Fe-Si-Al Flaky Magnetic Powder Coercive Force Control
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Solution Overview
Problem
Traditional flaky soft magnetic powders face limitations in achieving high magnetic permeability due to variations in coercive force and oxygen content, which affect their magnetic properties and sheet performance.
Innovation Solution
A flaky soft magnetic powder with specific composition and production methods, including an Fe—Si—Al alloy with controlled oxygen and manganese content, and a heat-treatment process to minimize coercive force and maximize magnetic permeability, is developed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If sendust powder is excessively flattened to maximize aspect ratio, then the aspect ratio increases, but the average particle size (D50) decreases
Solution Approach 1:
The patent applies parameter changes by controlling the flattening degree within a specific range (aspect ratio 2.5 or more but not excessive) and adjusting heat treatment temperature (700-900°C) and time (1-5 hours) to achieve the optimal balance between aspect ratio and particle size retention, rather than maximizing aspect ratio without limits
2Length of moving object
If flattening time is extended to increase average particle size, then D50 increases, but the bulk density decreases
Solution Approach 1:
The patent uses parameter changes by optimizing the combination of flattening time, heat treatment temperature (700-900°C), and heat treatment time (1-5 hours) to achieve the desired particle size while minimizing bulk density loss, rather than simply extending flattening time
3Reliability
If flattening is performed to reduce coercive force, then magnetic permeability improves, but oxygen content increases due to oxidation
Solution Approach 1:
The patent applies inert atmosphere by conducting heat treatment in a nitrogen or argon atmosphere, which prevents oxidation of the powder surface during the necessary flattening and heat treatment processes, thereby maintaining low oxygen content while achieving low coercive force through controlled flattening
Solution Approach 2:
The patent uses parameter changes by optimizing heat treatment temperature (700-900°C) and time (1-5 hours) to reduce coercive force and improve magnetic permeability while controlling oxygen intake through the inert atmosphere, rather than performing flattening without atmospheric control
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 resulting powder achieves high magnetic permeability and improved sheet performance, with a coercive force of 106 A/m or less and a tap density ratio of 0.17 or less, enhancing the magnetic properties of the powder and the magnetic sheets produced.
Implementation Method 1
heat-treating the flattened powder at 700 to 900° C. under vacuum or in an argon atmosphere
Implementation Method 2
a flaky soft magnetic powder comprising an Fe—Si—Al alloy having an oxygen content of 0.6 mass % or less
Data Source
AI summary
Provided is a flaky soft magnetic powder including an Fe—Si—Al alloy having an oxygen content of 0.6 mass % or less, a manganese content of 0.1 mass % to 1.0 mass %, and the balance incidental impurities. The flaky soft magnetic powder has an average particle size of 43 to 60 μm and exhibits a coercive force Hc of 106 A/m or less as measured under application of a magnetic field in an in-plane direction of the flaky soft magnetic powder. The ratio of the tap density to the true density of the flaky soft magnetic powder is 0.17 or less. Also provided is a method of producing the flaky soft magnetic powder. The use of the flaky soft magnetic powder can produce a magnetic sheet having particularly high magnetic permeability.