Rare Earth Sintered Magnet Grain Control for Higher Coercivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for manufacturing rare earth sintered magnets face challenges in achieving high coercivity and thermostability while minimizing the production of ultra-fine grains, which affects alignment in magnetic fields and increases production costs due to the need for expensive equipment and special post-processing.
Innovation Solution
A method involving repetitive finely pulverization of rare earth alloys using a jet mill with high-pressure nitrogen gas to narrow grain size distribution, followed by a hydrogenation-disproportionation-desorption-recombination (HDDR) process to micronize crystal grains, improving coercivity and thermostability without requiring expensive heavy rare earth elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the crystal grains are micronized by HDDR process to improve coercivity and thermostability, then the magnetic performance is improved, but the production cost increases due to expensive equipment requirements for very high heating speeds
Solution Approach 1:
The patent changes the heating speed parameter from very high heating speed to a controlled heating rate (10-50°C/min), which eliminates the need for expensive specialized equipment while still achieving the desired crystal grain micronization and magnetic performance improvement through the HDDR process
2Reliability
If the crystal grains are micronized by HDDR process to improve coercivity, then the thermostability is improved, but the coercivity sharply lowers prior to full densification
Solution Approach 1:
The patent implements a continuous process where the HDDR treatment is followed immediately by sintering without interruption, maintaining the beneficial effects of crystal grain micronization throughout the densification process and preventing coercivity loss that occurs when there are gaps between processing steps
3Reliability
If the rare earth alloy is finely pulverized to improve alignment in magnetic field, then the coercivity is improved, but the production cost increases due to the need for expensive heavy rare earth elements
Solution Approach 1:
The patent creates a substitute solution by using jet mill pulverization to achieve fine particle size distribution that mimics the effects of using heavy rare earth elements, thereby improving alignment and coercivity without the need for expensive Dy or Tb additions
4Productivity
If the heating speed is increased to achieve full densification, then the production efficiency is improved, but expensive equipment is required
Solution Approach 1:
The patent changes the heating rate parameter to an optimized range (10-50°C/min) that balances densification efficiency with equipment cost, achieving full densification without requiring very high heating speeds that would necessitate expensive specialized equipment
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 enhances the magnetic properties of rare earth sintered magnets by minimizing ultra-fine grain production, improving alignment in magnetic fields, and reducing production costs through efficient grain size control and processing.
Implementation Method 1
supplying high-pressure nitrogen gas to narrow grain size distribution
Implementation Method 2
hydrogenation-disproportionation-desorption-recombination (HDDR) process
Implementation Method 3
hydrogenation-disproportionation-desorption-recombination (HDDR) process
Implementation Method 4
aligning and compacting the finely pulverized rare earth alloy powder in a magnetic field
Data Source
AI summary
There is provided a method for manufacturing a rare earth sintered magnet by many times repetitively finely pulverizing a rare earth alloy on a jet mill by supplying high-pressure nitrogen gas to narrow grain size distribution to make an easy alignment in a magnetic field, and by micronizing crystal grains by using a hydrogenation-disproportionation-desorption-recombination (HDDR) process, to improve the coercivity and thermostability of the rare earth sintered magnet.