Sol-gel synthesis of a LAS glass ceramics and influence of additives on a phase transformation and crystallization.

Abstract

Course of synthesis of Li2O – Al2O3 – SiO2 (LAS) ceramic via sol – gel process made precursor was investigated. Powder precursor containing LAS components in molar ratio 1:1:4 were prepared by polycondensation technique in aqueous medium using lithium chloride (LiCl), hydrated aluminium nitrate (Al(NO3)39H2O) and silica sol (tosil), respectively. Heated sol was transformed into gel. The resulting gel was dried at temperature 105 °C and xerogel was next calcinated at 750°C. Further was evaluated influence of sintering additives (MgO, ZnO, Ca5(PO4)3OH) on the length of sintering interval. All of them have been stabilized spodumene in the solid solution. The properties of ceramic body prepared by sintering of precursor and grinded Li2CO2, Al2O3 a SiO2 powders were compared. Simultaneous thermogravimety and differential thermal analysis (TG-DTA), X-ray diffractions and heating microscopy were used to study sintering process of LAS ceramic