Equilibrium Phase Relations of a SiO(2)–Al(2)O(3)–FeO(x) System with 10 wt % CaO Addition for the Production of Continuous Basalt Fibers

[Image: see text] The continuous basalt fibers have been regarded as one of the most promising green materials in modern society; however, key thermodynamic equilibrium data are insufficient for a better understanding of the crystallization mechanism during the fiber forming process. In the present study, the equilibrium phase relations of the core SiO(2)–Al(2)O(3)–FeO(x) subsystem with fixed 10 wt % CaO were experimentally determined using the classic equilibrium-quenching technique with the scanning electron microscopy–energy-dispersive X-ray spectroscopy analysis. All samples were presented as liquid-silica coexisting within the basalt composition range. The 1300 and 1400 °C isotherms were constructed based on the experimental results. However, significant discrepancies were confirmed with further comparison of the experimental results with FactSage predictions, indicating that more efforts are needed for the optimization of the basalt oxide-related thermodynamic databases.