Melting behaviour of glasses in the SrO-MgO-ZrO2-SiO2 system

Abstract

In the SrO-MgO-ZrO2-SiO2 system a large range of compositions with 60, 55, 50, 45, 40 and 35 wt% silica has been thoroughly investigated The effect of silica and other constituents on melting, annealing and colour variations are reported here In the case of some glasses containing 60,wt% silica the high level of viscosity caused pouring difficulties although a very high melting temperature of 1650 degrees C was used. Both ZrO2 and SiO2 increased the viscosity but when the silica content decreased down to 45 or 40 wt%, glass melts showed less viscosity at the lowest melting temperatures used (such as 1400 degrees C). Glass products having only 35 wt% silica have not been achieved although a melting temperature of 1480 degrees C was sufficient to have melts,vith a low viscosity. From this melt some kind of brittle material,was formed during pouring. According to x-ray diffraction (XRD) studies only monolithic (m)-ZrO2 peaks have been observed the rest being amorphous phases. After all these investigations over melting behaviour it has been found that the SrO-MgO-ZrOrSiO(2) quaternary system has a very large melting region (between 60-40 wt% silica).