Alumina Silicate Glass Research Articles

Mineralogical Features of Ultrahigh Pressure Impact Glasses of the Kara Astrobleme (Pay-Khoy, Russia)

The behavior of the disordered systems in the conditions of the strong compression attracts particular interest in materials science. Natural impact glasses, being with a metastable state, can keep features of the structure for millions of years, form essential volumes compare to experimentally possible high-pressure products. The complex analysis of geological, mineralogical-petrographic, petrochemical features and degree of crystallinity of tagamites, vein glasses and vitro-clastic formations of the origin type of melt impactites of the Kara astrobleme including their phase state composition have been studied. The melt Kara impactites have dependence on the initial character of the melted sedimentary target and cooling velocity of an impact melt. The lowest order has been described for ultrahigh pressure vein-type glasses which contain silica drops with single crystalline coesite and firstly found melt-crystallized high pressure variety of smectite. The vein melt impactites consist of solidified impact melt presented by totally amorphous alumina silicate glass with augite microcrystallites and ultrahigh pressure silica glass with coesite microcrystals and “drops” of firstly found melt-crystallized high pressure variety of smectite. The boundary between alumina silicate and silica glass is characterized with liquated amorphous Fe-rich drops. The special feature of the studies melt impactites is low alteration in spite of 70 Ma age and high content of water. The large volumes of an impact melt created massive tagamite bodies have longer cooling underwent with the almost complete crystallization. The obtained data indicate the specific nature of melt glasses of vein type and prospects of their further research for fundamental study of amorphous state under ultrahigh pressure and propose new materials.

Quasi-static bending and low velocity impact performance of monolithic and laminated glass windows employing chemically strengthened glass

In this paper, firstly the quasi-static bending performance of chemically strengthened alumina silicate glass plates is investigated for different glass thicknesses: 2.2, 4.0 and 6.0 mm. The flexural strength is measured using coaxial double ring experiments. The 3D Digital Image Correlation (DIC) technique is employed to measure the strain at failure. The failure probability is then assessed using the Weibull statistical distribution. Secondly, the performance of the laminated glass windows made of these chemically strengthened glass plates is evaluated quasi-statically under concentrated and distributed loadings. The effects of polymer interlayer thickness, glass and polymer type and multi-layering the polymer interlayer on the structural performance are investigated. The type and thickness of the polymer interlayer, as well as the type of loading are found to influence the fracture sequence in the glass plates and consequently the post fracture safety of the structure. The response of laminated glass specimens is then assessed under low velocity soft impacts, for velocities up to 3.3 m s−1, using a drop tower facility. Laminated glass with a polyvinyl butyral (PVB) interlayer shows the greatest improvement in terms of peak force and absorbed energy.

Direct welding of glass and metal by 1 kHz femtosecond laser pulses.

In the welding process between similar or dissimilar materials, inserting an intermediate layer and pressure assistance are usually thought to be necessary. In this paper, the direct welding between alumina-silicate glass and metal (aluminum, copper, and steel), under exposure from 1kHz femtosecond laser pulses without any auxiliary processes, is demonstrated. The micron/nanometer-sized metal particles induced by laser ablation were considered to act as the adhesive in the welding process. The welding parameters were optimized by varying the pulse energy and the translation velocity of the sample. The shear joining strength characterized by a shear force testing equipment was as high as 2.34MPa. This direct bonding technology has potential for applications in medical devices, sensors, and photovoltaic devices.

Photocatalytic property of TiO 2 thin films sputtered-deposited on unheated substrates

TiO 2 films deposited on unheated substrates of alumina silicate glass by rf. (13.56 MHz) magnetron sputtering in the mixture of O 2 and Ar gases have been studied with X-ray diffraction (XRD), Atomic Force Microscopy (AFM) and optical spectroscopy. Structural and optical properties of TiO 2 films deposited at different O 2 concentrations and total pressures have been analyzed. Photocatalytic properties of TiO 2 films were characterized by following the degradation of methylene blue molecules under UV irradiation. It was found that the rate of methylene blue decomposition strongly depends on morphology and crystallinity of the deposited films, namely on the content of the anatase phase and on the size of the anatase grains. The best photocatalytic activity was found on TiO 2 films consisting of pure anatase phase with the size of grains of about 450 Å. With the help of those films a thin film reactor for water purification has been designed and tested.

Applications of high energy ion beam techniques in environmental science: Investigation associated with glass and ceramic waste forms

High energy ion beam capabilities including Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) have been very effectively used in environmental science to investigate the ion-exchange mechanisms in glass waste forms and the effects of irradiation in glass and ceramic waste forms in the past. In this study, RBS and NRA along with SIMNRA simulations were used to monitor the Na depletion and D and 18O uptake in alumina silicate glasses, respectively, after the glass coupons were exposed to aqueous solution. These results show that the formation of a reaction layer and an establishment of a region where diffusion limited ion exchange occur in these glasses during exposure to silica-saturated solutions. Different regions including reaction and diffusion regions were identified on the basis of the depth distributions of these elements. In the case of ceramics, damage accumulation was studied as a function of ion dose at different irradiation temperatures. A sigmoidal dependence of relative disorder on the ion dose was observed. The defect-dechanneling factors were calculated for two irradiated regions in SrTiO 3 using the critical angles determined from the angular yield curves. The dependence of defect-dechanneling parameter on the incident energy was investigated and it was observed that the generated defects are mostly interstitial atoms and amorphous clusters. Thermal recovery experiments were performed to study the damage recovery processes up to a maximum temperature of 870 K.

Interpretation of the critical length scale determining the conductivity in ionically conducting silicate glasses

Implications of basic percolation theories based on a random-barrier model for hopping conductivity have been explored for the interpretation of length scales determining dc conduction in ionically conducting alumina-silicate glasses. Independent measurements of activation energy E c, conductivity spectra and Mott–Schottky capacitance–voltage characteristics indicate a common typical size for the average extent of displacement at the frequency of onset of ac conduction, L c∼10 nm, which is interpreted as the effective correlation length of the infinite cluster determined by the percolation threshold ξ c= E c/ k B T. The localization of carriers in clusters of sites between critical barriers causes a reduction of the effective mobile ion concentration (≈4 × 10 16 cm −3) by many orders of magnitude below the nominal alkali concentration.

A New Sealant Material for Solid Oxide Fuel Cells Using Glass-Ceramic.

We report a new sealant material for solid oxide fuel cells (SOFCs) using glass-ceramic. A glass-ceramic based on the CaO-Al2O3-SiO2 system was selected as a sealant because it can be easily molded to give a gastight seal and remains in a solid-like state under typical fuel cell operating conditions. Calcium alumina silicate glass powder is placed in the gas-sealing area before crystallization. During heating, the glass softens and bonds with the SOFC components. At higher temperatures, bulk crystallization occurs in the glass and the viscosity of the glass-ceramic sealant increases. We show that this sealing material which is able to seal at higher viscosities compared with the melt sealing method produces a good gas-tight seal and is chemically stable in contact with SOFC components, e.g., yttria-stabilized zirconia electrolytes and lanthanum chromite separators.

Pressure polishing: a method for re-shaping patch pipettes during fire polishing

The resolution of patch-clamp recordings is limited by the geometrical and electrical properties of patch pipettes. The ideal whole-cell patch pipette has a blunt, cone-shaped tip and a low resistance. The best glasses for making patch pipettes are low noise, low capacitance glasses such as borosilicate and aluminasilicate glasses. Regrettably, nearly all borosilicate glasses form pipettes with sharp, cone-shaped tips and relatively high resistance. It is possible, however, to reshape the tip during fire polishing by pressurizing the pipette lumen during fire polishing, a technique we call ‘pressure polishing.’ We find that this technique works with pipettes made from virtually any type of glass, including thick-walled aluminasilicate glass. We routinely use this technique to make pipettes suitable for whole-cell patch-clamp recording of tiny neurons (1–3 μm in diameter). Our pipettes are made from thick-walled, borosilicate glass and have submicron tip openings and resistances <10 MΩ. Similar pipettes could be used to record from subcellular neuronal structures such as axons, dendrites and dendritic spines. Pressure polishing should also be useful in patch-clamp applications that benefit from using pipettes with blunt tips, such as perforated-patch whole-cell recordings, low-noise single channel recordings and experiments that require internal perfusion of the pipette.

Alumina-Silicate Glass Interfacial Properties Probed by Micromechanical Testing Techniques

AbstractMicromechanical properties of the interfaces between alumina and calcium-aluminosilicate (CAS) glasses were tested using various micro/nanoindentation techniques. The interfaces were produced by depositing continuous films of anorhtite (CaAl2Si2O8) onto single-crstal α-Al2O3 of two crystallographic orientations by pulsed-laser deposition (PLD).The mechanical behavior of the interfaces was examined using two different depthsensing indentation instruments. Three types of tests, namely indentation, microscratch, and in-situ indentation combined with atomic force microscopy (AFM) imaging were conducted using different operating modes. The deformation behavior observed for the indentations and microscratches has been correlated with irregularities observed in the load-displacement curves. In the first two cases, scanning electron microscopy (SEM) has been used to characterize the deformation structures associated with the deformed regions. The in-situ experiments allow force-displacement measurements and AFM imaging immediately before and after indentation. The preindent and postindent morphology of the surface could then be characterized.

A REVIEW OF THE DURABILITY OF INHALED FIBRES AND OPTIONS FOR THE DESIGN OF SAFER FIBRES

The hazards associated with inhaled fibres are linked with fibre shape, size, composition and durability Durability includes susceptibility both to dissolution and to mechanical disintegration. Most fibre types dissolve incongruently with some elements being preferentially leached from the fibre to leave it mechanically weakened. Incongruent dissolution is also associated with hydration of fibre surfaces and the associated volume changes can lead to mechanical failure of fibres. In general the asbestos minerals are more durable than most man-made vitreous fibres (MMVF), although some ceramic fibres may be more durable than chrysotile. The most soluble of the MMVF have relatively high alkali (Na and K) and alkali earth (Ca, Mg) contents, and low alumina and boron contents The least soluble MMVF are the high alumina silicate glasses (the ceramic fibres). The relative durability of different fibre types is governed by the physical and chemical environment which contains the fibres. The value of existing published data in determining the relative durabilities of different fibre types has been limited by the lack of comparability between studies The effective assessment of fibre durability is an important aspect in fibre safety and requires the development of better and more co-ordinated experimental design. It may ultimately be possible to design vitreous fibres which have low durabilities in the lung but are adequately durable in the intended environment of use.

Application of Sims Depth Profiling to Ceramic Materials

ABSTRACTDepth profiling is becoming a common method of determining composition gradients for those research facilities that have access to SIMS. The problems with this procedure are briefly discussed but well referenced for those interested in using the technique. Spectra for application of depth profiling to a tantalum pentoxide layer on tantalum, silicon implanted in silica, preferential sputtering of niobium and surface treated lithium alumina silicate glass are presented.

Glass Electrodes for the Direct Measurement of Sodium Ion Activity: Part II

Five Lithia Alumina Silicate glasses having different proportions of additives were melted and studied for their suitability as sodium electrodes. A particular composition was found to be the best so far as the sodium ion specificity was concerned. The effect of interfering ions like K+, Ca2+, Mg2+, Al3+, Fe3+ and SO42- was studied and it was found that only Al3+ and Fe3+ had interference which also could be completely suppressed by using triethanol-amine. The results of Na2O determinations made with sodium electrode were compared with those determined by flame spectrophotometry and they were analysed statistically.

Faraday Rotation in Praseodymium, Terbium, and Dysprosium Alumina Silicate Glasses

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Charles C. Robinson and Robert E. Graf, "Faraday Rotation in Praseodymium, Terbium, and Dysprosium Alumina Silicate Glasses," Appl. Opt. 3, 1190-1191 (1964) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article