contribution at the boundaries without significantly reducing the overall magnetization, as the main phase retains its high magnetic performance.
Solution Approach 2:
The patent uses composite materials by creating a multi-phase structure where Ce is combined with other rare earth elements in the grain boundary phase, while the main phase maintains a composition optimized for magnetization. This composite approach allows cost reduction through Ce addition while preserving magnetic properties through the Nd-rich main phase.
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 maintains high magnetic properties at room temperature and prevents degradation with temperature rise, reducing Nd and Dy usage without adding elements like Co or Ni.
Implementation Method 1
creating a core-shell structure that enhances magnetic anisotropy
Implementation Method 2
prevents Nd consumption at grain boundaries
Data Source
AI summary
A rare earth sintered magnet according to the present disclosure includes: a main phase satisfying general formula (Nd, La, Sm)—Fe—B and including crystal grains based on R2Fe14B crystal structures; and a crystalline subphase based on an oxide phase represented by (Nd, La, Sm)—O. The subphase has a higher concentration of Sm than the main phase.