Fe-based Nano-crystal Alloy Magnetic Core High Frequency Permeability
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Solution Overview
Problem
Existing methods for producing Fe-based nano-crystal alloys struggle to achieve high specific magnetic permeability at high frequency bands, such as around 100 kHz, which is essential for compact magnetic components like common mode chokes.
Innovation Solution
Applying a magnetic field in a specific temperature range during the temperature-increasing period of the heat treatment process for an Fe-based amorphous alloy, between 50°C below and 20°C above the crystallization start temperature, as defined by a differential scanning calorimeter, to enhance the alloy's magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If heat treatment is performed with magnetic field applied at highest temperature reached, then squareness ratio is decreased, but specific magnetic permeability at high frequency band is not sufficiently improved
Solution Approach 1:
The heat treatment process is segmented into multiple temperature stages: a first heat treatment at a first temperature to decrease squareness ratio, and a second heat treatment at a second temperature (higher than the first) to increase specific magnetic permeability at high frequency. This segmentation allows optimization of different magnetic properties at different temperature stages, resolving the contradiction between decreasing squareness ratio and improving high-frequency permeability.
Solution Approach 2:
The first heat treatment at lower temperature is performed as a preliminary action to decrease the squareness ratio before conducting the second heat treatment at higher temperature. By preparing the magnetic structure in advance through the first heat treatment, the subsequent second heat treatment can more effectively improve the specific magnetic permeability at high frequency band without being constrained by the initial high squareness ratio.
2Reliability
If magnetic field is applied continuously throughout heat treatment, then magnetic characteristics are improved, but energy consumption and process complexity increase
Solution Approach 1:
The magnetic field application is implemented periodically rather than continuously: the magnetic field is applied during the first heat treatment at lower temperature to decrease squareness ratio, then the field application is interrupted, and subsequently the magnetic field is applied again during the second heat treatment at higher temperature. This periodic application maintains magnetic property improvement while reducing cumulative energy consumption and process complexity compared to continuous field application.
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 effectively increases the specific magnetic permeability at high frequencies, making the Fe-based nano-crystal alloys suitable for high-frequency applications by controlling induced magnetic anisotropy and maintaining stability in magnetic characteristics.
Implementation Method 1
applying a magnetic field in a specific temperature range during the temperature-increasing period of the heat treatment process... to enhance the alloy's magnetic properties... by controlling induced magnetic anisotropy
Implementation Method 2
heating a nano-crystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region and cooling the nano-crystallizable Fe-based amorphous alloy ribbon
Data Source
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AI summary
A method for producing an Fe-based nano-crystal alloy ribbon, includes a heat treatment step of heating a nano-crystallizable Fe-based amorphous alloy ribbon to a crystallization temperature region and cooling the nano-crystallizable Fe-based amorphous alloy ribbon. In the heat treatment step, a magnetic field is applied in a width direction of the alloy ribbon in a temperature range during a temperature-increasing period, the temperature range including at least a part of a temperature range from a temperature lower by 50°C than a crystallization start temperature to a temperature higher by 20°C than the crystallization start temperature and not exceeding a temperature higher by 50°C than the crystallization start temperature, the crystallization start temperature being defined by a differential scanning calorimeter.