Electrical Steel Sheet Oxide Layers for Coating Adhesion and Iron Loss
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Solution Overview
Problem
Grain-oriented electrical steel sheets without inorganic coatings face challenges in achieving stable adhesion of tension-insulation coatings and optimal magnetic characteristics, as existing methods do not adequately address the adhesion and iron loss issues.
Innovation Solution
A grain-oriented electrical steel sheet is developed without an inorganic coating containing forsterite, featuring a silicon-containing oxide layer and an iron-based oxide layer formed through specific acid pickling and heat treatment, followed by a tension-insulation coating application, which improves adhesion and magnetic characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If inorganic coatings are removed to improve high magnetic field iron loss characteristics, then magnetic characteristics are improved, but adhesion of tension-insulation coating becomes unstable
Solution Approach 1:
An iron oxide layer is introduced as an intermediary between the steel sheet and the tension-insulation coating. This intermediate layer serves as a bonding bridge that ensures stable adhesion of the coating while allowing the steel sheet to operate without the magnetic interference that would occur with traditional inorganic coatings present.
Solution Approach 2:
The steel sheet surface is subjected to pickling treatment and heat treatment in advance to form the iron oxide layer before applying the tension-insulation coating. This preliminary preparation ensures that the surface has the necessary properties for stable coating adhesion, preventing adhesion problems that would arise if coatings were applied directly to untreated surfaces.
2Loss of energy
If inorganic coatings are eliminated to reduce magnetic interference, then high magnetic field iron loss is reduced, but coating adhesion and surface stability deteriorate
Solution Approach 1:
The surface composition is modified by changing the oxidation state and chemical composition through controlled heat treatment after pickling. This transforms the surface into an iron oxide layer with specific properties that provide both magnetic compatibility (no interference with high magnetic field performance) and chemical stability for reliable coating adhesion.
3Reliability
If conventional pickling and heat treatment are applied to form oxide layers, then coating adhesion is improved, but high magnetic field iron loss characteristics deteriorate
Solution Approach 1:
The treatment is applied selectively to create a localized iron oxide layer only on the surface where the coating will be applied, rather than uniformly throughout the material. This localized modification provides the necessary adhesion properties at the surface while maintaining the bulk magnetic properties of the steel sheet that enable excellent high magnetic field iron loss characteristics.
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 stabilizes the adhesion of the tension-insulation coating and achieves excellent magnetic characteristics, reducing high magnetic field iron loss, as demonstrated by the formation of specific oxide layers and optimized coating thickness.
Implementation Method 1
pickling to remove surface formations
Implementation Method 2
heating treatment to form an iron-based oxide layer and a silicon-containing oxide layer
Implementation Method 3
heating is performed at an average heating rate of 20 to 100° C./s within 1.0 to 20 seconds after the application, and baking is performed at a temperature of 850 to 950° C. for 10 to 60 seconds
Data Source
AI summary
The grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet which does not have an inorganic coating containing forsterite as a main component, including a base steel sheet having a predetermined chemical component, a silicon-containing oxide layer provided on the base steel sheet, an iron-based oxide layer provided on the silicon-containing oxide layer, and a tension-insulation coating provided on the iron-based oxide layer, having a thickness of 1 to 3 μm, and containing phosphate and colloidal silica as main components. When elemental analysis is performed from a surface of the tension-insulation coating in a sheet thickness direction by glow discharge optical emission spectrometry, predetermined requirements are satisfied.