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UV/VIS‐spectroscopy of molten and solid CaO‐MgO‐SiO 2 ‐ slags
Author(s) -
Okretic Stefano,
Nowack Norbert,
Mausbach Klaus
Publication year - 1998
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.199805547
Subject(s) - slag (welding) , silicate , analytical chemistry (journal) , chromium , chemistry , spectroscopy , evaporation , doping , redox , oxidation state , impurity , mineralogy , materials science , metallurgy , inorganic chemistry , thermodynamics , metal , physics , optoelectronics , organic chemistry , chromatography , quantum mechanics
The previously developed high temperature set‐up has been used to monitor the redox state of molten slags at 1500°C directly by UV/VIS spectroscopy. Slags of the CaO‐MgO‐SiO 2 ‐system were doped with Fe 2 O 3 mass contents of 0.80 and 5%. Spectroscopical results at different oxygen partial pressures of the investigated Fe 3+ charge‐transfer (CT) transitions in the wavelength range between 200 and 800 nm were found to be representative for the redox state of the slag. The peak positions and shifts give further information about the optical basicity and the structure of molten slags. The time dependence of the oxidation/reduction equilibrium process was measured and evaluated concerning diffusion mechanisms. In Cr 2 O 3 ‐doped silicate‐slags in the liquid state CrO 3 ‐ and Cr 3+ ‐ species occur. The different CrO 3 ‐species (CrO 4 2‐ and Cr 2 O 7 2‐ ) in silicate slags have been indicated spectroscopically and registed quantitatively. Further investigations on Cr 2 O 3 ‐doped slags uncovered the well known evaporation of chromium out of molten slags as a decrease in the CrO 3 concentration in time. In the molten slag the CrO 3 slowly evaporates, which can be seen spectroscopically as a decrease in the CT‐band intensity. The results obtained on numerous optical parameters of molten slags will establish the application of reflection spectroscopy at high temperatures.