TY - CONF A1 - Weh, Lothar A1 - Müller, Ralf A1 - Moseler, D. A1 - Heide, G. A1 - Frischat, G. T1 - Topographische Untersuchungen von Glasoberflächen mit Vickers-Eindrücken T2 - Kurzreferate der 74. Glastechnischen Tagung T2 - 74. Glastechnische Tagung CY - Ulm, Deutschland DA - 2000-05-29 PY - 2000 SP - 237 EP - 240 PB - DGG, Dt. Glastechn. Ges. CY - Frankfurt/M. AN - OPUS4-934 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - de Moraes, Flavia A1 - Frischat, G. H. A1 - Heide, G. A1 - Müller, Wolfgang A1 - Müller, Ralf T1 - Korrosions- und Kristallisationsphänomene an der Innenoberfläche von Glasbausteinen T2 - Kurzreferate / 77. Glastechnische Tagung T2 - 77. Glastechnische Tagung CY - Leipzig, Deutschland DA - 2003-05-26 PY - 2003 VL - 77 SP - 71 EP - 74 PB - DGG CY - Offenbach AN - OPUS4-2527 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Leschik, M. A1 - Heide, G. A1 - Frischat, G.H. A1 - Behrens, H. A1 - Wiedenbeck, M. A1 - Wagner, N. A1 - Heide, K. A1 - Geißler, Heinz A1 - Reinholz, Uwe T1 - Determination of H2O and D2O contents in rhyolitic glasses JF - Physics and chemistry of glasses N2 - Five distinct analytical techniques were compared for the quantification of the H2O (0·1-7·4 wt%) and D2O (up to 5·5 wt% D2O) contents in rhyolitic glasses. The hydrogen concentration in obsidians was measured using nuclear reaction analysis (NRA) and converted into H2O concentration. The bulk water content (H2O+D2O) of synthesised glasses was determined using thermal extraction in conjunction with Karl–Fischer titration (KFT). Unextracted H2O was measured by infrared (IR) spectroscopy after remelting the KFT products at high pressure. These well characterised glasses were subsequently used to calibrate secondary ion mass spectrometry (SIMS), infrared and evolved gas analysis (EGA). The calibrations of SIMS for H2O and D2O show a significant matrix effect at H2O and D2O concentrations larger than ~3 mol/l with the relative sensitivity factor (RSF) decreasing with bulk water content. Molar absorption coefficients for the OH stretching vibration band at 3570 cm-1 and the OD stretching vibration band at 2650 cm-1 in the infrared absorption spectra were reinvestigated. In the range 0·1-6 wt% the H2O content of glasses could be reproduced within analytical error using a constant linear molar absorption coefficient. However, it appears that the absorption coefficients for the 3570 cm-1 band as well as for the 2650 cm-1 band both decrease systematically with concentration of dissolved H2O and D2O (epsi3570=80 (±1) - 1·36(±0·23)CH2Ot and epsi2650=61·2(±1) - 2·52(± 0·30)CD2Ot). EGA allows quantification of the H2O content as well as the study of dehydration kinetics. It is shown that H2O is released under vacuum already at room temperature from glasses containing >7 wt% H2O. PY - 2004 UR - http://www.ingentaconnect.com/content/sgt/pcg/2004/00000045/00000004/art00003 SN - 0031-9090 VL - 45 IS - 4 SP - 238 EP - 251 PB - Thornton CY - Sheffield AN - OPUS4-6279 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - de Moraes, Flavia A1 - Müller, Wolfgang A1 - Frischat, G.H. A1 - Müller, Ralf T1 - Corrosion and crystallization at the inner surfaces of glass bricks JF - Journal of non-crystalline solids N2 - Glass bricks are important transparent building materials. They are produced by joining two halves of glass pressings at 600–700 °C. During this production process alkali oxides evaporate and are redeposited at the cooler inner front surfaces of the bricks. This surface layer reacts with H2O and CO2 from the residual brick atmosphere, leading to the formation of an alkali-rich silicate-hydrate layer of ≥50 nm thickness, which could be evidenced leading to a reduced nano-hardness of similar thickness, and from which NaHCO3 crystals can finally grow. Climate chamber experiments (repeated cooling between at -8 and -14 °C and reheating to 0 to 15 °C) resulted in reversible NaHCO3 crystallization and redissolution, presumably influenced by water evaporation or condensation and driven by the NaHCO3 supersaturation of the silicate-hydrate layer. Depending on the time–temperature schedule, different crystal morphologies became visible in this closed system, e.g. isolated spherical crystals, crystals arranged in chains and in double-chains, respectively, which can limit already the transmittance of the glass bricks. When a crack occurs or the brick is opened, the hygroscopic NaHCO3 crystals take up more H2O from the ambient, react irreversibly with the glass surface, finally leading to a total loss of transmittance. KW - Chemical properties KW - Chemical durability KW - Corrosion KW - Crystallization KW - Crystal growth KW - Nucleation KW - Glasses KW - Mass spectroscopy KW - Mechanical properties KW - Hardness KW - Indentation KW - Microindentation KW - Microscopy KW - Optical microscopy KW - Scanning electron microscopy KW - Optical properties KW - Optical spectroscopy KW - Oxide glasses KW - Alkali silicates KW - Soda-lime-silica KW - Surfaces and interfaces PY - 2008 DO - https://doi.org/10.1016/j.jnoncrysol.2007.07.086 SN - 0022-3093 VL - 354 IS - 2-9 SP - 284 EP - 289 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-16433 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -