Showing papers on "Glass microsphere published in 2000"

Fiber-coupled microsphere laser.

Abstract: We demonstrate a 1.5-mm-wavelength fiber laser formed by placement of glass microsphere resonators along a fiber taper. The fiber taper serves the dual purpose of transporting optical pump power into the spheres and extracting the resulting laser emission. A highly doped erbium:ytterbium phosphate glass was used to form microsphere resonant cavities with large gain at 1.5 mm. Laser threshold pump powers of 60 mW and fiber-coupled output powers as high as 3 mW with single-mode operation were obtained. A bisphere laser system consisting of two microspheres attached to a single fiber taper is also demonstrated. © 2000 Optical Society of America

Effect of immersion in SBF on porous bioactive bodies made by sintering bioactive glass microspheres

Abstract: Since the mid 90s it has been possible to draw fibers and manufacture microspheres of novel bioactive glasses. Thus, by sintering bioactive glass microspheres it is now possible to form porous textures, in which the bioactive surface area is increased manifold compared with non-porous bodies. Four different types of porous bodies were made by sintering glass microspheres of diameter 250–300 μm. Two of the body types contained only one kind of spheres; either highly bioactive glass spheres or spheres made of glass having a low bioactivity (biocompatible glass). Two additional types of test bodies were obtained by sintering mixtures of bioactive and biocompatible spheres (composites). The dissolution of silica and calcium into simulated body fluid (SBF) was determined at different time intervals using a direct current plasma atomic emission spectrometer (DCPAES). The influence of immersion on the mechanical strength of the porous structures was studied by means of a compression test. Further, the thickness of the silica-rich gel formation on the surface of bioactive glass spheres was measured at each time interval using back-scattered electron imaging of scanning electron microscopy (BEI-SEM). A non-porous glass rod made from the same bioactive glass was used as the control. The results showed that dissolution of silica and calcium into SBF from the porous glass texture was inversely related to the silica content of the glass. The rate of silica gel formation on the sintered bioactive microspheres was significantly higher than on a rod made from the same glass. The initial mechanical strength of porous bodies consisting of only one kind of glass was 17–20 MPa. However, these bodies lost their mechanical strength at an early stage of the immersion showing compression strength of only 7–8 MPa at 14 days of immersion. The initial strength of composite glass bodies (7–11 MPa) was lower compared with bodies containing only one kind of glass but the bodies showed no notable mechanical weakening during the test. Softening of the surface of smooth bioactive glass plates correlated well with the formation of the silica-rich layer on the plate. Interestingly, the study also showed that in porous glass structures containing both bioactive and biocompatible glass the biocompatible glass can act as a site for calcium phosphate precipitation.

Fine hollow glass sphere and method for preparing the same

Abstract: It is an object of the present invention to provide hollow glass microspheres having particle properties of a low particle density and grain size properties of a sharp grain size distribution, having a high homogeneity and having such strength that they are less likely to fracture during processing. In the present invention, a glass material containing a foaming agent and containing B 2 O 3 in an amount of from 9 to 20%, is subjected to wet grinding to obtain a slurry having an average particle size of at most 3 μm, droplets thereof are heated, to obtain hollow glass microspheres having an average particle size of at most 15 μm, a maximum particle size of at most 45 μm, a particle density of at most 0.5 g/cm 3 and a grain size gradient of at most 2.

Influence of chopped strand fibres on the flexural behaviour of a syntactic foam core system

Abstract: The comparative performance in a three point bending test of syntactic foam comprising epoxy resin and glass microballoons with and without the inclusion of glass fibre in the form of chopped strands is reported. Test samples having a span-to-depth ratio of 16:1 were used. The data show that the glass fibre reinforced foam system had a higher strength compared to the unreinforced system. Resorting to light macroscopic and scanning electron microscopic examinations on mechanically tested samples expanded the scope of the work for a structure–property correlation to emerge. © 2000 Society of Chemical Industry

Formation of glass microspheres with rotating electrical arc

Abstract: The paper presents the experimental device for obtaining glass microspheres in rotating electrical arc With this device, for arc power values of 5×103 W and for frequency of ν=850 s−1, the glass powder with arbitrary shaped particles was transformed in microsphere with diameters between 2 and 24 μm and the wall thickness between 04 and 16 μm The particles in the powder were up to 30 μm in diameters, have a flow rate of 2 g·min−1 and were transported in argon (5 Nl min−1) The mean diameter is d=562 μm

Method of applying a textured coating

Abstract: A textured coating and method of applying same. The coating comprises a high-solids polyamide epoxy having a resin and a hardener, and the epoxy is mixed with a texture aggregate filler being selected from the group consisting of perlite, glass microballoons, glass bubbles, phenolic microballoons, Q cel microspheres, and extendospheres, with the filler preferably being expanded perlite of a size such that about 20% maximum by weight is retained on a U.S. Std. Sieve No. 50 and such that about 65% maximum by weight is retained on a U.S. Std. Sieve No. 100. The epoxy and the filler are mixed in about equal volume. The method has the steps of: combining the resin and hardener to create the epoxy, then waiting a sweat-in time for the epoxy, then adding and blending the filler to the epoxy then adding thinner to the blended filler and epoxy to create a mixture of sprayable viscosity; then gently blending the mixture; and then spraying said blended filler and epoxy onto a surface using a spray gun, and then allowing the epoxy coating to cure.

Parts for heating castings

Abstract: A foundry exothermic assembly is formed by mixing hollow glass microspheres and an inorganic or organic binder with matrix forming constituents including an oxidizable metal, an oxidizing agent, a foundry refractory aggregate and, optionally, a pro-oxidant, and shaping and curing the mixture. The hollow glass microspheres are dispersed and embedded in the assembly matrix.

Phosphate ester coated hollow glass microspheres, resin compositions comprising such microspheres, and low density syntactic foams prepared therefrom

Abstract: Hollow glass microspheres having surfaces coated with a phosphate ester and optional surface tension reducer are provided. By virtue of the presence of the phosphate ester and optional surface tension reducer, unexpectedly high volumes of such coated hollow glass microspheres can be utilized in resin compositions. Low density resin compositions containing high volumes of such coated hollow glass microspheres are also provided. This invention further provides new, lower density syntactic foams derived from these compositions. Still further, this invention provides low density epoxy resin compositions that comprise hollow glass microspheres, resins, resin curing agents and/or catalysts, and certain phosphate esters. By virtue of the low density of such compositions, new, lower density syntactic foams derived from these compositions can be attained and are provided.

Use of hollow glass microspheres in organosilicon syntact foam plastics

Abstract: The use of hollow glass microspheres in syntact foam plastics with organosilicon binders is described. The physicomechanical and thermophysical properties of the heat-insulating materials obtained are investigated.

Preparation and Certification of K-411 Glass Microspheres.

Abstract: The production and characterization of NBS K-411 glass microspheres in the 2-40 µm range for certification as NIST Standard Reference Material(R) 2066 (SRM(R)) are described. Quantitative analysis and heterogeneity testing of the microspheres were done with an electron probe microanalyzer-X-ray energy dispersive spectrometry (EPMA-EDS) automated particle analysis procedure. Results for the trimmed and normalized data produced mean compositions for the elements Mg, Si, Ca, Fe, and O (calculated from stoichiometry) that are in good agreement with the certified values for the K-411 bulk glass (NBS SRM 470 Glasses for Mineral Analysis), but with uncertainties about twice as large as those for the bulk material. Differences from the bulk are attributable to microsphere geometry as well as mass and size effects.

Encapsulation technology for saw device

Abstract: A bi-layer encapsulation system for a planar acoustic wave device, e.g., a SAW device, employs a layer of controlled particles to contact the active surface of the SAW device, and another layer to lock the first layer in place. A back surface of the device is bonded to a supporting substrate, e.g., a ceramic backing. The particles may be glass microspheres of a nominal 50 micron size. A layer of microspheres cover the acoustically active area of the device. Then, an epoxy or other suitable potting material covers the glass microspheres and bonds to the device and to the supporting substrate. The glass spheres may be solid glass or balloon-like microspheres filled with nitrogen or another gas. A second layer of glass microspheres may be applied over the first layer and around the edges of the first layer. This layer may contain an appropriate B-stage epoxy or a commercially available syntactic foam material. A plurality of devices can be packaged and encapsulated together while in wafer form. A first wafer on which the devices are formed is laminated to a second ceramic wafer. Streets and alleys are removed, and the devices are wire bonded to conductive traces on the ceramic wafer. The devices are encapsulated while the ceramic wafer is still intact.

Plasma display panel production method

Abstract: The present invention intends to provide a manufacturing method for a plasma display panel, so as to overcome problems associated with a withstanding voltage of a dielectric glass layer. Glass particles have angular shapes after grinding with a grinder, but as the surface of them has been melted, they are converted into spheroids. Those glass particles can get wet evenly, so that a binder evenly adheres to the surface of a glass particle when a glass paste including the glass particles is applied to the surface of a substrate. In this case, there is a scarce possibility for a gas, generated by baking the binder, to remain in the form of bubbles in a formed dielectric glass layer. There are fewer bubbles remaining in a completed dielectric glass layer than in a dielectric glass layer than in a glass layer made from angular glass particles.

Thermally protective coating composition of the ablative type

Abstract: The liquid component comprises aqueous halogenated and silicone-type polymer emulsions and organic or mineral fibers. The solid component comprises hydraulic binder powder, glass fibers, ceramic or glass microspheres and pulverized zinc oxide. The composition comprises two separate components A and B that are mixed by a conventional mechanical method, at ambient temperature, directly before use. Component A is in liquid form and consists of: (a) 20-95 wt.% of halogenated polymer in form of aqueous emulsion (I); (b) 5-80 wt.% of silicone-type polymer also in form of aqueous emulsion (II), and (c) 0-5 wt.% of organic or mineral microfibers (preferably 5 wt.% of KevlarTM fibers). A may also contain an additional third polymer (III), in the form of an aqueous emulsion, compatible with polymers (I) and (II). Component B is in solid form and contains: (a) 30-90 wt.% of high resistance conventional hydraulic binder in the form of a powder; (b) 0-30 wt.% of commercially available glass fibers or cut glass threads (preferably cut glass threads of diameter 3-10 mm); (c) 0.5-15 wt.% of commercially available hollow ceramic or (preferred) glass microspheres; and (d) 0.1-20 wt.% of zinc oxide in pulverized form. The components are used in ratio 1 wt. part of A per 0.5-2 wt. parts of B.

Concrete-repairing material and repair

Abstract: PROBLEM TO BE SOLVED: To improve the flowability of a repairing material, to dispense with application work using a trowel, etc., while making a mixing ratio of water be not larger than a specific value and to effectively repair faults by including minute hollow spherical particles in a repairing material filled in the faults in the surface of concrete. SOLUTION: This concrete-repairing material comprising minute hollow spherical particles, cement and aggregate contains a polymer dispersion (e.g. a liquid acrylic resin-based, a vinyl acetate copolymer resin-based or an acrylic- styrene copolymer resin-based) or water in an amount of <=15 wt.%. The minute hollow spherical particles are called microspheres, microballoons, hollow bubbles or a syntactic foam material, and has a diameter of 5-300 μm and the specific gravity 0.6-0.8. Air exists in the above particles and therefore makes their weight lighter than that of solid particles of the same volume. The particles are made of a aluminosilicate-based inorganic filler material. In order to repair faults, the repairing material is taken in operator's hand and is filled into pinholes or the like.

Structural resonances in the Raman spectrum of glass microsphere

Abstract: Structural resonances have been found in the Raman spectrum of an optically levitated TiBa glass microsphere. The observed resonances could be assigned by using the well-known Lorenz-Mie Formalism. It was found that the diameter of the TiBa glass microsphere is 24.490micrometers , and the refractive index of TiBa glass is 1.895 at about 645nm.

Ceramics, Glass Structure and Properties

Abstract: Inorganic glasses are important ceramic materials and glasses share many of the desirable properties of crystalline ceramics even though they lack long-range order. The structure of glasses is not completely random, however. Glasses do have short-range order in the arrangement of anions around cations. Glasses, less thermodynamically stable than crystals, must be “captured” in a metastable state, and this is typically accomplished by rapid cooling of a liquid. The simplest inorganic glasses are composed of only one element: B, C, P, As, S, or Se. Glassy selenium in thin-film form has been used extensively in the photocopying industry. Inorganic glasses containing more than one element can be broadly categorized according to the type of anion. There are two main categories: chalcogenide glasses and halide glasses. Several criteria for predicting which compounds form glasses have been proposed. The best known guidelines are those originally presented for oxide glasses and known as Zachariasen Rules. The most striking and useful characteristic of common silicate glass is its transparency to visible light. This transparency results from the absence of grain boundaries and delocalized electrons, which tend to scatter and absorb light. There are many applications in which glass is used as an electrical insulator. One example is glass-to-metal seals. Moreover, other glasses are useful as a result of ionic or electronic conductivity. Glasses are good thermal insulators, making them ideal materials for windows in buildings. The thermal conductivity of a glass increases markedly as it is crystallized to form a glass–ceramic. The thermal conductivity of an aerogel is exceptionally low. Glass processing techniques include melt processing, sol–gel processing, vapor-phase processing, and thin-film techniques. Silicate glass is a familiar, ubiquitous material, used in beverage containers, window panes, and automobile windshields. Increasingly, however, unusual glasses are being employed in high technology applications, such as optical fibers for telecommunications, graded-refractive-index glasses, nonlinear optical glasses, acousto-optic glasses, fast-ion conducting glasses, glass–ceramics, and glass microspheres. Keywords: Ceramics; Glass; Types; Glass structure; Optical properties; Electrical Thermal properties; Processing

On the use of a syntactic foam as core for sandwich panels and as external coating for pressurised pipelines

Abstract: This work reports the main results of an experimental and numerical investigation on the mechanical properties and possible engineering applications of a syntactic foam. This foam consists of an epoxy resin matrix embedding randomly dispersed hollow glass microspheres made with a borosilicate glass; they present an average diameter of 70 µm and a wall thickness of 0.58 µm. To characterise this material, an extensive experimental programme has been carried out. The purpose of this paper is twofold: first, part of the experimental results obtained are briefly presented; second, two possible uses of the syntactic foam are discussed. In the first case the foam is used as the core of a composite sandwich conceived as a lightweight material for naval engineering applications; in the second case, the syntactic foam is employed as external coating of steel pipelines which are laid on the sea bed for pressurised oil transmission. This second application is explored due to the fact that the syntactic foam displays good mechanical properties and is at the same time a good thermal insulator.