Sm-Fe-N Magnetic Powder Nitrogen Distribution for High Coercivity
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Solution Overview
Problem
Conventional Sm—Fe—N-based magnetic materials exhibit insufficient coercive force, particularly in applications requiring heat resistance, leading to demagnetization at elevated temperatures.
Innovation Solution
A Sm—Fe—N-based magnetic material with a specific N content ratio in the main phase to grain boundary phase, achieved through a production method involving nitriding treatment followed by heat treatment in a controlled atmosphere to promote N atoms' solid solution in the crystal lattice, enhancing uniaxial magnetic anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional nitriding treatment is performed without further heat treatment, then production process is simplified, but coercive force is insufficient and heat resistance deteriorates
Solution Approach 1:
The patent applies preliminary action by performing a nitriding treatment before final heat treatment to pre-introduce nitrogen atoms into the Sm-Fe-based polycrystal. This preliminary nitrogen incorporation, followed by subsequent heat treatment, allows the nitrogen to dissolve in solid solution and distort the crystal lattice effectively, achieving high coercive force and heat resistance while maintaining a controlled production process.
Solution Approach 2:
The patent applies parameter changes by controlling the nitrogen content ratio between main phase and grain boundary phase, with the first content of N in main phase to second content of N in grain boundary phase being 0.84 or more. This specific parameter control during nitriding and heat treatment processes optimizes both coercive force and heat resistance properties.
2Reliability
If nitrogen content is increased to improve coercive force, then magnetic performance improves, but nitrogen distribution uniformity becomes difficult to control
Solution Approach 1:
The patent applies local quality by creating different nitrogen concentrations in different regions of the magnetic material. Specifically, it controls that the ratio of nitrogen content in main phase to nitrogen content in grain boundary phase is 0.84 or more, ensuring adequate nitrogen distribution in both regions while maintaining manufacturing control.
Solution Approach 2:
The patent uses parameter changes to optimize nitrogen distribution by controlling the nitrogen content ratio between main phase and grain boundary phase. By setting this ratio to 0.84 or more, the patent achieves both high coercive force and controlled nitrogen distribution uniformity through precise parameter management during nitriding and heat treatment.
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 resulting magnetic material demonstrates improved coercive force, making it suitable for high-temperature applications by minimizing demagnetization.
Implementation Method 1
N atoms are dissolved in solid solution in the crystal lattice of the Sm—Fe-based polycrystal, thereby distorting the lattice and developing uniaxial magnetic anisotropy
Implementation Method 2
heat treatment in a controlled atmosphere to promote N atoms' solid solution in the crystal lattice, enhancing uniaxial magnetic anisotropy
Implementation Method 3
subjecting the Sm—Fe-based polycrystal to a nitriding treatment
Data Source
AI summary
A Sm—Fe—N-based magnetic material that includes: a main phase including a plurality of Sm—Fe—N-based crystal grains; and a grain boundary phase present between adjacent Sm—Fe—N-based crystal grains of the plurality of Sm—Fe—N-based crystal grains, and the grain boundary phase contains N, in which a ratio of a first content of N in the main phase to a second content of N in the grain boundary phase is 0.84 or more on an atomic basis.