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Chair of Ceramics

Main Research

09/06/2011

Investigation of mould powders and slags

One of the main research interests of the chair of ceramics is the investigation of the structure of mould powders and slags as well as the characterisation of their melting and solidification behaviour. For these purposes original mould powders and samples taken from service (mould slags, slag rims) are analysed.

Abb. 1 (oben): Heiztischmikroskopische Untersuchung der Kristallisation einer Gießschlacke. Die Pfeile kennzeichnen die Cuspidinkristalle [2]

The therefore applied methods are listed below:

  • Reflected light and scanning electron microscope for mould powder, mould slags and samples annealed at selected temperatures (fig. 1 and fig. 2)
  • Hot stage microscope (fig. 3 and fig. 4) for investigation of mould powders, polished sections of mould powder specimen, as well as mould slags at temperatures up to 1500°C
  • XRD
  • Differential thermal analysis and thermogravimetry
  • Investigations using the double hot thermocouple technique (DHTT) (fig. 5): There the crystallisation behaviour of a mould slag in dependence of the temperature gradient is observed.
  • High temperature viscometer (fig. 6)

The characterisation of mould powders using the methods quoted above makes it possible to draw conclusions concerning operating performance and mould powder selection.


Fig. 2: Microstructure of a mould powder after annealing at 1000°C (scanning electron microscope, backscattered electron image); phases: cuspidine (1), feldspathoide (2), and glass phase (3) [1]


Fig. 3: Scanning electron microscope, backscattered electron image of a slag rim [1]


Fig. 4: Hot stage microscope [2]


Fig. 5: DHTT


Fig. 6: High temperature viscometer

References

 

[1] I. Marschall, H. Harmuth: “Investigation of the slag rim growth in the continuous casting process”, SCANMET III- 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden

[2] N. Kölbl, H. Harmuth: „Hot stage microscopy for in situ observations of the melting and crystallisation behaviour of mould powders”, SCANMET III- 3rd International Conference on Process Development in Iron and Steelmaking, 8-11 June 2008, Luleå, Sweden

 

Contact: Nathalie Kölbl, Irmtraud Marschall