Viscosity Measurement and Structure Analysis of Cr₂O₃-Bearing CaO-SiO₂-MgO-Al₂O₃ Slags

In this study, the effects of different Cr₂O₃ contents and optical basicity (denoted by Λ) on the viscosity and structure of the Cr₂O₃-bearing CaO-SiO₂-MgO-Al₂O₃ slag were investigated. The viscosities of Cr₂O₃-bearing CaO-SiO₂-MgO-Al₂O₃ slags in the liquid phase below 1823 K (1550 °C) were measured by rotating-cylinder method, and the structures of the slags were examined via Raman spectroscopy. Three different parameters were used to characterize the structures of the slags. The results showed that the viscosity of the slags increased as the Cr₂O₃ content increased, but decreased as Λ increased. The Cr³⁺ ions acted as network formers and increased the degree of polymerization (DOP), and thus, the addition of Cr₂O₃ to the slag increased the number of bridging oxygen atoms in the silicate structural units. Generally, the viscosity increased by increasing DOP. In addition, there was a linear inverse relationship between the viscous activation energy (E _μ ) and Λ. Furthermore, as the Cr₂O₃ content increased, the gradients of the plots of E _μ vs Λ decreased. This indicates that for a slag with a high Cr₂O₃ content, trying to improve the fluidity of the slag by increasing Λ has a limited effect.