THE INFLUENCE OF SPRAY-DRYING AND FREEZE-DRYING PREPARATION METHODS ON THE CHEMICAL-COMPOSITIONS OF 6 FELDSPATHIC GLASS FORMULATIONS

The successful application of non-conventional methods for preparing glasses for biomedical purposes depends on the ability to control the compositions during the synthesis. Six compositions of eight-component feldspathic glasses were synthesized from colloidal suspensions of silica and alumina with added alkalies and TiO2 by spray- and freeze-drying followed by calcination and fusion. Chemical compositions of the spray- and freeze-dried precursor powders and their final glass compositions were determined by atomic absorption spectrophotometry. A significant correlation was obtained between the solution and powder compositions. The percentage of potassium oxide could not be controlled in the final glass. This is attributed to the structural incompatibilities resulting from the high ratio of alkalies to silica and alumina.