International Journal of Applied Glass Science最新文献

As glass batch is charged into an electric melter, a cold cap forms on the glass melt surface. Heat transfer to the cold cap from the molten glass below and the melter atmosphere above determines the melting rate. A mathematical model of the cold cap and the experimental kinetic data of the feed-to-glass conversion that were collected for several simulated low-activity and high-level waste melter feeds allowed us to develop relationships between the internal structure of the cold cap, its properties, its thickness, and the internal heat transfer. This contribution shows the distribution of major crystalline phases and the cumulative evolution of gases within the cold cap. It also examines the temperature, conversion degree, and heating rate the melter feed is experiencing during the passage through the cold cap and their effects on the cold-cap bottom temperature and morphology, which are important for the computational fluid dynamics simulations of melters.

Herein, the crystallization behavior of a Li₂O–Al₂O₃–SiO₂ (LAS) glass system with the addition of ZrO₂ and SnO₂ as nucleating agents was investigated using X-ray diffraction, differential scanning calorimetry, four-dimensional scanning transmission electron microscopy, and X-ray absorption fine-structure measurements. At lower heat-treatment temperatures, the addition of ZrO₂ and SnO₂ afforded a ZrSnO₄ solid solution (SS), whereas at higher heat-treatment temperatures, the ZrSnO₄ SS decomposed, affording tetragonal ZrO₂ and tetragonal SnO₂. LAS-based crystalline phases, such as β-quartz and β-spodumene phases SS, were formed after the formation of the ZrSnO₄ SS. ZrSnO₄ SS particles a few nanometers in size were present in contact with the β-quartz SS particles a few dozen nanometers in size. This suggests that the ZrSnO₄ SS served as a crystal nucleus for the β-quartz SS, promoting its growth.

Rendering transparent materials extreme wettability, for example, superhydrophobicity or superhydrophilicity, has received considerable attention during the past decades. While fabrication of superhydrophobic glass with high processing efficiency and low production cost has always been a challenge. In this work, a laser-based surface functionalization process that combines ultraviolet (UV) nanosecond laser texturing and silicone oil-assisted heat treatment was employed to render glass superhydrophobicity with high process throughput. The wettability transition is attributed to the combined effects of laser texturing that induces hierarchical surface micro/nanostructures and silicone oil-assisted heat treatment that alters surface chemistry and lowers surface energy. The surface transmittance of the laser-based surface functionalized glass samples in the visible spectrum was experimentally measured and analyzed. The laser-based surface functionalized glass sample also exhibited long-term stability in air, mechanical robustness and good self-cleaning property. More importantly, the developed process shows both high process efficiency and cost effectiveness and has potential for applications where superhydrophobic glass is required.

The influence of Al₂O₃ addition on the precipitation of NaYF₄ crystals in oxyfluoride glasses has been investigated through the thermal, structural, and optical characterization of the parent glasses and corresponding glass–ceramics (GCs). The high-resolution transmission electron microscopy analysis of the GC with 5 mol% of Al₂O₃ shows the presence of phase-separated droplets about 69 nm in size containing several NaYF₄ nanocrystals with the diameter of about 10–15 nm. Raman and magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy were used to examine the structural changes attributed to the addition of Al₂O₃. The ¹⁹F MAS-NMR analysis indicated that fluorine atoms are present in different chemical environments (Na–F, Na–Si–F, Na–Al–F, and NaYF₄). The increasing amount of Al₂O₃ reduces the crystallization of NaYF₄ phase due to the increased fraction of fluorine bound in Na–Al–F environments. The visible luminescence investigation of the glasses and GCs demonstrated that the intensity of Er³⁺ ions emission transitions in the GCs was higher than that of the parent glass. This difference was attributed to the presence of Er³⁺ ions bound in NaYF₄ crystalline phase. Further evidence that the Er³⁺ ions were present in NaYF₄ phase was provided by the fact that the excited level Er³⁺:⁴S_3/2 lifetime was increased in GCs as compared to parent glass.

The control of humidity between certain limits is essential to avoid the alteration of historical objects, such as unstable historical glasses. However, the usual limits can be altered due to the presence of volatile organic compounds. This work presents the results of the exposure of soda, potash, and mixed-alkali silicate glasses to neutral and acidic (formic) atmospheres with ∼30%, ∼70%, and ∼100% relative humidity. The hygroscopic capacity of the glass was analyzed by gravimetry, and the surface alteration was evaluated by infrared spectroscopy, optical microscopy, and ion chromatography. In all glasses, the alteration begins with alkali ions’ lixiviation followed by the silica network's hydrolytic attack. The results showed that soda and mixed-alkali silicate glasses exhibit similar behavior, while the potash-lime one experienced the fastest degradation due to its composition. Results also confirmed that high humidity increased the alteration rate causing a higher hygroscopicity and reactivity of glasses. Finally, acidic environments promoted the ion-exchange reaction at high humidity, accelerating the lixiviation of alkaline ions and promoting the diffusion of water into the glass network.

In France, high-activity level wastes resulting from nuclear fission are conditioned in a homogeneous sodium-aluminoborosilicate glass by high-temperature vitrification. The tolerance of even a small fraction of crystals could enable an increase in the waste loadings, in addition to promoting process flexibility. If the waste loading were to be increased in French nuclear glass, cerianite (CeO₂) crystals could precipitate. In this study, we investigated the cerianite crystallization in a simplified nuclear glass melt at different temperatures, Ce₂O₃ wt%, and shear conditions. Furthermore, the evolution of the viscosity along with cerianite precipitation was followed. It was found that Ce₂O₃ is highly soluble in the glass melt, as even for a Ce₂O₃ wt% as high as 10% wt, the cerianite fraction in dynamic conditions at 1100°C after 8 h of crystallization was less than 1% vol. In addition, shear strongly accelerates cerianite crystallization and a high Ce₂O₃ content can engender the precipitation of highly branched dendrites. The evolution of the cerianite fraction did not significantly affect the viscosity of the glass melt. Finally, unlike what has been observed in the well-known platinum group metal (PGM)-bearing melts, a glass melt containing .8 vol% of cerianite crystals remains Newtonian.

A series of Mn²⁺ single-doped 0.2Gd₂O₃-0.2Al₂O₃-0.6SiO₂ (GAS: xMn²⁺) glasses with Si₃N₄ as reducing agent were prepared. The presence of [SiO_4-x] defects and Mn²⁺ ions was determined from the absorption and excitation spectra of the glasses. With the increase of Mn²⁺ concentration, the intensity of blue emission decreases, while the intensity of red emission increases. The color coordinate of GAS: 6Mn²⁺ glass is (0.264, 0.226). The lifetime of the glasses was tested. Under the monitoring of 440 nm, the fast components (τ_f) are between 17 and 85 μs, and the slow components (τ_s) are between 200–650 μs. The former belongs to [SiO_4-x] defects, and the latter is [⁴E(G), ⁴A₁(G)]→⁶A₁(S) transition of Mn²⁺ ions. Under the monitoring at 630 nm, the τ_f are between 110 and 300 μs, and the τ_s are between 680 and 1220 μs, which are due to ⁴T₁(G)→⁶A₁(S) transition of Mn²⁺ ions and Mn²⁺ pairs, respectively. The energy transfer mechanism of [SiO_4-x] defect→Mn²⁺ ions are explained. The efficient [SiO_4-x] defect →Mn²⁺ ions energy transfer process was demonstrated by time-resolved photoluminescence, and the energy transfer efficiency is over 85%. The maximum photoluminescence quantum yield (PL QY) of the glasses can reach 15.87%. The thermal activation energy of the glasses was calculated. In addition, X-ray excited red luminescence spectra and the mechanism of the glasses were investigated.

Stainless steel slag waste can be used to prepare value-added glass ceramics, which can fix potentially toxic Cr from the slag within the crystalline phase. The occurrence and distribution of Cr during the preparation of glass ceramics has a great influence on the final Cr fixation effect. In this study, the effects of the TiO₂ content on the occurrence and distribution of Cr during the nucleation and crystallization steps and on the final properties of the glass ceramics were systematically studied. In the nucleation stage, with increasing TiO₂ content, the Cr distributed in the spinel containing chromium nuclei first increases and then decreases. In the crystallization stage, Diopside crystal phase nucleates and grows with spinel containing chromium nanocrystals as heterogeneous nuclei. X-ray photoelectron spectroscopy analysis showed that the chromium distributed in the diopside crystals first increased and then slightly decreased as the TiO₂ content increased. The optimal TiO₂ content is 3.4 wt.%, which resulted in 97 wt.% of the total Cr being fixed in the diopside crystalline phase (with a very low Cr leaching concentration of 0.009 mg/L), and a high compressive strength of the final glass ceramic of 267.4 MPa, and a Vickers hardness of 1211.8 HV. The research results provide theoretical and technical support for strengthening Cr fixation to enable harmless and high-value utilization of stainless steel slag for fabricating glass ceramics.

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.