ИСТИНА

Basalt glasses belong to the iron-rich alumino-slicate systems. Due to their high thermal stability, chemical and mechanical resistance and low cost there are many types of materials that are manufactured on their base: rock (mineral or stone) wool, glass-ceramics and continuous fibers (BCF). The object of the study were basalt glass and fibers with follows composition: in wt% 55.6 % SiO2, 1.1% TiO2, 15.8 % Al2O3, 10.5 % FeO + Fe2O3, 3.7 % MgO, 9.2 % CaO, 2.2 % Na2O, 1.8 % K2O (Sil’tsevskoe deposit, Carpathians, Ukraine). Using methodology based on DSC data analysis it was shown that in contrast to the bulk glass the crystallization in continuous fibers begins on the surface. It was determined that activation energy of crystal growth (Ec) and Avrami parameter (n) of BCF were 33.6±0.2 and 1.0±0.1 respectively A phase transformations order was determined by quantitative phase analysis of basalt glass and fibers samples that was annealed at 700, 800, 900 and 1000 °C during 6, 12 and 24 hours. Using SEM and Mossbauer spectroscopy methods it was suggested the mechanism of crystallization of basalt glasses and fibers on their base. Crystallization in basalt glasses and fibers begins with liquid immiscibility. One of the liquid phases (iron-rich phase) promotes formation of a first crystal phase with spinel structure (spinelide). With a following thermal treatment, a monoclinic pyroxene solid solution precipitates onto the spinel crystals, which act as nuclei for crystallization.