Grain-Oriented Electrical Steel Oxide Layers for Coating Adhesion
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Solution Overview
Problem
Existing grain-oriented electrical steel sheets without inorganic coatings face challenges in achieving stable adhesion of tension-insulation coatings and optimal magnetic characteristics.
Innovation Solution
A method involving pickling treatments using specific acids and heating processes to form iron-based and silicon-containing oxide layers between the tension-insulation coating and the base steel sheet, enhancing adhesion and magnetic properties.
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 deteriorates
Solution Approach 1:
An iron oxide layer is introduced as an intermediary between the steel sheet surface and the tension-insulation coating. This intermediate layer serves as a bonding bridge that provides both magnetic smoothness for improved high magnetic field iron loss characteristics and adequate adhesion for the tension-insulation coating, resolving the contradiction between magnetic performance and coating adhesion.
Solution Approach 2:
The surface treatment parameters are changed by controlling the oxidation process to form an iron oxide layer with specific properties. By adjusting oxidation conditions (temperature, time, atmosphere), the iron oxide layer achieves optimal characteristics that simultaneously improve magnetic smoothness and provide sufficient adhesion for the tension-insulation coating.
2Loss of energy
If inorganic coatings are prevented from forming during final annealing, then high magnetic field iron loss characteristics are improved, but surface adhesion for coating application deteriorates
Solution Approach 1:
The iron oxide layer acts as a mediator that replaces the traditional inorganic coating's adhesion function. By forming this intermediate layer through controlled oxidation after final annealing, the steel sheet surface achieves both magnetic smoothness (without harmful inorganic coatings) and adequate adhesion properties for subsequent tension-insulation coating application.
Solution Approach 2:
The iron oxide layer is formed as a preliminary treatment before applying the tension-insulation coating. This preliminary oxidation step prepares the surface by creating an intermediate layer that will serve as the bonding interface, ensuring both magnetic performance and coating adhesion before the final coating process.
3Loss of energy
If mechanical polishing is used to create mirror surfaces, then magnetic smoothness is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The mechanical polishing process is replaced with a chemical/thermal oxidation process that forms the iron oxide layer. This substitution eliminates complex mechanical equipment and multi-step polishing operations, replacing them with a simpler oxidation treatment that achieves the same magnetic smoothness effect through chemical means rather than mechanical removal of material.
Solution Approach 2:
Instead of changing physical parameters like surface roughness through mechanical means, the invention changes the chemical composition and structure of the surface layer by forming an iron oxide layer. This parameter change from mechanical to chemical/thermal treatment simplifies the manufacturing process while achieving the desired magnetic smoothness.
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
This approach stabilizes the adhesion of tension-insulation coatings and improves magnetic characteristics, particularly reducing high magnetic field iron loss, even in the absence of inorganic coatings.
Implementation Method 1
subjecting a surface of a steel sheet to ordinary final annealing, pickling to remove surface formations
Implementation Method 2
forming an iron-based oxide layer and a silicon-containing oxide layer in a specific state between the tension-insulation coating and a base steel sheet
Implementation Method 3
performing a heating treatment and then further subjecting the grain-oriented electrical steel sheet to a pickling treatment
Implementation Method 4
Inorganic coatings containing forsterite (Mg 2 SiO 4 ) as a main component are generated on surfaces of grain-oriented electrical steel sheets by causing oxide layers containing silica (SiO 2 ) generated using a decarburization annealing process as a main component and magnesium oxides applied to a surface to prevent firing to react during final annealing
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A 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 and which includes: a base steel sheet containing a prescribed 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 the tension-insulation coating undergoes elemental analysis using a glow discharge optical emission spectrometry in a sheet thickness direction from a surface of the tension-insulation coating, a peak Si emission intensity satisfies a prescribed requirement.