TIME-RESOLVED FRACTOLUMINESCENCE CHARACTERIZATION IN SODA-LIME GLASS VIA NEAR HYPERVELOCITY KINETIC IMPACT FAST FRACTURE

Abstract

Low iron soda-lime glass (SLG) is a low-cost, bulk manufactured, commercially available off-the-shelf glass with high quality clarity and transparency, and superior percentage visible light transmittance with color that is resistant to yellowing over time. SLG has been used for various military applications and for the past 15 years, has been studied and viewed with borosilicate as ideal choices of glass for transparent armor applications. Prior research has demonstrated that SLG experiences fractoluminescence (FL), or the emission of photons during rapid dynamic fracture. Contested theories for the cause of FL include thermal origins, relaxation of non-bridging oxygen hole centers, and even Cherenkov radiation. This thesis investigated whether FL can be observed in SLG via near-hypervelocity kinetic impact utilizing a 40 mm powder gun. Target systems include both planar impact for standard diagnostics and gap-sealed cylindrical chambers to both minimize noise from external light and enable post-test analysis of impacted glass. A comparative analysis was conducted against borosilicate glass, which has no FL properties. Unique FL emission bands were observed during near hypervelocity impact of SLG at 423 nm (2.9 eV) at the frame of impact and 555 nm (2.2 eV) for the duration of fracture. Using a grey body spectral exitance emission spectra fit, a fracture emission temperature of 3200 K was calculated that does not support the theory of Cherenkov radiation as the cause of FL.