Strength Of Glass Research Articles

Impact of ZnO content in BAS glass–ceramics and pre‐oxidation temperature on Kovar alloys to their sealing strength

AbstractThis work studied the effect of Si/Zn ratio on the structure of B2O3–Al2O3–SiO2 (BAS) parent glass and the microstructure, properties of the resulting glass‐ceramics after heat treatment. Additionally, the effects of different pre‐oxidation temperature of Kovar alloys and sealing temperature on the shear strength of these sealed glass–ceramics‐to‐Kovar samples were studied. First, the parent glass precipitated three kinds of crystals Al0.52Zr0.48O1.74 (PDF#53‐0294), ZrO2 (PDF#37‐1484), and ZnAl2O4 (PDF#05‐0669) in BAS glass–ceramics. The coefficient of thermal expansion of glass–ceramics increased from 48.17 × 10−7 to 54.92 × 10−7°C−1 with the gradual increase of ZnO content. With an optimizing pre‐oxidized temperature of Kovar at 950°C, a champion sample with the highest sealing strength of 6.086 MPa was achieved when BAS glass–ceramics sealed to Kovar at 1000°C for 30 min. Moreover, the sealing interface was observed to consist of four distinct regions: the matrix alloy, the alloy iron‐deficiency area, the iron‐rich glass–ceramics, and the matrix glass–ceramics.

Nanoporous Structure Fabrication on Glass Surfaces for Enhanced Glass Adhesion Using Hydrogen Fluoride Gas.

The bonding between glass and other materials plays a crucial role when glass is used in industrial products. In this study, we propose a new approach to enhance the bonding strength of glass with other materials by fabricating nanoscale porous structures on glass surfaces via a chemical reaction with hydrogen fluoride gas. Herein, we present a methodology for controlling the thickness of the porous structure, clarify the relationship between the thickness and adhesion strength, investigate the shape of the formed porous structure, and propose a method to control its shape. Our findings reveal that the fabricated porous structure greatly improves the adhesion strength of the adhesive owing to the microscopic anchoring effect induced by the penetration of the adhesive into the porous structure. This approach is expected to be applied to architectural and automobile window glasses, solar panels, sensor cover glasses of autonomous vehicles, display devices (including smartphones), and wearable devices.

Numerical simulation of anti-shatter films (ASF) for mechanical post-breakage analysis of retrofitted glass

Post-breakage strength and residual mechanical capacity improvements are important tasks for load-bearing structural components in general, and even more for glass elements, in order to protect people from injury in case of breakage. For this reason, among others, the design of glass components and structures is based on key concepts that are generally summarized in structural safety, robustness and redundancy. With regard to the last fundamental requirement, nowadays the use of laminated glass (LG) sections is spread for many applications and new projects, such as automotive or aircraft windshields, but especially curtain walls and many other load-bearing applications in buildings. This strategy derives from the intrinsic safety and security levels of LG sections after possible glass breakage. When LGs are not available (i.e., existing components), anti-shatter safety films (ASF) for the retrofit of monolithic glass elements are expected to provide very similar post-breakage structural performances against bending and impact actions, by reducing the possible spread of glass shards. Besides, the residual load-bearing capacity of glass components retrofitted by ASF is still challenging to quantify. In this paper, the Cohesive Zone Model (CZM) theory is considered to investigate, with the support of experiments and Finite Element (FE) numerical models, the performance of small-scale monolithic glass specimens retrofitted by ASF under bending loads. Different ageing procedures and imposed displacement-rates are considered to evaluate the influence of basic operational parameters, such as temperature and humidity, on the mechanical efficiency of common ASF layers. In doing so, the sensitivity of fundamental input parameters (i.e., maximum tensile strength of glass and fracture energy of the ASF adhesive) on the mechanical performance at pre- and post-breakage stages of retrofitted monolithic glass elements is explored.

A Low-Hydroxyl Quartz Glass Prepared by Using a Plasma Heat Source as the Flame and High-Purity Quartz Sand as the Raw Material

In this paper, a quartz glass with low hydroxyl groups was prepared by combining the advantages of various processes, using a plasma heat source as the flame and high-purity quartz sand as the raw material. The purity of the quartz sand was 99.997%. The number of air bubbles in the quartz glass prepared using high-purity quartz sand was lower. The hardness and tensile strength of the quartz glass were 737.7–767.1 GPa and 6.88–9.64 MPa, respectively. The hydroxyl content of the sample was only 4.11 ppm, and the hydroxyl content of the homogenized quartz glass was reduced to 2.64 ppm, which was an improvement of about 35%. After homogenization, the fictive temperature (Tf) of the quartz glass was determined to be 1253 cm−1, and the variation of the Tf value along the radial direction was reduced, indicating a more homogeneous glass structure. The stress distribution in the quartz glass was significantly improved. These results indicate that the preparation of quartz glass from high-purity quartz sand using a plasma heat source as the flame opens up new avenues for optical applications.

Properties of foam glass produced with the use of soot from a cement factory as a foaming agent: A Study Based on Taguchi Design of Experiments

Cellular glass is a lightweight, porous medium with excellent heat transfer resistance that can be used in a variety of industries. This study investigated the use of soot from cement plants as a new foaming agent for producing foam glass. The experiments were designed using the Taguchi Design of Experiments (DOE) method. By applying this approach, instead of creating and testing 27 different groups of samples, only 9 groups were produced. The properties of the remaining 18 sample groups were then predicted based on Taguchi analysis. Soot and silicon carbide were used simultaneously (at weight ratios of 2% and 3%) as foaming agents in the samples. Alumina was also used as a modifier with weight ratios of 4%, and 8%. Mechanical strength, water absorption, density, and thermal resistance were evaluated. The findings indicated a direct correlation between elevated soot content and increased water absorption (open porosity), coupled with a reduction in compressive strength and overall density of the foam glass. Electron microscopy observations revealed a wide range of crystallite morphologies in the resulting foam glass, which results in diverse properties in the material. The developed glass foams exhibit a density spanning from 125 to 700 kg/m3, with compressive strength varying between 1.2 and 6.7 MPa, and thermal conductivity in the range of 0.08–0.5 W/m·K. The samples with 3% soot, 0% alumina, and 3% SiC exhibited exceptional thermal insulation properties. In contrast, the samples containing 1% soot, 8% alumina, and 1% SiC demonstrated the highest compressive strength. Overall, this study found that soot from cement plants is a viable foaming agent for producing foam glass with desirable properties. The use of soot from cement plants can not only reduce the dispersion of pollution in the environment but also produce a wide range of foam glass with different properties at a lower cost.

Constructing ZSM-5 loaded with 2-mercaptobenzimidazole on glass fiber for enhancing the anti-corrosion and erosion resistance properties of epoxy coating

Glass fiber reinforced polymer coatings (GFRPC) are used to protect steel structures in harsh Marine environments due to high mechanical strength and chemical stability. The composite coating not only suffers from impact damage by seawater and sediment but also experiences corrosion damage in the splash zone. However, the GF has weak interfacial adhesion with polymer resins due to the chemical inertia and smooth surface, which limits the service lifespan of GFPRC. Hence, ZSM-5 zeolites were in situ prepared on the surface of glass fibers by hydrothermal synthesis, and 2-mercaptobenzimidazole (MBI) was further adsorbed to obtain difunctional hybrid glass fibers (ZGFM) to enhance the interfacial adhesion strength of glass fiber/resin and also the erosion resistance and anti-corrosion ability of composite coatings. Compared to GF/EP, the interfacial shear strength of ZGFM/EP was increased by 104.39 %. After immersion under an alternating hydrostatic pressure of 20 MPa for 12 days, the impedance value of the ZGFM/EP composite coating remained at 6.40 × 109 Ω•cm2, demonstrating outstanding deep-sea anti-corrosion performance. Following the erosion test, the ZGFM/EP exhibited a reduction in mass loss and volume loss by 10.65 % and 12.55 %, respectively, in comparison to the pure EP coating. The excellent interfacial strength between ZGFM and EP ensured effective stress transfer, which prevented crack propagation, thus enhancing the mechanical properties and erosion resistance of the composite coating. Meanwhile, electrochemical experiment proves glass fiber with MBI loaded obviously inhibited the corrosion reaction.

Influence of Dentin Sealing Technique on the Shear Bond Strength between Lithium Disilicate Ceramics and Try-In-Paste-Contaminated Dentin

This study aimed to evaluate the effect of try-in paste contamination on the bond strength of lithium disilicate glass–ceramic to dentin treated with immediate (IDS) or delayed (DDS) dentin sealing techniques. Occlusal halves of 33 molars were decapitated and divided into three groups (n = 10). Lithium disilicate discs (3 × 5 mm) were prepared. For Group A, the provisional crown was applied over dentin and was soaked in distilled water. Lithium disilicate discs were cemented following dentin conditioning with a three-step etch and rinse adhesive. In Group B (IDS), the three-step adhesive was applied to dentin. The dentin surfaces were conditioned only in the final cementation for Group C (DDS). The intaglio surfaces of test groups were contaminated with try-in paste. All specimens were thermally cycled 3000 times at 5–55 °C and were subjected to shear tests. An additional three specimens for each group were contaminated with try-in paste and subjected to the same surface cleaning as the test specimens were examined with SEM/EDS. The adhesive surfaces were also examined with SEM/EDS for try-in paste remnants. Group C showed a significant decrease in bond strength values compared to Group B and Group A (5.84 ±1.4 MPa, 11.45 ±2.4 MPa, and 10.29 ±2.5 MPa, respectively). No statistically significant difference was detected between Group B and Group A (p ≥ 0.05). The SEM-EDS analyses revealed obstructions of the dentinal tubules in the try-in-paste-contaminated specimens. Immediate dentin sealing application enhanced the bonding strength of lithium disilicate to the try-in-paste-contaminated dentin. Try-in paste contamination over dentin negatively influenced the bonding process.

Shear strength and optical bandgap in As2Se3 glasses permanently compacted under GPa pressures

The application of GPa pressures on glassy As2Se3, at temperatures just below and above its glass transition, leads to permanently compacted glasses that exhibit increased densification. Also, melt-quenching of the same glass under a pressure of 7 GPa gives rise to the formation of its crystalline β-phase. The structure of these As2Se3 compacted solids have been explored by X-ray diffraction. Measurements of 10 MHz ultrasound velocities reveal that the density increase is associated with a substantial hardening of the elastic continuum as well as a growing shear strength of glassy solids: the shear modulus G increases by more than 35 % and the Poisson's ratio ν decreases by more than 13 %. The optical properties have been investigated by UV–VIS diffuse reflectance spectroscopy, which shows a well defined linear reduction of the optical bandgap Eg with increased density. All of these observations have been explained by considering a disordered layered structure of glassy As2Se3, where densification produced by compaction under GPa pressures gives rise to a progressive strengthening of the interlayer interactions.

Densification and network structural changes in binary aluminosilicate glass via cold sintering process

Binary aluminosilicate glasses containing 20–50 wt% Al2O3 were successfully densified through a cold sintering process (CSP) using 1–10 M NaOH solutions. The investigation focused on densification and structural unit changes in the cold-sintered binary aluminosilicate glasses. Specifically, the binary aluminosilicate glass with 40 wt% Al2O3, cold-sintered at 180 °C using 1–10 M NaOH solutions, achieved a relative density of up to 90 % at 10 M NaOH. This was attributed to an enhanced dissolution-precipitation process facilitated by an increased concentration of the NaOH solution. In aluminosilicate glasses with 20–50 wt% Al2O3, the relative densities approached 90 % after CSP at 180 °C using a 10 M NaOH solution. Al(OH)3 formation in the cold-sintered glasses was confirmed, particularly at higher concentrations of NaOH solution (>10 M) and higher contents of Al2O3 (>40 wt%). Changes in Si structural units were observed during CSP, with Al-rich Si units becoming dominant as the concentration of the NaOH solution increased. The higher substitution of Si-O-Si bonds by Si-O-Al bonds led to the precipitation of Al(OH)3, as well as an increased Vickers hardness and biaxial flexural strength of the cold-sintered glasses. These findings demonstrate that the Al2O3 content and NaOH concentration play important roles in the densification and enhancement of the mechanical property in the cold-sintered alumina-rich binary aluminosilicate glasses and offer insights into the optimal conditions for obtaining desirable aluminosilicate materials through CSP.

The Impact of Welding Parameters on the Welding Strength of High Borosilicate Glass and Aluminum Alloy

This study adopts a new surface pretreatment method, Laser Surface Remelting (LSR). This experiment aims to establish a set of laser welding process parameters suitable for aluminum alloy and glass under this specific pretreatment. This experiment explores the impact of laser welding parameters on the welding strength between high borosilicate glass and aluminum alloy. The study specifically investigates the effects of four process parameters: defocus amount, laser power, frequency, and pulse width on the welding outcome. The results indicate that the welding quality between the aluminum alloy and glass reaches its optimum when the defocus amount is zero (i.e., when the laser converges at the interface between the glass and the metal) and the laser welding parameters are set to a power of 250 W, a welding speed of 1 mm/s, a welding frequency of 10 Hz, and a pulse width of 2.5 ms. The experiment also analyzes the fracture morphology under different parameters, summarizing the locations and causes of fractures, and establishing the relationship between the fracture location and the welding strength.

Strengthening effects of indentation notches on metallic glasses and their sensitivity to stress triaxiality

In this study, a metallic glass sample with an annular indentation notch was successfully constructed by a compression rod cyclic compression strategy using molecular dynamics simulation, and the mechanical behaviors of cut-notched metallic glass samples with the same stress triaxiality and notch size under triaxial compression were comparatively analyzed. It is found that the indentation notch further improves the strength and plasticity of the metallic glass, while it is insensitive to the cut-notched metallic glass with the same notch size. During triaxial compression, rejuvenation and shear softening lead to an increase in free volume, while diffusion and residual compressive stresses lead to a decrease in free volume. The stress triaxiality plays a key regulatory role in their competition and affects the final state of free volume change. This study provides a new theoretical basis and process idea for the enhancement of strength and plasticity of metallic glass.

Phase field modeling of fracture mechanics for ion-exchanged glass considering large viscoelastic deformation, mechanic–electrochemical coupling

A phase field model is proposed to investigate the fracture mechanics of ion-exchanged glass, which involves significant viscoelastic deformation and stress-diffusion interaction. Based on this theoretical model, the fracture behavior of both double-sided and single-sided ion exchange processes was studied. The results indicate that, compared to single-sided ion exchange, the double-sided process is more likely to induce crack initiation and propagation, ultimately resulting in a notable reduction in glass strength. For both cases, increasing the glass thickness and interfacial energy density will significantly improve the fracture resistance of the glass. Notably, when the glass thickness or interfacial energy density is large enough, the crack can be completely closed, ensuring the integrity of the glass during the ion exchange process. Furthermore, the study conducted a preliminary investigation of two industrially relevant conditions: edging and impurities. The impacts of edging parameters, glass interfacial energy density, and covering radius on glass stress evolution, mechanical deformation, crack initiation, and crack propagation during chemical strengthening were summarized. These findings offer valuable theoretical support and a reference for optimizing chemical strengthening process parameters and enhancing the strength of glass products.

Optical properties of Ce: GdYAG phosphor in glass with high quality LAS glass system and its application in laser illumination

Nowdays, the demand for high-power laser lighting applications is on the rise, however, phosphor in glass (PiG) prepared using conventional glass systems often experience damage under intense laser irradiation. To tackle this issue, we introduce a novel LAS glass system for phosphor encapsulation to create PiG, and by utilizing a spray coating technique, we blend PiG with high thermal conductivity sapphire to obtain phosphor in glass film (PiF), effectively improving laser irradiation resilience and optical characteristics. In this study, a novel LAS glass system (SiO2–Li2CO3–MgO–Al2O3–CaO–P2O5–K2O–ZrO2–Na2O) was utilized to encapsulate Ce:GdYAG phosphors to prepare a series of PiG and PiF. The glass system exhibits multi-directional interlocking lithium disilicate crystals, significantly enhancing the glass's strength and fracture toughness. There is no apparent interface reaction between the glass system and the phosphors, indicating effective protection of the phosphor particles. The PiF sample demonstrates a minor decrease of 5.2 % in internal quantum efficiency compared to the original phosphor, while boasting a high thermal conductivity of 7.4 W m−1 K−1. Notably, the optimized PiF shows remarkable enhancements with a saturation threshold of 4.37 W mm−2, surpassing PiG (1.668 W mm−2), and achieving LFmax of 424.41 lm and LEmax of 147.16 lm W−1. It features a high color rendering index (CRI) of 68.7 and low color correlated temperature (CCT) of 3646 K, significantly improving laser irradiation resistance and optical quality, making it a promising warm yellow laser illumination converter for diverse lighting applications.

Glass Beams Used in Steel-glass Roofs for the Adaptive Reuse of Historic Buildings

This article concerns the use of structural glass in the adaptive reuse of historic facilities using glass beams as structural elements in steel-glass roofs. More and more often, glass is increasingly being used as a structural material. This fact provides new design possibilities in the adaptation of historic buildings due to the neutral perception of glass and, at the same time, offers the possibility of distinguishing modern structural elements in the historic fabric. The use of structural glass is, however, associated with limited spans of structural elements. For larger spans, solutions of mixed materials are proposed, which are exemplified by steel-glass roofings. Based on selected examples, steel-glass systems with the use of glass beams are characterised. The strength of glass as a structural material is discussed. The main approaches in the design of glass beams with the lateral-torsional buckling phenomenon are indicated.

Dynamic flexural strength of Aluminosilicate glass with a perspective of impulsive and quasi-impulsive responses: An experimental–numerical coupled evaluation

The flexural strength of glass is a critical design parameter for applications encountering impact loadings. However, the micro defects, specimen geometry, loading rate, and load transformation from a quasi-dynamic to quasi-impulsive state may influence the measurement accuracy. Due to the stochastic and amorphous nature of the material, an accurate determination of the flexural strength remains a challenge. In this two-fold study, a coupled experimental–numerical strategy was devised to evaluate the dynamic flexural strength. In the first phase, three-point bending experiments were conducted on a novel “Electromagnetic Split Hopkinson Pressure Bar (ESHPB)”. The incident stress signal and fracture time were recorded from experimental data, while the flexural strength was indirectly computed from a numerical algorithm. A quantitative comparison of the flexural strength with those in existing literature established the accuracy of the proposed methodology. Results of the study indicate that the specimen response became independent of the support conditions under impulsive loading. That being said, the specimen behaved like it had an infinite span length, and the measured flexural strength remained the same whether the specimen was supported or not. Besides, the specimen also maintained contact at the interfaces of the incident bar and fixture supports for the entire loading duration. In the second part of this study, the computed flexural strength was used to calibrate the existing JH-2 model. Numerical prediction of the damage propagation corroborated with that obtained from reprography images, though qualitatively. This work presents a precise and robust methodology to determine the dynamic flexural strength of brittle ceramics like Aluminosilicate glass over traditional experimental procedures to facilitate its adoption.

Commercial glass strengthening and safety technologies: lessons learned and yet to be learned

This is the fourth in this series of “Lessons Learned and Yet to be Learned” on topics related to glass strength.(1–3) In this paper we pick up the topic of stronger glass products from our earlier publication(2) and expand to discussing commercial technologies. Included in this discussion are a brief historical perspective of the initial technologies and update to newer technologies with the aim to obtain faster production rates that focus on lightweight glass products and a sustainable future with respect to resource conservation, reduced energy consumption and reduced CO2 emissions. Also included are glass products which focus on safety mostly and less on overall strength.

A finite difference method on crack resistance of reinforced glass beam with non-linear adhesive

Reinforced glass beam (RG beam) is a type of structural glass member that has been developed in recent years. This RG beam consists of a glass beam to which reinforcement material, such as steel, is adhesively attached in the tensile side to improve crack resistance. The adhesive plays a critical role in the structural performance of RG beam. However, the effect of non-linear shear-slip behavior of the adhesive layer remains unclear and has been neglected in most previous studies, which can result in inaccurate estimations. To address this issue, this paper presents a finite difference model (FDM) that utilizes an explicit step-by-step method and trial-and-error iterative method for interfacial stress analysis. The model predicts the static structural response of a simply-supported RG beam that simulates the adhesive with non-linear stress-slip behavior. Furthermore, the model describes the adherend’s shear deformation in elastic. The FDM results are then compared with the finite element method (FEM), adopting discrete nonlinear connectors (springs) to simulate the adhesion, and available analytical methods. Detailed parametric studies are further conducted to investigate the influences of glass strength, load pattern, reinforcement ratio and height-to-span ratio for proposing design recommendations.

Impact of Chemical Corrosion on Mechanical Properties of Boroaluminosilicate Pharmaceutical Glasses.

Boroaluminosilicate (BAS) glasses have excellent chemical durability and mechanical properties and are widely used in the pharmaceutical packaging industry. The corrosion behavior of boroaluminosilicate (BAS) glasses have been investigated for many years; however, the impact of chemical corrosion on mechanical properties of boroaluminosilicate glasses has not been well understood. In this work, the BAS glass samples were corroded in a 20 mM Glycine-NaOH buffer solution (pH = 10) at 80 °C for various durations. Within the corrosion durations, the corrosion of the glass is dominated by congruent dissolution. The results show that the elemental composition and structure of the glass surface are not altered significantly during the congruent dissolution, and the corrosion rate is mainly affected by the Si concentration in the solution. The structural change in the process of micro-crack decay is the main factor affecting the mechanical properties of the glass surface. Corrosion leads to the growth of micro-cracks and tip passivation, which causes the hardness and elastic modulus of the glass to first decrease and then increase. As corrosion proceeds, the microcracks are completely destroyed to form micropores, and the pore size and number increase with the corrosion process, resulting in the decrease in surface mechanical properties again. This work reveals the main influencing factors of congruent dissolution on mechanical properties and provides an important reference for the improvement of pharmaceutical glass strength.

88‐1: Distinguished Paper: Direct Laser Patterning of Glass Mask for Micro Display Using GHz Bursts

Development of high‐precision RGB patterning process is needed to implement high‐resolution micro display (OLEDoS) for next‐generation VR/AR products. In general, specially designed and manufactured masks are required to realize above 3,000ppi high‐resolution display in structured OLED material deposition. In this study, we implemented direct laser patterning IR‐fs optical system operating in MHz and GHz burst modes and evaluated its capability for precise micro‐drilling of alumino‐borosilicate glass materials. The fine hole‐shaped pattern is produced at a minimum of 5µm pitch level for about 0.6 inch area without sacrificing the glass strength. It is expected to contribute to the high precise manufacture of ultra fine mask (UFM) using thin glass platform corresponding to micro displays in the future.

Constant-curvature bending response of thin glass: Analytical, numerical and experimental study of “clamp-bending” tests

New generation thin, lightweight and damage-resistant glass, having impressively impact resistance and ability to be bent up to small radii, appears to be the optimal material for extremely deformable structural elements. Its structural use and design require an accurate evaluation of its mechanical properties. However, standard methods to test the glass strength, as the Four-Point Bending and the Coaxial Double Ring test, cannot be used for thin glass, due to its high deformability. Here, an innovative test is proposed, consisting into deforming a thin element into a costant-curvature shape, by prescribing a rotation on two opposite edges of a rectangular plate, while allowing the adjustment of the distance between the supporting hinges. This produces a deformation into an arch of a circle and to a constant stress distribution, allowing to determine the thin glass strength with very simple formulas. An innovative experimental setup, recently proposed for twisting tests on thin glass, has been adapted for constant-curvature bending tests, based on the results of both analytical modelling and numerical analyses. This has been used to perform an experimental campaign, comprising 15 destructive tests on chemically tempered thin glass.