Rapid quantitative analysis of fayalite and silica formed during decarburization of electrical steel

Abstract

Subscales on surfaces are affected by the temperature and oxidation potential during decarburization annealing of electrical steel containing 3 wt% silicon. Knowledge of the structural and chemical properties of the surface oxide layer subscales permits the control of high-temperature oxidation processes in the electrical steel. In the present work, the oxide layers were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometry, and glow discharge optical emission spectrometry (GD-OES). The main oxide compounds formed within the subscales during decarburization annealing of the electrical steel were fayalite (Fe 2 SiO 4 ) and silica (SiO 2 ). The fayalite and silica contents were quantitatively determined by wet analysis via the galvanostatic electrolysis method, and these oxide content measurements were compared with the fayalite content determined by FTIR spectrometry and the silica determined by GD-OES. The results determined by rapid methods and wet analysis showed good agreement. The present findings show that FTIR spectrometry and GD-OES measurements may be used for the rapid quantitative analysis of fayalite and silica in surface oxide layers during the manufacture of electrical steel.

Characterization of chemical information and morphology for in‐depth oxide layers in decarburized electrical steel with glow discharge sputtering

“…The glow discharge sampling was successfully employed to carry out the comprehensive analysis of the chemical information and microscopic features of the oxide layers in the direction of depth. Based on the previous analytical results of decarburized steel sheets by GD‐OES for their in‐depth compositional profile and by cross‐sectional SEM to observe the microstructure, the cross‐section‐specific depths were analyzed by XPS, FTIR spectrometry, scanning electron microscope, and transmission electron microscope. In particular, the equilibrium and kinetic considerations served by theoretical calculations of selective oxidation were examined in an attempt to understand the formation and behavior of the oxide layers, and their results were discussed in association with the above analytical results.…”

Effect of Annealing Time on Oxides Phases and Morphology along Oxidized Depth of Fe-3%Si Steel during Decarburization

“…19) Jung et al have indicated that the Fourier transform infrared (FTIR) spectrometry and glow discharge optical emission spectrometry (GD-OES) may be used for the rapid quantitative analysis of fayalite and silica in surface oxide layers. 20) In this paper, the optimum annealing condition of decarburization was studied by carbon-sulfur infrared analyzer under different annealing temperature and P H2O /P H2 . The evolution of oxides morphology in oxidized layer and the concentration distribution trend of silicon and oxygen in oxidized layer were observed by Scanning Electron Microscopy and Glow Discharge Spectrometer at different annealing time.…”

Effect of Surface Oxidation on Decarburization of a Fe-3%Si Steel during Annealing

“…When P H2O /P H2 reaches a certain level, water vapor reacts with iron to generate FeO, which further react with SiO 2 to generate Fe 2 SiO 4 particles. [4][5][6] When P H2O /P H2 is sufficiently high, Fe 2 O 3 is generated, which may react with FeO to form Fe 3 O 4 . [7][8][9] Stratton and Stanescu 10) found that the decarburization rate is faster under an atmosphere of N 2 + H 2 + H 2 O than under a carbonaceous-type atmosphere.…”