Insulating Coating Composition for Non-Oriented Electrical Steel Sheet

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Solution Overview

Problem

Non-oriented electrical steel sheets face challenges in achieving excellent insulating properties before and after stress-relieving annealing (SRA) with existing thin-film coatings, as increasing coating thickness deteriorates properties like wettability, heat resistance, and stacking factor.

Innovation Solution

A composition of mixed metal phosphate (aluminum and cobalt phosphate) combined with an organic/inorganic composite of epoxy resin and silica nanoparticles, where the silica nanoparticles are chemically modified and uniformly distributed, is applied to the steel sheets, enhancing insulating properties while maintaining thin-film thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the coating thickness is increased to secure excellent insulating property, then the insulating property is improved, but the wettability, heat resistance, adherence before/after SRA and stacking factor are deteriorated

Engineering Contradiction:
Improveinsulating propertyVSAvoidwettability, heat resistance, adherence, stacking factor
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the chemical composition parameters of the coating by incorporating specific metal phosphates (aluminum phosphate, cobalt phosphate, manganese phosphate) and controlling their ratios, along with using acrylic resin with specific functional groups. This compositional parameter change enables achieving excellent insulating properties at thinner coating thicknesses without sacrificing other critical properties like wettability, heat resistance, and adherence.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite coating material combining multiple metal phosphates (aluminum phosphate, cobalt phosphate, manganese phosphate) with acrylic resin. This composite structure provides synergistic effects where the metal phosphates contribute to insulating properties and heat resistance, while the acrylic resin provides wettability and adherence, thus resolving the contradiction between insulating property and other manufacturing properties.

Inventive Principle:
Principle #40Composite materials

2Reliability

If the coating thickness is increased to minimize Eddy Current Loss, then the insulating property between layers is improved, but the surface quality and stacking factor are deteriorated

Engineering Contradiction:
Improveinsulating property between layersVSAvoidsurface quality, stacking factor
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent modifies the coating composition parameters by using a specific formulation of metal phosphates and acrylic resin that achieves high insulating efficiency at reduced thickness. This parameter change allows the coating to provide sufficient electrical insulation between laminated sheets while maintaining smooth surface quality and high stacking factor, as the thinner coating creates fewer surface irregularities.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If a thin-film coating is applied to maintain good wettability and heat resistance, then the manufacturing properties are improved, but the insulating property before/after SRA is insufficient

Engineering Contradiction:
Improvewettability, heat resistanceVSAvoidinsulating property before/after SRA
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent develops a composite coating system where metal phosphates (aluminum phosphate, cobalt phosphate, manganese phosphate) are combined with acrylic resin. The metal phosphates provide excellent insulating properties that are resistant to degradation during SRA, while the acrylic resin ensures good wettability and heat resistance. This composite material approach allows thin-film application that simultaneously satisfies both manufacturing properties and insulating reliability after stress-relieving annealing.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the chemical composition parameters of the coating, specifically the ratios of different metal phosphates and the type of acrylic resin used. This parameter optimization enables the thin coating to achieve sufficient insulating property before and after SRA while maintaining excellent wettability and heat resistance, resolving the contradiction between thin-film benefits and insulating performance.

Inventive Principle:
Principle #35Parameter changes

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 insulating properties before and after SRA, maintaining excellent wettability, heat resistance, and corrosion resistance, with uniformly distributed silica nanoparticles ensuring effective barrier performance.

Implementation Method 1

an organic/inorganic composite of epoxy resin and silica nanoparticles, where the silica nanoparticles are chemically modified

Methodology Applied
Scientific EffectChemical modification: Chemical Bonding

Implementation Method 2

uniformly distributed silica nanoparticles ensuring effective barrier performance

Methodology Applied
Scientific EffectUniform distribution: Dispersion (of waves)

Implementation Method 3

an excellent insulating property between the layers of non-oriented electrical steel sheets, which the performance of motor can be maximized by minimizing Eddy Current Loss

Methodology Applied
Scientific EffectElectrical insulation: Electrical Resistance

Implementation Method 4

a composition of mixed metal phosphate (aluminum and cobalt phosphate) combined with an organic/inorganic composite of epoxy resin and silica nanoparticles

Methodology Applied
Scientific EffectProtective film formation: Coatings

Data Source

PatentEP2800103B1Insulation coating composition for non-oriented electrical steel sheet, method for manufacturing same, and non-oriented electrical steel sheet upon which the insulation coating composition is applied
Publication Date: 2022.02.16 POHANG IRON & STEEL CO LTD
  • EP2800103B1 patent drawingFigure 1
  • EP2800103B1 patent drawingFigure 2
  • EP2800103B1 patent drawingFigure 3

AI summary

Disclosed is an insulating film composition of a non-oriented electrical steel sheet. The insulating film composition of a non-oriented electrical steel sheet according to the present invention comprises a mixed metal phosphate consisting of aluminum phosphate (Al(H3PO4)x=1-3) and cobalt phosphate (Co(H3PO4)3), and an organic/inorganic composite consisting of epoxy resin and silica (SiO2) nanoparticle substituted on the functional group of the epoxy resin.