Grain-Oriented Electrical Steel Oxide Layers for Coating Adhesion
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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, particularly at high magnetic field strengths.
Innovation Solution
A method involving a pickling treatment with specific acids followed by heating to form iron-based and silicon-containing oxide layers, which enhances the adhesion of a tension-insulation coating comprising phosphate and colloidal silica, ensuring excellent magnetic properties even without inorganic coatings.
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 surface 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 detrimental effects of inorganic coatings at high magnetic field strengths.
Solution Approach 2:
The steel sheet surface is subjected to pickling treatment and heating treatment before applying the tension-insulation coating to pre-form the iron oxide layer. This preliminary preparation ensures that the coating adhesion problem is resolved in advance, preventing subsequent adhesion failures.
2Reliability
If inorganic coatings are formed during final annealing, then adhesion of tension-insulation coating is improved, but high magnetic field iron loss characteristics deteriorate
Solution Approach 1:
The inorganic coating is completely removed from the steel sheet surface through pickling treatment. The necessary adhesion function is then extracted and implemented through a different mechanism - forming an iron oxide layer that provides bonding without the harmful magnetic properties of inorganic coatings.
Solution Approach 2:
The chemical composition and structure of the surface layer are changed by controlling the pickling and heating treatments to form an iron oxide layer with specific properties that differ from traditional inorganic coatings, achieving both adhesion and reduced iron loss.
3Reliability
If pickling treatment and heating treatment are applied to form oxide layers, then adhesion of tension-insulation coating is stabilized, but manufacturing process complexity increases
Solution Approach 1:
The manufacturing process utilizes parameter changes in temperature and chemical environment during pickling and heating treatments to automatically form the desired iron oxide layer. By controlling these parameters, the complex outcome of stable adhesion is achieved through relatively simple process adjustments.
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 the tension-insulation coating and significantly reduces high magnetic field iron loss, improving the overall magnetic characteristics of the grain-oriented electrical steel sheets.
Implementation Method 1
a pickling treatment with specific acids followed by heating to form iron-based and silicon-containing oxide layers
Implementation Method 2
heating to form iron-based and silicon-containing oxide layers
Implementation Method 3
the adhesion of a tension-insulation coating comprising phosphate and colloidal silica
Data Source
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.