Soft Magnetic Powder Composition for Dense Dust Cores Withstand Voltage
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Solution Overview
Problem
Existing soft magnetic powders face challenges in achieving high density and high withstand voltage while maintaining magnetic properties, as insulating materials like silicone resin do not provide sufficient insulation and can decrease magnetic properties when added in large amounts.
Innovation Solution
A soft magnetic powder composition comprising Fe, Si, Cr, and Sn, with specific mass ratios and particle sizes, and a heat treatment to form Sn-substituted hematite, enhancing insulation and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large amount of insulating material such as silicone resin is added to increase withstand voltage, then the withstand voltage increases, but the density of the dust core decreases and magnetic properties may decrease
Solution Approach 1:
The invention changes the chemical composition parameters of the soft magnetic powder by adding specific elements (Al: 0.01-5 mass%, Ti: 0.01-5 mass%, B: 0.01-5 mass%) to form insulating compounds (Al2O3, TiO2, B2O3) during heat treatment. This approach achieves insulation functionality through compositional modification rather than adding external insulating materials, thereby maintaining high density while improving withstand voltage
Solution Approach 2:
The soft magnetic powder particles themselves generate the insulating layer through heat treatment in air atmosphere, where the added elements (Al, Ti, B) oxidize to form insulating compounds on the particle surfaces. This self-forming insulating layer eliminates the need for separate insulating material addition, simultaneously achieving both high density and high withstand voltage
2Reliability
If insulating material such as silicone resin is added to ensure insulating properties between particles, then insulating properties improve, but the amount of soft magnetic powder decreases and magnetic properties may decrease
Solution Approach 1:
The invention modifies the compositional parameters of the soft magnetic powder by incorporating elements (Al, Ti, B) that transform into insulating compounds during heat treatment. This compositional change enables the particles to possess inherent insulating properties, eliminating the need to add separate insulating materials and maintaining high soft magnetic powder proportion
Solution Approach 2:
The invention creates a composite structure where the soft magnetic powder particles contain embedded insulating compounds (Al2O3, TiO2, B2O3) formed during heat treatment. This composite material approach provides both magnetic and insulating properties within the same particle system, improving insulating properties without reducing the soft magnetic powder content
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 solution results in a soft magnetic powder that can produce high-density green compacts with improved fillability, permeability, and withstand voltage, reducing eddy current loss and maintaining magnetic properties.
Implementation Method 1
Sn-substituted hematite in which a part of Fe atoms forming hematite is substituted by Sn atoms is precipitated by a heat treatment in an air atmosphere
Implementation Method 2
Sn-substituted hematite in which a part of Fe atoms forming hematite is substituted by Sn atoms is precipitated by a heat treatment in an air atmosphere
Implementation Method 3
Sn-substituted hematite in which a part of Fe atoms forming hematite is substituted by Sn atoms is precipitated by a heat treatment in an air atmosphere
Implementation Method 4
a binding portion which is made of an Fe oxide and binds particles of the soft magnetic powder
Data Source
AI summary
A soft magnetic powder contains: Fe as a main component; Si having a content of 2.5 mass % or more and 7.5 mass % or less; Cr having a content of 1.0 mass % or more and 10.0 mass % or less; Sn having a content of 0.05 mass % or more and 1.10 mass % or less; and an impurity, in which a mass ratio Sn/Cr of a content amount of Sn to a content amount of Cr is 0.02 or more and 0.30 or less, an average particle diameter is 1.5 μm or more and 11.0 μm or less, and Sn-substituted hematite in which a part of Fe atoms forming hematite is substituted by Sn atoms is precipitated by a heat treatment in an air atmosphere.