Electrical Steel Insulating Coating With Oxide-Phosphate Adhesion
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Solution Overview
Problem
Existing methods for manufacturing grain-oriented electrical steel sheets with improved magnetic characteristics and adhesion without a forsterite-based coating are hindered by equipment costs and workability issues, such as the need for specialized annealing facilities and inadequate adhesion of tension coatings.
Innovation Solution
A grain-oriented electrical steel sheet with an iron-based oxide layer and an intermediate layer containing crystalline metal phosphate is formed, along with a tension coating layer, to enhance adhesion, tension, and magnetic characteristics, eliminating the need for forsterite-based coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a forsterite-based coating is generated in secondary recrystallisation annealing to apply tension and reduce iron loss, then iron loss is reduced, but the uneven structure at the interface hinders magnetic domain wall movement and adversely affects high magnetic field iron loss
Solution Approach 1:
The invention removes the forsterite-based coating from the steel sheet surface before applying the tension-applying insulating coating. This extraction eliminates the harmful uneven interface structure that hinders magnetic domain wall movement while preserving the ability to apply tension through the new coating system
Solution Approach 2:
The invention introduces an oxide layer as an intermediary between the steel sheet and the tension-applying insulating coating. This oxide layer serves as a bonding interface that enables both adhesion of the coating and smooth magnetic domain wall movement, replacing the problematic forsterite-based coating interface
2Object-generated harmful factors
If mechanical polishing or chemical pickling is used to remove the inorganic coating and bring the surface into a mirror state, then magnetic characteristics are improved, but equipment costs and workability issues arise
Solution Approach 1:
The invention uses the steel sheet's own oxide layer, formed during normal secondary recrystallisation annealing, as the bonding interface for the tension-applying insulating coating. This self-service approach eliminates the need for additional polishing or pickling equipment and processes
Solution Approach 2:
The oxide layer serves multiple functions: it provides a bonding interface for the tension-applying insulating coating, maintains smooth magnetic domain wall movement, and eliminates the need for separate surface treatment processes. This multi-functionality simplifies the overall manufacturing process
3Object-generated harmful factors
If a tension-applying insulating coating is formed on a steel sheet without forsterite-based coating, then magnetic characteristics are improved, but coating adhesion becomes insufficient
Solution Approach 1:
The oxide layer formed on the steel sheet surface during normal secondary recrystallisation annealing serves as an intermediary that enables strong adhesion between the steel sheet and the tension-applying insulating coating, while maintaining smooth magnetic domain wall movement
Solution Approach 2:
The invention changes the surface state parameter by utilizing the naturally formed oxide layer with specific thickness (50-500 nm) and composition, which provides optimal bonding characteristics for the tension-applying insulating coating while maintaining magnetic performance
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 results in a grain-oriented electrical steel sheet with excellent coating adhesion, tension, and magnetic characteristics, while avoiding the costs and workability challenges associated with existing techniques.
Implementation Method 1
a surface of the base steel sheet is in a state where an iron-based oxide layer containing an iron-based oxide is formed on an insulating coating side
Implementation Method 2
the insulating coating includes an intermediate layer formed on a base steel sheet side and containing a crystalline metal phosphate
Data Source
AI summary
This grain-oriented electrical steel sheet includes: a base steel sheet; and an insulating coating formed on a surface of the base steel sheet, in which the base steel sheet includes an iron-based oxide layer containing an iron-based oxide on an insulating coating side, the insulating coating includes an intermediate layer formed on a base steel sheet side and containing a crystalline metal phosphate, and a tension coating layer formed on a surface side of the insulating coating, an average thickness of the iron-based oxide layer is 0.10 to 1.50 μm, an average thickness of the intermediate layer is 0.3 to 10.0 μm, an average thickness of the insulating coating is 2.0 to 10.0 μm, the crystalline metal phosphate of the intermediate layer is one or two or more of zinc phosphate, manganese phosphate, iron phosphate, and zinc calcium phosphate, the tension coating layer contains a metal phosphate and silica, and an amount of the silica in the tension coating layer is 20 to 60 mass %.