Abstract
Alkoxy-derived cordierite gels were synthesized from tetraethylorthosilicate (TEOS), aluminum isopropoxide (Al(OPr i )3), and magnesium ethoxide (Mg(OEt)2). TEOS was partially hydrolyzed at molar ratios H2O/TEOS = 1.2, in the presence of hydrochloric acid as a catalyst, HCl/TEOS = 0.1. Aluminum and magnesium alkoxides were added successively or as a double alkoxide. Phase transformations occurring in the gel were studied by differential thermal analysis, x-ray diffractometry, and Fourier-transform infrared spectroscopy. In all cases, μ-cordierite crystallized at similar temperatures (950–1000°C) with small amounts of spinel, which confirms dominant influence of the optimal conditions for partial hydrolysis of TEOS on the gels homogeneity. The transformation of μ- into α-cordierite began at about 1100°C. Broadening of diffraction peaks and appearance of new bands in the FT IR spectra confirmed the transformation of α- into modulated β-cordierite at temperatures above 1300°C. Differential thermal analysis under nonisothermal conditions also proved homogeneous nucleation with constant rate and three-dimensional crystallite growth during μ-cordierite crystallization. The overall activation energy of the crystallization of μ-cordierite is 580 ± 81 kJ/mol.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
