Formation mechanism and microstructure of a forsterite film in grain-oriented electrical steel

Glass Film Formation on GOES Surface during High-Temperature Annealing: The Mechanism with Amorphous Phase Formation

“…Contemporary grain-oriented electrical steel (GOES) is a composite material that contains Fe-3%Si and has a ceramic metal film known as “the glass film” serving as an insulation coating (IC) [ 1 , 2 , 3 , 4 , 5 ]. The main purpose of IC is to create an isolation layer between sheets of magnetic cores.…”

“…The main purpose of IC is to create an isolation layer between sheets of magnetic cores. Owing to IC, each core coil loop serves as an individual magnetic flow conductor, thus minimizing eddy-current losses due to higher electrical resistance of the material at decreased thickness of core sheets [ 1 , 3 ]. In addition, IC protects the metal surface against corrosion.…”

“…In addition, IC protects the metal surface against corrosion. Moreover, it creates elastic tension stresses in GOES crystallites, which decrease the magnetic losses due to the size reduction of the domain structure [ 3 , 6 ].…”

“…As a prerequisite for obtaining a high-grade IC, the glass film layer that forms on the steel surface during HTA should have the required thickness and a certain chemical composition [ 1 , 3 ]. The glass film formation depends on many factors determined at the previous treatment stages.…”

“…Glass film formation under HTA is also a multi-stage process that includes several solid-phase reactions occurring in a wide range of temperatures [ 1 , 3 , 7 , 8 , 9 ]. The formation of GOES surface structure begins as oxidation during DA [ 3 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 ].…”