STRENGTH OF CHALCOGENIDE GLASSES OF THE SYSTEM Se-Ge-As

Les résistances macroscopiques et microscopiques (résistance à la flexion en quatre points σB, facteur d'intensité de contrainte critique KIc et microdureté indépendente de la charge L2VH) ont été déterminées pour des verres différents du système de chalcogénures Se-Ge-As. Les valeurs de σB se situent dans l'intervalle de 10 à 25 Nmm-2, les valeurs de KIc de 5.5 à 9.4 Nmm-3/2 et les valeurs de L2VH de 700 à 1400 Nmm-2. Les résultats des verres de type chalcogénure sont comparés aux résultats d'autres verres.Macro- and microstrength (four point bending strength σB, critical stress intensity factor KIc, and load-independent microhardness L2VH) were determined on different glasses of the chalcogenide system Se-Ge-As. σB values lay between 10 and 25 Nmm-2, KIc values between 5.5 and 9.4 Nmm-3/2 and L2VH values between 700 and 1400 Nmm-2. The values on chalcogenide glasses are discussed with respect to other glass compositions

Gasblasen in Glasschmelzen unter Beruecksichtigung technisch relevanter Gase Abschlussbericht

The objective of 'bubbles of technological important gases in glass melts' is to determine the diffusion coefficients and solubilities of gases in glass melts. These basic data are necessary to describe the behaviour of the small bubbles, occuring during technical glass melting, by nonempirical methods using a mathematical model. In 1992 a helium diffusion experiment was carried out during the IML-1 mission, in 1993 on the D2 mission a second one took place with oxygen. Taking also into consideration the first helium microgravity experiment of 1984 the temperature dependence at 936 to 1186 C of the helium diffusion in a soda-lime-silica melt can be described by: D = 3,80.10"-"3exp(-47,6kj/mol / RT). An apparatus was constructed to measure the solubility of oxygen in a soda-lime-silica melt. 1g-bubble experiments with oxygen yielded diffusion coefficients in the order of 2.10"-"6cm"2/s. These values correspond pretty good with diffusion coefficients published in literature. This report documents the sample preparation, the preliminary work for the microgravity experiments, both microgravity experiments, the construction of the apparatus for measuring solubilities, 1g-diffusion experiments with oxygen, the results of the 1992 helium microgravity experiment and of the ground based experiments with oxygen. (orig.)SIGLEAvailable from TIB Hannover: F95B2206+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Reaktionskinetik in Glasschmelzen Abschlussbericht

Available from TIB Hannover: F98B2131+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Optimierung mechanischer Eigenschaften von Chalkogenid-Glaskeramiken im Hinblick auf ihre technische Anwendung als optische Komponenten fuer den IR-Bereich Abschlussbericht

Available from TIB Hannover: F95B122+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Herstellung homogener Schwermetallfluoridglaeser Abschlussbericht

A part of the Russian space mission FOTON10 in February 1995 was SKAT-C1A. This experiment on the unmanned satellite contained doped and undoped glasses from the ZrF_4-BaF_2-LaF_3-AlF_3-NaF-InF_3 (ZBLAN) system. A total of six glass samples were melted in a modified Konstanta-02MG oven (Model 1) at a temperature of 800 C, held for 40 min and cooled at a rate of 15 K/min to room temperature. Using atomic force microscopy measurements, the rms roughness values and the micro structure development in the bulk and the boundary layer at the crucible wall were observed. The bulk is always more homogeneous, has a noticeably lower rms roughness value and a finer micro structure than glass that was in contact with the crucible wall. Although thermal treatment with different hold times coarsens the entire microstructure, the differences are still recognizable. Comparing the results under 1g conditions with those under #mu#g conditions demonstrates the influence of reduced convection. It could be shown that the boundary layer provides nucleation sites and that the heterogeneous nucleation is superimposed on the homogeneous nucleation. (orig.)SIGLEAvailable from TIB Hannover: F97B438+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA) GmbH, Bonn (Germany)DEGerman

Homogenitaet von Glaesern Abschlussbericht

SIGLEAvailable from TIB Hannover: F97B43 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman