Sm-Co Magnet Manufacturing via Cu Concentration Gradient Control
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Solution Overview
Problem
Conventional methods for manufacturing Sm-Co-based permanent magnets face challenges in achieving high coercive force, magnetization, and squareness ratio while maintaining a high Fe concentration, as increasing Fe concentration tends to deteriorate the squareness ratio.
Innovation Solution
A method involving a specific composition formula R p Fe q M r Cu t Co 100-p-q-r-t, where R is a rare earth element, M is Zr, Ti, or Hf, and the process includes preparing alloy powder, press-forming under a magnetic field, sintering, quality improvement treatment, solution treatment, and aging to control the Cu concentration gradient between crystal grains, forming a Th 2 Zn 17 crystal phase and Cu-rich phase for enhanced magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the concentration of Fe is increased to achieve higher magnetization, then the magnetization is improved, but the squareness ratio deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform Cu concentration distribution within the crystal grains. Specifically, a Cu-rich phase is formed at the grain boundaries while the cell phase maintains a lower Cu concentration. This localized differentiation allows the high Fe concentration in the cell phase to provide high magnetization, while the Cu-rich grain boundary phase provides strong domain wall pinning that maintains a high squareness ratio, thus resolving the contradiction between improving magnetization and maintaining squareness ratio
Solution Approach 2:
The patent employs composite materials by creating a multi-phase structure within the Sm-Co-based magnet. The composite consists of a cell phase (Th2Zn17 type) containing high Fe concentration for magnetization, and a Cu-rich phase at grain boundaries for coercive force enhancement. This composite structure enables the magnet to simultaneously achieve high magnetization from the Fe-rich cell phase and high squareness ratio from the Cu-rich grain boundary phase, resolving the technical contradiction
2Quantity of substance
If the concentration of Fe is increased to achieve higher magnetization, then the magnetization is improved, but the coercive force deteriorates
Solution Approach 1:
The patent applies local quality by creating a non-uniform Cu concentration distribution within the crystal grains. Specifically, a Cu-rich phase is formed at the grain boundaries while the cell phase maintains a lower Cu concentration. This localized differentiation allows the high Fe concentration in the cell phase to provide high magnetization, while the Cu-rich grain boundary phase provides strong domain wall pinning that maintains a high squareness ratio, thus resolving the contradiction between improving magnetization and maintaining squareness ratio
Solution Approach 2:
The patent employs composite materials by creating a multi-phase structure within the Sm-Co-based magnet. The composite consists of a cell phase (Th2Zn17 type) containing high Fe concentration for magnetization, and a Cu-rich phase at grain boundaries for coercive force enhancement. This composite structure enables the magnet to simultaneously achieve high magnetization from the Fe-rich cell phase and high squareness ratio from the Cu-rich grain boundary phase, resolving the technical contradiction
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 method achieves improved coercive force, magnetization, and squareness ratio in Sm-Co-based magnets with high Fe concentration by controlling the Cu concentration gradient, leading to better magnetic domain wall pinning and increased efficiency in motor applications.
Implementation Method 1
press-forming it while applying a magnetic field thereto, whereby a green compact whose crystal axes are oriented is manufactured
Implementation Method 2
sintering of the green compact by a heat treatment at a temperature of 1180°C or more and 1220°C or less and for 1 hour our more and 15 hours or less to obtain a sintered compact
Implementation Method 3
performing a quality improvement treatment after the sintering and before performing a solution treatment by retaining the sintered compact at a temperature of 1140°C or more and 1210°C or less
Data Source
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AI summary
A permanent magnet is expressed by a composition formula: RpFeqMrCutCo100-p-q-r-t. The magnet comprises a metal structure including a main phase having a Th2Zn17 crystal phase and a grain boundary phase. The main phase includes a cell phase having the Th2Zn17 crystal phase and a Cu-rich phase. A section including a c-axis of the Th2Zn17 crystal phase has a first region in the crystal grain and a second region in the crystal grain, the first region is provided in the cell phase divided by the Cu-rich phase, the second region is provided within a range of not less than 50 nm nor more than 200 nm from the grain boundary phase in a direction perpendicular to an extension direction of the grain boundary phase, and a difference between a Cu concentration of the first region and a Cu concentration of the second region is 0.5 atomic percent or less.