Electrical Steel Sheet Coating Agent for Stress Relief Annealing
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Solution Overview
Problem
Conventional insulation coating layers on grain-oriented electrical steel sheets deteriorate after stress relief annealing at high temperatures, leading to increased iron loss and reduced insulation efficiency in transformers.
Innovation Solution
A coating agent comprising a metal phosphate derivative solution, colloid silica, chromium oxide, and porous silica, with optional boron oxide, is applied to the steel sheet, which includes a condensation reaction of metal phosphate and boric acid, and is heat-treated at 550 to 900°C to maintain insulation and prevent iron loss deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-temperature stress relief annealing (≥850°C) is performed to ensure stress relieving effects within a short time, then stress relief efficiency is improved, but iron loss deteriorates and insulation property decreases
Solution Approach 1:
The coating layer is designed to form a protective barrier before the stress relief annealing process, preventing direct interaction between the steel sheet and high-temperature environment that would cause insulation degradation. The coating is applied in advance to withstand the subsequent thermal processing.
Solution Approach 2:
The coating layer composition is specifically designed with metal phosphate derivatives and silica that maintain stable chemical and physical properties at high temperatures (≥850°C), preventing the insulation property deterioration that normally occurs during stress relief annealing.
2Productivity
If high-temperature stress relief annealing (≥850°C) is performed to ensure stress relieving effects within a short time, then stress relief efficiency is improved, but iron loss increases
Solution Approach 1:
The coating layer is applied before stress relief annealing to create a protective environment that prevents the steel sheet from experiencing harmful thermal effects, thereby maintaining low iron loss even when high-temperature processing is used for efficiency.
Solution Approach 2:
The coating composition with metal phosphate derivatives and chromium oxide is designed to remain stable at high temperatures, preventing the chemical changes in the steel sheet that would lead to iron loss increase during rapid stress relief annealing.
3Reliability
If conventional insulation coating is applied to improve insulation property, then insulation is enhanced, but the coating deteriorates after high-temperature stress relief annealing
Solution Approach 1:
The coating layer uses a composite formulation combining metal phosphate derivatives, silica, chromium oxide, and other inorganic materials that work together to provide both insulation properties and high-temperature stability, preventing coating deterioration during stress relief annealing.
Solution Approach 2:
The coating composition is specifically designed with materials that maintain their chemical and physical structure at high temperatures, ensuring the coating does not degrade or lose its insulating properties after exposure to stress relief annealing conditions.
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 coating agent provides excellent insulation and prevents iron loss deterioration even after high-temperature stress relief annealing, ensuring transformer efficiency and maintaining coating integrity.
Implementation Method 1
a condensation reaction of metal phosphate and boric acid
Implementation Method 2
it is performed with a stress relief heat treatment for removing stress generated by the process
Implementation Method 3
stress relief heat treatment for removing stress
Data Source
AI summary
A coating agent for an electrical steel sheet and a manufacturing method therefor are disclosed. A coating agent for an electrical steel sheet according to an example embodiment of the present invention includes a metal phosphate derivative solution, colloid silica, chromium oxide, and solid silica, and a solvent, wherein the metal phosphate derivative is a single material of a magnesium phosphate derivative or a mixed material of an aluminum phosphate derivative and a magnesium phosphate derivative, and in the mixed material, an amount of aluminum phosphate derivative is 10 wt % or less (not including 0%).