Crystallization and thermo-mechanical properties of Li2O-ZnO-CaO-SiO2 glass-ceramics with In2O3 and Fe2O3 additives

Abstract

Li2O-ZnO-CaO-SiO2 based glasses were prepared by the conventional melting technique and subsequently converted to glass-ceramics by controlled crystallization. The nucleation and crystallization temperatures were determined by differential thermal analysis (DTA). The effects of adding In2O3 and Fe2O3 addition on the crystallization behaviour and thermo-mechanical properties of the prepared glass-ceramics were investigated. A study on the microstructure, close to the internal phases of the resulting glass-ceramics, was followed by using scanning electron microscope (SEM). The dilatometric thermal expansion and Vickers? microhardness of the crystalline products were also evaluated. The crystalline phases that can be found in the resulting glass-ceramics, identified by X-ray diffraction (XRD) analysis, are ?-quartz-[SiO2], lithium zinc silicate-[Li2ZnSiO4], lithium disilicate-[Li2Si2O5], wollastonite-[CaSiO3], wollastonite containing iron, ferrobustamite-[(Ca0.79Fe0.21)SiO3], and lithium indium silicate of pyroxene type-[LiInSi2O6]. Average thermal expansion coefficient (in the temperature range 25-700?C) decreased from 191?10-7 1/?C to 115?10-7 1/?C and the Vickers? microhardness increased from 3.56 to 5.44GPa with the increase of In2O3 and Fe2O3 contents in the glass-ceramics. The changes in the obtained expansion coefficient and microhardness were due to the formation of different phases which in turn influenced the rigidity/bonding and microstructure in the resultant glass-ceramics.