Electromagnetic Steel Sheet Insulating Coating Adhesion
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Solution Overview
Problem
Conventional electromagnetic steel sheets with insulating coatings have relatively lower insulating properties, leading to adhesion issues and coating detachment during stripping, and lack the necessary adhesion and corrosion resistance required for high-reliability miniaturized motors, particularly in generators.
Innovation Solution
An electromagnetic steel sheet with an insulating coating comprising a binder solution containing metal phosphate and a silicate filler with specific particle diameter and specific surface area ranges, along with an organic resin, applied in a thickness that exceeds the filler particle diameter, and baked at controlled temperatures to enhance adhesion and blocking resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional insulating coating is applied to electromagnetic steel sheets, then the coating provides basic insulation, but the insulating properties are relatively low leading to adhesion issues and coating detachment
Solution Approach 1:
The patent applies a composite coating system consisting of multiple layers: a base coat containing inorganic elements (phosphoric acid-based or chromic acid-based) and organic resin, and a top coat containing inorganic elements and organic resin. This multi-layer composite structure provides both excellent insulating properties and strong adhesion to the steel sheet surface, resolving the contradiction between insulation and adhesion strength.
Solution Approach 2:
The patent optimizes specific parameters including the ratio of inorganic to organic components, particle diameter of inorganic fillers (2 μm or more), coating thickness, and baking temperature. By carefully controlling these parameters, the coating achieves high interlayer resistance while maintaining strong adhesion and preventing detachment during stripping.
2Reliability
If chromic acid-based inorganic elements are used in the insulating coating, then the coating exhibits good adhesion and corrosion resistance, but environmental concerns arise due to hexavalent chromium content
Solution Approach 1:
The patent extracts and eliminates the harmful hexavalent chromium component from the coating system. It replaces chromic acid-based inorganic elements with phosphoric acid-based inorganic elements, thereby removing the environmental hazard while preserving the essential functions of adhesion and corrosion resistance.
Solution Approach 2:
The patent changes the chemical composition parameter by substituting phosphoric acid-based inorganic elements for chromic acid-based ones. This parameter change maintains the protective and adhesive properties of the coating while eliminating the harmful hexavalent chromium, thus resolving the environmental concern.
3Reliability
If the insulating coating thickness is increased to improve insulation, then interlayer resistance improves, but the coating becomes more prone to detachment during stripping
Solution Approach 1:
The patent uses a composite coating structure with inorganic elements and organic resin in specific ratios. This composite formulation provides high interlayer resistance at moderate thickness levels while maintaining strong blocking resistance and adhesion, preventing the coating detachment issue that occurs with thicker conventional coatings.
Solution Approach 2:
The patent optimizes the particle diameter of inorganic fillers to 2 μm or more and controls the coating thickness and composition ratios. These parameter changes enable the coating to achieve high insulating properties without becoming overly thick, thereby maintaining good blocking resistance and preventing detachment during stripping.
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 improved insulating, adhesion, corrosion, and blocking resistance properties, ensuring reliable performance and durability of the electromagnetic steel sheet, particularly in generator motors, while eliminating the need for costly varnish treatments.
Implementation Method 1
an insulating coating comprising a binder solution solid content containing metal phosphate and a silicate filler
Implementation Method 2
baked at controlled temperatures to enhance adhesion and blocking resistance
Data Source
Figure 1
AI summary
The present invention provides an electromagnetic steel sheet having an insulating coating on a surface of the electromagnetic steel sheet, the insulating coating including: a binder solution solid content containing metal phosphate; and a silica or silicate filler having an average particle diameter in a range of 2.0 µm to 15.0 µm and an average specific surface area in a range of 1.0 m2/g to 40.0 m2/g, a content of the silica or silicate filler being 1 to 40 parts by mass relative to 100 parts by mass of the binder solution solid content.