Wolfgang Pluschkell

Nucleation and growth kinetics of inclusions during liquid steel deoxidation

Abstract The phenomenon of solid inclusion nucleation and growth during the liquid steel deoxidation process is studied numerically. It is shown that the diffusion of atoms, the Ostwald ripening effect, and Brownian movement together control the growth of small size particles. It appears that this stage of initial precipitation lasts for only about 10 s. When the particle diameter exceeds a threshold of ~1 μm, the growth process becomes dominated by particle collisions and agglomeration. The efficiency of these mechanisms depends on the particle size distribution as produced during growth. Comprehensive evaluations are still impeded by the limited capacity of computers at present.

Ligand field absorption spectra of quenched MnO−SiO2-Base slags equilibrated with various oxygen and sulfur pressures

Absorption spectra in the visible range have been measured on quenched, glassy MnO−SiO2 slags, equilibrated with various oxygen and sulfur pressures at 1350°C. The absorption peaks are due to the electron transitions between different energy levels of 3d shell of divalent manganese cation Mn2+. The charge transfer bands habe also been measured. From the positions of the peaks and the charge transfer bands, the following results are deduced: sulfur is dissolved in silicate slags predominantly as free sulfur anions but not combined in silicate anion polymers. The tetrahedral arrangement of oxygen anions around a managanese cation is more favorable than the octahedral at higher oxygen and sulfur pressures and smaller CaO content. Electronic conduction in slags, generally very slight compared with ionic conduction, will be increased with increase in oxygen and sulfur pressure and decrease in CaO content. The reproducibility of the peak positions was within 50 cm−1 or 0.006 ev and the relative error in the molar extinction coefficient was estimated to be ±15 pct. The quenching rate had no effect on the absorption spectra.