Grain-Oriented Steel TiN Coating via Final Annealing
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Solution Overview
Problem
The high manufacturing cost and requirement for special facilities to form ceramic coatings like TiN with a lower coefficient of thermal expansion on grain-oriented electrical steel sheets, which are necessary for improving magnetic properties and reducing iron loss, pose significant challenges in industrial implementation.
Innovation Solution
A method to form a TiN coating during the final annealing process of grain-oriented electrical steel sheet production using a high-temperature hydrogen atmosphere, where TiO2 is reduced to form TiN by trapping nitrogen with metal Ti, without adding a special step, thereby achieving a high TiN ratio coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ceramic coating like TiN with lower coefficient of thermal expansion is formed on grain-oriented electrical steel sheet, then magnetic property is improved and iron loss is reduced, but manufacturing cost increases and special facilities are required
Solution Approach 1:
The patent combines the coating formation process with the existing final annealing process by adding TiO2 to the annealing separator. The TiO2 is reduced to Ti and then nitrided to TiN during the final annealing in hydrogen atmosphere, merging two functions (annealing and coating formation) into one process step, thereby avoiding special facilities and reducing manufacturing cost while still achieving the desired TiN coating for improved magnetic property
Solution Approach 2:
The patent uses TiO2 as an intermediary substance added to the annealing separator. TiO2 serves as a precursor that is first reduced to metallic Ti by hydrogen during final annealing, and then the metallic Ti reacts with nitrogen to form TiN coating. This intermediary approach allows the coating to be formed using existing annealing equipment rather than requiring specialized ceramic deposition facilities
2Reliability
If ceramic coating like TiN with lower coefficient of thermal expansion is formed on grain-oriented electrical steel sheet, then magnetic property is improved and iron loss is reduced, but special facilities are required
Solution Approach 1:
The patent merges the coating formation function with the existing final annealing process by incorporating TiO2 into the annealing separator. The TiO2 is reduced and nitrided during the standard final annealing in hydrogen atmosphere, combining what would otherwise require separate specialized deposition facilities into the existing annealing line, thereby reducing device complexity
Solution Approach 2:
The existing final annealing process, which already provides high-temperature hydrogen atmosphere and nitrogen environment, is made to serve the dual purpose of both annealing the steel and forming the TiN coating. The process conditions required for TiO2 reduction and TiN formation are achieved through the standard final annealing parameters, making the existing facility self-sufficient for coating formation without additional specialized equipment
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
This approach allows for the formation of a base coating with a high TiN ratio that applies high tension to the steel sheet, enhancing its magnetic properties while reducing iron loss without increasing manufacturing costs or requiring special facilities.
Implementation Method 1
TiO2 is reduced to form TiN by trapping nitrogen with metal Ti
Implementation Method 2
TiO2 is reduced to form TiN by trapping nitrogen with metal Ti
Implementation Method 3
have a low coefficient of thermal (heat) expansion, and so have an effect of reducing iron loss by applying tension to the steel sheet from the difference in coefficient of thermal expansion between the steel sheet and the coating when decreased to ambient temperature
Data Source
AI summary
A grain-oriented electrical steel sheet that includes a base coating with a high TiN ratio advantageous for the application of tension to the steel sheet and has excellent magnetic property is provided. The grain-oriented electrical steel sheet includes: a base coating having a peak value PTiN of TiN in the form of osbornite, observed in a range of 42°<2θ<43° and a peak value PSiO2 of SiO2 in the form of cristobalite, observed in a range of 23°<2θ<25° of both more than 0 and satisfying a relationship PTiN≥PSiO2, in thin-film X-ray diffraction analysis; and an iron loss W17/50 of 1.0 W/kg or less.