Fe-Clustered Magnesium Oxide Powder for Uniform Annealed Coil Coating
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Solution Overview
Problem
Conventional grain-oriented electromagnetic steel sheets face challenges in achieving a uniform coat external appearance and preventing deformation of the internal circumferential shape of annealed coils, due to insufficient coating reactivity of magnesium oxide powders.
Innovation Solution
A magnesium oxide powder with an Fe element, where at least a part of the Fe element forms a cluster structure, is used as an annealing separating agent. This powder has a BET specific surface area of 10 to 40 m^2/g and includes a B element in amounts ranging from 0.05 to 0.50% by weight, enhancing its coating reactivity and catalytic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If Fe2O3 is added to MgO annealing separating agent to control volume shrinkage factor, then coil deformation is restrained, but coating reactivity is insufficient and coat external appearance uniformity deteriorates
Solution Approach 1:
The patent changes the chemical form of Fe from Fe2O3 (conventional) to FeCl2 (invention), which fundamentally alters the Fe content distribution and cluster formation characteristics. This parameter change enables simultaneous achievement of controlled volume shrinkage (20-60%) and high coating reactivity, resolving the contradiction between coil shape stability and coat uniformity
Solution Approach 2:
The patent creates a composite structure where Fe elements form clusters within the MgO matrix. This composite material approach, with Fe content of 0.01-0.10% and specific cluster distribution, enables the MgO to exhibit both controlled shrinkage behavior and enhanced coating reactivity, solving the contradiction between preventing coil deformation and achieving uniform coat appearance
2Manufacturing precision
If MgO coating reactivity is increased to improve coat external appearance, then coat uniformity is improved, but volume shrinkage factor increases causing coil deformation
Solution Approach 1:
The patent changes the Fe compound from Fe2O3 to FeCl2, which has different reactivity characteristics. FeCl2 provides high coating reactivity at low concentrations (0.01-0.10% Fe content) while maintaining controlled volume shrinkage (20-60%), whereas conventional Fe2O3 requires higher additions that excessively increase shrinkage and cause coil deformation
Solution Approach 2:
The patent creates localized Fe clusters within the MgO powder at specific concentration ranges. These local Fe-rich regions provide catalytic activity for enhanced coating reactivity and uniformity, while the overall low Fe content (0.01-0.10%) prevents excessive volume shrinkage and coil deformation
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 magnesium oxide powder effectively restrains the deformation of the internal circumferential shape of annealed coils and achieves a sufficiently uniform coat external appearance, while maintaining a controlled volume shrinkage factor to prevent coil deformation.
Implementation Method 1
at least a part of the Fe element has a cluster structure
Implementation Method 2
a reaction is caused between MgO, which is a main component of the annealing separating agent, and the oxide coat, which is formed by the decarbonizing annealing and is made mainly of SiO2, to form a forsterite (Mg2SiO4) coat called a glass coat
Implementation Method 3
the powder is also high in self-sintering reactivity
Implementation Method 4
the powder has a high self-sintering reactivity, it is therefore difficult to keep the shape of the coil
Data Source
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AI summary
The present invention provides a magnesium oxide powder capable of restraining the deformation of the internal circumferential shape of an annealed coil, and further giving a sufficiently uniform coat external appearance after the annealing; and a method for producing the powder. The magnesium oxide powder of the invention is a magnesium oxide powder including an Fe element, wherein a content of the Fe element is from 0.03 to 0.20% by weight, and at least a part of the Fe element has a cluster structure.