Dust Core Fe-Si Oxide Coating Corrosion Resistance
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Solution Overview
Problem
Current dust cores used in motors and coil devices face challenges in corrosion resistance, particularly when containing Cr, as it narrows material selection, and existing coatings like phosphate have low toughness or require high-temperature processing that can damage insulation.
Innovation Solution
A dust core comprising a metal magnetic material with 85-99.5 wt% Fe and 0.5-10 wt% Si, an intermediate Fe-Si-O based oxide layer, and a Si-O based oxide insulation film, which enhances corrosion resistance and joint strength between the metal and insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Cr is contained in the metal magnetic material to improve corrosion resistance, then corrosion resistance is improved, but the range of material selection is narrowed
Solution Approach 1:
The invention changes the compositional parameters by specifying Fe content at 85-99.5 wt% and Si content at 0.5-10 wt%, eliminating the need for Cr while maintaining corrosion resistance through optimized Fe-Si alloy composition
Solution Approach 2:
The invention extracts Cr from the metal magnetic material composition, removing the harmful element that narrows material selection while maintaining or improving corrosion resistance through the Fe-Si-O coating system
2Reliability
If phosphate coating is applied to improve corrosion resistance, then corrosion resistance is improved, but the coating film may be broken when molding pressure is increased due to low toughness
Solution Approach 1:
The invention uses a composite coating system consisting of an intermediate layer (Fe-Si-O based oxide) and an insulation film (Si-O based oxide), where the intermediate layer provides toughness and adhesion while the insulation film provides corrosion resistance
Solution Approach 2:
The intermediate layer acts as a mediator between the metal magnetic material and the insulation film, providing mechanical support and adhesion that prevents coating film breakage under molding pressure
3Reliability
If high temperature heating (800°C or more) is applied to coat magnetic product with ceramics and resin to improve corrosion resistance, then corrosion resistance is improved, but the insulation of insulated copper wire may be broken
Solution Approach 1:
The invention changes the processing temperature parameter from high temperature (800°C or more) to low temperature (below 800°C), enabling corrosion resistance improvement without damaging wire insulation
4Reliability
If insulation film is applied directly on metal magnetic material, then insulation is provided, but joint strength between metal and insulation may be insufficient and corrosion resistance may be compromised
Solution Approach 1:
The intermediate layer serves as an intermediary between the metal magnetic material and the insulation film, enhancing adhesion and joint strength while maintaining corrosion resistance
Solution Approach 2:
The dual-layer coating structure (intermediate layer + insulation film) creates a composite material system that combines the adhesion benefits of the intermediate layer with the insulation and corrosion resistance benefits of the outer film
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 significantly improves corrosion resistance and maintains high initial permeability, preventing insulation damage during molding and ensuring reliable performance in various environments.
Implementation Method 1
the intermediate layer comprises a Fe—Si—O based oxide
Implementation Method 2
the insulation film comprises a Si—O based oxide
Data Source
AI summary
A dust core includes a metal magnetic material, a resin, an insulation film, and an intermediate layer. The insulation film covers the metal magnetic material. The intermediate layer exists between the insulation film and the metal magnetic material and contacts therebetween. The metal magnetic material includes 85 to 99.5 wt % of Fe, 0.5 to 10 wt % of Si, and 0 to 5 wt % of other elements, with respect to 100 wt % of the entire metal magnetic material. The intermediate layer includes a Fe—Si—O based oxide. The insulation film includes a Si—O based oxide.