Grain-Oriented Steel Coating with Iron Phosphate Interlayer
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Solution Overview
Problem
Existing grain-oriented electrical steel sheets face challenges in achieving high magnetic field iron loss reduction, coating adhesion, and corrosion resistance due to the presence of forsterite films, which hinder domain wall movement, and require costly and complex facilities for alternative coating methods.
Innovation Solution
A grain-oriented electrical steel sheet with an amorphous iron phosphate intermediate layer between the base steel sheet and a tension coating, combined with a metal phosphate and silica tension coating, to enhance adhesion and magnetic characteristics while ensuring corrosion resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a forsterite film is formed on the steel sheet surface through final annealing, then coating adhesion is improved, but iron loss increases due to hindered domain wall movement
Solution Approach 1:
The invention removes the forsterite film from the steel sheet surface before forming the insulating coating, thereby eliminating the harmful effect of domain wall hindrance while maintaining coating adhesion through direct coating on the cleaned steel sheet surface
Solution Approach 2:
The invention introduces a phosphate-based intermediate layer between the steel sheet and the insulating coating, which serves as an adhesion promoter to ensure coating adhesion without requiring a forsterite film, thus resolving the contradiction between adhesion and iron loss
2Loss of energy
If the forsterite film is removed to reduce iron loss, then magnetic characteristics improve, but coating adhesion deteriorates
Solution Approach 1:
The invention introduces a phosphate-based intermediate layer between the steel sheet and the insulating coating, which serves as an adhesion promoter to ensure coating adhesion without requiring a forsterite film, thus resolving the contradiction between adhesion and iron loss
Solution Approach 2:
The invention changes the chemical composition and structure of the intermediate layer from forsterite (Mg2SiO4) to phosphate-based materials, which provide both adhesion functionality and compatibility with the steel sheet surface, enabling good coating adhesion without forsterite film
3Loss of energy
If conventional methods are used to form insulating coating without forsterite film, then iron loss is reduced, but complex facilities and costly processes are required
Solution Approach 1:
The invention uses a self-service approach where the steel sheet surface is pickled and directly coated with phosphate-based intermediate layer and insulating coating in sequence, eliminating the need for complex forsterite film removal facilities while achieving low iron loss through the phosphate-based coating system
Solution Approach 2:
The invention changes the process parameters by using aqueous phosphate solutions at controlled pH and temperature for intermediate layer formation, replacing complex mechanical or chemical removal processes with simpler wet chemical treatments that are easier to implement
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 proposed solution provides a steel sheet with improved coating adhesion, tension, and magnetic properties, along with sufficient corrosion and elution resistance, without the need for complex facilities, thus addressing the limitations of existing methods.
Implementation Method 1
an intermediate layer formed on the base steel sheet side and containing an amorphous iron phosphate
Implementation Method 2
A forsterite film (inorganic coating) having excellent coating adhesion, generated by a reaction between an oxide on a sheet surface and an annealing separator in a final annealing step of an electrical steel sheet is a coating capable of applying tension to the steel sheet
Implementation Method 3
generated by a reaction between an oxide on a sheet surface and an annealing separator in a final annealing step
Data Source
AI summary
This grain-oriented electrical steel sheet has: a base steel sheet; and an insulating coating formed on a surface of the base steel sheet, in which the insulating coating has: an intermediate layer formed on the base steel sheet side and containing an amorphous iron phosphate; and a tension coating layer formed on a surface side of the insulating coating, the intermediate layer has an average thickness of 0.10 to 3.0 μm, the tension coating layer contains a metal phosphate and silica, and the amount of the silica in the tension coating layer is 20 to 60 mass %.