Intralaboratory calibration of the DSC shift-factor approach for melt viscosity determination: A case study on lead metasilicate glass

The differential scanning calorimetry (DSC) shift-factor approach provides a powerful tool for determining the shear viscosity of glass-forming melts across several orders of magnitude. Its accuracy, however, depends on the proper determination of the shift factor (K) – a process of establishing K by linking DSC data to viscometry, herein termed 'intralaboratory calibration' – which then connects the fictive temperature to viscosity. In this study, we determine K for lead metasilicate (PbSiO3) glass by integrating conventional DSC, flash DSC, and ball penetration viscometry measurements on samples obtained from the same batch. Raman spectroscopy was employed to verify sample integrity before and after measurements. Our results confirm the applicability of the DSC shift-factor approach, yielding shift factors of Konset = 10.92 ± 0.04, Kpeak = 9.41 ± 0.08, and Kendset = 8.71 ± 0.07. These findings underscore the importance of intralaboratory calibration in refining the DSC-based method for accurate viscosity determination in glass-forming systems.