Magnetic Base Body Oxide Control for Insulation and Permeability
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Solution Overview
Problem
Magnetic base bodies formed with metal magnetic grains face challenges in achieving excellent electrical insulating properties due to oxidation reactions and reduced magnetic permeability when using insulating layers, particularly when heat-treated in high oxygen concentration atmospheres.
Innovation Solution
A magnetic base body composed of metal magnetic grains with high Fe and Si content, featuring oxide layers with specific molar ratios of Fe2SiO4 and Fe2O3, formed through degreasing in a low oxygen atmosphere and subsequent heat treatment in an inert atmosphere, to enhance electrical insulation and magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating layers are formed on metal magnetic grains by heat treatment in high oxygen concentration atmosphere, then electrical insulating property is improved, but magnetic properties deteriorate due to increased oxide content between grains
Solution Approach 1:
The patent applies inert atmosphere heat treatment (using nitrogen or other inert gases) instead of air or high oxygen concentration atmosphere. This prevents excessive oxidation of metal magnetic grains while still forming sufficient insulating oxide layers between grains. The inert environment maintains magnetic properties by limiting oxide formation to only what is necessary for electrical insulation, resolving the contradiction between improving insulating property and maintaining magnetic properties.
2Power
If metal magnetic grains are used to achieve high current flow, then performance is enhanced, but electrical insulating property deteriorates compared to ferrite materials
Solution Approach 1:
The patent creates a composite structure where metal magnetic grains (Fe-Si-Cr alloy) are combined with controlled insulating oxide layers (FeSiO3, Fe2SiO4) formed on grain surfaces and at grain boundaries. This composite approach allows the bulk metal grains to provide high magnetic permeability and current flow capability while the surface oxide layers provide the necessary electrical insulation, thus resolving the contradiction between power capability and insulating property.
Solution Approach 2:
The patent applies local quality by creating different oxidation states at different locations: the interior of metal grains remains highly reduced to maintain magnetic properties, while the surfaces and grain boundaries develop controlled oxide layers for insulation. This spatial differentiation of oxidation states allows simultaneous achievement of high electrical insulation and maintained magnetic performance.
3Reliability
If oxide content between metal magnetic grains increases, then electrical insulation is improved, but specific magnetic permeability drops
Solution Approach 1:
The patent changes the parameters of heat treatment (temperature, time, oxygen partial pressure, inert gas composition) to precisely control the amount and type of oxide formed between grains. By optimizing these parameters, the patent achieves the minimum necessary oxide content for electrical insulation while minimizing the impact on magnetic permeability. The key is maintaining oxide content at threshold levels rather than allowing excessive oxidation.
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 provides a magnetic base body with improved electrical insulating properties and mechanical strength, maintaining high magnetic permeability while reducing energy loss in coil components.
Implementation Method 1
the components constituting the metal magnetic grains actively undergo oxidation reaction and the amount of oxide between the metal magnetic grains tends to increase
Implementation Method 2
Metal magnetic materials are inferior to ferrite materials in electrical insulating property, so when they are used, in order to obtain a magnetic base body offering sufficient electrical insulating property, oftentimes insulating layers are formed on the surface of grains formed by the metal magnetic materials to electrically insulate the grains from each other
Implementation Method 3
the ratio (IFe2SiO4/IFe) of the strongest diffraction line intensity (IFe2SiO4) observed in a range of 30.8°≤2θ≤32.2° to the strongest diffraction line intensity (IFe) observed in a range of 43.8°≤2θ≤45.2° in X-ray diffraction measurement using the CuKα ray
Data Source
AI summary
A magnetic base body is constituted by: metal magnetic grains containing Fe, and Si as an optional component, where the total content of the Fe and Si is 99% by mass or higher; and oxide layers present between the metal magnetic grains; wherein the ratio (IFe2SiO4/IFe) of the strongest diffraction line intensity (IFe2SiO4) observed in a range of 30.8°≤2θ≤32.2° to the strongest diffraction line intensity (IFe) observed in a range of 43.8°≤2θ≤45.2° in X-ray diffraction measurement using the CuKα ray is 0.0020 or higher; and the ratio (IFe2O3/IFe) of the strongest diffraction line intensity (IFe2O3) observed in a range of 33.0°≤2θ≤34.4° to the IFe in X-ray diffraction measurement using the CuKα ray is lower than 0.0010.