MgO Mixed Powder Composition for Defect-Resistant Electrical Steel Coatings
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Solution Overview
Problem
Existing methods for manufacturing grain-oriented electrical steel sheets using MgO-based annealing separators fail to adequately suppress coating defects while maintaining good external appearance characteristics due to excessive boron content, which can deteriorate magnetic properties.
Innovation Solution
A mixed powder containing controlled amounts of Al and B, with specific particle sizes and ratios, is used to form an annealing separator, ensuring the proportion of tri-coordinated boron is within a certain range to enhance coating and magnetic characteristics without promoting unwanted grain growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of boron in MgO is increased to improve coating characteristics and magnetic properties, then coating external appearance and magnetic characteristics are improved, but boron excessively enters the steel sheet and causes coating defects
Solution Approach 1:
The patent changes the chemical composition parameters of the annealing separator by controlling boron content within a specific range (0.003-0.03 mass%) and adjusting the Al/B ratio (0.05-5.0), thereby optimizing coating characteristics and magnetic properties while preventing coating defects caused by excessive boron entry into the steel sheet
Solution Approach 2:
The patent creates a composite annealing separator material combining MgO with controlled amounts of Al and B, where the synergistic interaction between these elements improves coating external appearance and magnetic characteristics while the specific composition ratio prevents harmful effects
2Reliability
If tri-coordinated boron proportion is increased to enhance coating reaction behavior at high temperature, then purification of impurities is improved, but decomposition of precipitates is promoted and unwanted grain growth occurs
Solution Approach 1:
The patent optimizes the proportion of tri-coordinated boron within a specific range (5-70 mass%) to enhance coating reaction behavior and impurity purification at high temperature, while simultaneously controlling the Al content and Al/B ratio to suppress decomposition of precipitates and prevent unwanted grain growth during annealing
3Reliability
If the content of Al and B is increased to improve magnetic characteristics, then magnetic properties are enhanced, but coating defects may occur due to excessive boron entry
Solution Approach 1:
The patent simultaneously optimizes multiple parameters including boron content (0.003-0.03 mass%), aluminum content (0.0003-0.01 mass%), and the Al/B ratio (0.05-5.0) to achieve the desired magnetic characteristics while preventing coating defects caused by excessive boron entry into the steel sheet
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 effectively suppresses coating defects and maintains good external appearance characteristics by optimizing the Al and B content, thereby improving the magnetic properties of the grain-oriented electrical steel sheets.
Implementation Method 1
silicon dioxide (SiO2) on a surface of a steel sheet reacts with MgO at the time of final annealing to apply tension to the surface of the steel sheet and form a forsterite (Mg2SiO4)-based coating
Implementation Method 2
form a forsterite (Mg2SiO4)-based coating (primary layer) that plays a role of imparting insulation properties to the steel sheet
Implementation Method 3
a proportion of tri-coordinated boron in the boron is 70% or more and 95% or less... tri-coordinated boron affects the coating reaction behavior at a high temperature... affects purification of impurities
Data Source
AI summary
The mixed powder is a mixed powder for an annealing separator containing MgO as a main agent, wherein the mixed powder contains Al and B, an Al content contained in the entire mixed powder is 0.0007 mass % or more and 0.050 mass % or less, a B content contained in the entire mixed powder is 0.005 mass % or more and 0.040 mass % or less, the B contains tri-coordinated boron, an average particle size of the mixed powder is 0.08 μm or more and 9.0 μm or less, and a formula (1) below is satisfied.0.06≤[Al]/[BO3]<5.Formula (1)In the formula (1), [Al] is an Al content (mass %) in the mixed powder, and [BO3] is a content (mass %) of the tri-coordinated boron in the mixed powder.