R-T-B Permanent Magnet with Y and Ce Substitution
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Solution Overview
Problem
The use of Nd—Fe—B based permanent magnets in rotating machines increases the moment of inertia and reduces controllability due to their high weight, making it difficult to replace them with lighter alternatives without compromising magnetic properties.
Innovation Solution
The development of an R-T-B based permanent magnet with a composition of (R1−x(Y1−zCez)x)2T14B, where R includes rare earth elements like Y and Ce, selectively replacing Nd in the 4f site to reduce weight while maintaining magnetic properties, utilizing Y and Ce to stabilize the crystal structure and adjust ionic radii for optimal magneto crystalline anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Nd-Fe-B based permanent magnets are used in rotating machines, then magnetic properties are improved, but the moment of inertia increases and controllability is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the permanent magnet by replacing Nd with lighter rare earth elements (Y, La, Pr) in the R2Fe14B structure. This composition modification reduces the density and weight of the magnet while attempting to maintain acceptable magnetic properties through careful selection of replacement elements and ratios.
Solution Approach 2:
The patent creates a composite permanent magnet material by combining multiple rare earth elements (Y, La, Pr, Nd) in the R2Fe14B structure. This composite approach allows optimization of both weight and magnetic properties by leveraging the advantages of different rare earth elements, achieving a balance between light weight and sufficient magnetic performance.
2Weight of moving object
If lighter rare earth elements like Y are used to replace Nd, then weight is reduced, but magnetic properties are significantly lowered
Solution Approach 1:
The patent applies local quality by selectively replacing Nd with lighter rare earth elements at specific sites within the crystal structure. By controlling the distribution and concentration of different rare earth elements in the R2Fe14B structure, the patent optimizes the local magnetic environment to maintain coercivity and other magnetic properties while reducing overall weight.
Solution Approach 2:
The patent modifies the compositional parameters by using multi-element rare earth combinations (Y, La, Pr, Nd) in the R2Fe14B structure. This parameter optimization allows the material to achieve a balance point where weight is reduced compared to pure Nd-Fe-B, but magnetic properties remain acceptable through careful tuning of element ratios and crystal structure characteristics.
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 results in a lighter permanent magnet with magnetic properties comparable to Nd—Fe—B magnets, suitable for use in permanent magnet synchronous rotating machines, offering improved controllability and responsiveness without significant reductions in magnetic flux density or coercive force.
Implementation Method 1
utilizing Y and Ce to stabilize the crystal structure and adjust ionic radii for optimal magneto crystalline anisotropy
Implementation Method 2
utilizing Y and Ce to stabilize the crystal structure and adjust ionic radii for optimal magneto crystalline anisotropy
Implementation Method 3
Magneto crystalline anisotropy, as the origin of the coercive force of rare earth based magnets, is generated by the single-ion anisotropy of rare earth ions constraining the entire magnetic moment of the crystal
Implementation Method 4
Magneto crystalline anisotropy, as the origin of the coercive force of rare earth based magnets, is generated by the single-ion anisotropy of rare earth ions constraining the entire magnetic moment of the crystal
Data Source
AI summary
A R-T-B based permanent magnet which has equivalent magnetic properties as the existing Nd—Fe—B based permanent magnet and light mass but also can be suitably used as a magnet for field system of a permanent magnet synchronous rotating machine. The magnet can be obtained in a case where the composition of the compound for forming the main phase is (R1−x(Y1−zCez)x)2T14B (R is rare earth element(s) consisting of one or more elements selected from La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu, Y is yttrium, Ce is cerium, T is one or more transition metal elements with Fe or Fe and Co as essential element(s), B is boron, 0.0<x≤0.5 and 0.0≤z≤0.5), by making the abundance ratio of Y4f/(Y4f+Y4g) in relation to the Y occupying the 4f site of the tetragonal R2T14B structure (i.e., Y4f) and the Y occupying the 4g site (i.e., Y4g) satisfies 0.8≤Y4f/(Y4f+Y4g)≤1.0.