Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10624877 | Ceramics International | 2014 | 9 Pages |
Abstract
The preceramic mixtures appropriate to the composition of cordierite are composed of talc, kaolinite and vermiculite (Ver), and/or organovermiculite (Ver-org) as a pore-forming agent. The preceramic mixtures for sintering at 1300 °C were prepared in two different ways, loosely in crucibles and compressed into pellets. Structural characterization of cordierite/steatite ceramic was performed using X-ray powder diffraction (XRD), FTIR spectroscopy, scanning electron microscopy analysis and porosity measurement. The ceramic samples showed (1) bimodal meso-macropore size distribution and unimodal macropore size distribution, when the preceramic mixtures included Ver and Ver-org, respectively, and (2) higher porosity when sintering mixtures occurred in crucibles in comparison with pellets. The XRD patterns and quantitative XRD phase analysis revealed cordierite/steatite ceramics in the composition of indialite (IND) and two orthorhombic forms of enstatite: protoenstatite (PEN) and orthoenstatite (OREN). All cordierite/steatite samples contained a greater amount of PEN than OREN and a slightly higher quantity of IND when sintered in crucibles compare to pellets. The ceramic samples prepared from the preceramic mixtures with twice the amount of Ver-org contained a high quantity of IND (91 vol%), PEN (about 9 vol%) and no OREN. The unit cell parameter c in comparison with the pure IND was about 0.001-0.003 nm shorter at all INDs. The pore-forming Ver-org supports structural substitution of cations during crystallization of IND with the substitution Ca0.50Mg1.50-Ca0.25Mg1.75. The IR spectra in the 400-1600 cmâ1 region confirmed the presence of cordierite and steatite.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
M. ValáÅ¡ková, J. Zdrálková, J. Tokarský, G. Simha Martynková, M. Ritz, S. Å tudentová,