Bonded Magnet Material With Magnetic Grain Boundary for High Coercivity
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Solution Overview
Problem
Existing magnet materials for bonded magnets do not exhibit high intrinsic coercive force due to the incompatibility of heat treatment processes with resin-modified bulk bodies, limiting their application in bonded magnets.
Innovation Solution
A magnet material comprising a RE2Fe14B tetragonal compound as the main phase with an amorphous and magnetic grain boundary phase containing F, RE, and Fe, and B, where the RE is at least Nd or Pr, and a binder, achieving high intrinsic coercive force HcJ.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is applied to improve coercive force in sintered or hot-deformed magnets, then intrinsic coercive force is improved, but the process is incompatible with bonded magnets where resin is modified and melted
Solution Approach 1:
The invention changes the fundamental parameters of the magnet material by using rapidly solidified alloy with amorphous or fine-grained structure and controlled grain boundary phases, enabling high coercive force without requiring post-manufacturing heat treatment that would damage the resin binder in bonded magnets
Solution Approach 2:
The invention creates a composite microstructure consisting of RE2Fe14B main phase grains surrounded by amorphous or fine-grained grain boundary phases containing RE-Fe-B or RE-O elements, which provides both high intrinsic coercive force and compatibility with bonded magnet manufacturing processes
2Reliability
If crystal grain size is reduced to increase coercive force, then intrinsic coercive force improves, but manufacturing precision and control become more difficult
Solution Approach 1:
The invention utilizes phase transition during rapid solidification to directly form the desired microstructure with fine grains and amorphous phases, achieving precise grain size control (10-70 nm) through cooling rate control rather than post-processing heat treatment
Solution Approach 2:
The invention performs the microstructure formation action during the solidification process itself, creating the fine-grained or amorphous structure and grain boundary phases in advance during manufacturing, rather than requiring subsequent heat treatment steps to achieve the desired grain structure
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 material exhibits high intrinsic coercive force HcJ, residual magnetic flux density Br, and maximum energy product (BH)max, suitable for applications in rotating machines and household appliances.
Implementation Method 1
a magnet material for a bonded magnet includes: a RE2Fe14B tetragonal compound as a main phase, the RE2Fe14B tetragonal compound has an average crystal grain size of 10 nm or more and less than 70 nm
Implementation Method 2
an amorphous and magnetic grain boundary phase surrounding the main phase, the amorphous and magnetic grain boundary phase containing F, RE, Fe, and B
Data Source
AI summary
A magnet material that includes: a RE2Fe14B tetragonal compound as a main phase, the RE2Fe14B tetragonal compound has an average crystal grain size of 10 nm or more and less than 70 nm; and an amorphous and magnetic grain boundary phase surrounding the main phase, the amorphous and magnetic grain boundary phase containing F, RE, Fe, and B, wherein the RE is at least one rare-earth element containing at least Nd among Nd and Pr.