Untersuchung des Schmelz-, Lösungs- und Kristallisationsverhaltens oxidisch-silikatischer Systeme mittels HT-LSCM

Translated title of the contribution: Investigation of melting-, dissolution- and crystallization behavior in oxidic-siliceous systems

Research output: ThesisDoctoral Thesis

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Dissolution kinetics of alumina and zirconia particles in original continuous casting mold slags were investigated by means of high-temperature laser scanning confocal microscopy. The results show that for both oxides the dissolution rate increases with C/S ratio and decreases with increasing viscosity. The dissolution rate of alumina was about 3 times higher than that of the zirconia. Due to volatiles in original slags it is not possible to determine exact effective binary diffusion coefficients. The dissolution behavior of ideal spherical (Al2O3 and ZrO2) and real as well as poly- and monocrystalline zirconia particles was compared. Experiments with cubic calciastabilized zirconia showed that a higher CaO content favors dissolution. The dissolution of ZrO2 particles in ZrO2-saturated slags showed erosive wear of polycrystalline zirconia. Dissolution experiments of Al2O3 and ZrO2 particles in synthetic slags and in an original mold slag were simulated by four different methods and analyzed for errors. Effective binary diffusion coefficients for alumina and zirconia dissolution are given for the smallest error. The crystallization experiments were carried out using original mold slags. After the Continuous Cooling Transformation and Time Temperature Transformation experiments, crystal shapes were determined, mean crystallization rates calculated, and a CCT- and TTT-diagrams generated. At different cooling rates, flake-shaped, needle-like or planar dendritic crystallization occured. All three continuous casting slags exhibited a maximum crystallization rate at 1100 °C and crystallized slower at the same temperature with increasing viscosity and decreasing basicity. Three infiltrated post-mortem refractory bricks have been investigated in terms of first liquid formation. The bricks were analyzed chemically and mineralogically and measured by HT-LSCM, ranked according to the increasing number of mineral phases. Results were compared with phase diagrams and thermochemical calculations to evaluate the reliability of the method. The magnesia chromite brick has the most complex phase paragenesis because it is infiltrated with calcium ferritic and sulphidic slag. By means of different furnace atmospheres, it was possible to examine roasting and melting of sulphides separately. The measurements confirm the suitability of the HT-LSCM for the investigation of melting-, dissolution- and crystallization behavior in oxidic-siliceous systems.
Translated title of the contributionInvestigation of melting-, dissolution- and crystallization behavior in oxidic-siliceous systems
Original languageGerman
  • Harmuth, Harald, Supervisor (internal)
  • Bernhard, Christian, Assessor A (internal)
Publication statusPublished - 2017

Bibliographical note

embargoed until null


  • alumina
  • zirconia
  • diffusion coefficient
  • dissolution
  • High-temperature laser scanning confocal microscopy
  • crystallization
  • crystal shape
  • invariant point
  • IP
  • continuous casting slag
  • mold slag
  • mould slag
  • Synthetic slag
  • dissolution behavior
  • refractory

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