311 results
Search Results
Now showing 1 - 10 of 311
- Itemstress generation modulus as a counterpart of the stress relaxation modulus(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1995) Brückner, Rolf; Hessenkemper, Heiko; Habeck, Andreas; Yue, YuanzhengIn order to measure the time dependence of the stress relaxation modulus, E, a stress-strain deformation has to precede which induces a stress within the viscoelastic sample from which the sample relaxes. The generation of stress is characterized by a strain rate-dependent and relaxation rate-dependent portion which exhibits a maximum value, E_max, which is called "stress generation modulus". E_max was called the "maximum stress relaxation modulus" in earlier papers. Meanwhile, however, it turned out that a better verbal distinction should be made in future by the new term "stress generation modulus" because E_max is about one order of magnitude larger than E.
- 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]
- ItemThermodynamic calculations of chemical solubilities of gases in oxide melts and glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Pelton, Arthur D.The Reddy-Blander thermodynamic model for calculating sulfide solubilities in oxide melts and glasses has been modified and extended to predict a priori solubilities of sulfide, sulfate, phosphate, carbonate and halides in multicomponent oxide melts and glasses, from a knowledge of the thermodynamic activities of the basic component oxides (SiO₂, Na₂O, K₂O, CaO, etc.), in most cases with no adjustable parameters. Agreement with measured solubilities is within or nearly within experimental uncertainties over wide ranges of composition in two-, three-, four- and five-component melts and glasses. Particularly good agreement is obtained for the dissolution of sulfur, SO₂ and SO₃ as sulfate. The oxide activities used in the computations are calculated from a database of model parameters obtained by optimizing thermodynamic and phase equilibrium data for oxide Systems. Sulfide, sulfate, phosphate, carbonate and halides as solutes have now been included in this database. Software for Gibbs energy minimization with automatic access to this and other databases permits the calculation of solubilides in multicomponent oxide melts and glasses in equilibrium with other phases such as gases, molten salts, solids and metals, and can be useful to model evaporation processes and bubble formation.
- ItemKonventionell beheizte Glasschmelzöfen für die Hohl- und Flachglasherstellung im deutschsprachigen Raum - Ergebnisse einer HVG-Umfrage - Teil 1. Beheizung, bauliche Merkmale, Schmelzleistung(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Fleischmann, Bernhard[no abstract available]
- ItemIn-situ investigations of sintering and crystallization of lithium aluminosilicate glass-ceramics(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Zimemr, José; Raether, Friedrich; Müller, GerdThe sintering and crystalhzation behaviour of a Li₂O-Al₂O₃-SiO₂ glass powder containing TiO₂ and ZrO₂ was investigated by the in-situ measuring methods of high-temperature dilatometry, high-temperature X-ray diffractometry and differential thermal analysis at heating rates between 0.5 a n d 20 K/min. By comparing the results of the different methods the shrinkage could be explained as an overlap of sintering and crystallization processes. When increasing the heating rate, the sintering and crystallization processes are separated mor e sharply, so that higher final densities of the sintered samples can be achieved.
- ItemUV-VIS spectroscopic investigations of amber glass at high temperatures(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Müller, Matthias; Rüssel, Christian; Claußen, OlafThe absorption spectra of iron-containing glasses and an amber glass were recorded in the temperature ränge of 25 to 700 °C. Α shift of the UV absorption edge towards lower wave numbers with increasing temperature was found. The amount of the shift depends on the Fe³⁺ concentration. Here, the UV absorption edge may superimpose or even cover up the absorption bands of colouring ions with increasing temperatures. For an amber glass sample, with increasing temperature, the intensity of the absorption bands of the amber chromophore decreases slightly. However, above 550 °C the decomposition of the chromophore is observed. All changes are reversible when temperature is decreased again. The decomposition of the chromophore and the attributed temperature ränge are in agreement with thermodynamic calculations.
- ItemDetermination of the composition of glass, glass-ceramics and glass raw materials with Laser-ICP-MS(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Strubel, Christine; Meckel, Lothar; Effenberger, RuthΑ mass-spectrometric method with an inductively coupled plasma as an ion source (ICP-MS) is presented which uses an excimer laser for direct ablation of solid material. The oxide compositions of a television screen glass, a glass-ceramic and a quartz powder analyzed by LA-ICP-MS are given and compared with data obtained by wet chemical analysis. Fundamental processes of the technique are described and advantages and disadvantages for the analysis of glass are discussed.
- ItemEinsatz von Recyclingglas in der Hohlglasschmelze(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1995) Beutinger, Markus[no abstract available]
- 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.
- ItemComparison of the diffusion approximation and the discrete ordinates method for the investigation of heat transfer in glass(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Lee, Kong Hoon; Viskanta, RaymondHeat transfer by combined conduction and radiadon has been investigated in a one-dimensional glass layer. The layer is semitransparent to radiadon and the dependence of the absorption coefficient on wavelength is accounted for. The discrete ordinates method and the diffusion approximation are used to analyze radiative transfer. The differencing scheme for the discrete ordinates method has been investigated to obtain the constant total heat flux distribution across the glass layer as required by the energy conservation equation, and the best uniformity is obtained with the diamond scheme. The results predicted by the discrete ordinates method are in good agreement with those based on the exact (integral) equation formulation of radiative transfer. The diffusion approximation greatly underpredicts the temperature and heat flux distributions in the glass layer when the thickness or the opacity of the layer is small. The predictions of the diffusion approximation are only reasonable for thick glass layers. This approximation should be used with extreme caution to obtain quantitatively accurate results.