Application of Stereological Relations for the Characterization of Porous Materials via Microscopic Image Analysis

Abstract:

In this work we demonstrate the application of stereology-based image analysis for the characterization of highly porous cellular ceramics (alumina foams) prepared by biological foaming with yeast and subsequent drying (80-105 °C) and firing (1570 °C). It is shown that the ceramics prepared usually have total porosities in the range 78-84 % and that the porosities made up by large pores (volume fraction of foam bubbles) are usually in the range 58-75 %. Further it is shown that the mean chord length and the Jeffries size, i.e. pore size measures related to the interface density and the mean curvature integral density, respectively, are relatively close to each other (usually 0.8-1.4 and 0.8-1.2 mm) with a ratio close to unity (0.9-1.3) and that the mean surface-to-surface distance of pores gives a realistic picture of the average pore wall thickness (usually 0.46-0.69 mm). Using a special processing variant (excess ethanol addition) it is possible to obtain microstructures with lower porosity (total porosity 68-70 %, foam bubble volume fractions 50-56 %) and smaller pore size (approx. 0.5 mm). Absolute errors are calculated using normalized deviations corresponding to 95 % reliability in the Student distribution and the standard errors for the quantities in question (both observed and estimated). Relative errors are found to be below 12 % when the number of measurements is of order 400-1000.

• Periodical: Key Engineering Materials (Volume 647)
• Pages: 180-187
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.647.180
• Online since: May 2015
• Authors: Tereza Uhlířová*, Eva Gregorová, Willi Pabst
• Keywords: Stereology, Alumina, Biological Foaming, Cellular Ceramic, Delesse-Rosiwal Law, Interface Density, Jeffries Size, Mean Curvature Integral Density, Microscopic Image Analysis, Porosity, Porous Ceramic, Saltykov Relation, Yeast

References

[1] W. Pabst, E. Gregorová, T. Uhlířová, Characterization of microstructures of heterogeneous materials via stereological relations, submitted to Ceramics-Silikáty (2014).

[2] T. Uhlířová, Highly porous cellular ceramics prepared via biological foaming, M. Sc. thesis, ICT Prague, Prague, 2014 (in Czech).

[3] T. Uhlířová, E. Gregorová, W. Pabst, M. Veselý, Influence of the type and amount of starch on the biological foaming of alumina suspensions, in: R. Řápková, J. Čopíková, E. Šárka (Eds. ), Proceedings of the 9th International Conference on Polysaccharides – Glycoscience, Czech Chemical Society, Prague, 2013, pp.58-63.

[4] M.A. Delesse, Procédé mécanique pour déterminer la composition de roches, C. R. Acad. Sci. (Paris) 25 (1847) 544-545.

[5] A. Rosiwal, Über geometrische Gesteinsanalysen – ein einfacher Weg zur ziffernmässigen Feststellung des Quantitätsverhältnisses der Mineralbestandteile gemengter Gesteine, Verh. K. K. Geol. Reichsanstalt (Vienna) 5/6 (1898) 143-175.

[6] E. Thompson, Quantitative microscopic analysis, J. Geol. 38 (1930) 193-222.

[7] A.A. Glagolev, On the geometrical methods of quantitative mineralogic analysis of rocks, Trans. Inst. Econ. Min. (Moscow) 59 (1933) 1-47.

[8] S.A. Saltykov, Stereometrische Metallographie, Deutscher Verlag für Grundstoffindustrie, Leipzig, (1974).

DOI: 10.1002/mawe.19750060613

[9] R.L. Higginson, C.M. Sellars, Worked Examples in Quantitative Metallography, Maney, London (2003).

[10] ASTM E 112-96, Standard Test Methods for Determining Average Grain Size, American Society for Testing of Materials, West Conshohocken, PA, (1996).

[11] H.E. Exner, Quantitative description of microstructures by image analysis, in: E. Lifshin (Vol. Ed. ), Characterization of Materials Part II = Volume 2b of R.W. Cahn, P. Haasen, E.J. Kramer (Series Eds. ) Materials Science and Technology – A Comprehensive Treatment, Wiley-VCH, Weinheim 2005, pp.281-350.

DOI: 10.1002/crat.2170290603