Real-time analysis of molten slag, flux, and glass by in situ high-temperature Raman spectroscopy

This work presents a fiber-optic Raman probe specifically designed for real-time, in situ spectral measurements of high-temperature materials such as steelmaking slag, mold flux, and bioactive glass. To withstand extreme environments, the probe incorporates a customized external telescope that increases the working distance, allowing safe operation and reliable data collection at temperatures up to 1500 °C. The technique’s versatility was demonstrated through tests on three high-melting-point samples, revealing significant temperature-dependent molecular structure changes. Raman spectra acquired at both room temperature and elevated temperatures showed key transformations, including the decomposition of carbonate phases and structural shifts in silicate network units (Q⁰, Q¹, Q², Q³). A deconvolution algorithm was employed to resolve overlapping spectral features, confirming the probe’s ability to perform detailed compositional analyses of complex multicomponent melts. In bioactive glass studies, the system effectively monitored temperature-induced phosphate and silicate transitions, highlighting its potential for biomedical materials research. Simultaneously, the analysis of molten slag and flux provided valuable insights into polymerization states that are crucial for steel processing applications. Overall, this high-temperature fiber-optic Raman technique delivers a portable, flexible solution for monitoring the evolving chemistry and structural dynamics of materials under extreme conditions. Its capability for real-time, on-site analysis offers significant benefits for process optimization, quality control, and materials development in the glass, steel, and biomedical industries.