Rare Earth Sintered Magnet Grain Boundaries for Deep RH Diffusion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional R-T-B system rare earth sintered magnets face challenges in diffusing heavy rare earth elements deeper into the magnet while maintaining magnetic properties, as neodymium oxyfluoride compounds can reduce the content of essential rare earth elements, leading to deteriorated magnetic properties.
Innovation Solution
A rare earth sintered magnet with a grain boundary phase enriched in Sm and heavy rare earth elements, where Sm substitution in the NdO phase and selective diffusion of heavy rare earth elements into the peripheries of Sm enriched portions allow deeper penetration without compromising magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements RH are diffused into the grain boundary of an R-T-B system rare earth sintered magnet containing neodymium oxyfluoride, then the heavy rare earth element RH can diffuse into the grain boundary without being oxidized, but the neodymium oxyfluoride containing F remains as a compound in the rare earth sintered magnet, causing the contents of rare earth elements R and Fe to relatively decrease and magnetic properties to deteriorate
Solution Approach 1:
The patent extracts and removes the harmful neodymium oxyfluoride compound from the grain boundary phase through controlled sintering conditions, eliminating the source of magnetic property deterioration while preserving the beneficial diffusion of heavy rare earth elements
Solution Approach 2:
The patent changes the sintering temperature parameters to a specific range (900-1300°C) where neodymium oxyfluoride decomposition occurs, transforming the chemical composition of the grain boundary phase to eliminate harmful compounds while maintaining desired element distribution
2Loss of substance
If the content of neodymium oxyfluoride is reduced to suppress deterioration of magnetic properties, then magnetic properties are improved, but heavy rare earth elements RH cannot diffuse into the inside of the rare earth sintered magnet
Solution Approach 1:
The patent performs preliminary removal of neodymium oxyfluoride before the diffusion process by controlling sintering conditions, creating a clean grain boundary environment that facilitates subsequent deep diffusion of heavy rare earth elements without oxidation barriers
Solution Approach 2:
The patent utilizes specific sintering temperature ranges (900-1300°C) to decompose neodymium oxyfluoride and enable deep diffusion of heavy rare earth elements simultaneously, achieving both reduced harmful compounds and increased diffusion depth
3Reliability
If heavy rare earth elements RH are diffused deeply into the rare earth sintered magnet to improve heat resistance, then coercive force is improved, but the content of rare earth elements R and Fe decreases, leading to deteriorated magnetic properties
Solution Approach 1:
The patent achieves local enrichment of heavy rare earth elements at the grain boundaries through controlled diffusion, creating a non-uniform distribution where RH concentrates at grain boundaries while preserving the bulk composition and magnetic element content in the main phase regions
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 enables deeper diffusion of heavy rare earth elements, reducing the coercive force difference within the magnet and conserving these elements, thereby maintaining high residual magnetic flux density and coercive force while suppressing magnetic property deterioration.
Implementation Method 1
Sm substitution in a crystalline NdO phase
Implementation Method 2
heavy rare earth element RH is enriched at least on part of peripheries of the Sm enriched portions
Implementation Method 3
sintering the compact at a temperature between 600 deg C. and 1300 deg C.
Implementation Method 4
aging the compact at a temperature equal to or lower than the sintering temperature
Data Source
AI summary
A rare earth sintered magnet includes a plurality of regions of a main phase each having an R2Fe14B crystal structure containing at least Nd as a rare earth element R and a grain boundary phase formed among the plurality of regions of the main phase. The grain boundary phase has Sm enriched portions in which Sm is enriched by Sm substitution in a crystalline NdO phase and heavy rare earth element RH enriched portions in which a heavy rare earth element RH is enriched at least on part of peripheries of the Sm enriched portions. This allows the heavy rare earth element RH to diffuse deeper into the rare earth sintered magnet while suppressing the deterioration of the magnetic properties.