Crystallization kinetics of glass–ceramics prepared from high-carbon ferrochromium slag

Abstract Glass-ceramics were successfully prepared from high-carbon ferrochromium slag (HCFS), and the optimum heat-treatment conditions were determined by analysis of the crystallization kinetics. The parent glass is first prepared in five different ratios of HCFS to waste glass (R(H/W)), then heat-treated separately at five heating rates (α) and monitored by DSC. As the value of R(H/W) increases from 0.60 to 1.67, the crystallization activation energy (E c ) decreases from 253.41 to 183.52 kJ/mol. The nucleation and crystallization temperatures decrease from 641.7 to 612.2 °C, and 822.8–814.7 °C, respectively, and both are lower than that of ordinary metallurgy slag. These results indicate that using HCFS to produce glass-ceramics both facilitates its production and saves energy. The crystallization index (n) increases with increasing R(H/W), and when n exceeds 2.32, all of the parent glass samples with different R(H/W) crystallize as bulk crystallization. The crystallization index (n) increases as the heating rate α decreases from 25 to 5 °C/min, with a maximum value of n (5.94) observed when α is 5 °C/min. These conditions produce the largest aspect ratio and highest density of the crystal grain in the glass-ceramics. Our results show the optimal HCFS-based glass-ceramics were obtained with a R(H/W) of 1.29 and a 5 °C/min heating rate; under those conditions, the parent glass nucleates and crystalizes at 627.1 and 820.9 °C, respectively.