Composition Engineering on the Structure and Transport Properties of CaO–SiO2–P2O5 System: A Computational Insight

In order to support the engineering research on the composition-structure-viscosity of metallurgical slag, molecular dynamics methods are used to systematically study the changes in the microstructure and transport properties of CaO–SiO2–P2O5 ternary system under different ratios of network modifiers to network formers. The results show that with increasing basicity and CaO/P2O5 (C/P) ratio, the average bond lengths of Ca–O and P–O slightly increase, while that of Si–O decreases. The coordination of P–O and Si–O is relatively stable at CN = 4, and the bond angles of O–P–O and O–Si–O are close to those of the standard tetrahedral structure. An increase in proportion of Ca2+ will break the bridge oxygen linkage, and form more non-bridge oxygen linkage and free oxygen, resulting in a decrease in network polymerization. The increase in basicity and C/P ratio significantly increases the proportion of Q0 structures in [SiO4]4− and [PO4]3− tetrahedral, while the sum of the proportion of Q2 + Q3 decreases. The decrease in viscosity is consistent with the decrease in the polymerization degree of the microstructure of the CSP system. With increasing basicity and C/P ratio, the enthalpy values of the CSP system both increase exponentially to varying degrees. In the range of research composition, the order of the influence degree of components on microstructure and viscosity is large in order of CaO > SiO2 > P2O5.