Coating and Heat Treatment for Magnet Coercive Force
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Solution Overview
Problem
Existing methods for increasing the coercive force of rare earth magnets often result in significant decreases in remanence and magnetic energy product, require large amounts of heavy rare earth elements, and involve complex, difficult-to-control processes.
Innovation Solution
A method involving a coating step with a colloidal solution containing metal calcium particles and rare earth elements, followed by heat treatment under specific temperature conditions to diffuse the rare earth elements into the magnet's grain boundaries, enhancing coercive force while minimizing the use of heavy rare earth elements and maintaining remanence and magnetic energy product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional diffusion and infiltration methods are used to increase coercive force, then coercive force increases, but remanence and magnetic energy product significantly decrease
Solution Approach 1:
The patent applies local quality by concentrating the heavy rare earth elements specifically at the grain boundaries through controlled diffusion and infiltration, rather than uniformly distributing them throughout the magnet. This localized approach allows the grain boundaries to acquire enhanced coercive force properties while the bulk magnetic matrix maintains its high remanence and energy product characteristics, thus resolving the contradiction between increasing coercive force and preserving magnetic performance.
2Force
If heavy rare earth elements are used to increase coercive force, then coercive force increases, but the amount of heavy rare earth element required is large, increasing cost
Solution Approach 1:
By localizing the heavy rare earth elements at the grain boundaries, the patent achieves high coercive force with minimal amounts of expensive heavy rare earth materials. The grain boundaries act as the critical region where these elements provide maximum benefit, eliminating the need for large quantities throughout the entire magnet structure, thus reducing material cost while maintaining performance.
Solution Approach 2:
The patent employs an intermediary substance (such as fluoride or oxide compounds of heavy rare earth elements) that facilitates controlled diffusion and infiltration into the grain boundaries. This intermediary approach allows for precise delivery and distribution of the heavy rare earth elements exactly where needed, improving efficiency and reducing the total amount of expensive material required compared to direct addition methods.
3Force
If diffusion and infiltration processes are used to improve grain boundaries, then coercive force increases, but the process becomes complex and difficult to control
Solution Approach 1:
The patent applies preliminary action by pre-coating the magnet surface with the heavy rare earth element compounds before the diffusion and infiltration process. This pre-preparation step ensures that the heavy rare earth elements are already positioned and ready for controlled diffusion into the grain boundaries, simplifying the overall process and improving controllability compared to attempting to introduce these elements during or after the main magnetization process.
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
Significantly increases coercive force with minimal decrease in remanence and magnetic energy product, reduces the amount of rare earth elements needed, and simplifies the process, making it suitable for industrial-scale production.
Implementation Method 1
metal calcium particles... reducing rare earth element compounds
Implementation Method 2
heat treating the magnet... so that the rare earth element is absorbed in the magnet
Data Source
AI summary
The present invention provides a method for improving coercive force of magnets, this method comprises steps as follows: S2) coating step: coating a coating material on the surface of a magnet and drying it; and S3) infiltrating step: heat treating the magnet obtained from the coating step S2). The coating material comprises (1) metal calcium particles and (2) particles of a material containing a rare earth element; the rare earth element is at least one selected from Praseodymium, Neodymium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium and Lutetium. The method of the present invention can significantly increase coercive force of a permanent magnet material, while remanence and magnetic energy product hardly decrease. In addition, the method of the present invention can significantly decrease the amount of a rare earth element, and accordingly, decrease the production cost.