Analysis of oxide layer structure in nitrided grain-oriented silicon steel

Influence of oxidizing and Nitriding parameters on nitrogen concentration of electrical steels

“…Calculations confirm the present experimental observations of retained austenite by XRD at the surface of samples (Figure 9). Austenite was also observed experimentally at the extreme surface of the oxide layer in other recent works [16,25]. The fraction of austenite increases in agreement with the nitrogen content according to GDOES analysis and the Fe-N phase diagram [28].…”

“…Development of the non-equilibrium nitriding treatment regarding the magnetic properties has been reached identifying the acceptable range of nitrogen concentration for an efficient abnormal grain growth, the corresponding temperature of nitriding, and the range of ammonia to dihydrogen ratio to use in order to get satisfying precipitation of inhibitors [12][13]. Prior to nitriding, oxidizing aims decarburizing electrical steels as well as the later growth of an insulated layer (glass film) [14][15][16]. Studies were carried out on the structure of the oxides' layer and on influence of process parameters on oxides' layer properties.…”

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

“…The formation of IC on GOES is a multi-stage process that includes several thermochemical treatment operations [ 2 , 7 ]. GOES production consists of the following four main stages, which have a significant impact on the IC formation [ 2 , 7 , 8 , 9 ]: decarburizing annealing (DA), heat-resistant coating, high-temperature annealing (HTA) and the application of an electrical insulation coating.…”

“…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 ].…”

“…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 ]. An ultrathin layer, mainly consisting of silicon oxide SiO 2 coated with (FeMn)SiO 3 /(FeMn) 2 SiO 4 shells, forms on the steel surface after DA [ 12 , 13 ].…”