Annealing Of Glass Research Articles

Термічне розширення аморфних халькогенідних матеріалів в околі температури склування

The patterns of thermal expansion of chalcogenide materials in the temperature range from room temperature to the beginning of deformation of the samples under the action of the measured force of the dilatometer cell were investigated. Above the glass transition temperature, the coefficient of linear thermal expansion of stabilized samples increases dramatically. For tempered glasses, the course of the temperature dependences of the relative elongation of the samples significantly depends on their thermal history and is of a complex nature. According to dilatometric measurements, the characteristic temperatures of the glass transition interval were determined, a qualitative assessment of structural changes was made depending on the temperature-time regimes of synthesis and annealing of chalcogenide glasses.

Mineral resource base of Kazakhstan for the production of window glass

The chemical compositions of natural and man-made raw materials of Kazakhstan: quartz sand, quartzite, aluminum, calcium and alkali-containing components used in the production of window glass are investigated. According to the chemical composition, all quartz sand deposits meet the requirements of GOST, except for the content of iron oxide. To use quartz sands in the production of flat glass, it is necessary to enrich them. Chemical compositions of feldspar, quartz-feldspar, pegmatite, kaolin have been studied. Deposits of high-quality feldspar raw materials have been found in the Khantau, Maikul deposits (Zhambyl region), in Kostanay (Bisembaevskoye and Marinskoye pegmatite deposits) and Akmola regions (Zerendinskoye field). Alekseyevsky kaolin is of interest, with a high content of aluminum oxide (38.2 %) and a low content of iron oxide. There are quite large reserves of limestones and dolomites in the Republic of Kazakhstan, including the Karatau, Talgar and Shieli deposits. Reserves of chalk with a calcium carbonate content of 94-98 % and insignificant iron oxide are available in the Mangistau region. Kazakhstan has deposits of natural sodium sulfate in the form of solid deposits and brine of numerous lakes. The phase composition of local quartz sands and feldspar has been studied by X-ray phase analysis. Compositions have been developed and experimental glass cooking has been carried out. The content of silicon oxide as the main component in the initial quartz sand is 99.1 %, and the coloring glass of iron oxide is 0.08 %. Therefore, the enrichment method was used to reduce the content of iron oxide in the sand.Studies have shown that magnetic separation can reduce the Fe2O3 content from 0.08 to 0.06 %, by washing from 0.08 to 0.05 %, by flotation to 0.03 %. The size of quartz sand is within the limits that do not complicate the glass cooking process:the content of large grains larger than 0.8 mm is 0.3 %, small grains smaller than 0.1 mm -3 %. The mass fraction of the heavy fraction with a density of more than 2900 kg/m3 is -0.2%. According to complex indicators, the sand corresponds to the VS-030-1po GOST 22551-90 brand. The characteristic intervals of changes in the viscosity of cooking, production, molding, annealing and the corresponding temperatures are determined. The values of the physico-chemical and technological properties of the glasses were obtained by the calculation method. A schedule of annealing of flat glass has been developed.

Crystallization behavior of As40Se60 glass

The thermal annealing of As40Se60 glass and its optical properties were studied and compared with other chalcogenide glasses. It is found that the infrared transmittance of As40Se60 decreases after higher temperature annealing, but it can be recovered to a level near the original glass transmittance after surface polishing, which is different from 0.3PbSe-0.7Ge1.5AS0.5Se3 and 96Ge20Sb10Se65Te5-4CsI glasses. Analysis shows that the crystalline mainly occurs on the As40Se60 surface layer. ​SEM analysis shows that the crystalline phase in As40Se60 glass changes from oval to whisker-like shape as the annealing temperature increases, and the higher the temperature, the longer the branch.

Slow coarsening of tetragonal zirconia nanocrystals in a phase-separated sodium borosilicate glass

A Zr4+-containing sodium borosilicate glass (ZNBS) and a zirconium-free reference glass (NBS) were prepared by melt quenching. Thermal analysis revealed two glass transitions, indicating that both glasses exhibit phase separation into boron- and silica-rich domain structures already after quenching to room temperature. Electron micrographs showed that annealing of NBS and ZNBS glasses initiated the coarsening of these domains and the precipitation of metastable t-ZrO2 in the boron-rich matrix of the ZNBS glass. The coarsening kinetics of the silica-rich domains followed the theoretical predictions (power law exponent = 1/3), while the coarsening of the t-ZrO2 crystallites was much slower. The time evolution of the average size of t-ZrO2 nanocrystallites from small angle X-ray scattering (SAXS) and high-temperature X-ray diffraction (HTXRD) experiments revealed a coarsening exponent of ∼1/6. This slow coarsening of t-ZrO2 is assumed to be confined by the domain structure of the primary phase separation.

Powder sintering and gel casting methods in making glass foam using waste glass: A review on parameters, performance, and challenges

The application of insulation materials in buildings and energy storage facilities is gaining global attention to reduce energy consumption, heat loss, and CO 2 emissions. Given the high insulation performance, glass foam is gaining popularity replacing combustible, high energy-consuming, and costly conventional insulation materials. The industrial process of glass foam manufacturing is an energy-consuming and non-ecofriendly process which requires the annealing of glass around its melting temperature. Therefore, researchers have developed powder sintering and gel casting methods to sinter glass foam mix at a temperature slightly above its glass transition point. However, research findings on these two methods are scattered because of the different parameters being used by researchers. The properties and performances of glass foam depend on the processing parameters, especially on the materials design and sintering conditions. Therefore, this study aimed to provide a comprehensive review on the key parameters for material selection and sintering of glass foams and provide necessary guidelines for the best practice and a direction for future research. Moreover, this review covers the current strategies and challenges associated with the powder sintering and gel casting methods including their sustainability and environmental performance.

The role of annealing in determining the yielding behavior of glasses under cyclic shear deformation

Yielding behavior in amorphous solids has been investigated in computer simulations using uniform and cyclic shear deformation. Recent results characterize yielding as a discontinuous transition, with the degree of annealing of glasses being a significant parameter. Under uniform shear, discontinuous changes in stresses at yielding occur in the high annealing regime, separated from the poor annealing regime in which yielding is gradual. In cyclic shear simulations, relatively poorly annealed glasses become progressively better annealed as the yielding point is approached, with a relatively modest but clear discontinuous change at yielding. To understand better the role of annealing on yielding characteristics, we perform athermal quasistatic cyclic shear simulations of glasses prepared with a wide range of annealing in two qualitatively different systems-a model of silica (a network glass) and an atomic binary mixture glass. Two strikingly different regimes of behavior emerge. Energies of poorly annealed samples evolve toward a unique threshold energy as the strain amplitude increases, before yielding takes place. Well-annealed samples, in contrast, show no significant energy change with strain amplitude until they yield, accompanied by discontinuous energy changes that increase with the degree of annealing. Significantly, the threshold energy for both systems corresponds to dynamical cross-over temperatures associated with changes in the character of the energy landscape sampled by glass-forming liquids.

Effect of annealing close to Tg on the short-range order of lithium disilicate glass

Annealing of glasses at temperatures close to Tg is a usual procedure to reduce internal stresses induced by the conventional melting/quenching process. In this work, the effect of the annealing temperature and time on short-range order of lithium disilicate glass was investigated. The total structure factor and radial distribution function of annealed samples at distinct temperatures and times were derived from synchrotron XRD measurements. The results suggest that short and medium range-orders were affected by the annealing conditions, even for temperatures well below the glass transition temperature, Tg. After annealing at temperatures close to Tg, local arrangements were identified with those corresponding to crystalline phases of lithium disilicate and lithium metasilicate. For temperatures below Tg, the diffusion of lithium atoms was already taking place, while the rearrangements of the SiO4 tetrahedra from the network former started to happen for temperatures close to or higher than Tg.

Is the structural relaxation of glasses controlled by equilibrium shear viscosity?

AbstractKnowledge of relaxation processes is fundamental in glass science and technology because relaxation is intrinsically related to vitrification, tempering as well as to annealing and several applications of glasses. However, there are conflicting reports—summarized here for different glasses—on whether the structural relaxation time of glass can be calculated using the Maxwell equation, which relates relaxation time with shear viscosity and shear modulus. Hence, this study aimed to verify whether these two relaxation times are comparable. The structural relaxation kinetics of a lead metasilicate glass were studied by measuring the refractive index variation over time at temperatures between 5 and 25 K below the fictive temperature, which was initially set 5 K below the glass‐transition temperature. Equilibrium shear viscosity was measured above and below the glass‐transition range, expanding the current knowledge by one order of magnitude. The Kohlrausch equation described very well the experimental structural relaxation kinetics throughout the investigated temperature range and the Kohlrausch exponent increased with temperature, in agreement with studies on other glasses. The experimental average structural relaxation times were much longer than the values computed from isostructural viscosity, as expected. Still, they were less than one order of magnitude higher than the average relaxation time computed through the Maxwell equation, which relies on equilibrium shear viscosity. Thus, these results demonstrate that the structural relaxation process is not controlled by isostructural viscosity and that equilibrium shear viscosity only provides a lower boundary for structural relaxation kinetics.

Automation of thermal processing of quartz glass with the following computer treatment of the quality of siloxane communication

The strength characteristics and isotropic physical properties of quartz glass give broad prospects for its use as a resonator for navigation systems of aircraft, as well as for complex optical systems and automation elements. To obtain a sufficiently hard surface with the desired properties, it is necessary to create conditions for the occurrence of siloxane bonds - silicon and oxygen compounds. During the formation of such bonds, the process of polymerization and annealing of quartz glass, high-strength resonator samples are obtained. The quality of the resulting surface is determined by different methods - fractal geometry, recumbent drop and Vickers. In the presented material, the authors propose to use the recumbent drop method (distilled water was used). To obtain samples of resonators, a resistance furnace has been designed and constructed, which operates in an automated mode using a personal computer control. Also, a computer program “Droplet stacking method” was written in Delphi 7.0, which presents the results of monitoring the annealing process, including the surface annealing temperature and contact angle. The results of measurements and calculations can be recorded as a file and observed on the display. The program interface is intuitive and convenient for controlling the process of obtaining samples. In addition, to form a high-quality connection, a program was also written to determine the radius of the nucleus and the value of the Gibbs free energy, which is necessary for the formation of the nucleus. The experimental results obtained and the calculations performed by the lying drop and fractal geometry methods have demonstrated the agreement between the results within the error limits of the methods.

Abnormal orderly transformation in supercooled state of an Al-based alloy

To understand the underlying mechanism behind the precipitation of high-density face-centered cubic Al nanoparticles during the annealing or preparation of Al-based metallic glass, we used molecular dynamics simulation technique to study the atomic structure evolution of Al-rich and Al-depleted melts in the Al-Zr binary system under rapid cooling conditions. From the quantitative characterization of thermodynamic properties, kinetic properties, and atomic structure, we found that an abnormal orderly transformation occurs in the supercooled liquid of Al-rich alloy, which includes two basic stages, namely, directional diffusion and stabilization of defect clusters. The thermodynamic essence of this transformation is to reduce the Gibbs free energy of the entire system by improve the cluster packing efficiency of atomic structure, preventing the supercooled liquid from being in an unstable state. An important consequence of the abnormal orderly transformation is the formation of nanoscale Al-rich regions in the supercooled liquid. These regions can readily promote the precipitation of high-density face-centered cubic Al nanoparticles, thereby reducing the complete amorphization ability of Al-based alloy melt.

Intermediate structural state for maximizing the rejuvenation effect in metallic glass via thermo-cycling treatment

Annealing of metallic glasses (MGs) at temperature near glass transition temperature (Tg) triggers relaxation and often hampers their performances in service. Rejuvenation treatment of MGs by thermal cycling is recently intensively investigated. However, the mechanism responsible for the structural rejuvenation still remains elusive. In this work, we present a systematic study on the rejuvenation effect of a Zr46Cu38Al8Ag8 MG annealed at 0.9Tg for various durations, subjected to thermo-cycling treatment. It is found that well relaxed samples after long-term annealing are almost unaffected, while short-term annealed samples exhibit large rejuvenation effect by thermo-cycling treatment. Using synchrotron X-ray diffraction, we find that thermal cycling results in a disordering at the short-range scale, where the rejuvenation effect is large in a heterogeneous sample. More interestingly, the thermo-cycling treatment on intermediate structure with 20 h-annealed sample relatively exhibits a high degree rejuvenation effect, as compared to shorter- and longer-term annealed samples. This finding indicates that the activation barrier for rejuvenation strongly depends on the original structural states, e.g., free volume, inherent stress and structural heterogeneity.

Reduction in internal friction in silica glass with high OH content

AbstractThe aim of this article was to investigate processes occurring during annealing of silica glass classified as being of type III (J Non Cryst Solids. 1970;5(2):123‐75). This is an inexpensive silica glass produced by many manufacturers across the globe. However, it can be successfully used for fabrication of high‐Q mechanical resonators. The relationship between residual internal stress and internal friction is elucidated. Quantitative analysis of the structural relaxation kinetics is presented. The influence of the cooling process for structural transformation is also discussed. On the basis of our results, we suggest optimal annealing conditions for minimizing internal friction type III silica glass. The results will be useful for further improvement of the Q‐factor of mechanical resonators, including the test masses of the next generation of gravitational wave detectors. Our approach might, in addition, be used for studying the modification of atomic structure in multicomponent glasses.

Laser Pulse Annealing of Glass Plates Partially Covered by Radiation

The action of pulsed laser radiation on a plate is studied as a quasi-static problem of thermoelasticity. An analytic relation expressing the thermal strength condition for a plate is derived, making it possible to determine non-destructive regimes of laser processing in the case where the diameter of the laser beam is smaller than the diameter of the worked plate. The obtained results were checked experimentally.

Optical Characterization of Nano- and Microcrystals of EuPO₄ Created by One-Step Synthesis of Antimony-Germanate-Silicate Glass Modified by P₂O₅.

Technology of active glass-ceramics (GC) is an important part of luminescent materials engineering. The classic method to obtain GC is based on annealing of parent glass in proper temperature and different time periods. Generally, only the bulk materials are investigated as a starting host for further applications. However, the effect of an additional heat-treatment process on emission and structural properties during GC processing is omitted. Here, we focus on the possibility of obtaining transparent glass-ceramic doped with europium ions directly with a melt-quenching method. The influence of phosphate concentration (up to 10 mol %) on the inversion symmetry of local environment of Eu3+ ions in antimony-germanate-silicate (SGS) glass has been investigated. The Stark splitting of luminescence spectra and the local asymmetry ratio estimated by relation of (5D0→7F2)/(5D0→7F1) transitions in fabricated glass confirms higher local symmetry around Eu3+ ions. Based on XRD and SEM/EDX measurements, the EuPO4 nano- and microcrystals with monoclinic geometry were determined. Therefore, in our experiment, we confirmed possibility of one-step approach to fabricate crystalline structures (glass-ceramic) in Eu–doped SGS glass without additional annealing process.

Control of the Annealing Process in the Production of Sheet Glass by the Float Method

Amathematical model based on fuzzy sets that describes the dependence of the residual stresses in sheet glass on the annealing regime is developed. An adaptive system for controlling the annealing of the glass by using a model describing the dependence of the residual stresses on the annealing regime is proposed. Simulation modeling is used to show that the residual stresses in the produced glass can be stabilized using the operating equipment by automating the control of the technological process of annealing.

Structural and volume changes and their correlation in electron irradiated alkali silicate glasses

Two binary alkali silicate glasses (15K2O·85SiO2 – denoted as K15 and 15Li2O·85SiO2 – denoted as Li15) were irradiated by 50keV electron beams with doses within the range of 2.1–15.9kC/m2. Volume changes induced by electron irradiation were monitored by means of Atomic Force Microscopy (AFM). Raman spectra were taken from the irradiated spots to observe structural changes. Volume compaction observed at lower doses was correlated with the increase of the D2 peak. Volume expansion at higher doses was related to migration of alkali ions. Irradiated glasses were annealed at 400°C and 500°C for 60min. After annealing irradiated spots were again examined by AFM and Raman spectroscopy in order to determine volume and structural relaxation of radiation induced changes. Annealing at higher temperatures resulted in the levelling of the pits created by irradiation, but only for doses below incubation dose. The pits created by doses above incubation dose were not levelled. Annealing caused decrease of D2 peak and shift of the Si-O-Si vibrations band in direction to original structure. Low-frequency region of annealed Li15 glass was undistinguishable from that of pristine glass, while annealing of K15 glass did not result in the full reversion to the original shape. The differences between glasses were attributed to higher Tg of K15 glass. Q-motives bands of both glasses were not completely restored after annealing due to the absence of alkali ions.

Self-supported copper (Cu) and Cu-based nanoparticle growth by bottom-up process onto borophosphate glasses

In this study, we present a new method for obtaining an effective catalytic system composed of glass, with Cu or CuO nanoparticle growth on a glass matrix through bottom-up process. The system is based on active borophosphate glass material doped with $$\hbox {Cu}^{+}$$ ions, which was obtained by a classical melt-quenching glass production technique. The thermal annealing of doped glasses under reductive/oxidative atmosphere enables the glassy material to act successfully as host material of both copper and copper oxide nanoparticles. We have investigated the structural and optical properties of the $$\hbox {Cu}^{0}$$ and CuO nanostructures by using X-ray diffraction, scanning electron microscopy, electron paramagnetic resonance and Raman spectroscopy. Supported nanostructures with triangular and acicular shape were made without the necessity of chelating agents. The catalytic activity of these systems was efficiently tested for the reduction of p-nitrophenol in the presence of $$\hbox {NaBH}_{4}$$ , achieving a good rate constant around $$2.8 \times 10^{-3}$$ and 7.3 $$\times 10^{-3}\,\hbox {s}^{-1}$$ for $$\hbox {Cu}^{0}$$ and CuO nanostructures, respectively. The catalyst was reused for three times without losing its activity significantly, simply taking and washing the pellet in fresh water, making these materials promising candidates for applications in the fields of catalysis.

Unexpected high performance of Fe-based nanocrystallized ribbons for azo dye decomposition

Fe-based multiphase nanocrystallized ribbons (CR-II) prepared by annealing of metallic glasses show unexpected high performance for Orange II degradation.

Light scattering investigation of a slow relaxation process of boric oxide in the glass-transition region

The data on the relaxation process of the polarized V ν component of the integral intensity of light scattering in glassy boric oxide at 320°C are presented. It was shown that the variations of the intensities were adequately described by the exponential function on time. The relaxation time of intensity was found to be equal about 50 min which far exceeds the expected times of structural relaxation at this temperature. The increase of both polarized and depolarized components of light scattering intensity in the process of low-temperature annealing of glass at 200°C was presumably related to the development of elastic stress in the sample volume.

Modeling of plastic deformation of glasses in creeping and stress relaxation regimes

Molecular-dynamic (MD) modeling of low-temperature deformation of the uniaxial compression and tension of glass of 1000 molecules of C13H28 oligomer is carried out. The influence of annealing and second deformation of glass on the σ-e diagram and the dependence of the system relaxation rate on its deformation degree and sample creeping are investigated. The modeling results of mechanical behavior are in good agreement with the experimental data for the glassy polymers that allows one to use MD modeling for further deep study of the glass behavior mechanisms under mechanical actions.