Samarium-Iron-Nitrogen Magnet Composition for Heat-Stable Coercivity

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Solution Overview

Problem

Existing samarium-based rare-earth permanent magnet materials suffer from poor oxidation resistance and magnetic property degradation at high temperatures, and their preparation processes are complex and costly.

Innovation Solution

Introduce vanadium, copper, and molybdenum elements into the samarium-iron-nitrogen alloy, adjusting the atomic ratios, and employ a preparation method involving melting, rapid-solidification, grinding, nitriding, ball-milling, phosphating, and heat treatment to enhance magnetic performance and oxidation resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional sintering methods are used to prepare Nd-Fe-B magnets, then production efficiency is improved, but oxidation and grain boundary issues occur leading to reduced magnetic properties

Engineering Contradiction:
Improveproduction efficiencyVSAvoidmagnetic properties
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies parameter changes by conducting sintering in a nitrogen atmosphere instead of conventional air or vacuum conditions, and by optimizing the temperature range (1000-1100°C) and time (5-15 minutes) to achieve both high productivity and preserved magnetic properties through controlled atmospheric and thermal parameters

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements an inert atmosphere solution by using nitrogen gas during the sintering process to prevent oxidation of the magnet material, thereby maintaining magnetic properties while enabling efficient production without requiring vacuum conditions

Inventive Principle:
Principle #39Inert atmosphere (Inert environment)

2Power

If high-performance Nd-Fe-B magnets are produced, then magnetic energy product is improved, but production cost increases due to expensive raw materials

Engineering Contradiction:
Improvemagnetic energy productVSAvoidproduction cost
Core Design Contradiction:
PowerVSEase of manufacture

Solution Approach 1:

The patent applies local quality by selectively substituting only part of the expensive neodymium with samarium in the Nd1-xSmxFeB system, achieving improved magnetic properties at high temperatures while controlling costs through partial rather than complete material substitution

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent implements composite materials by creating a Nd-Sm-Fe-B alloy system that combines the high magnetic performance of neodymium with the high-temperature stability of samarium, achieving a balance between performance and cost through material composition optimization

Inventive Principle:
Principle #40Composite materials

3Power

If magnet size is increased for high-power applications, then power output is improved, but eddy current losses increase reducing efficiency

Engineering Contradiction:
Improvepower outputVSAvoideddy current losses
Core Design Contradiction:
PowerVSLoss of energy

Solution Approach 1:

The patent applies segmentation by introducing a non-conductive grain boundary phase that effectively divides the conductive magnetic grains, thereby interrupting eddy current paths and reducing energy losses while maintaining the magnet's overall size and power output capability

Inventive Principle:
Principle #1Segmentation

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 samarium-based rare-earth permanent magnet material achieves excellent magnetic properties with remanence up to 7180 Gs, coercivity of 10350 Oe, and a magnetic energy product of 12.3 MGOe, while maintaining cost-effectiveness and simplicity in the preparation process.

Implementation Method 1

Samarium-based rare earth permanent magnet material

Methodology Applied
Scientific EffectMagnetism: Magnetism

Implementation Method 2

Nd-Fe-B type permanent magnet material

Methodology Applied
Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentEP4379755B1Samarium-based rare earth permanent magnet material, and preparation method therefor and application thereof
Publication Date: 2026.05.06 HENGDIAN GRP DMEGC MAGNETICS CO LTD

AI summary

Disclosed in the present invention are a samarium-based rare earth permanent magnet material, and a preparation method therefor and an application thereof. In the samarium-based rare earth permanent magnet material Sm2FeαCuβVγMoδNε, 11.5 ≤ α ≤ 17.5, 0.1 ≤ β ≤ 0.4, 1.0 ≤ y ≤ 1.8, 0 ≤ δ ≤ 1.0, and 2.9 ≤ ε ≤ 4.0. According to the samarium-based rare earth permanent magnet material provided by the present application, a good balance of the remanence and the coercivity is promoted by doping with vanadium, copper, and molybdenum and adjusting to an appropriate atomic ratio range, such that the samarium-based rare earth permanent magnet material has excellent comprehensive magnetic performance. The preparation method provided by the present application is simple to operate, low in cost, and suitable for the fields of small and special motors, magnetic sensors, or audio equipment.