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|Type:||Artigo de periódico|
|Title:||Study Of The Sol-gel Processing Of Glass-ceramic Powders In The Sio2-al2o3-cao-caf2 System. I. Effect Of Powder Composition On Gel Time And Temperature|
|Abstract:||To determine the effect of powder composition on gel time and temperature, 12 sol-gel derived glasses in the SiO2-Al2O3-CaO-CaF2 system with different compositions chosen from a 21-point design generated through the mixture design technique were synthesised. Gel times varied from a few seconds at room temperature to a few hours at 75°C, as the fluoride content was increased. The longest gel times were observed for those compositions with the largest amounts of aluminium regardless of their fluoride ion concentrations. As the fluoride ion concentration was increased, the effect of both silicon and calcium concentrations on the gel times became gradually smaller. Accordingly, gel temperatures were found to vary from 75°C, for glasses with low fluoride content (3 mol% as H2SiF6), to room temperature, for those with higher fluoride contents (9 and 15 mol% as H2SiF6). Experimental data on the compositional dependence of gel time for the system studied was fitted using a quadratic model, with a square multiple correlation coefficient of 0.9962.|
|Editor:||Elsevier Science Publishers B.V., Amsterdam, Netherlands|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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