Electrical Steel Insulating Coating with Phosphate Interlayer
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Solution Overview
Problem
Existing methods for manufacturing grain-oriented electrical steel sheets without inorganic coatings face challenges in achieving excellent coating adhesion, coating tension, and magnetic characteristics while maintaining high workability and cost-effectiveness, due to the need for specialized equipment and facilities, and issues with adhesion and tension retention of insulating coatings.
Innovation Solution
A grain-oriented electrical steel sheet with an intermediate layer formed of crystalline metal phosphate between the base steel sheet and a tension coating, where the intermediate layer contains zinc phosphate, manganese phosphate, or iron phosphate, and the tension coating layer includes metal phosphate and silica, enhancing adhesion and magnetic properties without the need for forsterite-based coatings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a forsterite-based coating is generated in secondary recrystallisation annealing to apply tension and reduce iron loss, then coating adhesion is improved, but the uneven structure at the interface hinders magnetic domain wall movement and adversely affects iron loss
Solution Approach 1:
The coating system is divided into two distinct layers: a forsterite-based coating layer generated during secondary recrystallisation annealing that provides tension application and adhesion, and a separate insulating coating layer applied afterward that provides magnetic smoothing. This segmentation allows each layer to perform its specific function without interfering with the other, resolving the contradiction between adhesion and magnetic domain wall movement.
Solution Approach 2:
The insulating coating acts as an intermediary layer between the forsterite-based coating and the steel sheet surface. It provides a smooth interface that facilitates magnetic domain wall movement while the forsterite-based coating underneath maintains coating adhesion and tension application. The intermediary layer decouples the conflicting requirements of adhesion and magnetic performance.
2Loss of energy
If mechanical polishing or chemical pickling is used to remove inorganic coating and create a mirror surface, then magnetic domain wall movement is improved, but coating adhesion and tension retention become insufficient
Solution Approach 1:
The forsterite-based coating is generated in advance during secondary recrystallisation annealing to provide a foundation for subsequent insulating coating application. This preliminary action ensures that the adhesion-promoting layer is already in place before the insulating coating is applied, avoiding the need for mechanical polishing or chemical pickling that would compromise adhesion.
Solution Approach 2:
The coating system uses a composite structure combining forsterite-based coating material and insulating coating material. The forsterite-based layer provides adhesion and tension, while the insulating layer provides magnetic smoothing. This composite approach allows both adhesion and magnetic performance to be achieved simultaneously without removing either layer.
3Loss of energy
If specialized equipment and facilities are used to manufacture grain-oriented electrical steel sheets without inorganic coating, then magnetic characteristics are improved, but workability and cost-effectiveness deteriorate
Solution Approach 1:
The manufacturing process merges the generation of forsterite-based coating during secondary recrystallisation annealing with the subsequent application of insulating coating in a coordinated sequence. This combining of steps allows the steel sheet to achieve both magnetic smoothing and adequate adhesion using standard manufacturing equipment, eliminating the need for specialized facilities while maintaining excellent 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 provides excellent coating adhesion, coating tension, and magnetic characteristics, improving iron loss performance and maintaining high workability and cost-effectiveness by eliminating the need for specialized equipment and facilities, while ensuring sufficient adhesion and magnetic domain wall movement.
Implementation Method 1
an intermediate layer which is formed on a base steel sheet side and contains a crystalline metal phosphate
Implementation Method 2
a tension coating layer which is formed on a surface side of the insulating coating... forming a coating of a material having a coefficient of thermal expansion smaller than that of a steel sheet on a surface of the steel sheet at a high temperature is an effective measure for reducing the iron loss
Implementation Method 3
an insulating coating formed on a surface of the base steel sheet
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 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 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 %.