Glass Side Research Articles

A nanoscale study of the formation of Fe-(hydr)oxides in a volcanic regolith: Implications for the understanding of soil forming processes on Earth and Mars

Abstract Iron(hydr)oxides are one of the most important constituents of regoliths and soils derived from volcanic rocks both on Earth and Mars, often giving them their characteristic red color. This study deciphers for the first time an underlying mechanism for the formation of Fe-(hydr)oxides in a regolith which can occur during the weathering of basaltic glass; Fe-(hydr)oxides are prominent alteration products of volcanic regolths. An excellent example of these conditions is the early stage of basaltic glass weathering in the Martian regolith simulant JSC MARS-1A. In this study, a combination of focused ion beam technology and analytic transmission electron microscopy is employed in order to characterize basaltic glass weathering down to the nanometer level. Our results show that the formation of Fe-(hydr)oxide phases such as ferrihydrite, magnetite/maghemite and hematite during alteration of basaltic glass is based on complex and formerly unknown sequences of dissolution-precipitation reactions and pressure induced coalescence, segregation, aggregation, densification and growth processes. The weathering of the glass starts with its dissolution and subsequent precipitation of hydrous amorphous silica-bearing pockets rimmed by nano-size domains of ferrihydrite. An increase in molar volume during this process leads to an overall volume expansion, which promotes (a) growth of the hydrous silica through coalescence of individual pockets, (b) agglomeration of ferrihydrite domains to larger and denser aggregates in between layers or along the surfaces of plagioclase, hydrous amorphous silica and amorphous Al-(hydr)oxides, (c) formation of hematite within dense aggregates of ferrihydrite or as larger nanoparticles within an hydrous amorphous Si-Al-rich phase and (d) the break-up of plagioclase crystals and the replacement of these fragments by an hydrous amorphous Fe-Al-Si-bearing phase. At a later weathering stage, ferrihydrite nano-domains can also transform into magnetite/maghemite nanoparticles, which occur as layers around and on the surface of larger plagioclase crystals. This study also indicates the presence of past nano-environments in close proximity to each other, as for example layers of imogolite and ferrihydrite/hydrous amorphous silica occur only nanometers apart from each other on the opposite sides of unaltered glass. In accord with previous mineralogical studies of JSC MARS-1, the observed bulk and nano-mineralogical composition indicate that early alteration processes of basaltic glass under dry and cold conditions are mainly controlled by the formation of Fe-(hydr)oxides and minor imogolite and kaolinite. Recent mineralogical studies indicate that alteration processes at these conditions may have been the dominant weathering processes over long time periods on the Martian surface.

Computational fluid-dynamics-based simulation of heat transfer through vacuum glass

The heat transfer process of vacuum glass is very complicated. In particular, the heat transfer process of functional vacuum glass, which includes the coupling of heat conduction, convection, and radiation, does not have an exact mathematical solution. The most important parameter representing the thermal properties of vacuum glass, the heat transfer coefficient, is difficult to measure online because it increases over time, thereby decreasing the thermal-insulation performance. Thus, measuring it quickly and accurately for a vacuum glass in use is difficult. This study was conducted to develop an efficient method to simulate heat transfer through vacuum glass. To this end, based on advanced numerical-simulation technology, a computational fluid dynamics software was used to analyse the heat transfer process, and the simulation results applied to guide and analyse the non-steady-state test method. It was found that when a circular heating plate is used to heat the side of the vacuum glass, the ratio of the radius of the heating plate to the thickness of the vacuum glass should exceed three. This approach guarantees that the centre of the heating plate undergoes one-dimensional heat transfer, and the temperature measurement at the centre of the non-heated surface is of practical significance.

Deposition of highly transparent and conductive Ga-doped zinc oxide films on tilted substrates by atmospheric pressure plasma jet

Oblique angle deposition (OAD) has become a cost-effective method for depositing nanostructured films. Films with various degrees of porosity, anisotropy, and crystallographic texture have been successfully demonstrated. However, most studies were based on the more established processes, such as evaporation and sputtering; oblique angle deposition using atmospheric pressure plasma jet (APPJ) has not been reported. Here we deposit Ga-doped zinc oxides (GZO) on tilted substrate using APPJ, and study how the film properties are affected by the oblique angle and nozzle scanning trajectory. We found that the trajectory plays a key role in determining the optoelectronic properties of the obliquely deposited films. If the nozzle scans from the upstream side of the substrate to the downstream side, the resistivity, carrier concentration and mobility deteriorate considerably near the downstream region. The film becomes more porous with the haze factor rising significantly from <5% to ∼80%, while the total transmittance remains high (>80% at 550 nm). This degradation can be attributed to the “pre-deposition” of the GZO adsorbed particles on the downstream side of the bare glass where the nozzle has not scanned. Such undesirable pre-deposition occurs due to the combined effect of asymmetric plasma jet and gas flow, both pointing toward downstream, compared to axial symmetric pattern observed in the normal case. More importantly, this undesirable phenomenon can be removed by merely reversing the scanning trajectory, i.e. from downstream to upstream. In this case, a dense film has been formed in the downstream region so the subsequent exposure of the biased plasma jet and gas flow do not result in ad-particles deposition. Therefore, highly transparent and conductive OAD films as good as the normally deposited films can be achieved, a unique phenomenon not reported before. Our findings may shed light on the development of curved display technology, and may also be applied to other deposition methods with moving nozzle or moving stage such as spray pyrolysis.

Hydrophobicity of Polyacrylate Emulsion Film Enhanced by Introduction of Nano-SiO₂ and Fluorine.

This study proposes to utilize modified Nano-SiO2/fluorinated polyacrylate emulsion that was synthesized with a semi-continuous starved seed emulsion polymerization to improve the hydrophobicity, thermal stability, and UV-Vis absorption of polyacrylate emulsion film. To verify the proposed method, a series inspection had been conducted to investigate the features of the emulsion film. The morphological analysis indicated that Nano-SiO2 was surrounded by a silane molecule after modification, which can efficiently prevent silica nanoparticles from aggregating. Fourier transform infrared spectra confirmed that modified SiO2 and dodecafluoroheptyl methacrylate (DFMA) were successfully introduced to the copolymer latex. The particle size of latex increased with the introduction of modified Nano-SiO2 and DFMA. UV-Vis absorption spectra revealed that modified silicon nanoparticles can improve the ultraviolet shielding effect obviously. X-ray photoelectron spectroscopy illustrated that the film–air interface was richer in fluorine than film section and the glass side. The contact angle of modified Nano-SiO2/fluorinated polyacrylate emulsion containing 3 wt % DFMA was 112°, slightly lower than double that of polyacrylate emulsion, indicating composite emulsion films possess better hydrophobicity. These results suggest that introducing modified Nano-SiO2 and fluorine into polyacrylate emulsion can significantly enhance the thermal stability of emulsion films.

Local ordering and interfacial structure between spinel crystal and aluminosilicate glasses from molecular dynamics simulations

AbstractMolecular dynamics simulations were performed to investigate the interfaces of soda magnesia aluminosilicate glass and MgAl2O4 spinel crystals. The glass structures were first generated and characterized. It was found that the glass‐forming network consists of fourfold coordinated [SiO4] and [AlO4] tetrahedra connected through corner sharing with Na+ and Ca2+ acting as modifiers or charge compensators. The glass and crystal interfaces were then constructed on low energy spinel surfaces with special measures to ensure two natural interfaces. The interfacial structures were characterized by z‐density profile, pair distribution function and coordination number analysis. The results show that there exist local ordering on the glass side and preferential adsorption of specific cation near the interface. Cation coordination analyses showed that aluminum ions changed from mainly fourfold coordination in the glass to five and sixfold coordination near the interface suggesting a gradual change in structural role of aluminum from the glass to the crystal. The ordering and segregation of cations, as well as change in aluminum coordination, at the glass/crystal interface strongly suggest that the ordered crystal structure influence the atom distribution and local structure of the adjacent glasses and this ordering can be the initial stage of nucleation or crystal growth.

Study of the turbulent flow in a newly solar air heater test bench with natural and forced convection modes

In this work, the turbulent flow was studied in a new SAH (solar air heater) test bench. Particularly, we have considered the natural and the forced convection modes. The used test bench is composed by two passages separated by an absorber and powered by a fan working in a delivery mode, placed in the inlet side the insulation, for the forced convection mode. On this system, a glass is hanging on the front side and an absorber is inserted inside. On the glass side, it is connected to the box prototype through a pipe. The hot air flow is routed towards the box prototype. Two circular holes, are located in the same face of the box prototype. The inlet hole allows the hot air supply. However, the outlet hole allows its escape into the ambient environment. By using the ANSYS Fluent 17.0 software, the Navier-Stokes equations coupled with the standard k-ω turbulence model were solved. The numerical results were compared with our experimental data, established in the second passage of the SAH test bench. The good agreement confirms the validity of the numerical method. The range of temperatures is very useful in many applications such as industrial and domestic applications.

Performance of a structural acrylic adhesive for linear glass-metal connections under shear and tensile loading

Glass-metal elements with composite action based on linear adhesive connections show a high potential in terms of structural efficiency. The adhesives considered for such applications need to fulfil a wide range of requirements and generally exhibit a non-linear material behaviour. This is also the case of the two-component structural acrylic adhesive investigated in this article. For this adhesive an experimental programme is carried out to assess its structural performance and its adhesion to selected metal and glass surfaces. Furthermore, the influence of different joint dimensions on the stress-strain properties of the adhesive in glass-metal connections, under shear and tensile loading, is analysed. The best results in terms of adhesion are obtained on stainless steel surfaces grinded with an abrasive paper P150 and on the tin side of float glass, respectively. To predict the mechanical behaviour of such connections, the suitability of material models covering both classic and porous plasticity is studied by means of non-linear finite element simulations. A novel surface fitting equation is introduced to obtain stress-strain data at constant true strain rates from uniaxial tensile test results performed at constant displacement rates. A good agreement between experimental and numerical results for shear loading is achieved based just on classical elasto-plasticity formulations. For tensile loading the numerical results show that voids in the adhesive material have to be considered for a reasonable estimation.

Nontraditional, Safe, High Voltage Rechargeable Cells of Long Cycle Life.

A room-temperature all-solid-state rechargeable battery cell containing a tandem electrolyte consisting of a Li+-glass electrolyte in contact with a lithium anode and a plasticizer in contact with a conventional, low cost oxide host cathode was charged to 5 V versus lithium with a charge/discharge cycle life of over 23,000 cycles at a rate of 153 mA·g-1 of active material. A larger positive electrode cell with 329 cycles had a capacity of 585 mAh·g-1 at a cutoff of 2.5 V and a current of 23 mA·g-1 of the active material; the capacity rose with cycle number over the 329 cycles tested during 13 consecutive months. Another cell had a discharge voltage from 4.5 to 3.7 V over 316 cycles at a rate of 46 mA·g-1 of active material. Both the Li+-glass electrolyte and the plasticizer contain electric dipoles that respond to the internal electric fields generated during charge by a redistribution of mobile cations in the glass and by extraction of Li+ from the active cathode host particles. The electric dipoles remain oriented during discharge to retain an internal electric field after a discharge. The plasticizer accommodates to the volume changes in the active cathode particles during charge/discharge cycling and retains during charge the Li+ extracted from the cathode particles at the plasticizer/cathode-particle interface; return of these Li+ to the active cathode particles during discharge only involves a displacement back across the plasticizer/cathode interface and transport within the cathode particle. A slow motion at room temperature of the electric dipoles in the Li+-glass electrolyte increases with time the electric field across the EDLC of the anode/Li+-glass interface to where Li+ from the glass electrolyte is plated on the anode without being replenished from the cathode, which charges the Li+-glass electrolyte negative and consequently the glass side of the Li+-glass/plasticizer EDLC. Stripping back the Li+ to the Li+-glass during discharge is enhanced by the negative charge in the Li+-glass. Since the Li+-glass is not reduced on contact with metallic lithium, no passivating interface layer contributes to a capacity fade; instead, the discharge capacity increases with cycle number as a result of dipole polarization in the Li+-glass electrolyte leading to a capacity increase of the Li+-glass/plasticizer EDLC. The storage of electric power by both faradaic electrochemical extraction/insertion of Li+ in the cathode and electrostatic stored energy in the EDLCs provides a safe and fast charge and discharge with a long cycle life and a greater capacity than can be provided by the cathode host extraction/insertion reaction. The cell can be charged to a high voltage versus a lithium anode because of the added charge of the EDLCs.

Multifunctionality in coating films including Nb-doped TiO2 and CsxWO3: near infrared shielding and photocatalytic properties

Various types of coating films were obtained from hydrothermally synthesized Nb-doped TiO2 (NTO) and CsxWO3 (CWO) nanoparticles. The coating films possessed multifunctionality including near infrared (NIR) absorption and photocatalysis abilities. The NTO and CWO nanoparticles were synthesized by a unique solvothermal reaction in which water induced by an esterification reaction between alcohol and carboxylic acid can act as a hydrolyzing agent for metal precursors. NTO was synthesized by the unique solvothermal reaction for the first time. The reaction accompanied by the reduction of Ti4+ to Ti3+ led to the formation of nanoparticles with both NIR absorption and photocatalytic properties. The effect of the ethanol–acetic acid ratio on the morphology of the obtained NTO was investigated, and the larger amount of acetic acid led to a larger nanoparticle size, indicating the size controllability. The two types of coating film, including CWO and NTO nanoparticles, were obtained for comparison: (1) coexistent coating film: one side of the quartz glass was coated with a dispersion, including both CWO and NTO nanoparticles, and (2) double-sided coating film: a quartz glass coated with a CWO dispersion on one side and an NTO dispersion on the other side. The double-sided coating led to higher multifunctionality. Furthermore, the optimized condition for the double-sided coating was investigated by using various NTO particles obtained using different ethanol–acetic acid ratios.

Crystallisation behaviour of CH3NH3PbI3 films: The benefits of sub-second flash lamp annealing

Crystallisation of the spin-coated hybrid perovskite films has some basic issues restraining the up-scaling of this technology. The reason consists in substantial chemical impact of the solvent during drying that lessens control of crystallisation and reproducibility. This current investigation proposes very fast crystallisation by means of a flash lamp to solve those issues. CH3NH3PbI3 films were prepared on glass and silicon substrates by spin-coating from N,N-dimethylformamide based solutions with various CH3NH3I to PbI2 ratios (1:1, 2:1 and 3:1). Thermal annealing of as-deposited films at 85 °C, 120 °C and 140 °C was compared with the flash lamp annealing realised via sub-second high energy xenon light illumination from the uncoated glass side. Optimal light pulse length and energy density were found to be 2.7 ms and 8 J/cm2, respectively. According to our simulations based on the finite element model the perovskite layers underwent to a short-term heating to 350–425 °C followed by cooling to 100 °C within 3 ms. No decomposition of the perovskite was detected. Conversely its crystallinity according to the X-ray diffraction was prominently better as for thermally annealed films. Fourier-transform infrared spectroscopy revealed the effective elimination of the solvent from perovskite films by flash lamp annealing. High temperature was found to be crucial for the completeness of PbI2 reaction into the perovskite in stoichiometric films. High heating rate appeared to suppress the gel-like phase formation in super-stoichiometric films that helped to avoid the formation of pores. The flash lamp crystallised films revealed pore free microstructure with longitudinally extended grains regardless of the precursor ratio.

Guiding principle for crystalline Si photovoltaic modules with high tolerance to acetic acid

A guiding principle for highly reliable crystalline Si photovoltaic modules, especially those with high tolerance to acetic acid generated by hydrolysis reaction between water vapor and an ethylene-vinyl acetate (EVA) encapsulant, is proposed. Degradation behavior evaluated by the damp heat test strongly depends on Ag finger electrodes and also EVA encapsulants. The acetic acid concentration in EVA on the glass side directly determines the degradation behavior. The most important factor for high tolerance is the type of Ag finger electrode materials when using an EVA encapsulant. Photovoltaic modules using newly developed crystalline Si cells with improved Ag finger electrode materials keep their maximum power of 80% of the initial value even after the damp heat test at 85 °C and 85% relative humidity for 10000 h. The pattern of dark regions in electroluminescence images is also discussed on the basis of the dynamics of acetic acid in the modules.

An improved bulk acoustic waves chip based on a PDMS bonding layer for high-efficient particle enrichment

In this work, we developed a feasible way to package bulk acoustic waves chip with sandwich structure by inserting a polydimethylsiloxane (PDMS) layer as the adhesive between cover glass and silicon substrate. After spin-coating and curing process, a PDMS layer was formed on one side of the cover glass and then bonded to the silicon substrate with microchannels by oxygen plasma treating. Both simulation and experiment showed that the chip was not leaking and the acoustic waves produced by the piezoelectric transducer could be propagated through the PDMS layer. Finally, a standing wave field was formed in the microchannels. Compared with traditional chip bonded by anodic bonding, simulation results showed that this packaging method did decrease the acoustic pressure in the channel, but the reduction was acceptable. After optimizing the experimental parameters, we successfully aggregated 15-μm silica spheres under a very low input power (21 dBm) at a flow velocity of 1 ml/h, and the enrichment efficiency of silica spheres was greater than 97%.

New insights into nanoindentation crack initiation in ion‐exchanged sodium aluminosilicate glass

AbstractThe effect of ion‐exchange on the fracture behavior and the threshold load is investigated for radial crack initiation resulting from cube‐corner indentation. Both tin and air sides of the sodium aluminosilicate float glass are considered. The threshold load and mechanical properties are experimentally measured by nanoindentation. A qualitative explanation of crack initiation is developed by analyzing the stresses at the indentation site. The ion‐exchanged glasses show a lower threshold load for radial crack initiation with a cube‐corner indenter than the raw glass, and this is due to a higher crack driving stress for ion‐exchanged glasses. However, the compressive stress on the surface of the ion‐exchanged glasses can inhibit the expanding of the radial cracks. The air side always shows higher values for the threshold load than the tin side before and after ion‐exchange, which is in accordance with the calculated crack driving stress results.

Bubble nucleation in superhydrophobic microchannels due to subcritical heating

This work experimentally studies the effects of single wall heating on laminar flow in a high-aspect ratio superhydrophobic microchannel. When water that is saturated with air is used as the working liquid, the non-wetted cavities on the superhydrophobic surfaces act as nucleation sites and allow air to effervesce out of the water and onto the surface when heated. Previous works in the literature have only considered the opposite case where the water is undersaturated and absorbs air out the cavities for a microchannel setting. The microchannel considered in this work consists of a rib/cavity structured superhydrophobic surface and a glass surface separated by spacers. The microchannel is 60 mm long by 14 mm wide and two channel heights of nominally 183 μm and 366 μm are explored. The superhydrophobic side is in contact with a heated aluminum block and a camera is used to visualize the flow through the glass side. Thermocouples are embedded in the aluminum to record the temperature profile along the length of the channel. Temperatures are maintained below the boiling temperature of the working liquid. The friction factor-Reynolds product (fRe) is obtained via pressure drop and volumetric flow-rate measurements. Five surface types/configurations are investigated: smooth hydrophilic, smooth hydrophobic, superhydrophobic with ribs perpendicular to the flow, superhydrophobic with ribs parallel to the flow, and superhydrophobic with ribs parallel to the flow with several breaker ridges perpendicular to the flow. The surface type/configuration has a significant impact on the mass transport dynamics. For surfaces with closed cell micro-structures, large bubbles eventually form and adversely affect fRe and lead to higher temperatures along the channel. When degassed water is used, no bubble nucleation is observed and the air initially trapped in the superhydrophobic cavities is quickly absorbed by the water.

Increased Efficiency of Solar Cells Protected by Hydrophobic and Hydrophilic Anti-Reflecting Nanostructured Glasses.

We investigated the fabrication of large-area (cm2) nanostructured glasses for solar cell modules with hydrophobic and hydrophilic properties using soft lithography and colloidal lithography. Both of these techniques entail low-cost and ease of nanofabrication. We explored the use of simple 1D and 2D nanopatterns (nanowires and nanocones) and the effect of introducing disorder in the nanostructures. We observed an increase in the transmitted light for ordered nanostructures with a maximum value of 99% for wavelengths >600 nm when ordered nanocones are fabricated on the two sides of the solar glass. They produced an increment in the efficiency of the packaged solar cell with respect to the glass without nanostructures. On the one hand, the wettability properties showed that the ordering of the nanostructures improved the hydrophobicity of the solar glasses and increased their self-cleaning capacity. On the other hand, the disordered nanostructures improved the hydrophilic properties of solar glasses, increasing their anti-fogging capacity. The results show that by selecting the appropriate nanopattern, the wettability properties (hydrophobic or hydrophilic) can be easily improved without decreasing the efficiency of the solar cell underneath.

Preparation and Characterization of TiO2-LaFeO3 based Mixed Matrix Membrane for Oily Wastewater Treatment

The aim of this study was to investigate the effects of catalyst loading in mixed matrix membrane. LaFeO3 and TiO2-LaFeO3 were synthesized by sol-gel glucose method. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), contact angle, membrane permeation testing unit and UV-Vis spectrophotometer techniques are used for characterization. FTIR showed the successful transformation of photocatalyst TiO2, LaFeO3 and TiO2-LaFeO3. Due to increase in nanoparticles loading, the hydrophilicity of the membrane had improved thus increase the permeation flux. The cross-section morphology of membranes (PTL-1, PTL-3 and PTL-4) indicated that all the membranes were found to have asymmetric structure, consisting of dense top layer (air side), a porous sublayer (finger-like) and a small portion of sponge-like bottom surface layer (glass side). But as for the PTL-2, the cross sections of the membranes have a fully sponge-like structure. The formation of sponge-like structure was associated to the slow solidification process during the casting. The highest oily wastewater rejection was 76.26% with highest permeation flux and lower contact angle. This result showed that nanoparticles with membrane had improved the oily wastewater rejection. It proved that the fabricated nanoparticles with mixed matrix membrane exhibits a high flux, which is 2 to 3 orders of magnitude higher than commercial filtration membranes with an acceptable separation performance.

Study on the Fabrication and Characteristics of the Bandpass Filter for Slit Lamp

Purpose: The 450nm~500nm bandpass filters for slit lamp were fabricated and the characteristics of these filters were studied. Methods: The 450nm~500nm bandpass filter was designed by combining a longpass filter and a shortpass filter, which were based on the data of the 450nm~500nm bandpass filter design and were fabricated by electron beam evaporation apparatus. SEM photographs were taken to observe the cross section of the fabricated filters, and the spectrophotometer was used to measure the transmittance of the filters. Results: The experimental values of the fabricated shortpass filter were similar to the design values, but differed from the design values at a wavelength of about 490 nm and 350 nm to 400 nm. These differences were considered to be due to the fact that as the number of layers increased, the uniformity of the thin film became poor and the refractive index of the filter was changed slightly, resulting in a large difference in the slope of the transmittance. The experimental values of the fabricated longpass filter were similar in design values and the experimental curve was slightly shifted to the right as a whole. Therefore, the experimental curve of the 450 nm~ 500nm bandpass filter was shifted a little into the design curve of bandpass filter at 450 nm wavelength due to the right shift of the experimental curve of the longpass filter and the transmittance dropped about 20% at 500 nm wavelength. From the SEM photographs, the thicknesses of the fabricated shortpass filter and longpass filter were found by observing the cross section of the filters. Conclusions: The shortpass filter was fabricated on one side of the BK7 glass and the longpass filter was fabricated on the other side, and therefore the 450nm ~ 500nm bandpass filter was fabricated. The 450nm ~ 500nm bandpass filter was to increase the contrast of the area we want to see in observing the dry of the eye and the gap between contact lens and cornea.

Encapsulant for glass-glass PV modules for minimum optical losses: gas or EVA?

Our simulation work aims at analyzing optical loss mechanisms for two types of glass-glass modules: laminated modules, using for example EVA (ethylene vinyl acetate) as encapsulant, and modules without encapsulant that are filled with neutral gas. The simulation results give arguments in favor of the use of gas as encapsulant in glass-glass PV modules instead EVA. Indeed, with an anti-reflection coating (ARC) on both sides of the front glass of the module and an appropriate ARC on the cell, the collected current of a cell encapsulated with gas is almost equal than the one obtained for a standard EVA module with a single side ARC on the glass and an appropriate ARC on the cell under an AM1.5G spectrum.Because of the different spectral behavior of the two materials, a careful filtering of lamps used in solar simulators is mandatory due to the high-infrared content, in order to compare gas filled modules to EVA laminated ones. Low UV content in the incident spectrum underestimates the optical losses in the EVA module and high-infrared content overestimates the optical losses in the gas filled module. This analysis shows that the refractive index of SiN of industrial solar cells and the current spectral distribution of solar simulators defined according to the norm IEC 60904-9 could penalize gas filled modules in comparison to EVA laminated ones.

Continuous-wave laser-induced glass fiber generation

Pulsed-laser-induced glass fiber generation has been reported. We demonstrate a novel glass fiber generation technique by continuous-wave laser illumination and reveal the generation mechanism. In this technique, borosilicate glass, metal foil, and a heat insulator are stacked and clamped by a jig as the sample. Glass fibers are ejected from the side surface of the borosilicate glass by laser illumination of the sample from the borosilicate glass side. SEM observation shows that nanoparticles are attached on the glass fibers. High-speed imaging reveals that small bubbles are formed at the side surface of the borosilicate glass and the bursting of the bubble ejects the fibers. The temperature at the fiber ejection point is estimated to be ~1220 K. The mechanism of the fiber ejection includes the following steps: the metal thin foil heated by the laser increases the temperature of the surrounding glass by heat conduction. Since the absorption coefficient of the glass is increased by increasing the temperature, the glass starts to absorb the laser irradiation. The heated glass softens and bubbles form. When the bubble bursts, molten glass and gas inside the bubble scatter into the air to generate the glass fibers.

A micromechanical derivation of the macroscopic strength statistics for pristine or corroded/abraded float glass

The macroscopic strength of float glass is governed by the presence of micro-cracks, whose size, orientation and distribution affects the corresponding statistics. A micro-mechanically motivated model is here proposed, which spells out the connection between crack population and strength statistics, leading to generalized distributions of the Weibull type. Aging in the form of corrosion or abrasion can produce a variation of the defectiveness scenario originally present on the pristine glass surface, and we discuss how such a modification can statistically affect the macroscopic strength. A practical application is made to justify the change in strength experimentally observed passing from the “air” to the “tin” side of float glass. Assuming that the contact with the tin bath and the rollers produce a damage equivalent to the abrasion of the glass surface, we theoretically derive a bimodal Weibull statistics that agrees with the experimental evidence.