The influence of local raw materials on phase crystallization of Nepheline-Pyroxene Glass-ceramics

A series of local raw materials using different nucleating agents like Tio2, LiF and Cr2O3, have been studied to examine the crystallization phases of Nepheline-Pyroxeneglass-ceramic. The DTA traces of the glasses showed that the crystallization reactions occurred at a temperature range of 559-715 degree Celsius. TiO2 rapidly crystallized the glass sample and the nepheline (K AlSi3O8) and titanite (Ca TiSiO5) phases. The nucleation of LiF in glass samples revealed the formation of wollastonite (CaSiO3), akermanite (Ca2 MgSi2O7) and Diopside Ca (MgFeAl) Si. Cr2O3 helped in the formation of diopside on the crystallization of nepheline (KNa) AlSiO4, diopside Ca (MgFeAl) Si, akermanite (Ca2 MgSi2O7) and gehlenite (Ca2Al2SiO7) phases. The thermal coefficient values of sample heat treated at 1000C/30h progressively increased from 50.7x10 C when different nucleating agents were added. It is found that different type of the nucleating agents, CaO/MgO content and heat treatment affected the mineral constitution of the crystalline material formed and their thermal coefficients. (author)