Non-Oriented Electrical Steel Coating for Chromate-Free Adhesion
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Solution Overview
Problem
Insulating coating films for non-oriented electrical steel sheets without chromate content lack sufficient adhesiveness, hygroscopic resistance, corrosion resistance, and heat resistance, and existing methods like phosphoric acid pickling treatment hinder industrial productivity.
Innovation Solution
A non-oriented electrical steel sheet with an insulating coating film containing metal phosphate, organic resin, and water-soluble organic compound, where the metal phosphate is predominantly aluminum phosphate with a controlled crystallinity of 0.5 to 5.0%, and the organic resin and water-soluble organic compound have specific SP values to enhance adhesiveness, hygroscopic resistance, and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an insulating coating film without chromate is used, then environmental compatibility is improved, but adhesiveness, hygroscopic resistance, corrosion resistance, and heat resistance deteriorate
Solution Approach 1:
The patent uses a composite insulating coating film containing multiple components: metal phosphate (5-50 mass%), organic resin (45-90 mass%), and water-soluble organic compound (5-50 mass%). This composite structure combines the benefits of different materials to achieve both environmental compatibility and superior coating properties including adhesiveness, corrosion resistance, and heat resistance without using chromate
Solution Approach 2:
The patent optimizes specific parameters of the coating components to achieve desired properties. The organic resin has an SP value of 18.0-24.0 (MPa)^0.5 and the water-soluble organic compound has an SP value of 19.0-35.0 (MPa)^0.5. The metal phosphate crystallinity is controlled at 0.5-5.0% by XRD. These parameter optimizations enable the coating to achieve excellent adhesiveness and corrosion resistance without chromate
2Reliability
If phosphoric acid pickling treatment and drying treatment are performed in advance, then appearance and adhesiveness are improved, but industrial productivity deteriorates
Solution Approach 1:
The patent combines multiple functions into a single insulating coating film application step. The coating film simultaneously provides insulation, corrosion protection, adhesiveness, and surface appearance without requiring separate pickling and drying treatments. This integration eliminates additional process steps and improves industrial productivity while maintaining excellent appearance and adhesiveness
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 non-oriented electrical steel sheet with improved insulation property, workability, adhesiveness, hygroscopic resistance, and corrosion resistance without chromate, while maintaining industrial productivity.
Implementation Method 1
an insulating coating film that is formed on a surface of the base metal steel sheet
Implementation Method 2
the organic resin has an SP value that is within a range of 18.0 (MPa)0.5 or more to less than 24.0 (MPa)0.5
Data Source
AI summary
There is provided a non-oriented electrical steel sheet that includes a base metal steel sheet and an insulating coating film that is formed on a surface of the base metal steel sheet, wherein the insulating coating film mainly contains metal phosphate, organic resin, and water-soluble organic compound, the metal phosphate contains at least aluminum as a metallic element, the organic resin has an SP value being within a range of 18.0 (MPa)0.5 or more to less than 24.0 (MPa)0.5, the water-soluble organic compound has an SP value being within a range of 19.0 (MPa)0.5 or more to less than 35.0 (MPa)0.5, and when measurement by X-ray diffractometry is performed on the insulating coating film, a degree of crystallinity of aluminum phosphate calculated from a peak from the metal phosphate is within a range of 0.5 to 5.0%.