Commercial Float Glass Research Articles

Appearance and prevalence of float glass inclusions with a diameter smaller than 500 µm, focused on the identification of nickel sulphide

In most float glass productions, quality control systems will remove glass inclusions with diameters above 500 µm, since smaller inclusions are usually not visible to the human eye. Yet, they can still become relevant in glass construction, one example being nickel sulphide which can cause spontaneous fracture of thermally prestressed glass. This research presents statistical data on the prevalence of inclusions in the size range with a diameter between 50 and 500 µm, obtained from thorough scans of commercial float glass, showing that the inclusion size distribution follows an exponential curve. Also, many of the found inclusions are investigated by ultra-high-resolution optical microscopy down to resolutions close to the wavelength of visible light, the physical limit of such inspection, while still in the intact glass. Images taken under different lighting conditions and with different types of microscope cameras help in the identification and differentiation of inclusion types. Photoelastic stress measurements and laser interferometry also non-destructively show mechanical stress and deformation inside the glass around inclusions. Due to the risks emerging from this inclusion type, a special focus of the presented work is on the identification of nickel sulphide and its precursors which can be identified by its characteristic surface structure and colour as well as its shape.

Structural, shear and volume relaxation in a commercial float glass during aging

Density, Raman spectroscopy and viscosity measurements are utilized to probe, respectively, the volume, structural and shear relaxation behavior of a Na-Ca-Mg silicate glass of standard commercial float composition at ∼80 °C below its calorimetric glass transition. The results, when taken together, indicate that the lowering of fictive temperature of the glass during aging results in a Q-species disproportionation of the type Q2+Q4→2Q3, and all three relaxation processes are characterized by stretched exponential kinetics with similar average timescale (〈τ〉∼ 300 h) and stretching exponent (β ∼ 0.4), implying a close mechanistic relationship. It is hypothesized that the coexistence of strongly and weakly constrained domains or structural moieties in the network of a glass or supercooled liquid can give rise to a temporal decoupling between the structural and shear relaxation processes, as has been reported in some of the recent studies in the literature.

Photooxidation of acetaldehyde over TiO2 film: Impact of the substrate glassy structure on the photonic efficiency

Mesoporous TiO2 films were dip-coated onto diverse conductive glass substrates such as Indium Tin Oxide (ITO) and F-doped Tin Oxide (FTO) as well soda-lime glass (SL). The mesoporous TiO2 films were assessed for their photodegradation of CH3CHO in gas phase as a probe molecule and compared with both nonporous TiO2 film deposited on FTO and commercial float glass. The thickness and surface areas of the mesoporous TiO2 film were determined to be around 228 ± 10, 184 ± 15 and 205 ± 15 nm and 215, 352 and 295 m2/cm3 deposition on SL, FTO and ITO, respectively. The prepared mesoporous TiO2 film deposited on SL, FTO and ITO exhibited higher photonic efficiency than nonporous TiO2 film and float glass. The photonic efficiency of mesoporous TiO2 film is the following order FTO> ITO > SL. The photonic efficiency of TiO2/FTO is greater 21 and 3 times than that float glass and nonporous TiO2/FTO, respectively. In addition, the outstanding photocatalytic activity of mesoporous TiO2/FTO substrate is shown in recycling tests in which no significant reduce in the photonic efficiency was recognized after five cycles for 10 h continuously, indicating a promising materials for potential applications.

Paraffin wax–Cs0.33WO3 composite windows with excellent near infrared shielding and thermal energy storage abilities

Cesium tungsten bronze (Cs0.33WO3) coatings can effectively depress solar heat gain and air-conditioning energy consumption of buildings, because of their highly selective near infrared (NIR) absorbing ability. However, the absorbed solar energy may overheat the window glasses due to the high photothermal conversion efficiency of Cs0.33WO3 coatings, discounting their transparent heat insulating performance. To solve this issue, we design a new energy-efficient composite window by integrating NIR-shielding Cs0.33WO3 with phase change materials (PCMs, paraffin wax in our case). In the composite window, the hexagonal-phase Cs0.33WO3 is prepared by a solid-state reaction method, and then coated onto commercial float glass as Cs0.33WO3–SiO2 composite films via a sol–gel process. Afterwards, a homemade double-plane window consisting of a float glass and a Cs0.33WO3–SiO2-coated glass is filled by molten commercial paraffin wax to obtain the paraffin wax–Cs0.33WO3 composite window. Cs0.33WO3 in the window can reduce solar heat gain of the buildings. Meanwhile, the paraffin wax component can accumulate the Cs0.33WO3-captured thermal energy by its endothermic molting processes, protecting the window from overheating. When the ambient temperature drops low enough, the stored thermal energy in the paraffin wax can be gradually released back by reverse solidifying processes. Therefore, this paraffin wax–Cs0.33WO3 composite window should be very effective to keep indoor temperature stable and comfortable. Performed on a homemade house model, the paraffin wax–Cs0.33WO3 composite window can depress indoor temperature variation from 24.2 down to 7.3 °C, compared with a bare glass window. This composite window is expected to improve energy efficiency of buildings locating in areas with high day–night or summer–winter temperature fluctuations.

Modifying the surface wetting behavior of soda-lime silicate glass substrates through thermal poling

Thermal poling, i.e., exposure of a glass to a DC electrical field at moderate temperature, enables the generation of an anisotropic surface layer. Cation motion on the anode side results in the formation of an internal gradient in the electrical potential which can be frozen-in upon cooling. This is accompanied with a change in the polarity of the anode surface and, hence, a change in surface wettability. In this article, we study the effect of thermal poling on the wettability of soda-lime silicate glasses. We confirm a poling-induced increase in surface hydrophobicity on the air-side of commercial float glass, with a water wetting angle increase of around 20° for poling at 210°C and 1.5kV. The effect is persistent after storage for three months under ambient conditions. Significant variation between air and tin-side of the float glass indicates strong compositional dependence and offers a route for tailoring the surface chemical properties of functional glass substrates.

A novel method for the evaluation of stress-optic coefficient of commercial float glass

The measurement of residual stress in float glass is important in glass industries as they affect their cutting quality. Photoelasticity can be used for residual stress analysis of float glass as they exhibit stress induced birefringence. Stress measurement using photoelasticity necessitates the knowledge of the stress-optic coefficient of float glass. Carrier fringe method in conjunction with digital photoelasticity is used for the photoelastic calibration of float glass. The conventional method of photoelastic calibration is improved to calibrate float glass with residual stress which eliminates the need for annealing them. The new method developed is self consistent as the results are verified by the reconstruction of the composite fringe pattern. The use of the improved method is recommended for calibration of float glass as it takes into account the residual stress in glass sample apart from its potential for automation.

Residual Stress Analysis of Commercial Float Glass Using Digital Photoelasticity

Residual stresses are generated in float glass at the time of manufacturing due to thermal gradients created during the cooling process. The quantification of these residual stresses is important in glass industries as they affect their cutting quality. Photoelasticity can be used for residual stress analysis of glasses, as glass exhibits stress‐induced birefringence. In this study, a methodology involving carrier fringes in conjunction with digital photoelasticity is used to quantify the residual stress in float glass. The results are verified by six‐step phase‐shifting technique (a subset of ten‐step phase‐shifting method) using an automatic polariscope. Finally, to demonstrate the utility of the proposed method, the residual stress is measured in float glasses of different thicknesses. A method for approximate estimation of residual stress which does not require sophisticated digital image acquisition and processing systems is also reported.

Studying the counting rate capability of a glass multigap resistive plate chamber at an increased operating temperature

It is shown that a multigap resistive plate chamber made of commercial float glass is capable of sustaining high counting rates at an increased operating temperature. Two glass chambers were investigated on the test beamline of the U-70 accelerator at the Institute for High Energy Physics. The required radiation flux density at the detector was produced by means of radioactive sources. The time resolution of 80 ps or better was attained at a rate of ∼20 kHz/cm2 and an operating temperature of 45°C.

Characterization of thin polycrystalline silicon films deposited on glass by CVD

We deposited polycrystalline silicon (poly-Si) thin films on commercial float glass by chemical vapour deposition from trichlorosilane at temperatures between 735 and 870 °C. The structural properties of the films were evaluated by means of scanning electron microscopy, x-ray diffraction, atomic force microscopy, reflectance in the ultraviolet region and Raman spectroscopy. The electrical characterization involved measurements of dark conductivity and photoconductivity as a function of temperature, Hall effect, ambipolar diffusion length from the steady-state photocarrier grating technique and density of defects by means of modulated photoconductivity. By using boron tribromide as a doping agent, degrees of doping ranging from intrinsic to clearly p-doped were obtained. The process, the reactants and the substrate used are of low cost, and proved to be adequate for direct poly-Si deposition, giving films of good structural and electrical properties.

Polycrystalline silicon thin films on glass deposited from chlorosilane at intermediate temperatures

We show that commercial float glass can be used as a substrate to deposit polycrystalline silicon (poly-Si) by chemical vapor deposition from trichlorosilane at temperatures between 740 and 870 °C. By using scanning electron microscopy an average grain size lower than 0.4 μm was observed, with a columnar structure suitable for the electrical conduction in photovoltaic cells. X-ray diffraction reveals a strong (2 2 0) preferential orientation of the films, which is indicative of a low density of intra-grain defects. Atomic force microscope images reveal a conical structure, with a root mean square roughness of ~65 nm for samples of around 3 μm in thickness. This natural texture is a positive characteristic from the point of view of light trapping. By using boron tribromide as a doping agent, degrees of doping ranging from intrinsic to clearly p-doped were obtained, as shown by dark conductivity measurements as a function of temperature. The process, the reactants and the substrate used are of low cost and proved to be adequate for direct poly-Si deposition.

Effect of temperature on glass-ceramic films prepared by impregnation of commercial float glass surfaces with oxide powders under pressure

SnO 2 samples were prepared as ultrafine powder by a chemical synthesis method and deposited on the surface of commercial float glass substrates. The glass surface was impregnated with these powders under high gas pressure (1.6–1.8 MPa) and heating to below the glass transition temperature in a designed pressurized chamber, forming SnO 2 films on glass surface. Phases were analyzed by X-ray diffraction and the results confirmed the SnO 2 powders as a single-phase tetragonal structure. Analysis of the chemical composition of glass substrates before and after powder impregnation revealed an ion exchange process caused by the substitution of sodium ions by tin ions on the glass surface. Differences in the surface morphology of SnO 2 films on glass surface were related to the morphology of synthesized powders for deposition and impregnation. The mechanism of SnO 2 films on glass surface was based on mass transfer between the glass substrates and SnO 2 powders as a function of the treatment temperature.

Effects of Surface Chemistry on the Nanomechanical Properties of Commercial Float Glass

Nanoindentation was used to evaluate the mechanical properties of commercial float glass surfaces that were subjected to various surface cleaning treatments and other short‐term corrosion conditions. The changes in the plane strain elastic modulus , where νs and Es are the Poisson ratio and Young modulus of the specimen, respectively) and hardness after exposure to dilute hydrochloric acid (pH 0.9), reverse osmosis water (pH 7.1), and commercial cleaning solutions (pH 9.5) were found to be 0.5%–9% and 2%–35%, respectively. Similarly, weathering in a humid atmosphere and leaching in hot deionized water also had a distinct effect on the measured properties of the float glass surfaces. Moreover, both the surface cleaning treatments and the short‐term corrosion exposures affected the tin side of the float glass differently than the air side. This work suggests that many of the discrepancies in the literature on the effect of tin concentration on the nanomechanical properties of float glass surfaces are likely due to variability in the surface cleaning and exposure history of the samples and calibration glasses that have been used.

Nanomechanical properties of glass–ceramic films obtained by pressure impregnation of oxide powders on commercial float glass surfaces

The fracture toughness, hardness and elastic modulus of thin films prepared by high air pressure impregnation of SnO 2 nanoparticles on glass surfaces were measured using indentation techniques. The films were produced by two SnO 2 synthesis routes, at varying temperatures and constant pressure and time. The fracture toughness of the films was measured by the length of radial cracks determined by Vickers indentation. The hardness and elastic modulus were measured by the nanoindentation technique using a Berkovich tip. The mechanical properties of the surfaces modified with SnO 2 nanoparticles showed changes when compared with the mechanical properties of unmodified alkaline glass.

Microstructure of ceramic particles infiltrated into float glass surfaces by high gas pressure impregnation

Glass–ceramics were produced by impregnation of powders onto a surface under pressure. Samples of four classes of oxide powders (SnO 2, Co 3O 4, TiO 2and Al 2O 3) were infiltrated into a commercial float glass substrate. These powders were impregnated on the glass surface under high gas pressure (16–18 atm) and below the T g temperature in a specially designed pressurized chamber to form M x O y –SiO 2 films. The phases were analyzed by X-ray diffraction (XRD), and the results reveal the structure and crystallinity of the selected oxide powders as prepared and after inclusion in the glass substrate. The formation of films by the proposed method is viable due to the mean particle size of the powders deposited on the glass surface. Differences in the surface morphology of glass–ceramics films were attributed to the morphology of the powders used for impregnation. The formation mechanism of M x O y –SiO 2 films was based on compositional differences in the glass substrate before and after the powder impregnation process and on their surface morphology.

Nanomechanical properties of commercial float glass

The float process produces flat glass with a tin-rich surface due to contact with the molten metal bath. The incorporation of tin into the glass network is expected to modify the mechanical properties of the surface and the relative durability of the two sides of the material. In this work nanoindentation was used to evaluate the elastic modulus and hardness of a 2mm thick commercial float glass. The near-surface elastic modulus (depths<400nm) of both sides of the glass was elevated by up to 10%, and could not be attributed solely to the presence of tin. However, slight differences in hardness (<10%) between the air and tin sides of the float glass were observed. These results suggest that tin may alter the flow properties of the glass, but the elastic modulus changes are masked by other structural and chemical differences between the air and tin sides of the float glass.

Sodium and hydrogen analysis of room temperature glass corrosion using low energy Cs SIMS

Corrosion affects commercial float glass production and glasses used to contain high level nuclear waste. In order to prevent the corrosion it is necessary to understand the composition of the corroded glass and the corrosion mechanism taking place. SIMS depth profiling lends itself well to monitoring the compositional changes that occur during the corrosion process. However, most studies have analysed glass that has been corroded using accelerated ageing conditions. In this work a soda–lime glass has been aged at room temperature under known atmospheric humidity for increasing periods of time. The aged glass has then been depth profiled using a low energy (1 keV) Cs beam monitoring both the sodium and hydrogen signals concurrently. The depth profiles show that in the region directly below the glass surface that is severely depleted in sodium, there is an increased level of hydrogen compared to the bulk glass indicating an increase in the water content within this region.

Room temperature corrosion of museum glass: an investigation using low-energy SIMS

Glass is often regarded as a stable durable material and the wide range of contemporary applications of glass reinforces this belief. There is nothing inherent in the glassy state, however, that confers stability, and the problem of glass corrosion has been well documented since the 17th century. Glass corrosion still affects commercial float glass production and glasses used to contain high level nuclear waste, but one area in particular where glass corrosion is very common is in the museum environment. In order to conserve these artefacts it is essential to understand fully both the composition of the corroded glass and the corrosion mechanism. In this study, the application of low-energy SIMS for the depth profiling of corroded glass is studied with the aim of finding a suitable environment for the safe storage of glass objects in a museum.

Sulfate Decomposition and Sodium Oxide Activity in Soda–Lime–Silica Glass Melts

Reaction equilibrium constants for the sulfate decomposition process, which releases oxygen and sulfur oxide gas in soda–lime–silica glass melts, have been determined. The chemical solubility of SO2, probably in the form of sulfite ions in soda–lime–silica melts, has also been determined. The chemical solubility value of SO2, dissolving as sulfite, ranges between 0.02 and 0.06 wt% SO32− at 1 bar SO2 pressure in the temperature range of 1600–1800 K. Results of square‐wave‐voltammetry studies and measurements of the temperature‐dependent sulfur retention after the fining process of commercial float glass melts and a model soda–lime–silica melt, with 74 wt% SiO2, 16 wt% Na2O, and 10 wt% CaO, are presented. The measured sulfur retention data and the results of the square‐wave‐voltammetry studies are used to determine the equilibrium constant of the sulfate decomposition reaction in the temperature range of 1600–1800 K. The thermodynamic relations and properties found for sulfate decomposition are used to derive activities of sodium oxide in soda–lime–silica melts. Literature values for sodium oxide activities in these glass melts are rare. In this study, these activities have been determined by a method, based on the measurement of sulfate decomposition equilibrium constants and the residual sulfate concentrations in glass melts, equilibrated with almost pure sodium sulfate galls.

The diffusion mechanism of tin into glass governed by redox reactions during the float process

The diffusion mechanism of tin into glass was investigated using a lab-scale float apparatus, with which it was possible to independently vary the heating parameters, in order to determine the reasons for the characteristic tin penetration profile of float glass. Tin penetration profiles of glass samples with heating at various temperatures, times and atmospheres were measured by means of SIMS. The tin enriched inner layer, which is characteristic of the tin penetration profile of float glass, was seen to be formed by heating at more than 800°C. It was found that the depth of the tin enriched inner layer was proportional to the holding time at the maximum temperature during the heat treatment, and was inversely proportional to the Fe 3+ concentration in the glass. It was also proven that the tin enriched inner layer was formed by penetration of hydrogen from the atmosphere through the molten tin into the glass. These facts indicate that the reaction between hydrogen and Fe 3+ is involved with the formation of the tin enriched inner layer. Consequently, it has been proposed that the formation mechanism of the tin enriched inner layer is governed by two redox reactions and the diffusion behaviors of both Sn 2+ and Sn 4+. Namely, one of these two redox reactions is the reduction of Fe 3+ to Fe 2+ due to hydrogen, resulting in the formation of a reduced surface layer. Another is the oxidation of Sn 2+ to Sn 4+ due to Fe 3+ in the glass. Furthermore, it was revealed by the analysis of commercial float glass with various thicknesses that the depth of the tin-enriched inner layer is also influenced by the stretch coefficient for the attenuation of the glass during the float process. These analytical results leading to a successful control of tin penetration into glass during the float process are discussed in detail.

Nanoindentation and Nanowear Studies of Sputter-Deposited Ultrathin Tin Oxide Films on Glass Substrates

ABSTRACTTin oxide thin films on glass are used in a variety of applications ranging from transparent conductors to coupling layers to wear resistant coatings. The mechanical properties and wear resistance are crucial to most applications of tin oxide films. In the present study, ultrathin tin oxide films were sputter-deposited on the two different glass substrates. Nanoindentation, nanoscratch and nanowear experiments were performed on the tin oxide films with different thickness using a Hysitron TriboScope at different loads. Hardness and Young's modulus of elasticity were determined from the depth sensing load-displacement data. A lower friction coefficient was observed on the thinner film using the ramping load scratch test. Critical loads were determined by the ramping load scratch test and multi-slide nanowear tests on the tin oxide film deposited on the alkali contained commercial float glass (LOF-P16) glass. Discussion on the effect of surface chemistry on the mechanical properties was made.