Oriented Electrical Steel Sheet Coating Adhesion via Alkali Metal Interface
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Solution Overview
Problem
Grain oriented electrical steel sheets face issues with high tension requirements and coating adhesion, particularly at the interface between crystalline and glassy coatings, leading to peeling and potential electrical conduction issues during lamination.
Innovation Solution
A grain oriented electrical steel sheet with a crystalline coating A and a glassy coating B, where an alkali metal element is concentrated at the interface between the two, improving adhesion by increasing wettability and maintaining high tension through specific element profile ratios, as determined by radio frequency glow discharge optical emission spectroscopy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a coating containing glassy substance is formed to exert high tension to the steel sheet, then the tension is improved, but the coating adhesion deteriorates due to low adhesiveness of glass to metal
Solution Approach 1:
The patent introduces a forsterite coating layer as an intermediary between the steel sheet and the glassy substance coating. The forsterite coating has good adhesion to both the steel sheet and the glassy substance, acting as a mediator that transfers the tension force from the glassy coating to the steel sheet while maintaining strong bonding at the interfaces. This resolves the adhesion problem of glassy substances while preserving the high tension effect.
Solution Approach 2:
The patent creates a composite coating structure consisting of a forsterite coating layer and a glassy substance coating layer. The forsterite layer provides strong metal-ceramic bonding and thermal expansion matching, while the glassy substance layer provides insulation and additional tension. The composite structure combines the advantages of both materials to achieve both high tension and good adhesion.
2Force
If the coefficient of thermal expansion of the coating is reduced to exert tension to the steel sheet, then the tension is improved, but the coating adhesion deteriorates due to excessive thermal stress
Solution Approach 1:
The patent carefully controls the chemical composition parameters of the glassy substance coating, specifically limiting Al2O3 to 2-10 mass% and Fe2O3 to 0.1-5 mass%, while setting SiO2 at 65-80 mass%. These parameter adjustments optimize the thermal expansion coefficient to be sufficiently lower than the steel sheet to generate tension, while preventing excessive thermal stress that would cause adhesion failure. The forsterite coating's composition is also optimized (MgO 80-95 mass%, Fe2O3 0.1-5 mass%) to provide a gradual transition in thermal expansion properties.
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 ensures excellent coating adhesion and high tension exerted to the steel sheet, preventing peeling and electrical conduction issues, while maintaining sufficient tension to reduce iron loss and noise in transformers.
Implementation Method 1
These coatings are formed at high temperature and have a lower coefficient of thermal expansion than that of the steel sheet, and a tension is therefore exerted to the steel sheet owing to a difference in a coefficient of thermal expansion between the steel sheet and each coating when the temperature drops to room temperature
Implementation Method 2
element profiles acquired in a direction from the coating B toward the steel sheet using radio frequency glow discharge optical emission spectroscopy
Data Source
AI summary
Provided are: an oriented electrical steel sheet having a high tension applied to a steel sheet and excellent adhesion to a film; and a method for producing the same. This oriented electrical steel sheet includes: a steel sheet; a film A containing a crystalline material disposed on the steel sheet; and a film B containing a vitreous material disposed on the film A, wherein an element profile, which is obtained by using a high-frequency glow discharge light-emission surface analysis method, in the direction from the film B to the steel sheet satisfies formulae (1) and (2). 0.35≤(tA/tFe/2)≤0.75 . . . (1), 0.25≤(tA/2/tFe/2)≤1.00 . . . (2), where tA represents the peak time of an alkali metal element profile, tA/2 represents the half time of an alkali metal.