Effect of Li2O on rheological properties, structure, and crystallization of mould flux for high-speed thin-slab continuous casting

The effects of Li2O content on the rheological properties, melt structure, and crystallization behaviour of mould flux for high-speed thin slabs are systematically studied. The results show that when the Li2O content increases from 0.86% to 5.81%, the viscosity of the mould flux decreases, the melting range increases, and the break temperature initially decreases followed by an increase. Further study shows that Li2O can release O2- and depolymerize complex Si-O-Si and Al-O-Al structural units into Si-O and Al-O structures. Simultaneously, Li2O can compensate for the charge between Si4+ and Al3+ by providing Li+ in combination with the mould-flux network structure, making the Si-O-Al structure unit more stable. With the increase in Li2O content in the slag, the crystallization of the mould flux is inhibited at first, and subsequently, it is enhanced. When the Li2O content is 4.33%, the precipitation of Lithium metaaluminate enhances the crystallization behaviour of the mould flux.