Grain-Oriented Steel Coating Geometry for Lower Iron Loss
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Solution Overview
Problem
Existing grain-oriented electrical steel sheets with surface grooves face issues of increased iron loss due to improper coating thickness and direction on groove walls, compromising insulation properties and corrosion resistance.
Innovation Solution
A grain-oriented electrical steel sheet design with controlled coating thickness and morphology on groove walls, adhering to specific ratios and dimensions, and optionally incorporating a glass coating, to maintain insulation and corrosion resistance while reducing iron loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If grooves are formed on the surface of grain-oriented electrical steel sheet to refine magnetic domains, then iron loss is reduced, but coating is locally fractured causing problems of insulation properties and corrosion resistance
Solution Approach 1:
The patent applies different coating thicknesses to different regions: the flat surface coating portion has thickness t1, while the groove forming surface coating portion has thickness varying from t2Min to t2Max. This local differentiation allows the coating to follow the groove profile, filling it completely while maintaining adequate thickness for insulation and corrosion resistance, thus resolving the contradiction between iron loss reduction and reliability maintenance
Solution Approach 2:
The groove forming surface coating portion is designed to extend to the bottom surface of the groove before final coating application. This preliminary coating layer ensures that when grooves are formed, the coating is already in position to fill and protect the groove walls, preventing subsequent coating fracture and maintaining insulation properties while enabling iron loss reduction through proper magnetic domain refinement
2Reliability
If coating thickness on groove walls is increased to maintain insulation properties, then corrosion resistance is improved, but iron loss increases due to improper coating morphology
Solution Approach 1:
The patent specifies precise parameter ranges for coating thickness: t2Min/t1≥0.4 and t2Max/t1≤3.0, and the geometric parameter d/w≥1/3 where d is the effective depth of the tension coating and w is the groove width. These parameter changes optimize the coating morphology to reduce iron loss while maintaining adequate insulation properties, preventing the iron loss increase that would result from improper coating thickness
3Ease of manufacture
If coating is applied uniformly across the surface, then manufacturing is simplified, but groove walls receive improper coating thickness leading to increased iron loss
Solution Approach 1:
The patent implements local quality by defining distinct coating thickness zones: the flat surface coating portion with average thickness t1 and the groove forming surface coating portion with thickness ranging from t2Min to t2Max. This approach maintains manufacturing simplicity through a single coating process while achieving proper thickness distribution to reduce iron loss, avoiding the need for complex multi-step coating operations
Data Source
AI summary
This grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet including a base steel sheet and a tension coating, in which, when an average coating thickness of a flat surface coating portion is referred to as t1 (μm), a minimum coating thickness of a groove forming surface coating portion is referred to as t2Min (μm), and a maximum coating thickness of the groove forming surface coating portion is referred to as t2Max (μm), Expressions (1) and (2) are satisfied, and when a value of 0.95 times a distance D of the tension coating along a sheet thickness direction from a bottom surface position of the groove forming surface coating portion to a bottom surface position of the flat surface coating portion is referred to as an effective depth d (μm), Expression (3) is satisfied.t2Min/t1≥0.4 (1)t2Max/t1≤3.0 (2)t2Max≤d/2 (3)