Effect of acidity coefficient on crystallization behaviour of modified blast furnace slag

Abstract

Crystallization of molten blast furnace slag directly affects the fibre forming rate and stability of fibre. The single hot thermocouple technique was used to investigate the crystallization behaviour of modified blast furnace slag. The results revealed that, with increasing acidity coefficient of modified blast furnace slag during the isothermal process, the initial crystallization temperature of modified blast furnace slag gradually decreased, which were at 1390°C, 1330°C and 1180°C, respectively, and TTT curves changed from double C-type curve to single C-type curve. Through a continuous cooling process, the critical cooling rate decreased from 6°C s⁻¹ to 0.5°C s⁻¹ when the acidity coefficient of modified blast furnace slag increased from 1.05 to 1.40. Based on these findings, we conclude that, the crystal growth rate is controlled by diffusion driving force and undercooling driving force.

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