International Journal of Applied Glass Science最新文献

Lead–bismuth eutectic (LBE), a promising coolant in advanced nuclear systems, can be activated by neutrons during nuclear reactor operations. The decommissioning of nuclear facilities would generate lead–bismuth (Pb–Bi) alloy-contaminated nuclear waste. The current metallic nuclear waste treatment approach involves remelting followed by cementitious solidification. This increases the waste volume and the risk of radionuclide migration in groundwater. Therefore, this study developed a method for vitrification of Pb–Bi alloy waste. Different amounts of SiO₂ were added at 750–1100°C in the air to turn the simulated LBE waste into glass waste form. The values of the normalized elemental leaching rates (Pb, Bi, Si, Te, and Ni) determined using the 28-day static leaching test were less than .2 g m⁻² d⁻¹ and varied with SiO₂ addition. Furthermore, a three-stage evolution of the glass structure with SiO₂ addition was proposed according to the structural analysis performed using Raman and X-ray photoelectron spectroscopies. The evolution stages were as follows: (i) the stage of heavy metal transition from covalent to ionic heavy metals (7.5 wt% < SiO₂ < 15 wt%), (ii) the stage of increase in bridging oxygen (15 wt% < SiO₂ < 20 wt%), and (iii) the stage of domination of the Si–O network (20 wt% < SiO₂ < 25 wt%). The evolution of the glass structure resulted in varying glass chemical durability. Finally, the glass-forming region of (20–48)PbO–(35–70)Bi₂O₃–(7.5–25)SiO₂ (wt%) and the temperature needed to melt those glasses were determined through the melting test, where radionuclides and toxic heavy metals showed undetectable volatilization during vitrification. Hence, turning LBE waste into glass waste form will be a potential approach for treating Pb–Bi alloy nuclear waste.

Amorphous silica (SiO₂) nanoparticles (NPs) can be applied in environmental pollutant remediation, element removal, and water purification. The content of surface silanol groups in amorphous SiO₂ NPs affects the characteristics of SiO₂ NPs. However, the regulation of surface silanol group content in amorphous SiO₂ NPs below 10 nm remains a challenge. Herein, tunable surface silanol group content was achieved in disperse ultrafine amorphous SiO₂ NPs by controlling calcination and rehydroxylation. The surface silanol group content in amorphous SiO₂ NPs is low (10 nm) and can be tuned from 0% to 2.5%. The amount of naphthalene adsorbed by the SiO₂ NPs increases with increasing surface silanol group content. The surface silanol group content in SiO₂ NPs can be an effective means to tune their adsorption performance and applications.

The preparation of 0.58 Li₂S + 0.315 SiS₂ + 0.105 LiPO₃ glass, and the impacts of polysulfide and P^1P defect structure impurities on the glass transition temperature (T_g), crystallization temperature (T_c), working range (ΔT≡ T_c - T_g), fragility index, and the Raman spectra were evaluated using statistical analysis. In this study, 33 samples of this glass composition were synthesized through melt-quenching. Thermal analysis was conducted to determine the glass transition temperature, crystallization temperature, working range, and fragility index through differential scanning calorimetry. The quantity of the impurities described above was determined through Raman spectroscopy peak analysis. Elemental sulfur was doped into a glass to quantify the wt% sulfur content in the glasses. Linear regression analysis was conducted to determine the impact of polysulfide impurities and P^1P defect impurities on the thermal properties. Polysulfide impurities were found to decrease the T_g at rate of nearly 12°C per 1 wt% increase in sulfur concentration. The sulfur concentration does not have a statistically significant impact on the other properties (α = 0.05). The P^1P defect structure appears to decrease the resistance to crystallization of the glass by measurably decreasing the working range of the glasses, but further study is necessary to fully quantify and determine this.

IPS e.max Press, a lithium disilicate-based glass ceramic, is renowned in dental restorations for its mechanical strength and aesthetic appeal. This study delves into its behavior within oral environments, employing electrochemical and surface analysis techniques. By utilizing cyclic polarization curves and impedance spectroscopy, we evaluated its degradation resistance. Surface morphology, composition, and crystal stability were explored through scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD) analysis. The glass ceramic exhibited robust resistance to localized degradation across all tested electrolytes. The degradation potential (E_corr) varied with time and pH, indicating electrolyte influence. SEM/EDX affirmed oxide layer formation, while XRD confirmed a stable structure. While showcasing favorable resistance in saliva, citric acid, and lactic acid, IPS e.max Press demonstrated susceptibility to acetic acid. This comprehensive analysis enhances our understanding, providing valuable insights for the development of durable dental materials through a combination of electrochemical analysis and surface characterization.

Globally, the operational energy usage in buildings accounts for about 30% of the final energy consumption and 26% of the energy-related emissions. In 2022, the building sector recorded 132 EJ in energy usage and 9.8 Gt of CO₂ emissions. Energy-intensive space heating and air conditioning play a significant role in these statistics, with slightly over half of US home energy usage attributed to them. Thus, energy-efficient buildings, incorporating effective thermal insulation, are essential for addressing climate change. Fiberglass is the dominant insulation material used in US homes, comprising about 71% of installations. The paper discusses the fundamental aspects of heat transfer in fibrous insulation in general and fiberglass insulation in particular. The thermal performance of a fibrous insulation is characterized by an effective thermal conductivity, which combines conductive and radiative terms. The former represents heat conduction through the gas–fiber network and the latter the absorption and the scattering of thermal radiation by the fibers. The paper describes mathematical formulations for these terms and presents results showing the dependence of the effective conductivity on insulation density, fiber diameter, and temperature. The predicted values of the effective conductivity are found to be in good agreement with the measured ones.

During glass production, phase separation can result in the formation of suspended liquid droplets, which can cause changes in the system rheology. In nuclear waste vitrification context, some new glassy matrices may present this phase separation matter, but the mechanisms controlling the viscosity changes have not yet been determined. Here, we measure the viscosity of a sodium-borosilicate melt containing dissolved MoO₃ at different temperatures and subject to different applied shear strain rates. We observe that (i) the viscosity increases sharply as the temperature decreases and (ii) at any constant temperature below 1000°C, the system presents non-Newtonian response. Using transmission electron microscope observations coupled with viscosity calculations, we interpret the cause of the observed changes as the result of phase separation. We show that the viscosity increase on cooling is in excess of the predicted temperature dependence for a homogeneous melt of the starting composition. The increase is due to the formation of a second phase and is controlled by chemical and structural modifications of the matrix during the loss of the elements that form the droplets. This work provides insights into the rheology of a system composed of two composition sets due to a miscibility gap.

Infrared graded-index (GRIN) lenses are desirable for realizing miniaturization and lightweight of infrared imaging systems. Chalcogenide glasses have excellent infrared transparency, good rheological property, and large refractive index range, making them preferred materials for infrared GRIN lenses. In this work, aiming to find thermally matched chalcogenide compositions with high refractive index contrast for preparing GRIN glasses by the stacking diffusion approach, we investigated characteristic temperature, thermal expansion coefficient and refractive index of Ge-As-Se and Ge-As-Se-Te glasses, optimized the glass compositions, and evaluated the feasibility of preparing GRIN glass using the optimized chalcogenide glass powders. It is found that Ge₂₀As₂₀Se₂₀Te₄₀ and Ge₁₂As₂₂Se₆₆ glasses have similar softening temperature (247°C vs. 249°C), reasonably difference of thermal expansion coefficient (3.8 ppm/K), and large refractive index contrast (∼.48). The glass powders with composition xGe₂₀As₂₀Se₂₀Te₄₀-(1-x) Ge₁₂As₂₂Se₆₆ can be hot-pressed into glass disks with good transmittance at the same temperature and pressure. Graded refractive index profile is formed near the interface between the layers after the co-pressed glass is thermally treated. These results demonstrate the prospect of the compositions for preparing infrared GRIN glasses.

Glass sagging is a subsequent process to the CVD process used for large-size and high-purity silica glass synthesis. Physical phenomena taking place in this process are complicated which need an in-depth understanding for better control. In this paper, a comprehensive study is conducted for the sagging process using a level-set and enthalpy-porosity coupled model. With this model, the deforming behavior of glass ingot and evolution of OH uniformly distributed region are well predicted. Then, two performance indices (the effective yield rate and maximum extension radius of OH uniformly distributed region) are proposed based on different applications, and important factors, including geometrical parameters (the ingot initial length, crucible diameter and pedestal height) and operating parameter (the heater power allocation scheme), are explored for their effects on the two indices. The orthogonal test design method is adopted to further determine the collective effects of the four factors. According to the range analysis results, the initial ingot length has the greatest effect, while the crucible diameter has the least effect on the effective yield rate; and for the maximum extension radius, the crucible diameter becomes the major factor, while the pedestal height is the most insensitive factor. The corresponding optimal schemes are proposed for the two indices finally, which are believed to provide useful guidance for improving the sagging process.

The Gladstone–Dale relation is among one of the many formulae put forward in the 19th century to try and relate the index of refraction and density of a material. Compared to other relations of the time, the Gladstone–Dale relation is advantageous as it is relatively simple to use. It has been suggested that the Gladstone–Dale relation can be used as a reliable way to calculate the index of refraction for oxide glasses because of the additive nature of the relation, making it ideal for glass compositions. The reliability of the Gladstone–Dale relation with regards to its use in glass science has been explored. Various oxide glass systems that use different network formers, conditional network formers, modifying oxides, and dopants have been obtained from the literature to determine the reliability of the relation with regards to index-of-refraction calculations. The benefits and faults of the relation are discussed, and it was found that it is not universally applicable for all glass compositions.

Nucleation behaviors in glasses/supercooled liquids (SCLs) such as lithium disilicate Li₂O–2SiO₂, cordierite Mg₂Al₄Si₅O₁₈, fresnoite Ba₂TiSi₂O₈, and K₂O–Nb₂O₅–GeO₂/TeO₂ glasses were analyzed and discussed from the interfacial energy γ at SCL–nucleus interfaces and nanoscale composition fluctuations. Based on the fragility concept for SCLs and the intrinsic origin of γ, the magnitude order of γ(fragile SCL) < γ(strong SCL) was proposed to be a crucial guide for an understanding of high homogeneous nucleation rates and prominent nanocrystallization. The role of nucleating agent TiO₂/ZrO₂ in accelerating the nucleation rate in cordierite-based and β-spodumene-type Li₂O–Al₂O₃–SiO₂-based glasses was discussed from the new perspective of γ(homoepitaxial-like nucleation) < γ(heteroepitaxial-like nucleation). Ferroelectric nanocrystals such as Sr_xBa_1–xNb₂O₆ in borate glasses and fluoride nanocrystals such as CaF₂ are also well understood from the proposed guidelines. The present article provides a new perspective for nucleation in glasses/SCLs, contributing to the comprehensive composition design of new innovative glass-ceramics.