Anisotropic Rare Earth Magnet Powder Coercivity via Nd-Cu Enveloping Layers
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Solution Overview
Problem
Current bonded magnets with rare earth magnet powders face challenges in maintaining stable magnetic characteristics at high temperatures due to the scarcity and high cost of elements like dysprosium (Dy) and gallium (Ga), necessitating a method to enhance coercivity without relying on these scarce elements.
Innovation Solution
The development of anisotropic rare earth magnet powder with R2TM14B1-type crystals and enveloping layers containing Nd and Cu, which improves magnetic flux density and coercivity without using Dy, Tb, Ho, or Ga, utilizing easily available and cost-effective materials for the enveloping layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dysprosium (Dy) or gallium (Ga) are added to rare earth magnet powder to improve coercivity, then magnetic characteristics are enhanced, but resource scarcity and cost increase
Solution Approach 1:
The patent replaces expensive scarce elements (Dy, Ga) with cheaper alternative elements (Cu, Al, Ni, Co, Mn, Zn) that can achieve similar coercivity enhancement. The enveloping layer uses these abundant elements to provide the necessary magnetic property improvement without relying on depletable resources.
Solution Approach 2:
The patent changes the compositional parameters by introducing specific ratios of alternative elements (Cu: 0.05-2 at.%, Al: 0.1-5 at.%, Ni: 0.1-5 at.%, Co: 0.1-5 at.%, Mn: 0.1-5 at.%, Zn: 0.1-5 at.%) to achieve coercivity enhancement. This parameter substitution allows maintaining magnetic performance while avoiding scarce elements.
2Reliability
If dysprosium (Dy) or gallium (Ga) are added to rare earth magnet powder to improve coercivity, then magnetic characteristics are enhanced, but manufacturing cost increases
Solution Approach 1:
The patent substitutes expensive Dy and Ga with much cheaper alternative elements (Cu, Al, Ni, Co, Mn, Zn) that are abundant and cost-effective. This substitution directly reduces raw material costs while maintaining the coercivity enhancement effect through the enveloping layer structure.
Solution Approach 2:
The patent modifies the compositional parameters by using inexpensive elements in controlled amounts (total 0.2-18 at.%) to achieve the desired magnetic properties. This parameter change strategy reduces manufacturing cost by replacing expensive materials with affordable alternatives.
3Ease of manufacture
If conventional rare earth magnet powder is used, then production is simple, but magnetic characteristics are insufficient at high temperatures
Solution Approach 1:
The patent creates a composite structure consisting of R2TM14B1-type crystals (main phase) with an enveloping layer (composite coating) containing multiple alternative elements. This composite structure provides both the simplicity of conventional production and enhanced high-temperature magnetic characteristics through the synergistic effect of the enveloping layer.
Solution Approach 2:
The patent applies the enveloping layer selectively on the surface of the R2TM14B1-type crystals, providing local enhancement of magnetic properties where it is most needed (at grain boundaries and surfaces). This local quality approach maintains production simplicity while improving high-temperature performance through targeted element distribution.
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 achieves high coercivity and magnetic flux density while ensuring stable supply and reducing costs, as the enveloping layers effectively correct surface distortions and suppress reverse magnetic domains, enhancing the magnetic characteristics of the anisotropic rare earth magnet powder.
Implementation Method 1
the enveloping layers effectively correct surface distortions and suppress reverse magnetic domains, enhancing the magnetic characteristics of the anisotropic rare earth magnet powder
Data Source
AI summary
Anisotropic rare earth magnet powder particles include R2TM14B1-type crystals of a tetragonal compound consisting of one or more rare earth element, B, and one or more transition element, and enveloping layers containing at least Nd and Cu. Surfaces of the R2TM14B1-type crystals are enveloped by the enveloping layers. The particles has an average crystal grain diameter of 0.05 to 1 μm. The particles contain, when the whole particles are taken as 100 atomic %, 11.5 to 15 atomic % of total rare earth element (Rt); 5.5 to 8 atomic % of B; and about 0.05 atomic % to about 2 atomic % of Cu. The powder particles have an atomic ratio of Cu, which is a ratio of the total number of Cu atoms to a total number of atoms of Rt, falling within the range of 1 to 6%. The powder particles do not include dysprosium Dy, Tb, Ho and Ga. Coercivity of the magnetic powder is more than 955 kA/m.