Composition and structural evolution of basalt melt during homogenization

During fabrication of basalt fiber, one critical procedure is the homogenization of melt, which typically lasts over 10 h at ∼1500°C. However, the changes in composition and structure of basalt melt during the homogenization process remain poorly understood. In this study, basalt melts were held at 1550°C for various durations and then rapidly quenched to form basalt glasses, enabling analyses of their compositional and structural evolution. Compositions of glasses were analyzed using chemical titration, energy dispersive X-ray, and inductively coupled plasma optical emission spectrometry methods. The crystallization process was examined through differential scanning calorimetry analysis, while structural evolution was investigated via Raman and X-ray photoelectron spectroscopy O1s spectroscopy. The results showed that the primary composition change during homogenization was the valence transition from Fe³⁺ to Fe²⁺. The O^2- produced with the valence transition gradually converted the Q³ units into the Q² units. The homogenization process reached the stability of composition and structure after 8 h. A high proportion of Q² units will align along the fiber axis, enhancing the melt spinnability and reinforcing the basalt fiber.