Sm-Fe-N Magnet Powder Composition for Coercivity-Magnetization Balance
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Solution Overview
Problem
Existing samarium-iron-nitrogen based magnets face a trade-off between coercivity and magnetization, with existing solutions like adding bismuth not adequately addressing both properties simultaneously.
Innovation Solution
A samarium-iron-nitrogen based magnet powder is formulated with specific atomic ratios of bismuth and tungsten, within certain limits, to enhance both coercivity and magnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If bismuth is added to samarium-iron-nitrogen based magnet powder to increase coercivity, then coercivity is improved, but magnetization becomes insufficient
Solution Approach 1:
The patent applies composite materials by combining samarium-iron-nitrogen base with both bismuth and tungsten additives to create a multi-element composite magnet powder. This composite approach allows synergistic effects where bismuth contributes to coercivity enhancement while tungsten maintains magnetization levels, resolving the trade-off between these two magnetic properties that cannot be achieved with single-element additives alone.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the atomic ratios of bismuth (1.00 at % or less) and tungsten (0.05 at % or more and 0.60 at % or less) with a W/Bi ratio of 1.0 or more and 30.0 or less. By optimizing these compositional parameters, the patent achieves simultaneous improvement in both coercivity and magnetization, transforming the previously conflicting parameters into compatible performance characteristics.
2Ease of manufacture
If samarium-iron-nitrogen based magnet powder is sintered at high temperature to improve densification, then manufacturing is improved, but magnetic properties especially coercivity are greatly reduced
Solution Approach 1:
The patent applies preliminary action by pre-forming magnet powder particles with specific crystal structures and compositions before sintering. The powder is prepared with controlled particle morphology and phase structure that are resistant to degradation during subsequent high-temperature sintering, allowing densification to proceed without significant loss of coercivity.
Solution Approach 2:
The patent uses parameter changes by optimizing the compositional parameters (bismuth and tungsten content ratios) to alter the thermal stability of magnetic properties. This compositional optimization enables the material to maintain its coercivity even under high-temperature sintering conditions, effectively decoupling the densification process from magnetic property degradation.
Data Source
AI summary
A samarium-iron-nitrogen based magnet powder includes a lanthanoid (Ln), iron (Fe), bismuth (Bi), tungsten (W), and nitrogen (N), wherein the lanthanoid includes samarium (Sm), an atomic ratio of bismuth to a 5 sum of the lanthanoid, iron, bismuth, and tungsten (Bi/(Ln+Fe+Bi+W)) is 1.00 at % or less, an atomic ratio of tungsten to the sum of the lanthanoid, iron, bismuth, and tungsten (W/(Ln+Fe+Bi+W)) is 0.05 at % or more and 0.60 at % or less, and an atomic ratio of tungsten to bismuth (W/Bi) is 1.0 or more and 30.0 or less.