Annealing Separator MgO Ageing for Uniform Forsterite Coatings
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Solution Overview
Problem
Current annealing separators for grain-oriented magnetic steel production often suffer from issues such as depressed deformation, inadequate performance, and the inability to form uniform, dense forsterite layers, which are crucial for achieving excellent insulation and electromagnetic properties.
Innovation Solution
A method for producing an annealing separator involving the high temperature ageing and low temperature ageing of magnesium hydroxide precursors, followed by mixing and burning to obtain magnesium oxide with controlled properties, ensuring high purity, excellent dispersibility, and bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If aggregated MgO microparticles are used to reduce water and O2 contents, then purity is improved, but water residue is produced which is harmful for high quality magnetic steel production
Solution Approach 1:
The patent applies parameter changes by controlling the burning temperature (800-1150°C) and ageing conditions (temperature and time parameters) to transform the magnesium hydroxide precursor into magnesium oxide with specific properties. This resolves the contradiction by finding optimal parameter ranges that achieve low water/O2 content without producing harmful water residue.
Solution Approach 2:
The patent employs preliminary action through the ageing process before burning, where magnesium hydroxide is aged at specific temperatures (50-200°C) for predetermined times (1-24 hours). This preliminary treatment prepares the precursor structure to ensure complete decomposition during burning, eliminating water residue while achieving the desired purity.
2Ease of manufacture
If conventional annealing separators are used, then production process is simple, but uniform and dense forsterite layers cannot be formed
Solution Approach 1:
The patent applies preliminary action by implementing controlled ageing of magnesium hydroxide before burning to create a precursor with optimized structure. This preliminary treatment ensures that the subsequent burning process produces magnesium oxide that forms uniform and dense forsterite layers, resolving the manufacturing precision issue while maintaining reasonable process simplicity.
Solution Approach 2:
The patent uses parameter changes by optimizing multiple process parameters including ageing temperature (50-200°C), ageing time (1-24 hours), and burning temperature (800-1150°C). These controlled parameter variations enable the formation of uniform and dense forsterite layers, achieving high manufacturing precision through systematic parameter optimization.
3Reliability
If high temperature ageing alone is applied, then reactivity is improved, but particle aggregation increases reducing dispersibility
Solution Approach 1:
The patent applies segmentation by dividing the single ageing process into two distinct stages: low temperature ageing (50-100°C) followed by high temperature ageing (100-200°C). This segmentation allows each stage to serve a specific function - the first stage maintains dispersibility while the second stage enhances reactivity, resolving the contradiction between these two properties.
Solution Approach 2:
The patent uses parameter changes by implementing a two-stage ageing process with different temperature ranges and time durations. The first stage uses lower temperatures (50-100°C) to preserve particle dispersion, while the second stage uses higher temperatures (100-200°C) to enhance reactivity. This staged parameter variation resolves the contradiction between reactivity and dispersibility.
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 resulting annealing separator enables the formation of uniform, dense forsterite layers on grain-oriented magnetic steel, leading to improved insulation and electromagnetic properties.
Implementation Method 1
burning to obtain magnesium oxide
Implementation Method 2
MgO in the annealing separator and the main component which is precipitated on the steel sheet surface during recrystallizing annealing (decarburized annealing) react with the oxide layer of SiO2 to form a forsterite layer
Data Source
AI summary
The invention provides a method of producing an annealing separator, an annealing separator and a grain-oriented magnetic steel. An annealing separator obtained by the method has high purity and excellent dispersibility and bonding strength, thus allowing formation of a uniform, dense forsterite layer on the surface of a grain-oriented magnetic steel. The method of producing an annealing separator comprises the following steps: step (1) in which magnesium oxide and an ammonium salt solution are mixed and reacted to prepare a magnesium salt solution and ammonia, and then the purified magnesium salt solution and the ammonia are reacted to obtain magnesium hydroxide, step (2) in which one portion of the obtained magnesium hydroxide is subjected to high temperature ageing at 155 to 230° C. while another portion of the obtained magnesium hydroxide is subjected to low temperature ageing at 10 to 100° C., and step (3) in which the magnesium hydroxides aged under the different conditions are mixed and burned to obtain magnesium oxide for use as an annealing separator.