Preparation and crystallization of glasses in the system tetrasilicic mica-fluorapatite-diopside

The production of glasses whose composition ranged between tetrasilicic mica and fluorapatite-diopsite 50/50 (in wt.%) was investigated. Glass-ceramics were obtained by both bulk crystallization and sintering of glass powder compacts. The experimental results showed that increasing amount of apatite and diopsite components in the ternary system until 50% mica content generally caused decrease of melting temperature and increasing stability of glass against spontaneous crystallization during cooling after casting. Liquid immiscibility, whose features depend on the particular glass composition, characterized all the investigated glasses but it was more pronounced in the glasses with higher amount of apatite and diopsite components. The investigated glasses are preferably crystallized in bulk form between 700 and 900 °C, resulting in formation of different combinations between mica, fluorapatite and diopsite, depending on the particular composition. The obtained glass-ceramics exhibited attractive aesthetics, structural integrity and dense structure.