Sol-gel synthesis and crystallization of aluminum borosilicate

The Al2O3-B2O3-SiO2 System is explored; in the composition Al16B6Si2O37, fo r the effect of the preparation conditions on the properties of the final p roduct. The sol-gel method was tried to prepare this composition both in an aqueous and non aqueous media. The crystalline phases developed were found to be mullite, Al4B2O9 and B-mullite (Al18B4O33) in addition to some amorp hous compositions of the aluminum borosilicate system rather than a pure cr ystalline Al16B6Si2O37 phase. XRD and FT-IR showed that the gel prepared in non-aqueous medium could be thermally treated giving some crystalline spec ies at lower temperatures than the gel formed in aqueous medium. In contras t to this result, DTA of the former product show an exothermic change at hi gher temperature than that of the later. This change could be attributed pr obably to an oxidation rather than to crystallization. (C) 2001 Elsevier Sc ience Ltd and Techna S.r.l. All rights reserved.