Soft Magnetic Powder Composition for Permeability and Fillability
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Solution Overview
Problem
Existing soft magnetic powders face challenges in achieving high magnetic permeability and fillability during compacting due to compromised particle shape and oxidation resistance, leading to reduced magnetic properties and increased iron loss.
Innovation Solution
A soft magnetic powder composition with iron (Fe) as the main component, silicon (Si) at 2.5-7.5 mass %, chromium (Cr) at 1.0-10.0 mass %, and controlled particle and crystal grain diameters, along with optimized oxygen and impurity content, to enhance magnetic permeability and oxidation resistance, while maintaining deformability and fillability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If water atomization method is used to rapidly cool molten metal, then fine crystal grain diameter is achieved, but particle shape is compromised and fillability is deteriorated
Solution Approach 1:
The patent applies parameter changes by controlling the cooling rate during atomization to produce a specific crystal grain diameter range (5-20 μm) that optimizes both magnetic properties and particle shape. By adjusting the cooling parameters, the invention achieves fine crystal grains while maintaining good spherical shape and fillability, resolving the contradiction between fine grain structure and particle morphology.
2Force
If water atomization method is used to rapidly cool molten metal, then fine crystal grain diameter is achieved, but fillability is deteriorated
Solution Approach 1:
The invention uses parameter changes by optimizing the crystal grain diameter to 5-20 μm through controlled cooling rates. This specific parameter range ensures fine magnetic properties while maintaining good flowability and fillability during compacting, resolving the contradiction between fine grain structure and filling capability.
3Reliability
If Si content is increased to improve electrical insulating properties, then saturation magnetization is maintained, but particle deformability is reduced
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Si content within 2.5-7.5 mass%. This optimized concentration range provides sufficient electrical insulating properties to maintain saturation magnetization while preventing excessive hardness that would reduce particle deformability during compacting, thus resolving the contradiction between insulation and deformability.
Solution Approach 2:
The invention uses composite material principles by combining Si with Cr (1.0-10.0 mass%) and Fe to create a multi-element alloy system. This composite approach balances the electrical insulating properties from Si with the deformability and magnetic properties from Cr and Fe, resolving the contradiction between insulation and particle workability.
4Reliability
If Cr content is increased to improve oxidation resistance, then magnetic properties are enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies parameter changes by optimizing Cr content to 1.0-10.0 mass%, with a preferred range of 3.0-6.0 mass%. This controlled parameter range provides adequate oxidation resistance to protect the soft magnetic powder while avoiding excessive alloying complexity. The specific concentration range balances performance enhancement with manufacturability, resolving the contradiction between oxidation protection and manufacturing simplicity.
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 optimized composition results in high magnetic permeability, low iron loss, and improved fillability of the green compact, enabling high-performance and compact-sized electronic devices.
Implementation Method 1
the particle surface is covered with an oxide film
Implementation Method 2
a Vickers hardness of a cross section of a particle is 150 or more and 350 or less
Data Source
AI summary
A soft magnetic powder contains: Fe as a main component; Si a content of which is 2.5 mass % or more and 7.5 mass % or less; Cr a content of which is 1.0 mass % or more and 10.0 mass % or less; and impurities. A Vickers hardness of a cross section of a particle is 150 or more and 350 or less, and A/B is 2.0 or more and 8.0 or less, where A is a particle diameter [μm] as an equivalent circle diameter of the particle, and B is a crystal grain diameter [μm] as an equivalent circle diameter of a crystal included in the particle.