SmFeN Rare Earth Magnet Sintering Window for Density and Magnetization
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Solution Overview
Problem
Conventional methods for producing SmFeN-based rare earth magnets face challenges in improving magnetic properties due to strain accumulation in the magnetic phase and excessive reactions between SmFeN-based magnetic powder and zinc components during pressure sintering.
Innovation Solution
A method involving the preparation of a magnetic powder containing Sm, Fe, and N, and a modifier powder containing metallic zinc or a zinc alloy, followed by compression molding in a magnetic field and pressure sintering at specific conditions of pressure (500 MPa to 900 MPa) and temperature (360°C to 390°C) for 1 hour to 24 hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If high pressure (200 MPa or more) is applied during pressure sintering to increase density, then density of the sintered body is improved, but strain accumulates in the magnetic phase causing residual magnetization to decrease
Solution Approach 1:
The patent applies parameter changes by optimizing the pressure range to 500-900 MPa and temperature range to 360-390°C, which resolves the contradiction between increasing density and maintaining residual magnetization. This specific parameter window allows sufficient densification while preventing excessive strain accumulation in the magnetic phase.
2Volume of stationary object
If high temperature (300°C or more) is applied during pressure sintering to increase density, then density of the sintered body is improved, but excessive reaction between SmFeN-based magnetic powder and zinc component reduces magnetic phase proportion
Solution Approach 1:
The patent applies parameter changes by optimizing the temperature range to 360-390°C, which resolves the contradiction between increasing density and maintaining magnetic phase proportion. This specific temperature window provides sufficient thermal energy for densification while preventing excessive reaction between the magnetic powder and zinc component.
3Volume of stationary object
If long sintering time is used to increase density, then density of the sintered body is improved, but magnetic properties deteriorate due to prolonged exposure to sintering conditions
Solution Approach 1:
The patent applies parameter changes by optimizing the sintering time range to 1-24 hours, which resolves the contradiction between increasing density and maintaining magnetic properties. This time window allows sufficient densification while preventing degradation of magnetic 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 method enhances the density of the sintered body and suppresses strain in the magnetic phase, leading to improved magnetic properties such as increased residual magnetization.
Implementation Method 1
performing pressure sintering on the magnetic field molded body to obtain a sintered body
Implementation Method 2
the magnetic field molded body is pressed and sintered at a pressure of 500 MPa or more and 900 MPa or less and at a temperature of 360° C. or more and 390° C. or less for 1 hour or more and 24 hours or less
Data Source
AI summary
A method for producing a rare earth magnet that can improve magnetic properties by both increasing a density of a sintered body and suppressing strain of a magnetic phase. The method includes preparing a magnetic powder containing Sm, Fe, and N, preparing a modifier powder containing at least one of metallic zinc or a zinc alloy, mixing the magnetic powder and the modifier powder to obtain a mixed powder, performing compression molding on the mixed powder in a magnetic field to obtain a magnetic field molded body, and performing pressure sintering on the magnetic field molded body to obtain a sintered body. In the pressure sintering, the magnetic field molded body is pressed and sintered at a pressure of 500 MPa or more and 900 MPa or less and at a temperature of 360° C. or more and 390° C. or less for 1 hour or more and 24 hours or less.