Glass Suspension Research Articles

Manufacturing fused silica hemispherical resonators using polymer glass suspension and replication molding

This work introduces a new method for manufacturing fused silica (FS)-based hemispherical resonators (HSRs) using a printable polymer glass mixture and replication molding. This process involves 3D printing to create the mold, followed by the casting of a photo-reactive pre-polymer glass mixture. This technique allows us to produce complex 3D geometries and offers faster production of resonators compared to other traditional methods. In this study, we manufactured three devices and successfully identified resonance modes with two (N = 2), three (N = 3) and four (N = 4) nodes/antinodes in all three HSRs, demonstrating the repeatability of our new manufacturing method. The highest quality factor of 482 k was achieved for the N = 3 resonance mode using the ring-down method. Some of the key advantages of our method include producing multiple devices efficiently with relatively good surface quality, making it a viable option for producing high-precision devices in the future. Our new fabrication technique results in a device surface roughness of ∼100 nm (measured over an area of 250 μm × 250 μm) and manufacturing yield of over 90%. Moreover, all the steps involved in this method can be completed outside of a specialized cleanroom environment.

Colorimetric Signal Readout for the Detection of Volatile Organic Compounds Using a Printable Glass-Based Dielectric Barrier Discharge-Type Helium Plasma Detector.

In this paper, we report on a printable glass-based manufacturing method and a new proof-of-concept colorimetric signal readout scheme for a dielectric barrier discharge (DBD)-type helium plasma photoionization detector. The sensor consists of a millimeter-sized glass chamber manufactured using a printable glass suspension. Plasma inside the chip is generated using a custom-built power supply (900 V and 83.6 kHz), and the detector uses ∼5 W of power. Our new detection scheme is based on detecting the change in the color of plasma after the introduction of target gases. The change in color is first captured by a smartphone camera as a video output. The recorded video is then processed and converted to an image light intensity vs retention time plot (gas chromatogram) using three standard color space models (red, green, blue (RGB), hue, saturation, lightness (HSL), and hue, saturation, value (HSV)) with RGB performing the best among the three models. We successfully detected three different categories of volatile organic compounds using our new detection scheme and a 30-m-long gas chromatography column: (1) straight-chain alkanes (n-pentane, n-hexane, n-heptane, n-octane, and n-nonane), (2) aromatics (benzene, toluene, and ethylbenzene), and (3) polar compounds (acetone, ethanol, and dichloromethane). The best limit of detection of 10 ng was achieved for benzene at room temperature. Additionally, the device showed excellent performance for different types of sample mixtures consisting of three and five compounds. Our new detector readout method combined with our ability to print complex glass structures provides a new research avenue to analyze complex gas mixtures and their components.

Switching Impulse Flashover Performance of Nonuniform Pollution Insulators in Natural Environment

Under natural conditions, insulators show a nonuniform pollution state, which has a great influence on the switching impulse flashover voltage of insulators. Meanwhile, the insulation level of transmission lines is selected according to the switching impulse flashover voltage of nonuniform pollution insulators. For this purpose, in this article, the wet pollution method is used to simulate nonuniform pollution conditions. Then, the switching impulse flashover tests and the switching impulse flashover tests with preloading ac voltage are conducted on two types of insulators, XP-70 and LXY-70, in natural environment. The flashover voltage of insulators is obtained, flashover performances are analyzed, and the flashover processes of insulators are photographed. Moreover, the equations of flashover voltage gradient <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{{50}}$ </tex-math></inline-formula> under nonuniform pollution conditions are established. The results indicate that there is a conspicuous polarity effect and a polarity reversal phenomenon under different conditions. Besides, as the increase of the ratio of bottom surface pollution to top surface pollution, the flashover voltage changes in the opposite case of preloading and non-preloading ac voltage. Finally, the switching impulse flashover voltage of ordinary porcelain and glass suspension insulators under nonuniform pollution conditions can be calculated based on the established equations of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${E}_{{50}}$ </tex-math></inline-formula> . The results can provide theoretical support for the reasonable selection of the insulation level of transmission lines, which in turn can greatly reduce the cost of the transmission lines.

Glass Suspension Footbridge: Human-Induced Vibration, Serviceability Evaluation, and Vibration Mitigation

Glass suspension footbridges or glass-bottomed suspension footbridges, such as the Zhangjiajie Grand Canyon Glass Bridge in China, are increasingly constructed in scenic regions as tourist attractions due to the glass-bottomed and transparent characteristics. Being installed in the second phase as a constant load, the glass deck is not designed to participate in the load bearing of the whole structure and thus the structure requires larger load-bearing capacity from other parts and a slightly different load-bearing system. More importantly, the glass deck weakens structural integrity and results in slightly smaller structural stiffness, which may result in globally lower natural frequencies. These structures may inevitably be more sensitive to the pedestrian-induced excitations. This paper investigates the human-induced vibrations of a typical glass suspension footbridge in China. The investigations are first performed based on intensive parametric studies. Except for the boundary conditions, the interlayers of glass, the vertical rise–span ratio and the axial stiffness of main cables, other governing parameters of the modal parameters for this type of structures are also identified, including the pavement load of the bridge deck system, the central buckle, and the prestress of wind-resistant cables. It may guide designers to take effective measures to improve the dynamic behavior of this type of structure. Next, the vibration serviceability assessments were performed based on different standards and guidelines such as the UK National Annex (NA) to Eurocode 1 (2008), the Bro2004 specification of Sweden, the HiVoSS guideline, and the ISO standard. Comparisons show that the UK NA to Eurocode 1, the HiVoSS guideline, and the ISO standard are more suitable for the vibration serviceability evaluations. These three codes consider the pedestrian-induced vibrations in both lateral and vertical directions and also consider both a small number of pedestrians and crowd-induced loads with different densities. Furthermore, comfort limits are not defined by only one limiting value but sorted into different levels. This may provide reference for the vibration serviceability evaluations of the other glass suspension footbridges. The assessments also show that changing the structural parameters can only partially reduce vibration levels and may result in different modal parameters to dominate the vibration responses. Thus, they recommend taking vibration mitigation measures to improve the vibration serviceability and suggest performing careful response calculations to ensure the effectiveness of vibration serviceability design if via changing the structural parameters. Finally, tuned mass dampers (TMDs) are installed to the structure. The results show that the popular TMD may effectively reduce the vibration levels.

Experimental study of porcelain and toughened glass suspension insulators under desert contamination

In this paper, the performance of porcelain and toughened glass suspension insulators artificially polluted with desert contamination is investigated experimentally. The withstand flashover voltage (FOV), and equivalent salt deposit density (ESDD) of desert contaminated insulators have been studied and reported. Artificial pollution testing was carried out, and desert contaminations were prepared in advance for four solutions (NaCl, CaSO4, KCl, and CaO) of different concentration levels to investigate the influence of desert contamination on the insulators of transmission lines. The flashover analyses are completed on 11 kV insulators with artificial pollution coatings. The contaminations materials are (a) Desert Salt Pollution-Dry pollution (b) Natural Fog Condition. Results have proven that flashover voltage decreased with the increase in the dry dessert pollution level at constant pressure and temperature condition. However, the study has also revealed that in the case of natural fog conditions, the flashover voltage of porcelain and toughened glass disc insulator became much lower than the dry test. From the results, it can be detected that engineers can predict and plan for the maintenance schedule of the poor performance of the insulators under different effluence environmental conditions. The study tested the effect of AC voltage flashover on the suspension insulators. However, the DC voltage is suggested to be used and results to be compared with the current study.

Получение теплоизоляционных материалов на основе торфа Тюменской области

At present, research on expanding the raw material base for new building materials appears to be relevant. In world practice, the development of new locally-based materials takes place alongside a detailed analysis of existing deposits in order to determine possible means of their application. The present study is focused on the possibility of obtaining thermal insulation composites based on peat obtained from the Gusevskoye deposit (Tyumen Oblast) and tripoli from the Sukholozhskoye deposit (Sverdlovsk Oblast) were studied. Results of thermo gravimetric and laser diffraction granulometric analyses determining the chemical, thermal and thermo physical properties composition of the obtained raw materials are presented. Particle size was determined using a Fritsch Nano Tex laser analyser with a range of 0.01–2100 μm. A liquid glass suspension was obtained by hydrothermal leaching in order to obtain kinetic thermal decomposition parameters. Taking into account the chemical and mineralogical features of the peat from Gusevskoye deposit (Tyumen Oblast) and the tripoli from Sukholozhskoye deposit (Sverdlovsk Oblast), the liquid glass is obtained with the main component presented by opal rock. A method for producing a thermal insulation material is developed. The hydrothermal leaching method of tripoli appears to be resource-saving, less energy-consuming and, as a result, more economically feasible as compared to the classical method of liquid glass production. The resulting material is established to be environmentally-friendly and energy efficient.

Vibration experiments for diagnostic investigations on a glass suspension footbridge

Structural glass represents a relatively innovative and not well-known solution for constructions, where it is largely used for facades, roofs, footbridges, etc. There, multiple (sandwich) glass members can interact with traditional building materials, and should offer appropriate fail-safe performances, within the full life time. However, severe operational conditions, or extreme loads, can increase the intrinsic vulnerability glazing systems. In this paper, the dynamic characterization and damage diagnostic assessment of an existing glass footbridge is carried out, based on Operational Modal Analysis (OMA) techniques.

Numerical probing of suspended lactose droplet drying experiment

Single droplet drying (SDD) device has been extensively used to measure drying kinetics of droplets of 0.5–2 mm initial diameter. Despite the large size, it has deemed to be the most practical for such purposes in the past 40 years. There is a surplus of numerical investigations of SDD in the literature. However, this is the first time detailed computational fluid dynamics (CFD) simulations were carried out on the actual fluid behaviour inside and around a lactose solution droplet in SDD by glass suspension experiment. The full set of the governing equations were solved and the fluid flow was investigated. A lactose concentration gradient was developed within the droplet due to momentum transfer and water removal. The CFD predictions of lactose concentrations could be used to predict the formation of crust or crystallization in the droplet. Furthermore, accumulation of solute within the droplet indicated the tendency to form solid structure. The simulated overall drying rate curve compared well with the available laboratory data. The predicted temperature results have also been benchmarked against the experimental measurements generated from the thermal history of lactose droplet drying. More importantly, CFD simulations have been extended to similar small droplet sizes occurring during spray drying, which are experimentally inaccessible with SDD. These analyses are relevant to spray drying to validate simpler 1D models.

Diagnostic analysis and dynamic identification of a glass suspension footbridge via on-site vibration experiments and FE numerical modelling

Structural glass represents a relatively new solution for constructions, requiring appropriate knowledge, but is largely used for facades, roofs, footbridges, etc. There, composite systems in which multiple glass members can interact with traditional building materials, should offer appropriate fail-safe performances, within the full lifetime. Further efforts are needed for the vulnerability assessment of glazing systems under extreme loads (seismic events, fire, etc.) or severe operational conditions. In this paper, the dynamic characterisation of an existing glass suspension footbridge is presented for a case study structure in Italy. On-site vibration experiments are first discussed, based on Operational Modal Analysis (OMA) techniques, so as to estimate the fundamental parameters of the composite glass footbridge. A Finite Element (FE) numerical study is then carried out, to further assess and explore the structure performance, including a sensitivity investigation. It is shown how the key dynamic parameters can be susceptible to even minor variations of few geometrical/mechanical influencing parameters, or to possible localised damage scenarios, hence affecting the overall composite behaviour of the glazed structure and requiring careful consideration for design and maintenance purposes. Degradation phenomena in the bonding layers, in particular, can severely affect the overall structural estimates and performances. While existing analytical models can provide simplified estimations only, in addition, the actual restraint configuration of all the assembly components should be also properly taken into account for reliable predictions.

A niobophosphate bioactive glass suspension for rewetting dentin: Effect on antibacterial activity, pH and resin-dentin bonding durability

PurposeThe aim of this study was evaluate the effect of rewetting suspensions of niobium phosphate bioactive glass (NbG) on the shear bond strength to dentin (SBS) and antibacterial activity. Materials and methodsThe NbG was prepared and characterized by XRD and SEM/EDS. Antibacterial activity (Streptococcus mutans ATCC 159) of suspensions NbG was evaluated (n = 6). The pH of control and of suspensions NbG were monitored in different times. Dentin surface of sixty-five human third molars was etched with 35% phosphoric acid, rinsed with water and air-dried (n = 13). The specimens were assigned into 5 groups of four different concentrations of NbG suspensions in distilled water (5%, 10%, 20%, 40% w/v) and one control group (distilled water). Dentin surface was dried and rewetted according to their respective groups and adhesive system (One Step) was applied. The specimens were assembled for SBS testing (Ultradent Jig) and two cylinders of resin composite (ÆLITE) were built on the bonded dentin surface. Specimens were tested after 24 h and 3 months storage in PBS at 37 °C. The data from each test were analyzed by appropriate statistical methods. ResultsSuspensions containing the bioactive glass NbG can neutralize the pH. Significant reductions on SBS were observed after 3 months PBS storage for control and NbG 5% suspension groups. All the suspension groups showed significantly inhibition of S. mutans. ConclusionRewetting demineralized dentin with NbG 40% prevented bond strength reduction after 3 months storage and showed antibacterial effect against S. mutans.

An experimental study of multimodal glass suspension rheology to test and validate a polydisperse suspension viscosity model

Experimental measurements of non-colloidal multimodal suspension viscosities are performed over a wide range of mixing ratios and used to test the robustness and predictive capability of a recent viscosity model (Mwasame et al. in Phys Fluids 28:061701, 2016b), subsequently referred to as the MWB model. Three unimodally distributed particle suspensions with narrow size distributions are blended to make the bimodal and trimodal suspensions used in the rheological experiments. We demonstrate how predictions for mixture viscosities can be made using the MWB model only requiring the volume-weighted average particle sizes and viscosity correlations of the individual unimodal suspensions comprising the blend. The resultant model predictions are found to be in good agreement with measured bimodal and trimodal viscosity data to within expected experimental uncertainty. The datasets provided here can be used to validate future modeling efforts, and the MWB model can be used to optimize the viscosity of multimodal suspension mixtures for specific performance criteria.

A novel fabrication method for glass foams with small pore size and controllable pore structure

AbstractIn this paper, a novel fabrication method for glass foams has been introduced based on colloidal suspension foaming method using waste glass as starting materials. It is demonstrated for the first time that foam stabilization via in‐situ hydrophobization of waste glass particles is possible. The fabrication conditions for stable glass particle‐stabilized foams are optimized by investigating the influences of pH value, concentration of propyl gallate and ball milling time, respectively. It is demonstrated that this is a versatile method for fabrication of stable foamed glass suspension and final glass foams with small pore size of dozens of microns, which is much smaller than that of most glass foams in previous literatures. This novel method enables both closed pore structure and open pore structure simply by tailoring solid loading of glass suspension. A “sieve‐like” hierarchical pore structure can be achieved by adjusting sintering temperature. The glass foams with controllable structure could be applied in thermal insulation fields for closed pores, and in catalyst loading, filtration, and separation fields for open pores and hierarchical pore structure.

Bioactive glass coatings by suspension plasma spraying from glycolether-based solvent feedstock

Bioactive glasses are emerging as a substitute of hydroxyapatite in the development of bioactive coatings for biomedical applications. The deposition of these coatings is carried out by a wide range of methods, being atmospheric plasma spraying the most employed technique. However, the research on the deposition of these coatings from suspension feedstocks by thermal spraying is still incipient, therefore more research about this topic is needed.Thus, a bioactive glass suspension, composed of fine glass particles, was prepared and stabilised through rheological and sedimentation tests to be used as a feedstock in plasma spraying. The solvent used in the suspension preparation was dipropylene glycol methyl ether in order to develop a new type of bioactive suspension. Consequently, as a new type of solvent was used, its effect on the plasma torch properties was determined. On other hand, the rheological behaviour of the suspension feedstock was assessed by means of a simple viscosity model.This suspension was deposited onto metallic substrates by plasma spraying, employing several spraying distances. All coatings displayed a suitable adherence and similar thickness. However, the microstructure of the obtained coatings is highly affected by the spraying distance as it can be seen in coatings surface and cross-section field emission gun environmental scanning electron microscopy examination. Thus, a relation between the spraying distance and coatings microstructure was found. On the other hand, X-ray diffraction confirmed the amorphous nature of the obtained coatings.

Processing and strengthening of 58S bioactive glass-infiltrated titania scaffolds.

In this work, TiO2 ceramic scaffolds were fabricated by the replica method using polyurethane (PU) sponges. Suspensions with high solid content were used to achieve scaffolds with improved mechanical behavior. TiO2 ceramic suspensions were optimized by rheological studies using different additives. It was found that the composition with 0.5 wt % Darvan enhanced the covering of the sponge struts. PU sponges of 45 to 80 ppi (pore per inch) were well coated without clogging pores. A thermal treatment with varying holding times, temperatures and heating rates was adjusted. The influence of different pore sizes on mechanical strength was evaluated. It was possible to obtain TiO2 scaffolds with 90% porosity and high pore interconnectivity, having compressive strength exceeding 0.6 MPa. TiO2 scaffolds were filled up with a 58S bioactive glass suspension to impart bioactive character to the scaffolds. These hybrid structures presented mechanical strengthening of about 26-213% depending on their sponge porosity. The prediction for cells viability via zeta potential measures indicated that this hybrid material is very promising for scaffold application with -19 to -25 mV between pH of 7.35-7.45. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 590-600, 2017.

Electrophoretic deposition of bioactive glass nanopowders on magnesium based alloy for biomedical applications

To slow down the initial biodegradation rate of magnesium (Mg) alloy, crystalline nano-sized bioactive glass coating was used to deposit on micro-arc oxidized AZ91 samples via electrophoretic deposition (EPD). Zeta potential and conductivity of the bioactive glass suspension were characterized at various pH values to identify the most stable dispersion conditions. The bone-bonding properties of bioactive glass coated samples were evaluated in terms of apatite-forming ability during the immersion in simulated body fluid (SBF) solution. Results revealed that the ability to form a bioactive glass coating via EPD was influenced by the degree of its crystalline phase composition. Moreover, the potentiodynamic polarization tests recorded significant drops in corrosion current density and corrosion rate of the coated samples which implies a good level of corrosion protective behavior. These preliminary results show that this process will enable the development of Mg implants in the later stage of bone healing.

Effect of electrical test methods on dc flashover performance of ice-covered ceramic insulators

In artificial icing tests, three test methods are frequently used for evaluating the electrical characteristic of ice-covered insulator strings, they are: average flashover voltage method (AM), 50% withstand voltage method (WM) and minimum flashover voltage method (MM). Based on measurements of DC flashover characteristics of ice-covered porcelain and glass suspension insulators in an artificial climate chamber, this paper studied the influences of various test methods on DC flashover voltage of insulators. Test results revealed that the average flashover voltage (Uave obtained using AM) is the highest, followed by the 50% withstand voltage (U50% obtained using WM). The minimum flashover voltage (Ufmin obtained using MM) is the lowest. The fitting formulas between DC flashover voltage (Uf) and conductivity of the icing water (γ20) are consistent for the three test methods. Moreover, the differences on exponent b characterizing the influence of conductivity of the icing water (γ20) on the flashover voltages are not remarkably different for the three electrical evaluation methods.

Structural Characterization and Mechanical Evaluation of Bioactive Glass 45S5 Foams Obtained by a Powder Technology Approach

Bioactive glass 45S5 foams were produced using a powder technology process developed by The National Research Council Canada–Industrial Materials Institute. NRC–IMI's proprietary process, combining powder technology and polymer foam technique, allows the production of materials having different structures and properties. It can be used to produce components into various forms, such as fully porous bodies or coatings on solid structures. During foaming, the foaming agent is decomposed and expands the binder‐bioactive glass suspension. Then, the binder is burnt out by heating the sample at 500°C and finally the bioactive glass particle network is sintered to consolidate the material. Foams sintered at various temperatures were characterized from a microstructural and mechanical point of view. The foam structure and properties are affected by the sintering temperature when it is varied between 950°C and 1025°C. Foams exhibited open porosity (64%–79%) and pore size (335–530 μm) optimal for bone ingrowth. In all cases, the glass crystallized during sintering and the material was mostly composed of Na6Ca3Si6O18 and Na2Ca4(PO4)2SiO4 phases. The mechanical strength increased from 1.7 to 5.5 MPa while the density of the material increased from 0.56 to 0.97 g/cm3.

Use of the Co-grinding Method to Enhance the Dissolution Behavior of a Poorly Water-Soluble Drug: Generation of Solvent-Free Drug–Polymer Solid Dispersions

The solid dispersion (SD) technique is the most effective method for improving the dissolution rate of poorly water-soluble drugs. In the present work, SDs of the Ca2+ channel blocker dipfluzine (DF) with polyvinylpyrrolidone K30 (PVP) and poloxamer 188 (PLXM) were prepared by the powder solid co-grinding method under a solvent-free condition. The properties of all SDs and physical mixtures were investigated by X-ray diffraction, Fourier-transform infrared, differential scanning calorimetry, scanning electron microscopy, dissolution test, and particles size determination. Eutectic compounds were produced between the DF and PLXM matrix during the co-grinding process, whereas glass suspension formed in the SDs with PVP carrier. Hydrogen bond formation was not observed between DF and carriers and DF was microcrystalline state in the PVP and PLXM matrices. The solubility of DF in different concentration of carriers at 25, 31, and 37°C was investigated; the values obtained were used to calculate the thermodynamic parameters of interaction between DF and carriers. The Gibbs free energy (ΔrGθ) values were negative, indicating the spontaneous nature of dispersing DF into the carriers. Moreover, entropy is the drive force when DF disperses into the matrix of PVP, while, enthalpy-driven dispersing encounters in the PLXM carrier. All the SDs of DF/carriers showed a considerably higher dissolution rate than pure DF and the corresponding physical mixtures. The cumulative dissolution rate at 10 min of the SD with a 1 : 3 DF/carrier ratio increased 5.1-fold for PVP and 5.5-fold for PLXM.

Rheology and gelation behavior of gel-cast cordierite-based glass suspensions

A cordierite-based glass suspension was shaped by gel-casting method. Effects of various parameters like pH, volume fraction of glass particles, gelling agents and dispersant on the rheology of the prepared slurries were investigated. The results demonstrated that using sodium tripolyphosphate (STPP) dispersant brings about a suspension of minimum viscosity. The bending strength of the dried gels was increased with the gelling agents. In addition, the utilization of cross linkers at a fixed concentration of monomer led to the gradual enhancement of the bending strength of the dried bodies. A bending strength of ∼11 MPa was obtained for the most promising dried gel cast bodies.

Flashover prevention on high-altitude HVAC transmission line insulator strings

Numerical analysis, on-site measurements, and laboratory experiments are used in this paper to analyze and solve the flashover problems of 330 kV AC high altitudes transmission line middle phase glass suspension insulator strings. A sub-model approach based on a finite element method (FEM) applied in calculating the potential and electric field distribution along the insulator strings under clean and dry conditions. Using this approach, three dimensional electrostatic models (taking into account the grading rings, subconductors, tower framework, and yoke plates) are set up and investigated. On-site and laboratory measurements were also carried out to make a comparison. A relatively good agreement was obtained among the calculated, the on-site, and the laboratory measured results, which demonstrated that insulator disk nearest to the high-voltage end is required to withstand relatively high voltage according to the standard in China; in addition, the insufficient dry arc distance of the insulator strings is also proposed. Subsequently, the long insulator-string flashover tests under dry, wet, and artificial contaminated (ESDD=0.05 mg/cm/2, NSDD=0.3 mg/cm/2) conditions, considering the middle (flashover) and side phase (never flashover), respectively, are carried out to validate the proposed insufficient dry arc distance and discuss the measures for solving the flashovers. From the effective, convenient and economical standpoint for the reconstruction of the flashover lines, lowering the grading rings' position and adding a unit of insulator are considered to lengthen the dry arc distance of the middle-phase insulator string in the tests. The experimental results are compared and discussed, and it has been concluded that adding a unit of insulator is an effective and economical way to solve the flashover problems. The methods for analyzing the flashover problems are effective and can be used for other voltage-level transmission lines.