Valorization of waste borosilicate and flat glass in the production of cordierite glass–ceramics
摘要
Waste borosilicate and flat glass were successfully used as the binder phase in cordierite glass ceramics. Waste glasses were mixed with cordierite powder in an equal 50:50 mass ratio. Optical dilatometry analysis revealed that waste borosilicate glass provided approximately 80 °C lower sintering temperature than waste flat glass. Thermal analysis showed that cristobalite was devitrified from both glasses and crystallization of a new phase in flat glass at 900 °C. The presence of cristobalite was confirmed by XRD, and diopside was also identified as the new phase. The highest density of 2.30 g cm−3 was reached at 900 °C for borosilicate–cordierite glass ceramics, with almost no open porosity. However, the formation of diopside hindered the densification in the flat glass–cordierite system, forming a significant amount of open porosity (10%) even at 950 °C. Results from the dielectric measurement showed that the dielectric constant values were lower than 5.5 for both glass ceramics at all sintering temperatures, loss values were between 0.24 and 0.013 for borosilicate and flat glass-derived glass ceramics, respectively. Low sintering conditions and dielectric constant value of borosilicate added cordierite system show that waste borosilicate glass can be reused in cordierite glass–ceramic systems with high amounts and converted into a more valuable product.