Glass Bubbles Research Articles

Electrical Breakdown Characteristics of Superconducting Magnet System in Sub-Cooled Liquid Nitrogen

Dielectric characteristics of gaseous helium (GHe) injected into the cooling system to make sub-cooled nitrogen condition with constant pressure is found to be extraordinarily weak in dielectric strength by H. Mitsuii (1998). In high voltage superconducting machines using the sub-cooled nitrogen cooling system, the current lead part in GHe environment could be electrical weak points rather than the superconducting magnet part in liquid nitrogen (LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ). In order to enhance dielectric characteristics of current lead part, three methods are suggested in this paper. The first one is enclosing the current leads with solid dielectric material and the second is exposing the current leads to high vacuum, and the last is topping up the magnet system with dielectric materials such as Glass Bubbles (GB) which is usually used as heat insulator. In addition, the extinction time of bubbles caused by the electrical breakdown is measured to determine the suitable pressure of sub-cooled nitrogen system. It is found that the characteristics of bubble extinction in LN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> are drastically enhanced over 1 bar.

Processing, Properties and Coating of Micro‐Porous Syntactic Foams

The production of microporous syntactic foam by pressure infiltration of sintered preforms of micro glass bubbles with Al-, Zn- and Mg-alloys was examined. Compression tests with aluminium matrix specimens showed that this material has a very high compression strength and behaves almost like an ideal crash energy absorber. Due to their closed microscopic-scale porosity such foams can be surface treated e.g. by anodizing processes. The figure shows a cross section of an anodized aluminium syntactic foam.

Termination of BME–MLCC Using Copper–Nickel Bimetallic Powder as Electrode Material

Microstructure of termination of a base metal electrode multilayer ceramic capacitor (BME-MLCC) using copper-nickel bimetallic powder as electrode material was investigated. Thick film paste containing nonagglomerated monodispersed copper-nickel bimetallic powder was applied in preparing the termination electrode of a BME-MLCC. Influence of an inorganic binder on the microstructure of the termination of BME-MLCC was studied. The distribution of metallic copper on the surface of glass bubbles in termination was investigated by energy dispersive X-ray. A scanning electron microscope and a polarized light microscope were applied to discuss the microstructure of thick film. The results show that suitable binder and firing temperature result in the excellent connection between internal and termination electrode, as well as one between termination electrode and green chip. The BME-MLCCs with a dense surface of end termination, high adhesion, and qualified electrical behavior were obtained. The rough interface from interfacial reaction between glass and chip gives high adhesion

Designing dielectric loss at microwave frequencies using multi-layered filler particles in a composite

Microwave-absorbing materials find application in telecommunications, microwave heating and for representing the behavior of biological tissue in the presence of microwave radiation. Commonly, such materials are formed using ferromagnetic filler particles and rely on the phenomenon of ferromagnetic resonance for absorption of microwaves. Dielectric loss at microwave frequencies can be engineered through creating a phase lag, with respect to the applied electric field, of the movement of free charges in a composite formed using metal-coated filler particles. These materials can be engineered to be less dense and, therefore, more lightweight than those formed with ferromagnetic fillers, which is an advantage in some applications. Furthermore, theory shows that the frequency of maximum absorption can be tailored by selecting the conductivity and thickness of the particle coating although, in practice, it may be difficult to fabricate particles with tightly controlled physical parameters. In this work, theories for calculating complex permittivity of composites with layered filler particles are reviewed, and experimental observations of dielectric relaxation in composites formed by dispersing tungsten-coated glass bubbles in paraffin wax are shown

The Effect of Oxidation on Viscosity of Oil-Based Drilling Fluids

Abstract True downhole rheological properties affect equivalent circulating density, hole cleaning, barite sag, surge/swab pressures during tripping, pump pressure, and bit hydraulics. Gelation and excessive viscosity are major concerns at high temperatures. When using oil-based drilling fluids lightened by an injection of de-oxygenated air (containing small amounts of oxygen, usually around five per cent) in underbalanced drilling (UBD) operations, there is a need to be able to predict the effect of oxidation on the viscosity of the oil-based muds as a function of temperature and pressure. This paper presents the results of an experimental investigation that was aimed at establishing the effect of oxidation on the viscosity of an oil-based drilling fluid. The drilling fluid was aged for 2.5 days and for 7 days in the presence of air at temperatures ranging from 100 to 150 °C and at pressures ranging from 14 to 44 MPa. The viscosity of the drilling fluid samples after aging is compared with the corresponding fresh samples (before aging). The results show that oxidation causes an increase in viscosity. The amount of the increase depends on the amount of oxygen reacted, which is a function of temperature, pressure, and time. The higher temperatures of the reactors lead to the higher increases in viscosity. Furthermore, at higher temperatures, solid (mostly coke) formation was observed. Introduction Underbalanced drilling (UBD), in which drilling fluid pressure is lower than reservoir pore pressure, has been studied by many researchers since the late 1980s. This method can improve the financial returns on drilling a well by reducing formation damage (especially in horizontal wells and depleted reservoirs), minimizing lost circulation (especially in fractured reservoirs and depleted reservoirs), increasing the penetration rate of drilling, increasing bit life, minimizing differential sticking, reducing stimulation, and improving formation evaluation(1). The underbalanced condition is created by using different drilling fluids such as dry air, nitrogen, natural gas, mist, stable foam, stiff foam, gasified liquids, glass bubbles, and liquids. In gasified liquids, a gas is injected into the liquid to reduce the density of the drilling fluid. In these mixtures, since the pressure difference between the formation and the wellbore is relatively low (1.72 - 3.45 MPa), these drilling fluids have fewer UBD related problems such as wellbore instability and formation fluid inflows(1). These specifications have made them the most appropriate drilling fluid in UBD. The unique performance of oils makes them preferable to water as the liquid phase in gasified liquids. Oils prevent clay swelling and they are resistant to contaminants. Their rheological properties are stable at high pressures and temperatures. Also, they are highly lubricious and non-corrosive. On the other hand, to prevent downhole fires, de-oxygenated air from membrane units with maximum five per cent oxygen is usually used as the gas phase in gasified liquids(2). The presence of oxygen causes the oil in the gasified liquid to be oxidized. In this paper, the effect of oxidation on the viscosity of the gasified liquids is investigated.

Hg0 absorption in potassium persulfate solution

The aqueous phase oxidation of gaseous elemental mercury (Hg(0)) by potassium persulfate (KPS) catalyzed by Ag(+) was investigated using a glass bubble column reactor. Concentration of gaseous mercury and potassium persulfate were measured by cold vapor atom absorption (CVAA) and ion chromatograph (IC), respectively. The effects of pH value, concentration of potassium persulfate and silver nitrate (SN), temperature, Hg(0) concentration in the reactor inlet and tertiary butanol (TBA), free radical scavenger, on the removal efficiency of Hg(0) were studied. The results showed that the removal efficiency of Hg(0) increased with increasing concentration of potassium persulfate and silver nitrate, while temperature and TBA were negatively effective. Furthermore, the removal efficiency of Hg(0) was much better in neutral solution than in both acidic and alkaline solution. But the influence of pH was almost eliminated by adding AgNO(3). High Hg(0) concentration has positive effect. The possible reaction mechanism of gaseous mercury was also discussed.

Eulerian approach for multiphase flow simulation in a glass melter

A glass furnace, consisting of a combustion space and a glass melter, uses combustion heat to melt sand and cullet into liquid glass to make products. Glass quality is mainly dependent on the temperature, glass composition, and the level of impurities in a glass melter, which include solid batch/cullet particles, liquid glass, and gas bubbles. A comprehensive computational model using an Eulerian approach has been developed to simulate multiphase flows in a glass melter. It includes all the phases, divides solid particles or gas bubbles into various size groups, and treats each group as a continuum. The derived mass, momentum, and energy conservation equations of the flow are solved for local properties for each phase. The simulation considers the heating and melting of the batch (mainly from the radiative heat from combustion and from the convective heat from the molten glass), the formation and transport of bubbles, and the heating and mixing of the liquid glass. The approach was incorporated into a multiphase reacting flow computational fluid dynamics code that simulates overall glass furnace flows to evaluate the glass quality and furnace efficiency.

Modelling local defects on the surface of high performance objective lenses

Performances of high quality imaging systems are often affected by surface or glass defects, like scratches, bubbles and other localized disturbances. The goal of the present investigation is the modelling of scratches on the surfaces of lenses and analysing the resulting changes in the diffraction spot quality. High numerical aperture focusing objectives used in optical storage are especially sensitive to this type of defect, since the size of the diffraction spot and the power–density distribution determines the quality of both the written pits and received signal. We used three different methods—based on the simple geometrical optical approximation, ideal diffraction model and point spread function based diffraction—to model local defects and compared the findings from these methods to the measurements. The model includes the DVD objective lens and the disc. Local defects are modelled as special apertures on the surface of the objective lens. From these computations we calculate the intensity distribution in the focal spot and the encircled energy in the Airy disc. A measurement set-up was built, which is capable of measuring the encircled energy in the Airy disc. Comparison of the measurement results to the calculations helps in determining the tolerances of DVD objective lenses to local surface defects as a function of the size of the defects. The practical application of the model will allow us to redefine the quality criteria for the DVD lenses used.

Specific properties and fracture toughness of syntactic foam: Effect of foam microstructures

Studies were performed on the specific strength, moduli and fracture toughness of varied microstructures of syntactic foam. The different microstructures were created by using three different types of microspheres, namely 3M Scotchlite ™ K15 and K46 glass bubbles, and Phenoset BJO-093 hollow phenolic microspheres, and by changing the volume fractions of microspheres from 0 to 50 vol%. Tension, compression, flexural and fracture tests were performed. Results showed that the tensile and flexural strengths decreased with increasing filler content. The behavior of the tensile and flexural strength was not affected by the component microspheres. Interestingly, the tensile and flexural moduli showed different trends for each type of microspheres with increasing filler content. Results of the compression tests revealed superior behavior of the high density microspheres. The specific fracture toughness data yielded maximum values at 30 vol% for each type of microspheres investigated. Scanning electron microscope studies were performed to determine the failure mode for each loading condition.

Optimal growth conditions and the cultivation of Chaetoceros calcitrans in airlift photobioreactor

The optimal conditions for the growth of a diatom Chaetoceros calcitrans were investigated in a 2.5 L glass bubble column. The light intensity for the highest growth rate was shown to be at around 400 μmol photons m −2 s −1. A modified standard F/2 medium with a two-fold of silica and phosphorus concentrations was illustrated to result in a better growth of this diatom. Vitamin B 12 in the range from 1 to 3 μg L −1 did not significantly affect the growth. A maximum cell density obtained from this small glass bubble column was approximately 5.8 × 10 6 cells mL −1 with a maximum specific growth rate of 3.80 × 10 −2 h −1. The cultivation of C. calcitrans in the 17 L airlift photobioreactor (ALPBR) was illustrated to be superior to that in the bubble column with the same size. The operation with superficial gas velocity of 3 cm s −1 was found to give a maximum specific growth rate of 7.41 × 10 −2 h −1 with a maximum cell concentration of 8.88 × 10 6 cells mL −1 in a batch culture. A semi-continuous culture could be achieved where the harvest was performed at every 12 h. In this case, the maximum specific growth rate ( μ) achievable was 9.65 × 10 −2 h −1 and the cell concentration during the harvest period was 4.08 × 10 6 cells mL −1.

Monodispersed Nano-Bubbles Generated from Porous Glass Membrane and Bubble Size Control

分相法により調製した細孔径の均一な多孔質ガラス膜から, 1 μm以下の平均気泡径を有する単分散状の微細気泡 (ナノバブル) の生成法を見出した. また, 膜の細孔径を変えることにより, 生成した気泡の気泡径を制御できることを明らかにした. 管状多孔質ガラス膜の内側に, 濃度が1.7 mol・m-3のドデシル硫酸ナトリウム水溶液を流しながら, 水相の流れに対して膜の外側から直角方向に空気を圧入分散したとき, バブルポイント圧を超える一定の圧力域において単分散状の気泡が生成した. この条件下で, 平均細孔径0.084 μmの膜から, 平均気泡径0.72 μmのナノバブルが生成した. また, 使用した膜の平均細孔径と平均気泡径の間には, 良好な比例関係が存在した. 一方, 膜の表面を疎水化した場合は, バブルポイント圧は観測されず, 多分散状の気泡が生成した. 膜の表面が親水性であっても, 水相に溶解したドデシル硫酸ナトリウムの濃度が1.7 mol・m-3より減少すると, 単分散状の気泡は生成されなかった.

Probing gas bubbles inside industrial glasses by Raman scattering

AbstractThe gas enclosed inside bubbles in industrial glasses was probed by micro‐Raman spectrometry. The rotational and vibrational Raman spectra for various gases can be measured with high sensitivity. The elimination of a parasitic signal due to air that makes the signal acquisition difficult is discussed. In situ high‐temperature Raman measurements were used to monitor the disproportionation reaction of SO2 inside bubbles. Copyright © 2003 John Wiley &amp; Sons, Ltd.

Fluorimetric determination of nitrogen oxides in the air by a novel red-region fluorescent reagent

A sensitive fluorimetric method for the determination of nitrogen oxides (NO x : NO+NO 2) in air is described. Nitrogen dioxide (nitrogen monoxide was previously converted to nitrogen dioxide in oxide tubes) was aspirated through a fritted glass bubble at a flow rate of 500 ml min −1 for 120 min and fixed as nitrite, using 0.1 N NaOH as a trapping solution with the empirical absorption efficiency 0.74 and the stoichiometric factor 0.5. The method is based on the fluorescence quenching of a red-region fluorescent reagent, tetra-substituted amino aluminum phthalocyanine (TAAlPc), after being diazotized by nitrite. Under optimal conditions the linear range of the calibration curve for nitrite is 1–40 ng ml −1 (NO 2 0.24–9.6 ppb, v/v). The detection limit is 0.34 ng ml −1 for nitrite (NO 2 0.08 ppb, v/v) and the relative standard deviation for six replicate measurements of 15 ng ml −1 nitrite is 3.2%. The method has been applied to the determination of nitrogen oxides in the air with satisfactory results. Typical gaseous co-pollutants such as SO 2, H 2S and HCHO did not interference the determination.

Fluid bubbles in melt inclusions and pillow-rim glasses: high-temperature precursors to hydrothermal fluids?

Hypotheses for the formation of many types of hydrothermal ore deposits often involve the direct contribution of magma-related fluids (e.g., Cu–Mo–Au porphyries) or their superimposition on barren hydrothermal cells (e.g., volcanic-hosted massive sulfide deposits). However, the chemical and phase compositions of such fluids remain largely unknown. We report preliminary results of a comprehensive study of fluid bubbles trapped inside glassy melt inclusions in primitive olivine phenocrysts and pillow-rim glasses from basaltic magmas from different tectonic environments, including mid-ocean ridges (Macquarie Island, SW Pacific and Mid-Atlantic Ridge 43°N Fracture Zone), ocean islands (Hawaii) and a variety of modern and ancient backarc–island arc settings (eastern Manus Basin, Okinawa and Vanuatu Troughs, Troodos, New Caledonia and Hunter Ridge–Hunter Fracture Zone). Fluid bubbles from all localities, studied using electron microscopy with EDS and laser Raman spectroscopy, are composed of CO 2-(±H 2O±sulfur)-bearing vapor and contain significant amounts of amorphous (Na–K–Ca–Fe alumino-silicates and dissorded carbon) and crystalline phases. The crystals are represented mainly by carbonates (magnesite, calcite, ankerite, dolomite, siderite, nahcolite and rhodochrosite), sulfates (anhydrite, gypsum, barite and anglesite), and sulfides (pyrite, arsenopyrite, chalcopyrite and marcasite), though other minerals (brukite, apatite, halite, clinoenstatite, kalsilite, nepheline, amphibole and mica) may occur as well. We argue that chemical components (e.g., C, H, S, Cl, Si, Al, Na, K, Fe, Mn, Cr, Ca, Mg, Ba, Pb and Cu) that later formed precipitates in fluid bubbles were originally dissolved in the magmatic fluid, and were not supplied by host glasses or phenocrysts after entrapment. Magma-related fluid rich in dissolved metals and other non-volatile elements may be a potential precursor to ore-forming solutions.

Special Issue Ceramics Integration. Formation of Optical Coupling Structure between Two Ends of Silica Glass Optical Fibers by Inserting Tellurite Glass Melt.

Several nano liters of tellurite glass melt was inserted and quenched between two ends of silica glass optical fibers to form a optical coupling structure, whose length was several hundred micron meters. Dispite the large gap of thermal expansion coefficient between these glass materials, neither fracture nor bubbles were observed, which usually lead to a large optical propagation loss. The insertion was less than 10dB, which was mainly due to the lack of an optical waveguide structure in the tellurite glass segment. Further loss decrease is expected to be possible by introducing a refractive index modulation.

Polipropileno Carregado com Microesferas Ocas de Vidro (Glass Bubbles™): Obtenção de Espuma Sintática

Espumas sintáticas são materiais cujas células são formadas por esferas ocas, de vidro ou poliméricas, com diâmetros na faixa de 10 a 100 µm. A utilização de Glass BubblesTM para a obtenção de espumas sintáticas de polipropileno é uma opção para obter material de baixa densidade sem grande perda de propriedades mecânicas. Os espaços vazios no material também melhoram as propriedades de isolamento térmico. Além disso, o formato esférico da carga promove distribuição isotrópica de tensões e melhor acabamento superficial das peças. As principais etapas deste trabalho foram: experimentos preliminares em um reômetro de torque para determinar a resistência das esferas a um mínimo de cisalhamento; extrusão do material em escala piloto, utilizando uma extrusora mono-rosca, seguida por peletização e injeção de corpos-de-prova; análise da homogeneidade dos compósitos e do grau de interação entre a matriz polimérica e a carga na presença e na ausência de agentes de funcionalização, através de microscopia ótica de varredura.

Interfacial dynamics of stationary gas bubbles in flows in inclined tubes

We have experimentally examined the effects of bubble size (0.4 [les ] λ [les ] 2.0), inclination angle (0° [les ] α [les ] 90°), and tube material on suspended gas bubbles in flows in tubes for a range of Weber (0 [les ] We [les ] 3.6), Reynolds (0 [les ] Re [les ] 1200), and Froude (0 [les ] Frα [les ] 1) numbers. Flow rates and associated pressure differences which allow the suspension of bubbles in glass and acrylic tubes are measured. Due to contact angle hysteresis, bubbles which dry the tube wall (i.e. form a gas–solid interface) may remain suspended over a range of flows while non-drying bubbles remain stationary for a single flow rate depending on experimental conditions. Stationary bubbles increase the axial pressure gradient with larger bubbles and steeper inclination angles leading to the greatest increase in the pressure gradient. Both the suspension flow range and pressure difference modifications are strongly dependent upon gas/liquid/solid material interactions. Stronger contact forces, i.e. smaller spreading coefficients, cause dried bubbles in acrylic tubes to remain stationary over a wider range of suspension flows than bubbles in glass tubes. Bubble deformation is governed by the interaction of interfacial, contact, and flow-derived forces. This investigation reveals the importance of bubble size, tube inclination, and tube material on gas bubble suspension.

Comparing gap-fillers used in conserving subfossil material

Often when conserving mechanically weak sub-fossil bone material, an inert volumising filler for a chosen adhesive (e.g. Paraloid B72) is needed to create a gap-filling substance to strengthen some bones, so as to reduce the potential of damage to some of the more fragile specimens. Although a frequent method, little is in print on this subject. Testing determined the comparative suitability of five materials (calcium carbonate, glass beads, crushed glass, glass bubbles and phenolic microballons) as polymer fillers in terms of strength, shrinkage, reversability, ease of use, and adhesive properties at various filler to resin ratios. Glass beads (44 microns average diameter) at a ratio of 3:1 filler to resin by weight out-performed the other fillers in most of the categories.

22aA3 CZ-Si成長用石英るつぼ中気泡の挙動その場観察(バルク成長I)

22aA3 CZ-Si成長用石英るつぼ中気泡の挙動その場観察(バルク成長I)

Behavior of Bubbles in Silica Glass for use in Silicon Crystal Growth as Crucibles

Behavior of Bubbles in Silica Glass for use in Silicon Crystal Growth as Crucibles