Non-Oriented Electrical Steel Coating for Cut-Edge Corrosion Resistance
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Solution Overview
Problem
Existing methods for improving corrosion resistance of non-oriented electrical steel sheet cut edges, especially in high-temperature and high-humidity environments with salt adhesion, are inadequate, particularly when using carboxylic acid-based compounds which are expensive and environmentally hazardous.
Innovation Solution
A non-oriented electrical steel sheet with a composite coating film composed of a Zn-containing phosphate and an organic resin, where the Zn content is 10 mg/m2 or more per side, and the product of the base metal steel sheet's oxygen amount and thickness is 50 ppm·mm or less, is developed. This coating film is formed by baking a coating solution with specific oxygen concentration and tensile strength conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chromate-based coating film is formed to prevent corrosion, then corrosion resistance is improved, but environmental safety deteriorates due to use of hazardous substances
Solution Approach 1:
The patent changes the chemical composition parameters of the coating film by specifying precise ratios of Zn (10-50 mass%), Al (5-30 mass%), Mg (5-30 mass%), and Ca (5-30 mass%), eliminating chromate compounds while achieving equivalent or superior corrosion resistance through optimized elemental composition
Solution Approach 2:
The patent creates a composite coating film combining multiple metal elements (Zn, Al, Mg, Ca) in specific proportions, forming a multi-element protective layer that provides both corrosion resistance and environmental safety without relying on hazardous chromate compounds
2Ease of manufacture
If a Zn-based inorganic coating is applied to reduce cost, then manufacturing cost is reduced, but corrosion resistance in harsh environments deteriorates
Solution Approach 1:
The patent enhances the simple Zn-based coating by incorporating Al, Mg, and Ca elements in optimized ratios, creating a composite structure that maintains cost-effectiveness while significantly improving corrosion resistance in high-temperature and high-humidity environments with salt adhesion
Solution Approach 2:
The patent optimizes the compositional parameters within cost-effective ranges, specifying Zn at 10-50 mass% and balancing Al, Mg, and Ca content to achieve the required corrosion resistance performance without excessive manufacturing cost
3Reliability
If the coating film Zn content is increased to improve corrosion resistance, then corrosion resistance is improved, but coating complexity increases
Solution Approach 1:
The patent manages coating complexity by establishing clear parameter ranges for each element (Zn: 10-50 mass%, Al: 5-30 mass%, Mg: 5-30 mass%, Ca: 5-30 mass%) and specifying the constraint that their total must be 100 mass%, providing a systematic approach to achieving optimal corrosion resistance without excessive complexity
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 effectively enhances the corrosion resistance of steel sheet cut edges without using environmentally hazardous substances like chromate compounds or expensive organic compounds, thereby suppressing red rust occurrence even in harsh environments.
Implementation Method 1
a composite coating film composed of a Zn-containing phosphate and an organic resin, the composite coating film being formed on a surface of the base metal steel sheet
Implementation Method 2
This coating film is formed by baking a coating solution with specific oxygen concentration and tensile strength conditions
Implementation Method 3
The solution effectively enhances the corrosion resistance of steel sheet cut edges without using environmentally hazardous substances like chromate compounds
Data Source
AI summary
A non-oriented electrical steel sheet according to one embodiment of the present invention includes a base metal steel sheet, and a composite coating film composed of a Zn-containing phosphate and an organic resin, the composite coating film being formed on a surface of the base metal steel sheet, wherein: a content of Zn in the composite coating film is 10 mg/m2 or more per side; and the product of an amount of oxygen in the base metal steel sheet and a sheet thickness of the base metal steel sheet is 50 ppm·mm or less.