Insulation-Coated Grain-Oriented Steel Sheet Heat Resistance
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Solution Overview
Problem
Grain oriented electrical steel sheets with insulating coatings exhibit poor heat resistance, leading to sticking issues during stress relief annealing, which affects workability and magnetic properties.
Innovation Solution
A grain oriented electrical steel sheet with an insulating coating containing elements like Mg, Ca, Ba, Sr, Zn, Al, Mn, Si, P, O, and Cr, where the outermost surface exhibits a Cr2p1/2 and Cr2p3/2 peak, achieved through a treatment solution with colloidal silica and a Cr compound, and specific baking and plasma treatment conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulating coating is used, then the steel sheet has basic insulation properties, but the coating has poor heat resistance causing sticking during stress relief annealing
Solution Approach 1:
The patent changes the chemical composition parameters of the insulating coating by incorporating specific elements (Cr, Si, Al, Ca, Mg, Ba, Sr, Zn, Mn) in controlled ratios. The Cr content is specifically controlled at 1-10 at% to achieve high heat resistance without causing adverse effects. This parameter optimization allows the coating to maintain structural stability at high temperatures during stress relief annealing, preventing sticking while retaining insulation properties.
Solution Approach 2:
The patent creates a composite insulating coating structure consisting of multiple elements working synergistically. The coating combines Cr for heat resistance, Si and Al for glassy phase formation, and other metal elements for enhanced thermal stability. This composite structure provides superior heat resistance compared to conventional single-element or simple multi-element coatings, enabling the coating to withstand stress relief annealing temperatures without sticking.
2Reliability
If the insulating coating is made thicker to improve insulation, then insulation properties improve, but the coating may cause more sticking at high temperatures
Solution Approach 1:
Rather than increasing coating thickness, the patent changes the compositional parameters to achieve high heat resistance. The optimized element ratios, particularly Cr at 1-10 at%, create a coating that maintains dimensional stability and resists softening at high temperatures. This allows adequate insulation properties without the sticking problems associated with thicker conventional coatings.
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 a highly heat-resistant insulating coating that prevents sticking and maintains magnetic properties, enhancing the workability and heat resistance of the steel sheets.
Implementation Method 1
whether Cr bonded to another element is present at the outermost surface of an insulating coating has an influence on the level of heat resistance of the insulating coating
Implementation Method 2
a treatment solution containing a phosphate (e.g., aluminum phosphate, magnesium phosphate), colloidal silica, and chromic anhydride
Data Source
AI summary
Provided are an insulation-coated oriented magnetic steel sheet having an insulating coat with excellent heat resistance; and a method for manufacturing the same. This insulation-coated oriented magnetic steel sheet has an oriented magnetic steel sheet, and an insulating coat arranged on the surface of the oriented magnetic steel sheet, the insulating coat containing Si, P, O, and Cr, and at least one element selected from the group consisting of Mg, Ca, Ba, Sr, Zn, Al, and Mn. The XPS spectrum of the outermost surface of the insulating coat has peaks observed at Cr2p1/2 and Cr2p3/2.