Artificial Permanent Magnet Powder Mixing
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Solution Overview
Problem
Existing methods for producing artificial permanent magnets struggle to enhance anisotropy field strength without compromising remanence, as additives homogeneously distributed during sintering often reduce remanence and are limited in their ability to influence larger magnets through grain boundary diffusion.
Innovation Solution
A method involving a powder mixture of a main phase powder with larger particles and an anisotropic powder of smaller particles, where the anisotropic powder melts first during sintering, allowing its elements to penetrate into the edge regions of the main phase powder, increasing anisotropy field strength without affecting the core region and thus remanence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If added elements are homogeneously distributed during sintering to increase anisotropy field strength, then anisotropy field strength is improved, but remanence is reduced
Solution Approach 1:
The patent applies local quality by creating a non-uniform distribution of added elements within the permanent magnet particles. Specifically, the added elements are concentrated in the edge regions (grain boundaries) of the particles while maintaining lower concentrations in the core regions. This localized distribution allows the edge regions to benefit from enhanced anisotropy field strength due to the presence of added elements, while the core regions preserve their original magnetic properties and remanence characteristics. The selective positioning of additives resolves the contradiction by making the improvement local rather than global.
2Force
If grain boundary diffusion is used to increase anisotropy field strength in larger magnets, then anisotropy field strength is improved, but the method is limited in effectiveness for larger magnet sizes
Solution Approach 1:
The patent employs preliminary action by pre-mixing the added elements with the main phase powder before the sintering process. This pre-distribution ensures that the added elements are already positioned throughout the material in appropriate concentrations before sintering begins. During the subsequent sintering process, these pre-positioned elements naturally diffuse to the grain boundaries and edge regions, achieving the desired local concentration without requiring post-sintering diffusion treatments. This approach makes the process scalable to larger magnet sizes while maintaining effectiveness.
3Force
If a higher proportion of anisotropic powder is used to enhance anisotropy field strength, then anisotropy field strength is improved, but production costs increase
Solution Approach 1:
The patent reduces costs by applying local quality - concentrating the expensive anisotropic powder and added elements only where they are most needed (at grain boundaries and edge regions) rather than distributing them uniformly throughout the entire magnet volume. This localized approach achieves the maximum possible anisotropy field strength enhancement with the minimum necessary quantity of costly materials, thereby reducing production costs while maintaining performance benefits.
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
This approach effectively enhances the anisotropy field strength of artificial permanent magnets, particularly in larger sizes, while maintaining or slightly improving remanence, and reduces production costs by using a lower proportion of anisotropic powder.
Implementation Method 1
the anisotropic powder of the smaller particle size added to the powder mixture starts melting or melts more rapidly during the sintering process
Implementation Method 2
The added elements contained in the anisotropic powder become rapidly mobile due to the early start of the melting of the smaller particles and they penetrate into edge regions of the considerably larger particles of the main phase powder
Implementation Method 3
In a subsequent cooling process, the liquid phase crystallizes on the edge regions of the particles of the main phase powder
Implementation Method 4
Due to grain boundary diffusion, the liquid phase is distributed rapidly and surrounds the particles of the main phase powder
Data Source
AI summary
A method is provided for producing an artificial permanent magnet, in a powder preparation step a main phase powder, which includes a rare-earth transition metal compound with permanently magnetic properties and has a first average particle size, is prepared and an anisotropic powder, which has a higher anisotropy field strength than the main phase powder and has a second average particle size, is prepared, wherein the second average particle size is smaller than the first average particle size. In a subsequent powder mixing step, the main phase powder and the anisotropic powder are mixed together to form a powder mixture and, in a subsequent heat treatment step, this powder mixture with the main phase powder of the first average particle size and with the anisotropic powder of the second average particle size is sintered to form an artificial permanent magnet.