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- 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.
- ItemZerstörungskennlinien für Verbundsicherheitsglasscheiben(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2001) Mayrhofer, Christoph; Kranzer, CarolineFür die Bewertung des Tragverhaltens von Bauteilen bei Explosionsereignissen sind sogenannte „Druck-Impuls-Diagramme" erforderlich. Diese geben in Abhängigkeit vom Druck und dem Impuls der Belastung an, für welche Wertepaare Zerstörung eintritt und welchen Belastungswerten das betrachtete Bauteil standhält. Derartige Zerstörungskennlinien sind am Fraunhofer EMI für eine Vielzahl von Werkstoffen entwickelt worden. Den Zerstörungskennlinien liegt das Rechenmodell des Ein-Massen-Schwingers zugrunde. Voraussetzungen für seine Anwendbarkeit sind Biegetragmechanismen, Bruch- bzw. Zerstörungskriterien (z.B. Grenzdurchbiegung) und die Kenntnis des statischen Last-Verformungsverhaltens. Untersuchungen ergaben, daß Verbundsicherheitsglasscheiben die Voraussetzungen für die Erstellung von Zerstörungskennlinien erfüllen. Es wird eine Näherungsmethode zur Erfassung des statischen Tragverformungsverhaltens unter Berücksichtigung von Membranspannungszuständen dargestellt. Am Beispiel anderer Werkstoffe wird die prinzipielle Vorgehensweise erläutert, da für Verbundsicherheitsscheiben bisher noch keine Bruchkriterien zur Verfügung stehen.
- ItemCollaborative study into the analysis of total selenium and selenium valence states in glass - a general method by hydride generation atomic absorption spectrometry and photometry : Report of the International Commission on Glass (ICG) Technical Committee 2 "Chemical Durability and Analysis"(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2000) Guadagnino, Emanuel; Çorumluoğlu, OrhanWhilst the determination of total selenium in glass is of great relevance to environmental purposes, the measurement of the oxidation states of selenium which may arise under different redox conditions may contribute to clarify the mechanisms of colour formation. In the proposed method, the determination of total selenium is carried out by hydride generation atomic absorption spectrometry (HGAAS) on three different glasses covering the range of selenium content between 10 and 130 mg/kg of glass. To prevent losses during the decomposition step, selenium is converted into a nonvolatile form as selenate (Se6+). When the sample is decomposed, the HCl Solution (c(HC1) = 10 mol/l) is made and selenium is pre-reduced to Se4+ by heating for 2 h at 80 °C. The determination of selenium oxidation states requires a stepwise approach. The measurement of Se0 is based on its insolubility in HF. After the sample is decomposed, Se0 is filtered off, dissolved from the filter with a HBr-Br2 mixture and finally measured by HGAAS. Se4+ and Se6+ are recovered in the filtrate of the same sample and determined together after conversion of Se4+ into Se6+. Se4+ is determined in the same filtrate by photometry with o-phenylenediamine (OPDA).
- 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]
- ItemStudy of surface changes on industrial glasses with AFM, FE-SEM, EDX, SNMS and LM : Part 1. Glass skin and corrosion(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Wang, Chun; Häfner, Wolfgang; Krausch, Georg; Rädlein, Edda; Tratzky, Stephan; Schramm, Manfred; Martinek, Klaus-PeterBy combining different analytieal techniques, including modern high resolution imaging tools such as field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM), new phenomena in the surface, near surface and bulk structure of various industrial glasses (without any cleaning process) have been diseovered. Investigations of soda-lime-silica container glass and lead silicate glass tubings exposed to atmospheric and to dried air are presented. The results of the first part of this paper can be explained with an SiO2 rich skin on the glass, which can protect the glass against the attack of external media. If the skin was mechanically injured, inhomogeneous corrosion products on pm scale grew around the injured site after exposure to humid air for times between days up to one year. Microchannels were formed through the injured site due to restricted ion exchange, followed by a local increase of the pH value and consequently the dissolution of the glass network. Finally some stress in the glass, yielded during manufacture, can be partially released and the cutting behaviour is improved. Faster cooling results in a thinner skin and the ions in the glass are able to migrate to the surface more easily when surrounded by some reactive media. Slower cooling results in thicker skin and wax-like droplets instead of erystallites are formed on the surface at a later stage in humid air. The wax-like droplets can etch the glass skin locally, followed by the growth of inhomogeneous corrosion products similar to the injury induced corrosion. If the fresh glass surface was hot-end treated, the quality of the adjacent coating layer depended strongly on the thickness of the skin.
- 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.
- ItemInfluence of modifier cations on the radiation-induced effects of metaphosphate glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2003) Ebeling, Polina; Ehrt, Doris; Friedrich, ManfredThe influence of different modifying cations on the radiation-induced defect generation in metaphosphate glasses was studied by optical absorption and electron paramagnetic resonance spectroscopy. For this task, several model glasses were prepared. These were simple metaphosphates of alkaline earths, aluminum and zinc. The synthesized glass samples were irradiated with X-rays and with UV light from an Xe/Hg lamp. The cation-dependent differences in the structure of the phosphate glasses were found to have a great influence on the concentration of some radiation-induced defects and thus on the optical absorption. The influence of the different cations became especially distinct under UV light Irradiation due to the selective interaction of the UV light with the glass samples. Some additional phenomena were observed for the irradiated zinc and magnesium metaphosphate glasses which were not found by the previously undertaken study of complex phosphate glasses.
- 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.
- ItemIn situ measurement of batch glass during melting(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Raether, Friedrich; Krauß, ManfredΑ novel optical measuring method is described which was used for the density measurement of model samples of glass batch during the melting process. It used a sample volume of some 1000 mm3, which was suffieiently large to suppress single particle effects. Shape changes of batch samples during heating were taken into account by the optical method. Volumetric changes of soda-limesilica glass batch were monitored between room temperature and 1100 °C. Initially a sintering stage was observed showing seif similar reduction in the sample volume. Thereafter, the sample shape approached the equilibrium surface of drops. This was accompanied by a large increase in volume, which was attributed to the formation of gas bubbles within the batch samples. Α strong influence of heating rate and composition on this volume increase was observed.