Soft Magnetic Alloy Oxide Layer for High-Permeability Coil Components
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Solution Overview
Problem
Magnetic bodies with high magnetic permeability face challenges due to the need for insulating films that reduce filling rates and magnetic properties, especially when using high Fe content soft magnetic metals, which are prone to oxidation, and low electrical insulation leading to increased grain distances and decreased magnetic performance.
Innovation Solution
A magnetic body composed of soft magnetic alloy grains bonded via an oxide layer with specific compositions of Si, Cr, and Al, where Si is the dominant element, and heat-treated in controlled oxygen atmospheres to form a thin, high-insulating oxide layer, maximizing Fe content and oxidation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an insulating film is formed on soft magnetic metal grains to electrically insulate them, then electrical insulation is improved, but the filling rate of soft magnetic metal decreases due to the volume occupied by the insulating film
Solution Approach 1:
The patent changes the chemical composition parameters of the insulating film by incorporating specific elements (B, P, C) that modify the oxide film structure. This allows the film to maintain electrical insulation while reducing its thickness and volume, thereby improving the filling rate of soft magnetic metal grains.
Solution Approach 2:
The patent creates a composite insulating film structure containing multiple elements (SiO2 base with B, P, C additions) that work synergistically. This composite approach provides effective electrical insulation with reduced film thickness compared to conventional single-component insulating films.
2Reliability
If the insulating film is made thick to ensure adequate electrical insulation, then electrical insulation is improved, but the distance among metal grains increases leading to lowered magnetic properties
Solution Approach 1:
The patent modifies the insulating film composition by adding B, P, and C elements to SiO2, which changes the film's electrical properties. This allows achieving adequate insulation with a thinner film, thereby maintaining closer metal grain distances and preserving magnetic properties.
3Manufacturing precision
If high Fe content soft magnetic metal is used to achieve high magnetic permeability, then magnetic properties are improved, but oxidation resistance deteriorates making the material prone to oxidation
Solution Approach 1:
The patent converts the harmful oxidation effect into a beneficial feature by forming a controlled oxide film on the high Fe content soft magnetic metal grains. This oxide film, modified with B, P, and C elements, protects the underlying metal from further oxidation while maintaining magnetic properties.
Solution Approach 2:
The patent creates a protective environment by forming an oxide film that acts as a barrier between the high Fe content soft magnetic metal and the external environment. This film prevents oxygen from reaching and oxidizing the metal grains, effectively creating an inert protective layer.
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 achieves high magnetic permeability and electrical insulation, inhibiting oxidation and maintaining magnetic properties while reducing the oxide layer thickness, resulting in a stable and efficient magnetic body for coil components.
Implementation Method 1
grains of a soft magnetic alloy bonded together via an oxide layer
Implementation Method 2
heat-treated in controlled oxygen atmospheres to form a thin, high-insulating oxide layer
Data Source
AI summary
A magnetic body is constituted by grains of a soft magnetic alloy bonded together via an oxide layer, wherein: the soft magnetic alloy is an alloy containing Si by 1 to 5.5 percent by mass, and Cr or Al by 0.2 to 4 percent by mass in total, as constituent elements, with Fe and unavoidable impurities accounting for the remainder; and the oxide layer contains Si, as well as at least one of Cr and Al, where, among Fe, Si, Cr, and Al, Si is contained in the largest quantity based on mass. The magnetic body can have high magnetic permeability.