Effect of Ce4+-modified amorphous SiO2 on phase transformation towards α-cordierite

The sintering temperature of cordierite ceramic is dependent on the transformation temperature to alpha-cordierite. In the present work, the effect of Ce4+-modified amorphous SiO2 on the transformation behavior of the ceramics were studied using the techniques such as X-ray Diffraction, Differential Thermal Analysis (DTA) and Infrared Spectrometry so as to decrease the sintering temperature. Experimental results show that, Ce4+-free amorphous SiO2 has no effect on the transformation, while Ce4+-modified amorphous SiO2 can obviously decrease the onset temperature. This is correlated to that Ce4+ addition, which makes the structure of tetragonal SiO2 loosened and decreases the transformation temperature Of SiO2 to tetragonal and so, improves the condition of solid solution of Al3+ and Mg2+ into tetragonal SiO2. Moreover, Ce4+ addition has little effect on the conversion rate, because it cannot effectively promote the diffusion of Al3+ and Mg2+ into tetragonal SiO2. (C) 2002 Elsevier Science B.V. All rights reserved.