Waste-derived glass-ceramic LTCC materials prepared from waste soda-lime-silicate glass and waste asbestos wool

Abstract

In this work, the harmless-treated asbestos wool is employed to develop waste-derived glass-ceramic LTCC materials with reliable properties. The waste asbestos wool was first fired at 700 °C for 2 h in order to destroy its hazardous fiber structures. Subsequently, glass-ceramic LTCCs with Ca2MgSi2O7 and Na4Ca4Si6O18 phases were successfully synthesized at temperature below 950 °C using waste soda-lime-silicate (SLS) glass and innocuous asbestos wool. In addition, alkaline earth metal oxides MO (M = Mg, Sr, Ba) were doped into the glass-ceramics as a structural modification to improve their dielectric properties. The findings indicate that the formation of CaMgSiO4 crystals in MgO-doped glass-ceramics resulted in an increase in porosity, which consequently deteriorated their dielectric and mechanical qualities. In contrast, doping glass ceramics with 2.5 wt.% SrO or BaO may reduce their sintering temperature and enhance their properties by eliminating coarse grains. In particular, the glass-ceramics doped with 2.5 wt.% BaO possess excellent dielectric properties [εr: 5.71, tanδ: 8.7 × 10−3 at 1 MHz and εr: 7.21, tanδ: 2.77 × 10−3 at 10 GHz], a thermal expansion coefficient of 9.77 × 10−6 /°C (50-300 °C), and a thermal conductivity of 1.16 W/(m·K). The current research can serve as a guide for the development of sustainable and eco-friendly electronic materials and the safe recycling of asbestos waste.