Ce-Enriched Grain Boundary Phase in R-T-B Permanent Magnets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current rare earth-based permanent magnets, such as Sm—Co and Nd—Fe—B, require high amounts of expensive and scarce heavy rare earth elements like Dy or Tb to achieve high coercivity, which are unstable in terms of supply and price, necessitating a solution that maintains magnetic properties without these elements.
Innovation Solution
A rare earth-free permanent magnet with a main phase of R2T14B and a grain boundary phase composed of CexM1-x, where Ce is used in the grain boundary phase to enhance coercivity, reducing the reliance on heavy rare earth elements, and optimizing the cross-sectional area ratio and dihedral angle for improved magnetic separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements (Dy, Tb) are added to R-T-B based magnet to increase coercivity, then magnetic properties are improved, but resource availability decreases and price becomes unstable
Solution Approach 1:
The invention changes the chemical composition parameters of the grain boundary phase by incorporating Ce along with Fe, Co, and other elements in specific proportions. This parameter change allows achieving high coercivity without relying on heavy rare earth elements, thus resolving the contradiction between maintaining magnetic properties and reducing rare earth element usage.
Solution Approach 2:
The invention creates a composite grain boundary phase consisting of multiple elements (Ce, Fe, Co, and others) that work synergistically. This composite structure provides the necessary magnetic properties through the combined effects of its constituents, eliminating the need for heavy rare earth elements while maintaining high coercivity.
2Reliability
If Ce is added to the grain boundary phase to improve coercivity, then magnetic separation is enhanced, but the cross-sectional area ratio must be precisely controlled
Solution Approach 1:
The invention specifies precise parameter ranges for the grain boundary phase composition (Ce content: 0.20≤x≤0.55, cross-sectional area ratio: 0.03≤Atre≤0.15) to optimize magnetic separation. By defining these parameter boundaries, the invention achieves reliable magnetic separation while providing clear manufacturing guidelines to control the cross-sectional area ratio within the required precision.
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 magnet achieves high coercivity and residual magnetic flux density without using heavy rare earth elements, ensuring a stable and cost-effective solution for applications like motors, while maintaining compatibility and corrosion resistance.
Implementation Method 1
magnetic separation is improved by means that the main phase grains are covered by the specified thermal treatment
Data Source
AI summary
The present invention provides an R-T-B based permanent magnet, comprising: a main phase which is composed of the structure of R2T14B (R is at least one element selected from Y, La, Ce, Pr, Nd, Sm, Eu and Gd, and T is one or more transition metal elements having Fe or a combination of Fe and Co as necessary); and a grain boundary phase which is composed of CexM1-x (M is at least one element selected from Mg, Al, Si, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ag, In, Sn, La, Pr, Nd, Sm, Eu, Gd, Hf, Ta, W and Bi, and x is within the range of 0.20≦x≦0.55), and the cross-sectional ratio Atre of the grain boundary phase to the whole magnet structure is within the range of 0.03<Atre<0.07.