Effect of Li 2 O on rheological properties,structure,and crystallization of mould flux for high-speed thin-slab continuous casting

Abstract

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.