Dynamic high‐temperature crystallization and processing properties of industrial soda–lime–silica glasses

In situ dynamic crystallization properties of industrial soda–lime–silica glasses at realistic processing temperatures have not yet been explored. Hence, we collected in situ high‐temperature X‐ray diffraction patterns for 10 different industrially manufactured soda–lime–silica glasses as a function of temperature between 900 and 1200°C to investigate the phase relations in their devitrified melts. The high‐temperature X‐ray diffraction study was complemented by measuring the liquidus temperature of those glasses by the temperature gradient technique. A multiple variable regression analysis was applied to the experimental and modeled data to produce a predictive model for the rate of solidification and liquidus temperature based on glass composition. We have demonstrated that forms of quartz (SiO2) and Na2CaSiO4, which are not traditionally identified by room temperature X‐ray diffraction studies of commercial soda–lime–silica glasses, are the dominant crystalline phases at 800 and 900°C. Upon further heating, different forms of cristobalite become the primary phase field prior to the formation of X‐ray amorphous melts, irrespective of the glass composition. Sporadic unidentified as well as high‐temperature stable SiO2 polymorphs that are not recoverable to room temperature were also observed. In contrast to the literature, wollastonite (CaSiO3) and devitrite (Na2Ca3Si6O16), which are the main predictor variables in previously developed liquidus temperature models, were not observed prior to the formation of X‐ray amorphous glass melts, and hence their influence on liquidus temperature may be questionable. It was also found that the difference between glass processing and liquidus temperatures can be excessively high, and such large temperature differences can potentially be exploited and reduced to enable decreases in melting or processing temperatures of industrial soda–lime–silica glass melts.