Glass Science and Technology
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- Item1H MAS NMR and IR studies on powdered alkali-lime-silica glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2000) Storek, Werner; Peuker, Christel; Geißler, HeinzPowdered samples of glasses with the composition 16 R2O ∙ 10 CaO ∙ 74 SiO2 (R = Na, K, Cs) and a concentration of water in glass of about 0.03 mol ∙ l^-1 were studied by solid state 1H MAS NMR (magic angle spinning nuclear magnetic resonance). Three superimposed NMR signals at about 6.3, 12.5 and 15.6 ppm were recorded, which were assigned to three different proton sites involved in weak, strong and very strong hydrogen bonds, respectively. The relative intensity of the NMR signals depends on the type of alkali in the glass. The amount of OH groups with strong and very strong hydrogen bonding increases in relation to the weakly bonded hydroxyl groups upon substitution of Na2O, K2O or Cs2O, respectively. The result is in good agreement with the earlier IR findings for these glasses. Thus, Scholze's interpretation [1 to 3] of the region of the OH stretching vibrations in the IR spectra could be verified firstly by NMR spectroscopy as an independent analytical method.
- ItemA novel route for the production of ultra pure SiO2 crucibles(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Günster, Jens; Engler, Sven; Heinrich, Jürgen G.; Schwertfeger, FritzA novel and cost-effective process is introduced for the production of ultra pure quartz parts on an industrial scale under clean room conditions. Starting with a colloidal SiO2 sol, SiO2 green bodies are fabricated by a pressure casting process. After drying, the SiO2 preforms are sintered with CO2 laser Systems providing a power Output of up to 12 kW. In contrast to the many applications of high power laser Systems the laser optics used widens the laser beam to a spot size of up to 100 mm. It could be shown that State of the art CO2 laser Systems are superior to heat sources commonly used for sintering of high purity ceramics since contamination of the material to be sintered can be virtually excluded and large SiO2 preforms can be sintered to graded structures without changing their geometry.
- ItemActive thermal conductivity of hot glass(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1994) Fotheringham, Ulrich; Lentes, Frank-ThomasFor (semi)transparent glass, it is suggested to distinguish between an active and a passive thermal conductivity. Essentially, the latter is attached to the heat transfer through long-range photons most of which are both emitted and absorbed outside the glass volume, the former to the heat transfer through phonons and short-range photons which have an intense energy exchange with the glass. As the temperature distribution in the glass volume can be influenced only by the heat exchange in which the glass is actively involved, it is determined by the active thermal conductivity. The sum of the active and the passive thermal conductivity, which is identical to the so-called apparent thermal conductivity, indicates the overall heat flux through the glass. Like the apparent thermal conductivity, the active thermal conductivity can be obtained from the prototype of thermal conductivity measurements where the heat flux through a sample between two heat reservoirs of different temperatures is measured. The apparent thermal conductivity follows from the usual reduction o f the measurement data, the active thermal conductivity is derived via a differentation rule. Comparing the calculation and the measurement of the temperature inside a cooling block of glass, this differentiation rule is verified.
- ItemAdvanced batch house technology for float glass - the new plant of SAINT-GOBAIN GLASS DEUTSCHLAND in Cologne/Porz(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2002) Drescher, Holger[no abstract available]
- ItemAdvanced combustion control - the basis for ΝΟx reduction and energy saving in glass tank furnaces(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Hemmann, Peter[no abstract available]
- ItemAdvanced melter operation and training tool(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2002) Muysenberg, Erik; Nováčková, Markéta; Trochta, Miroslav; Viktorin, PavelGlass Service Inc. uses the GS Glass Furnace Model as a base for a glass furnace simulator. It contains a user-friendly graphical front end, a simplified version of a furnace operation station, that allows modifying furnace settings (batch charging rate and properties, setup of bubblers, coolers, fuel profile, etc.). Behind this user interface, coupled glass and combustion models are run. The output of these calculations (shown again as a set of operator-friendly control screens) displays temperatures in positions where thermocouples and pyrometers are located in reality, exhaust gas properties, glass flow patterns, location of spring zone, quality indices, etc. The simulator has been validated and shows good agreement with reality.
- ItemAdvanced oxygen burner for the glass industry(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Legiret, Thierry; Philippe, Louis; Tsiava, Remi; Marié, Bruno[no abstract available]
- ItemAgeing kinetics and internal friction of oxide glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Nemilov, Sergei V.The detailed analysis of internal friction data of Silicate and phosphate glasses (frequencies of about 1 Hz) was done in comparison with the calculated temperature positions expected from the characteristic times of ageing which resulted from previous systematization of alkali-containing silicate glasses. As basis suggested for such comparison is the validity of secondary relaxation mechanism at high-temperature mechanical relaxation to that for ageing kinetics at room temperature. Practically in all cases the relaxadon times for the ageing process fit the distribution of relaxation times for internal friction. Thus the β-relaxation maximum (internal friction) may be considered as overlapping four narrow spectral components, at least. The characteristic times for ageing, contrary to continuous distribution for the mechanical relaxation, are discrete due to the condition of structure ordering. The nonbridging oxygens seem to be more probable participants of elementary relaxation events in both kinds of processes.
- ItemAlkali ion migration control from flat glass substrates(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2000) Janke, Nikolas; Grassmé, Oliver; Weißmann, RudolfSodium diffusion from flat glass substrates during annealing changes properties of refined flat glass. In the ease of the development of the CuInSe2 thin film solar eell, annealing at 550 °C is necessary for the formation of suitable crystalline phases. Sodium diffusing from the soda-lime-silica glass substrate influences crystal growth and the main electrical parameters of the solar cell. Different possibilities in sodium ion migration control are presented, considering the influence of glass composition on sodium diffusion and its chemical potential as well as passivation of sodium-containing glasses by diffusion barriers. Experimental results in connection with the thin film solar cell show that sodium-free substrates or glass compositions which immobilise sodium at tetrahedral sites of boron oxide or alumina can be used without further surface treatment. Soda-lime-silica glass with sputter-deposited AI2O3 and BiOx thin films or CVD coatings (SiNx: H, SiOx) as diffusion barrier coatings shows promise as a cheap substrate material. Alternatively, dealkalisation of soda-lime-silica glass in HCl atmosphere leads to silica-rich surfaces with excellent barrier properties. The investigations are carried out using various surface analytical tools like Auger Electron Spectroscopy (AES), X-Ray Diffractommetry under Grazing Incidence (GI-XRD), high-resolution Scanning Electron Microscopy (SEM), and Fourier Transform Infrared spectroscopy (FTIR).
- ItemAltglasaufbereitung: Farbsortierung und vollautomatische Qualitätskontrolle in Theorie und Praxis(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1996) Bayer, Wolfgang[no abstract available]
- ItemAlumina and zirconia as inhibitors of crystallization during sintering of borosilicate glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2002) Pascual, M. Jesus; Pascual, Luis; Durán, Alicia; Wange, Peter; Rüssel, ChristianThe glass composition (in mol%) 16 Na2O ∙ 24 B2O3 ∙ 60 SiO2 has suitable viscosity and dilatometric properties to be used as sealing material for the gas manifolds of molten carbonate fuel cells (MCFC). Nevertheless, quartz crystallization takes place during sintering of the borosilicate glass powder at temperatures between 600 and 700 °C. The quartz crystallization leads to the formation of pores and a variation in the thermal expansion coefficient; both giving rise to defects and tensions in the seal. In this work, the possibility of inhibition of quartz crystallization by substituting AI2O3 or ZrO2 for 2 or 5 mol% of SiO2 is described. The thermal properties and the viscosity-temperature curve of the new compositions, especially those containing alumina do not differ much from the original glass.
- ItemAmber chromophore formation in sulphur- and iron-containing soda-lime-silica glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2003) Beerkens, Ruud G. C.During cooling of reduced soda-lime-silica glass melts, doped with iron oxides and sulphur species, ferrous iron (Fe2+) reacts with sulphite (SO3 2-), and the Fe3+ (ferric iron) and also the S2- (sulphide) concentration will increase. The sulphite concentration in the amber glass melt after fining is sufficient to produce ferric iron and sulphide, required for amber chromophore formation during the cooling process. The product of the concentrations of Fe3+ and sulphide will strongly increase during coohng below about 1000 K. This mechanism implies that a necessary condition for amber formation is the availability of sufficiently large iron concentrations in the presence of a sufficient sulphite content in the high-temperature glass melt. The formation of a chromophore, based on Fe3+ - S2- - 3O2- - nNa+ complexes in the silicate glass will lead to amber colouring. Α strong dependency of the amber intensity of the glass on the maximum temperature of melting, the alkali concentration of the glass, the total iron concentration and on the oxidation-state of the melt has been found experimentally. The charge of the networkmodifying alkali ions stabilizes the ferric iron-sulphide-oxide-alkali chromophores. In strongly reduced melts, hardly any sulphite can be formed and during cooling, the amber chromophore formation is limited. Experiments show a decrease in ferric iron concentrations and in the amber intensity when over-reducing glasses. Α decrease in the amber intensity of amber glasses with increasing water content is probably caused by lower sulphite retention after fining of waterrich melts.
- ItemAnalyses of aluminum traces in sorted amber cullet(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Pitzel, Christian; Ehrig, Reiner; Stachel, DörteThis paper deals with analyses of aluminum impurities in already sorted cullet. Some ways of minimizing the amount of pure aluminum in this amber cullet are shown and discussed. By the mechanism presented the aluminum is oxidized with an alkaline Solution at pH 7.5 up to 11.5, as found in outside stored cullet. This proves to be a useful way of minimizing metallic aluminum in cullet and reduction of interfering inclusions in glasses.
- ItemAnalysis of as-prepared and corroded glass fibers by secondary neutral mass spectrometry(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Müller-Fildebrandt, Constanze; Priller, Stefan; Frischat, Günther HeinzThree types of glass fibers, differing mainly in their alumina, alkaline earth and alkali oxide contents, were investigated by secondary neutral mass spectrometry. The investigation was carried out on fibers as-prepared and after exposure to humidity and to attack in distilled water. Concentration-depth profiles of the fibers obtained by secondary neutral mass spectrometry showed that the asprepared fibers were already pre-experimentally weathered in a ≤50nm deep surface zone. The pattern of chemical change and leaching was found for each fiber to be similar after exposure to humidity and short-term attack by water, respectively, however with enhanced leaching observed in water, where the leached elements are removed from the fiber surfaces. Different leach mechanisms could be established for the different fiber types and changes of leach mechanisms with time could be observed. Altogether, the depth profiling method proved to be a powerful tool to elucidate the comphcated leach mechanisms also in the case of glass fibers.
- ItemAnalysis of dissolution of a spherical gas bubble in a glass melt in the presence of a flow and a fast redox reaction(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2003) Lertskrai, Supawan; Kalachev, LeonidModeling a process of dissoludon of a slowly moving gas bubble in a glass melt can be reformulated as a problem of dissoludon of a stadonary bubble in a flow. It is shown that in the presence of fast redox reaction (outside the bubble) the effect of the flow on the time of dissolution is negligible. Many authors omit the flow when modeling dissolution of bubbles in glass melts. This analysis specifies the conditions under which such omission can be justified. Due to the presence of fast reaction the problem is singularly perturbed. The boundary function method was used to obtain asymptotic approximation of the solution. Asymptotic results are compared with numerical computations performed for the original statement of the problem.
- ItemAnalysis of glass science and industry in the Czech Republic(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2000) Kasa, StanislavThis article analyses glass science, research and the glass industry in the Czech Republic from 1996 to 1998. It contains the principal economic data and the geographical distribution of the Czech glass industry, as well as its structure regarding the manufacture of individual products. The final chapter deals with the current state of glass science and research in the Czech Republic. Also included are the main research institutes, together with their respective fields of research.
- ItemAnalysis of heat transfer during glass forming(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2001) Viskanta, Raymond; Lim, JongmookΑ thermal model is described which is intended to simulate internal heat transfer in glass being cooled by the mold and plunger after pressing. The heat transfer analysis in glass accounts for the spectral nature of radiation, the dependence of the thermophysical properties of glass on temperature and the contact heat transfer between mold and glass as well as plunger and glass during and after pressing. Heat exchange between glass and mold as well as plunger across a very small gap by contact conduction and thermal radiation are also accounted for. To assess the utility of the Rosseland diffusion approximation for radiative transfer, the results are compared with those based on rigorous formulation of radiative transfer. Numerical solutions have been obtained for typical condidons simulating symmetric and asymmetric cooling as well as cyclic operation, and the results are presented and discussed. During the dwell time thermal contact conduction between the glass and the mold as well as plunger is the dominant heat extraction mechanism from the glass. Results show that radiation from the surface of the glass plays a relatively small part in the heat extraction process, but radiation from the interior of the glass is much more significant but less important than thermal contact conduction.
- ItemAnalysis of polyethylene-based cold end coatings on glass : Containers with contact angle and IR spectroscopy(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Geotti-Bianchini, Franco; Preo, MartinaThe aim of cold end coating is to protect the glass surface from abrasive wear with the help of a suitably anchored film of organic material which decreases friction, by preventing direct glass to glass contacts. At present, routine controls on cold end coatings are limited to a lubricity test, i.e. the determination of the slide angle. Α laboratory procedure based on the determination of the contact angle with water is described in this work. It allows one to estimate the coverage with cold end coating locally from the waterrepellence caused by the organic deposit. This method can be used to investigate a ränge of problems associated with glass wettability, including label adhesion, acid etching and washing residues. The contact angle correlates well with the slide angle. Qualitative information on the nature of cold end coatings is obtained by extracting the glass with volatile organic solvents such as methylene chloride, evaporating them and analyzing the residue with infrared spectroscopy. In the case of a coating with RP 40 LT the IR curves show the presence of Polyethylene partially oxidized in order to improve adhesion to the glass surface, besides Polyethylene glycol added as an emulsifying agent. If the cold end coated container is rinsed with water, the glycol dissolves, but the Polyethylene derivative remains strongly anchored. Such bond withstands even drastic washings with water and detergents, alkali or oxidizing acids. Even when the glass is extracted with organic solvents, only a fraction of the deposit is dissolved. Therefore, even a quantitative analysis of the IR spectrum of the extract provides values smaller than the true coverage due to incomplete extraction.
- ItemAnalysis of various plunger materials used in the container glass industry(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Tanhöfner, SandraThe achievement of high impact strength has a basic influence on the further development of lightweight container glass. The tested articles were 11 nonreturnable flint glass water bottles, produced in the NNPB process. The impact strength of the flint container glass wäre was tested by repeated hitting on the upper contact area in the Shoulder. Four different plunger materials were tested in a 12 section AIS Emhart machine. The test run was structured in an experimental and an analytical part. The paper includes graphic and diagrammatic interpretations concerning the impact strength, the elements from the plunger materials contained in the glass and furthermore the change in the chemical composition of the plunger material after use. The aim of this analysis was to fmd an ideal plunger material, which satisfies the requirements of higher strength for lightweight glass Containers.
- ItemAnalytical models for high-temperature corrosion of silica refractories in glass-melting furnaces(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2003) Nilson, Robert H.; Griffiths, Stewart K.; Yang, Nancy; Walsh, Peter M.; Allendorf, Mark D.; Bugeat, Benjamin; Marin, Ovidiu; Spear, Karl E.; Pecoraro, GeorgeCorrosion of refractory silica brick used to line the crown of many glass-melting furnaces is a serious problem in furnaces using oxygen-fuel rather than air-fuel mixtures. To better understand and to quantify this process analytical models are utilized to evaluate the importance of four potential rate-limiting processes: a) gas-phase transport of NaOH to the crown surface; b) diffusion of sodium-containing reactants through a liquid product layer that forms on the brick face; c) gas-phase diffusion of NaOH into refractory pores; and d) chemical-kinetic limitations at the silica grain surface. Predictions are compared with reported corrosion rates and product compositions previously determined by post-mortem analysis of refractory samples. It is concluded that corrosion occurs largely by reaction and removal of material from the exposed brick face, rather than by transport of reactants into the porous bricks. The observed presence of corrosion products deep within the brick pores is shown to be consistent with capillary suction of high-viscosity liquid products from the hot face into the interior. The results further suggest that mechanisms (b) and (c) do not substantially limit the rate of corrosion, but that mechanisms (a) and (d) may both be important. Comparison of measurements with equilibrium predictions of corrosion-product composition indicate that the corrosion reactions are likely to be close to equilibrium at the conditions and lifetimes typical of full-scale furnaces, but that significant departures from equilibrium may occur in short-duration tests. Although computed corrosion rates based on mass transport through a gas boundary layer are somewhat greater than those observed, the results are very sensitive to the gas-phase concentration of NaOH and to the refractory temperature, both of which contain significant uncertainties.