International Journal of Applied Glass Science最新文献

Experimental high temperature near infrared (NIR) absorption spectra of different SiO₂-based glasses, including lead silicate crystal glass, clear soda lime silicate (SLS) glass and fused silica with low and high OH content, are compared. The more polarizable the glass, the stronger is the increase in the high temperature NIR absorption at wavelengths < 2 µm, involving a red shift of the optical bandgap edge with increasing temperature. It appears that the modified glassy Urbach's rule provides a framework for describing the temperature red shift of the absorption edge of lead silicate crystal glass, even above T_g. This red shift causes a 4–7 times lower Rosseland thermal radiation conductivity of lead crystal glass melts compared to clear SLS glass melts. Low OH fused silica is practically transparent for NIR thermal radiation, also at high temperatures above T_g. Incorporation of water in fused silica increases the NIR absorption in the spectral region 1.7–3.4 µm, for all temperatures. An upper limit of the diffusion coefficient D of water in fused silica was estimated from the time to measure the high temperature NIR spectra of thin (∼2 mm) samples: D < 4 * 10⁻¹⁰ m²/s at temperatures up to around 2000°C.

Based on the current UK decarbonization policy, a general outlook on potential routes for the glass industry to achieve net-zero is discussed and the differentiation during decarbonization is specified. Biomass ash is considered a potential alternative raw material for low-carbon glass manufacture as it is rich in certain advantageous components, chiefly network modifiers. Simple sieving processes were shown to effectively separate impurities such as S, Cl, and C from some biomass ashes according to particle size distribution. The concentration of undesirable impurities decreased with increasing particle size. Morphologies and X-ray diffraction patterns of larger washed biomass ash particles indicated liquid/amorphous phase formation during biomass combustion. The washing of ashes was also shown to be a potential route to purification. A washed bracken ash relevant to both modern and ancient glass production was characterized for comparison. Ultraviolet-visible near-infrared (UV-Vis-near IR) absorption spectra of representative green container glasses produced using biomass ash confirmed that ∼5 wt.% ash in representative glass batches has little impact on the color and redox state of glasses; the redox status of glass produced using >2 mm biomass ash after washing was less reduced than that of glass produced using high levels (>∼9 wt.%) of >2 mm biomass ash after sieving alone, observed via the redox couple Cr³⁺/Cr⁶⁺ by UV-Vis-near IR absorption spectroscopy.

Bismuth-doped phosphosilicate fibers have become the most promising gain medium for O-band amplifiers. Yet scientific challenges on understanding the nature of bismuth active centers (BACs), mechanisms of bismuth cluster formation in the phosphosilicate glass network still exist. It is likely that multiple BACs with different oxidation states in different structural sites all contribute to the broad, nonsymmetric luminescence and gain spectra. Due to the progress in the fundamental understanding of bismuth-doped phosphosilicate glass, various designs of optical amplifiers with decent performances have been demonstrated.

We report the effect of high-repetition rate femtosecond (fs) laser irradiation on structure-terahertz (THz) property relationship for sodium borosilicate glasses. We have used nuclear magnetic resonance (NMR), terahertz time-domain spectroscopy (THz-TDS), and Raman spectroscopy to examine pristine and laser irradiated regions of these glasses to determine and quantify boron speciation, THz refractive index, n(THz), and change (Δn) in n(THz), and spectral, that is, structural, changes due to laser exposure, respectively. Our results suggest that laser irradiation-induced Δn(THz) values are dependent upon the glass composition, structural units, connectivity, and network, for example, the corresponding K- and R-values of the borosilicate glass. Depolymerized glass networks show no changes in NMR B₄ signal, slight changes in Raman spectral changes related to silicate structural units, for example, increase in Q³ tetrahedra with one nonbridging oxygen (nbO) atom, and higher measurable n(THz) and Δn(THz). More polymerized glasses, on the other hand, show changes in NMR B₄ signal, varying degrees of Raman spectral changes in the borate subnetwork and structural units, and lower n(THz) and Δn(THz). The THz refractive index is most sensitive to modifier ions in the glasses, which are directly responsible for nbO formation, glass structure, and network polymerization.

Borosilicate glass has been extensively studied due to its unique properties of solidifying high-level radioactive waste (HLW). However, the responses of borosilicate glass under γ irradiation are not fully understood. In this work, NBS9 and NBS10 glass were irradiated by γ-rays at absorbed doses of 8 kGy and 800 kGy, respectively. Scanning electronic microscopy, energy dispersive X-ray, and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to observe the surface morphology and elemental distributions. The results show that the borosilicate glass remains stable until the absorbed dose was up to 800 kGy. At 800 kGy, the samples precipitate particles composed of Na and O on the surface. Na and B near the surface are significantly reduced under γ-rays irradiation. The results indicate that the effects of γ irradiation on glass vitrification are obvious with certain accumulated doses. The changes of glass structures and elemental distributions by γ-ray irradiation are also dependent on glass compositions.

The paucity of crystallization resistant bioactive glasses with desired biological functions stands as a bottleneck toward the fabrication of various biomedical constructs such as amorphous coatings, scaffolds, and fibers for advanced tissue engineering applications. In this context, a series of borosilicate-based bioactive glasses with a range of compositions: (53.88 − x)SiO₂–21.7Na₂O–21.7CaO–1.7P₂O₅–xB₂O₃ (mol%) where x = 0, 13.47, 22.45, 31.43, and 40.41 were prepared to address such limitation. The glasses were primarily investigated for their potential to be processed into amorphous scaffolds through evaluation of crystallization kinetics, sintering behavior, and viscosity–temperature dependence. The inclusion of B₂O₃ gradually reduces the activation energy of crystallization (E_a), according to the prediction from different kinetic models, whereas Friedman's model-free method unraveled the variation in E_a as crystallization progresses. The crystallization event is further elucidated by obtaining the Avrami parameter (n) and dimensionality (m) through Matusita–Sakka equation. The optimization of the sintering schedule for amorphous scaffold preparation was accomplished by exploiting isothermal prediction from Avrami–Erofeev model. Moreover, viscosity–temperature relationship for the studied glasses was established to identify the processing window for drawing and sintering. This study proposes a comprehensive approach adopting theoretical models to elucidate suitable high-temperature process parameters of bioactive glasses avoiding devitrification.

A recently developed model of the cold cap—the reacting glass batch (melter feeds) floating on molten glass in an electric glass melter—couples heat transfer with the feed-to-glass conversion kinetics. The model allows for determining the distributions of temperature and various properties within the cold cap. In the present study, this model is applied to four melter feeds designed for high-level and low-activity nuclear wastes. Profiles of temperature, conversion degree, cold cap porosity and density, condensed matter velocity, and heating rate were determined using the material properties of the cold cap. Effects of vigorous foaming at the cold cap bottom were considered. Density, thermal conductivity, and glass production rate strongly affect the cold cap thickness and the fraction of undissolved silica entering the melt under the cold cap. The heating rate profile in the cold cap is highly nonlinear, with high heating rates observed in the foam layer.

Due to its extremely high optical uniformity and excellent hot stability, glass–ceramic serves as a key material for ultraprecision imaging of lithography lens, and low-deformation machining is of significance for achieving high-quality surface. Aiming at controllable processing, the annealing of different nanoscratches on glass–ceramic was investigated for revealing the mechanism of material removal and damage repair. The volume change of the single-pass nanoscratch under various normal loads and sliding velocities before and after the annealing was calculated for quantifying the contribution of shear flow, densification, and residual stress to the material removal, respectively. It is found that ductile removal under high normal load or low sliding velocity is dominated by shear flow, thereby improving removal efficiency and reducing machining deformation and defects caused by densification and residual stress. The changes of microstructures beneath the scratches before and after annealing further reveal that the excess processing energy will be absorbed in glass–crystal interface and form micro-cracks on crystal surface. For comparison, brittle removal under variable cycles was simulated by multi-pass nanoscratches, and it reveals that the shear flow ratio raises gradually with the increase of cycle number. These findings provide theoretical guidance for ultraprecision processing of glass–ceramic surfaces.