Grain-Oriented Steel Sheet Coating Adhesion During Bending
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Solution Overview
Problem
Existing grain-oriented electrical steel sheets face issues with coating peeling during strong bending in transformer manufacturing, particularly in wound core transformers, due to insufficient coating adhesion at strongly bent regions, which affects the core loss and magnetic flux density properties.
Innovation Solution
A grain-oriented electrical steel sheet with a primary coating composed mainly of forsterite, containing compounds like Ca, Sr, Ba, and rare earth metals, such as La and Ce, along with sulfur, is developed to enhance coating adhesion. This coating is applied using an annealing separator with specific compositions and processes to ensure strong adhesion during bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating methods are used on grain-oriented electrical steel sheet, then the coating provides basic insulation, but the coating peels during strong bending in transformer manufacturing
Solution Approach 1:
The invention changes the chemical composition parameters of the coating by incorporating specific compounds containing Ca, Sr, Ba, and rare earth metals along with sulfur. This compositional modification transforms the coating's physical and chemical properties, enabling it to maintain adhesion during strong bending operations while providing the required insulation properties.
Solution Approach 2:
The invention creates a composite coating material that combines multiple elements (Ca, Sr, Ba, rare earth metals, and sulfur) within the coating structure. This composite approach leverages the synergistic effects of different compounds to achieve both adhesion strength and flexibility, preventing peeling during transformer manufacturing processes.
2Ease of manufacture
If the coating composition is simplified, then the manufacturing process is easier, but the coating adhesion during strong bending is insufficient
Solution Approach 1:
The invention modifies the coating formulation by incorporating specific compounds with defined chemical compositions containing Ca, Sr, Ba, and rare earth metals. This parameter optimization allows the coating to achieve superior adhesion properties without significantly complicating the application process, as the compounds can be integrated into existing coating formulations.
3Productivity
If strong bending is performed to achieve high magnetic flux density, then the transformer efficiency improves, but the coating peels during the bending process
Solution Approach 1:
The invention changes the mechanical and chemical properties of the coating through compositional modification, enabling it to withstand the stresses of strong bending operations. The coating maintains its integrity during the high-efficiency transformer manufacturing process, allowing the bending operations to proceed without coating failure.
Solution Approach 2:
The composite coating structure provides both the flexibility needed for strong bending and the adhesion strength to prevent peeling. This enables the transformer manufacturing process to achieve high efficiency through strong bending operations while maintaining coating integrity throughout the process.
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 significantly reduces the coating exfoliation area rate during strong bending, maintaining excellent magnetic properties and enabling the industrial production of high-efficiency transformers with improved core loss and magnetic flux density.
Implementation Method 1
allowing S to pass from the annealing separator to penetrate the steel during finish annealing
Implementation Method 2
finish annealing the coated sheet
Implementation Method 3
a primary coating composed mainly of forsterite
Data Source
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AI summary
Grain-oriented electrical steel sheet excellent in coating adhesion is provided. The steel sheet contains Si: 2 to 7% mass% and has a primary coating composed mainly of forsterite on its surface. A compound (A) containing one or more elements selected from among Ca, Sr and Ba, at least one rare earth metal, and sulfur is incorporated in the primary coating so as to reside in the interface layer between the primary coating and the steel sheet. As a result, occurrence of primary coating exfoliation at regions that are strongly worked during manufacture of a wound core transformer or the like is prevented.