Iron Core-Shell Nanoparticles for Rare-Earth-Free Permanent Magnets
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Solution Overview
Problem
Current permanent magnets rely heavily on rare earth elements, which are scarce and expensive, and their manufacturing processes are costly and environmentally detrimental, while Fe16N2/Fe8N phase magnets are difficult to manufacture due to high anisotropy and require high temperatures.
Innovation Solution
Development of iron-based core-shell nanoparticles with a non-magnetic, anti-ferromagnetic, or ferromagnetic shell, formed through techniques like immersion in a salt composition or milling, followed by nitriding, to enhance coercivity and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare earth elements are used in permanent magnets, then high energy product and magnetic properties are achieved, but cost and supply availability deteriorate
Solution Approach 1:
The patent replaces expensive rare earth elements with inexpensive iron-based materials that can be readily manufactured. The core-shell nanoparticle structure uses iron cores with protective shells, creating a cost-effective alternative to rare earth magnets while maintaining functional performance.
Solution Approach 2:
The patent employs composite core-shell structures where iron-based cores provide magnetic properties and outer shells provide protective functions. This composite approach enables achieving desired magnetic performance without relying on expensive rare earth elements.
2Reliability
If rare earth elements are used in permanent magnets, then high energy product is achieved, but environmental impact worsens
Solution Approach 1:
The patent substitutes rare earth elements with abundant iron-based materials, eliminating the environmental damage associated with rare earth mining and processing while maintaining magnetic functionality.
Solution Approach 2:
The patent uses inert or protective shell materials to prevent oxidation and degradation of the iron-based core, enabling stable performance without requiring environmentally harmful protective measures.
3Reliability
If Fe16N2/Fe8N phase magnets are manufactured, then high magnetic anisotropy and saturation magnetization are achieved, but manufacturing difficulty increases
Solution Approach 1:
The patent divides the magnetic material into nanoscale core-shell particles, which simplifies the manufacturing process compared to bulk Fe16N2/Fe8N phase magnets. The segmented nanoparticle structure allows for easier synthesis and processing while maintaining high magnetic anisotropy.
Solution Approach 2:
The patent changes the size parameter to nanoscale dimensions, which fundamentally alters the manufacturing requirements. Instead of requiring high-temperature sintering of bulk materials, the nanoparticle approach enables synthesis through milder chemical or physical processes.
4Reliability
If Fe16N2/Fe8N phase magnets are manufactured, then high saturation magnetization is achieved, but sintering temperature requirement increases
Solution Approach 1:
The patent changes the temperature parameter by working at nanoscale dimensions, which allows achieving high saturation magnetization without requiring sintering temperatures over 1000°C. The nanoparticle synthesis can proceed at much lower temperatures through chemical reduction or other mild processes.
Solution Approach 2:
The patent applies local quality control through the core-shell structure, where the core provides high saturation magnetization and the shell provides protective and functional properties, enabling high performance without extreme processing temperatures.
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 core-shell nanoparticles enable the production of bulk permanent magnets with magnetic properties comparable to rare-earth magnets without using rare earth elements, offering high coercivity and saturation magnetization.
Implementation Method 1
The technique includes nitriding a composition comprising an iron-based core to form a shell comprising iron nitride on the iron-based core
Implementation Method 2
depositing a shell on an iron-based core by at least immersing the iron-based core in a salt composition for a predetermined period of time
Data Source
AI summary
Example nanoparticles may include an iron-based core, and a shell. The shell may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example alloy compositions may include an iron-based grain, and a grain boundary. The grain boundary may include a non-magnetic, anti-ferromagnetic, or ferrimagnetic material. Example techniques for forming iron-based core-shell nanoparticles may include depositing a shell on an iron-based core. The depositing may include immersing the iron-based core in a salt composition for a predetermined period of time. The depositing may include milling the iron-based core with a salt composition for a predetermined period of time. Example techniques for treating a composition comprising core-shell nanoparticles may include nitriding the composition.