Matthew Rowles and Brian O'Connor. Materials Research Group, Department of Applied Physics, Curtin University of. Technology, GPO Box U1987, Perth, WA ...
ZEOLITE FORMATION IN THE SYNTHESIS OF ALUMINOSILICATE INORGANIC POLYMERS: COMBINING THE POWER OF THE PDF AND SYNCHROTRON DATA Matthew Rowles and Brian O’Connor Materials Research Group, Department of Applied Physics, Curtin University of Technology, GPO Box U1987, Perth, WA 6845. Australia
In recent years, aluminosilicate inorganic polymers (AIPs), also known as geopolymers [1], have received increasing attention. AIPs ideally consist of an amorphous, three-dimensional structure resulting from the polymerisation of aluminosilicate monomers in an alkaline solution. Applications include replacing Portland cement in concrete manufacture, toxic waste immobilisation and the synthesis of structural ceramics at low temperatures. Synthesis may be done under mild conditions, with processing temperatures well below 100 °C. To transform AIPs into highly dense structural ceramic materials, the cured materials can be rapidly fired to 1000 - 1200 °C. This study follows that of the authors on chemical optimisation of the compressive strength of AIPs [2]. Synchrotron radiation diffraction (SRD) analysis of materials has revealed the presence of zeolites at AIP compositions differing substantially from the optimum composition for compressive strength maximisation, ca. molar ratios Si:Al = 2.5, Na:Al = 1.25. Identification of the ordered components with the PDF has revealed the presence of zeolites A, X and Y, as well as several ‘unnamed’ zeolites. The conditions for zeolite synthesis from coal fly ash have been reported as requiring high temperatures and pressures [3], whereas this study has shown that this is not necessarily the case. Synchrotron powder data were acquired using the Australian National Beamline Facility at the Photon Factory, Tsukuba, Japan – Beamline 20A. References
1. Davidovits, J. (1989). Geopolymers and geopolymeric materials, J Therm. Anal, Vol 35, 429-441. 2. Rowles, M. and O’Connor, B. (2003). Chemical optimisation of the compressive strength of aluminosilicate geopolymers synthesised by sodium silicate activation of metakaolinite. J Mater. Chem., Vol 13, 1161-1165. 3. Murayama, N., Yamamoto, H. and Shibata, J. (2002). Zeolite synthesis from coal fly ash by hydrothermal reaction using various alkali sources. J. Chem. Technol. Biotechnol., Vol 77, 280-286.
