Electrical Steel Insulating Coating with Gradient Adhesion Control
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Solution Overview
Problem
The existing insulating coatings on electrical steel sheets face issues with peeling due to excessive shear stress at the interface between the insulating tensile coating layer and the forsterite coating layer, particularly during the manufacturing of wound cores, leading to poor adhesion and coating detachment.
Innovation Solution
A method is developed to form a concentration gradient in the distribution of crystallized phases within the insulating tensile coating layer, reducing shear stress at the interface and enhancing the tension applied to the steel sheet without increasing the number of coating formation steps, using a treatment solution containing colloidal silica and specific salts, and heating at a controlled rate to achieve excellent adhesion and high tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the thermal expansion coefficient difference between the insulating coating and steel sheet is increased to apply higher tension, then magnetic characteristics are improved, but shear stress at the coating interface increases causing peeling
Solution Approach 1:
The patent applies local quality by creating a gradient in the forsterite crystal distribution within the insulating coating layer. The forsterite content is higher near the steel sheet interface and decreases toward the coating surface, allowing different regions of the coating to have different mechanical properties. This gradient structure reduces shear stress concentration at the interface while maintaining sufficient tension application, thereby preventing peeling during wound core manufacturing.
2Force
If a forsterite coating layer is formed to improve adhesion and apply tension, then magnetic characteristics are enhanced, but the coating may peel during wound core manufacturing
Solution Approach 1:
The patent changes the compositional parameter of the insulating coating by controlling the forsterite crystal distribution gradient. By adjusting the forsterite content from high near the steel sheet to low at the surface, the coating's thermal expansion characteristics and mechanical strength are optimized. This parameter gradient allows the coating to maintain integrity during wound core manufacturing while still applying the necessary tension to improve magnetic characteristics.
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 an insulating coating-attached electrical steel sheet with excellent adhesion and high tension, preventing peeling during the formation of wound cores and improving magnetic characteristics by maintaining a low thermal expansion coefficient.
Implementation Method 1
the insulating coating effectively applies a tension to the steel sheet due to a difference in thermal expansion coefficient between the steel sheet and the insulating coating when the temperature is lowered to room temperature
Implementation Method 2
forming, in the coating thickness direction, a concentration gradient in the distribution of crystalized phases within the insulating tensile coating layer A
Data Source
AI summary
An insulating coating-attached electrical steel sheet has, on at least one surface, an insulating coating including an insulating tensile coating layer A. A tension applied to the steel sheet by an insulating tensile coating layer having a coating weight of M/2 from a surface of the insulating tensile coating layer A is 0.80×σA or more, where M is a weight of the insulating tensile coating layer A, and σA is the tension applied to the steel sheet by the insulating tensile coating layer A. The insulating coating-attached electrical steel sheet has excellent adhesion of the insulating coating. A method for manufacturing the insulating coating-attached electrical steel sheet is also provided.