Preparation of Glass-Ceramics Using Low-Pressure Sintering Method for High-Value Utilization of Blast Furnace Slag

To utilize blast furnace slag in an environment friendly, economically efficient and high value-added manner, this study successfully prepared glass-ceramics by directly using high-basicity blast furnace slag (R = 1.26) as raw material through low-pressure sintering method (80 kPa). This study examined the influences of particle size, heat treatment temperature and duration on the sintering densification and crystalline phase transformation of glass-ceramics, employing both fine and coarse glass frits of blast furnace slag. Notably, since the crystallization mode of glass-ceramics was surface crystallization, this crystallization behavior leads to microscale inhomogeneity in coarse powder-based glass-ceramics, ultimately resulting in poor mechanical properties. Furthermore, the glass-ceramic features dendritic merwinite as the transitional phase and globular gehlenite magnesian as the crystalline phase. However, due to the smaller size of the glass frits, the fine powder-based glass-ceramics exhibit a higher degree of homogeneity, and the glass-ceramic sintered at 900 degrees C for 3 h exhibited a porosity of 6.81%, a flexural strength of 116.6 MPa. Furthermore, after being exposed to the solutions of 1 vol.% H2SO4 and 1 wt.% NaOH at room temperature for 650 h, it exhibits an acid resistance of 89.83% and an alkali resistance of 99.99%.