Silicon Oxide Intermediate Coating for Low-Loss Electrical Steel
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Solution Overview
Problem
Grain-oriented electrical steel sheets face challenges in achieving low iron loss and sufficient adhesion of insulation coatings, particularly due to interfacial unevenness caused by final-annealed films, which hinder magnetic properties and iron loss reduction.
Innovation Solution
A grain-oriented electrical steel sheet with a base steel sheet lacking a final-annealed film, featuring an intermediate layer of silicon oxide with a uniform thickness, ensuring strong adhesion of the insulation coating without the anchoring effects of uneven interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a final-annealed film is formed on the base steel sheet to ensure coating adhesion, then the adhesion of insulation coating is improved, but the iron loss increases due to interfacial unevenness
Solution Approach 1:
The invention removes the final-annealed film from the steel sheet surface, extracting the source of interfacial unevenness that causes increased iron loss. Instead of forming a forsterite-based final-annealed film through conventional heat treatment, the patent uses a silicate-based coating applied at lower temperatures to provide adhesion without creating harmful interface irregularities.
Solution Approach 2:
The invention changes the chemical composition parameters of the coating from forsterite-based (Mg2SiO4) to silicate-based (containing SiO2 and other metal oxides), and changes the formation temperature from 600-1200°C to 200-600°C. This parameter change allows the coating to provide adhesion without creating the interfacial unevenness that increases iron loss.
2Loss of energy
If the base steel sheet surface is smoothed to reduce iron loss, then the magnetic properties are improved, but the adhesion of insulation coating deteriorates
Solution Approach 1:
The silicate-based coating acts as an intermediary layer between the smoothed base steel sheet and the insulation coating. This intermediate coating provides the necessary adhesion function without requiring the interfacial unevenness that would otherwise be created by a final-annealed film, thus maintaining both low iron loss and good adhesion.
Solution Approach 2:
The invention uses a relatively thin silicate-based coating (1-10 μm) that serves the adhesion function effectively without creating persistent interface irregularities. This thinner, chemically different coating replaces the thicker final-annealed film and achieves adhesion through chemical bonding rather than mechanical anchoring.
3Loss of energy
If a silicate-based coating is applied at low temperature to avoid final-annealed film formation, then the adhesion is improved and iron loss is reduced, but the coating process complexity increases
Solution Approach 1:
The invention combines the adhesion coating formation with the insulation coating application in a single process step. The silicate-based coating is applied and dried at low temperature (200-600°C) as part of the insulation coating process, merging what would otherwise be separate operations and reducing overall process complexity despite the specialized coating composition.
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 results in improved adhesion of insulation coatings and reduced iron losses, enhancing magnetic properties and manufacturing efficiency by eliminating the need for final-annealed films and minimizing interfacial stress concentrations.
Implementation Method 1
an intermediate layer that is disposed on a surface of the base steel sheet and mainly contains silicon oxide
Implementation Method 2
a coating is formed on a surface of a base steel sheet to apply tension to the base steel sheet to reduce the iron loss
Implementation Method 3
baking and drying the coating solution within a temperature range of 300°C to 950°C for 10 seconds or longer
Data Source
Figure 1~2
AI summary
This grain-oriented electrical steel sheet has a base steel sheet in which a final-annealed film is substantially not present on a surface, an intermediate layer that is disposed on a surface of the base steel sheet and mainly contains silicon oxide, and an insulation coating disposed on a surface of the intermediate layer. In the intermediate layer, a value obtained by dividing a standard deviation σ of a thickness of the intermediate layer by an average value T of the thickness of the intermediate layer is 0.500 or less.