TY - CONF A1 - Müller, Ralf T1 - Untersuchungen zur Sinterfahigkeit von Glaspulvern T2 - Physikalisches Kolloquium des Lehrnstuhls für Anorganische Chemie der Brandenburgischen Universität Cottbus CY - Cottbus, Germany DA - 2002-06-11 PY - 2002 AN - OPUS4-6205 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Eberstein, Markus A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Rabe, Torsten A1 - Schiller, Wolfgang Arno A1 - Thiel, A. A1 - Deubener, J. T1 - Kinetic Modeling of LTCC Shrinkage: Effect of Alumina Content N2 - We studied sintering of LTCC-type glass matrix composites (GMCs) consisting of small glass and alumina particles of equal size. Primarily, crystals act as rigid inclusions, decelerating the densification rate. In later stages, they also dissolve, partially increasing the viscosity. Release of alumina finally induces crystallization of alumosilicates, which enables post-firing stability. To study both effects, two model GMCs were prepared: an α-Al2O3 + barium alumoborosilicate glass (BABS)–GMC, which shows neither significant dissolution nor crystallization, and an α-Al2O3 + calcium alumoborosilicate glass (CABS)–GMC, which dissolves readily and promotes crystallization. The kinetics of shrinkage for both GMC were modeled by utilizing Frenkel theory for the early stage and Mackenzie–Shuttleworth theory for the late stage, assuming that sintering is superimposed by the weighted contributions of triparticle glass–crystal clusters, their random occurrence (ideal mixing), and a shrinkage rate controlled by the GMC effective viscosity. In agreement with modeling, the experimental results showed that the shrinkage rate of BABS–GMC decreases progressively for crystal volume fractions Φ > 0.15. The attainable shrinkage is reduced by up to 8% for Φ = 0.45. For the CABS–GMC with Φ = 0.25, a reduction of Φ to 0.20 was evident due to partial α-Al2O3 dissolution. This effect was found able to increase the sintering temperature by ~50–60 K. KW - LTCC KW - Glas Matrix Composites KW - Inclusions KW - Sintering Kinetics KW - Modeling PY - 2007 SN - 1551-4897 VL - 4 IS - 4 SP - 173 EP - 180 CY - Washington, DC AN - OPUS4-16506 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Eberstein, Markus A1 - Deubener, J. A1 - Thiel, A. A1 - Schiller, Wolfgang Arno ED - J.G. Heinrich, ED - C.G. Aneziris, T1 - Effect of dispersed Al2O3 particles on sintering of glass matrix composites T2 - 10th International Conference of the European Ceramic Society CY - Berlin DA - 2007-06-17 KW - LTCC KW - Glass matrix composites KW - Inclusions KW - Sintering kinetics KW - Modelling PY - 2007 SN - 3-87264-022-4 SP - 290 EP - 295 PB - Göller CY - Baden-Baden AN - OPUS4-17445 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Deubener, J. T1 - Crystallization in multicomponent systems. Glasses for LTCC T2 - Meeting 2008 des TC7 der ICG am Rande der 9th ESG Conf. with the Annual Meeting of the ICG Glass-The challenge for the 21st century CY - Trencín, Slovakia DA - 2008-06-22 PY - 2008 AN - OPUS4-18106 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Ralf A1 - Reinsch, Stefan A1 - Eberstein, Markus A1 - Deubener, J. A1 - Thiel, A. A1 - Schiller, Wolfgang Arno T1 - Effects of dispersed Al2O3 particles on sintering of LTCC N2 - The sintering of Low Temperature Co-fired Ceramics prepared from alumoborosilicate glass- and Al2O3 powders of similar small particle size was studied by dilatometry, heating microscopy, microstructure analysis, glass- and effective viscosity measurements. The steric effect of Al3O3 inclusions was studied using a gnon-reactiveh model composite. With increasing Al3O3 volume fraction (Φ ≤ 0.45), sintering decelerates and its final stage shifts to higher temperature. The attainable shrinkage is reduced as Al2O3 particle clusters bearing residual pores become more frequent. The kinetics of sintering could be described formally superposing the weighed contributions of differentially sized and randomly composed glass-crystal particle clusters and assuming a sintering rate controlled by the effective matrix viscosity, which increases with Φ and with progressive wetting of Al2O3 particles during densification. The "reactive" model composite shows significant dissolution of Al2O3 into the glass, which has two opposed effects on sintering: reducing Φ and increasing glass viscosity. For the present case (Φ = 0.25), the latter effect dominates and sintering is retarded by Al2O3 dissolution. Crystallization of wollastonite starts after full densification. Dissolution of Al2O3 was found to promote the subsequent growth of anorthite. KW - LTCC KW - Glass matrix composites KW - Al2O3-inclusions KW - Sintering kinetics PY - 2005 SN - 1022-6680 SN - 1662-8985 VL - 39-40 SP - 375 EP - 380 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-18441 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zietka, S. A1 - Deubener, J. A1 - Behrens, H. A1 - Müller, Ralf T1 - Glass transition and viscosity of hydrated silica glasses N2 - The viscosity of silica glasses with different water contents was measured by penetration of sapphire microspheres in the range from 1012-1014·7 Pas at ambient pressure. Commercial silica glasses were used together with hydrous silica glasses, which were prepared by melting glass powder plus water in an internally heated pressure vessel at 2-3 kbar and 1350-1450°C. The temperature dependence of the viscosity of silica glasses with total water contents Cw of 5·4×10-4, 7·0×10-4, 1·00×10-2, and 1·55×10-2(Cw in mass fractions) can be described by Arrhenius equations. From the results, the linear dependence of the T12 isokom (K) with the logarithm of the water content was determined as T12=192-409 logCw. The analysis of the compositional dependence of the T12 isokom in the H2O-Na2O-SiO2 system reveals a temperature depression of up to 200 K for mixed water- and sodium-bearing glasses compared to H2O-SiO2 and Na2O-SiO2 glasses with same molar silica content. From these findings we conclude that protons may contribute significantly to the mixed alkali effect in glasses. KW - Wassergehalt KW - Silicatgläser KW - Viskosität PY - 2007 SN - 1753-3562 SN - 0017-1050 SN - 0031-9090 SN - 1750-6697 VL - 48 IS - 6 SP - 380 EP - 387 PB - Society of Glass Technology CY - Sheffield AN - OPUS4-18396 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Nascimento, M.L.F. A1 - Müller, Ralf A1 - Zanotto, E. D. T1 - Crystal growth kinetics in cordierite and diopside glasses in wide temperature ranges N2 - We measured and collected literature data for the crystal growth rate, u(T), of µ-cordierite (2MgO · 2Al2O3 · 5SiO2) and diopside (CaO · MgO · 2SiO2) in their isochemical glass forming melts. The data cover exceptionally wide temperature ranges, i.e. 800–1350 °C for cordierite and 750–1378 °C for diopside. The maximum of u(T) occurs at about 1250 °C for both systems. A smooth shoulder is observed around 970 °C for µ-cordierite. Based on measured and collected viscosity data, we fitted u(T) using standard crystal growth models. For diopside, the experimental u(T) fits well to the 2D surface nucleation model and also to the screw dislocation growth mechanism. However, the screw dislocation model yields parameters of more significant physical meaning. For cordierite, these two models also describe the experimental growth rates. However, the best fittings of u(T) including the observed shoulder, were attained for a combined mechanism, assuming that the melt/crystal interface growing from screw dislocations is additionally roughened by superimposed 2D surface nucleation at large undercoolings, starting at a temperature around the shoulder. The good fittings indicate that viscosity can be used to assess the transport mechanism that determines crystal growth in these two systems, from the melting point Tm down to about Tg, with no sign of a breakdown of the Stokes–Einstein/Eyring equation. KW - Crystal growth KW - Oxide glasses KW - Silicates KW - Kristallwachstumsgeschwindigkeit KW - Kinetik KW - Silikatgläser PY - 2008 DO - https://doi.org/10.1016/j.jnoncrysol.2008.09.007 SN - 0022-3093 VL - 354 IS - 52-54 SP - 5386 EP - 5394 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-18383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Eichelbaum, M. A1 - Rademann, K. A1 - Müller, Ralf A1 - Radtke, Martin A1 - Riesemeier, Heinrich A1 - Görner, Wolf T1 - Vom Atom zum Nanodraht: Kontrolliertes Wachstum von Edelmetall-Nanokristalliten in Kalk-Natron-Silikatglas T2 - 79. Glastechnische Tagung CY - Würzburg, Deutschland DA - 2005-05-23 KW - Glas KW - Metallnanocluster KW - Optische Eigenschaften PY - 2005 SN - 3-921089-43-3 SP - 15 Seiten PB - Deutsche Glastechnische Gesellschaft CY - Offenbach AN - OPUS4-7558 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Müller, Ralf A1 - Eberstein, Markus A1 - Reinsch, Stefan A1 - Schiller, Wolfgang Arno A1 - Deubener, J. A1 - Thiel, A. T1 - Effect of rigid inclusions on sintering of low temperature co-fired ceramics KW - Sintering KW - Glass Matrix Composites KW - Rigid Inclusion KW - Effective Viscosity KW - Kinetic Modelling KW - LTCC PY - 2007 SN - 1753-3562 SN - 0017-1050 SN - 0031-9090 SN - 1750-6697 VL - 48 IS - 4 SP - 259 EP - 266 PB - Society of Glass Technology CY - Sheffield AN - OPUS4-16211 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Thiel, A. A1 - Eberstein, Markus A1 - Müller, Ralf A1 - Deubener, J. T1 - Viskosität von Glasmatrix-Kompositen mit partiell löslicher kristalliner Dispersphase T2 - 81. Glastechnische Tagung und 4. DGG-Symposium "Novel Optical Technologies" CY - Aachen, Deutschland DA - 2007-06-04 KW - Glasmatrixkomposite KW - Lösung KW - Sintern PY - 2007 SN - 978-3-921089-52-1 IS - CD-ROM SP - 1 EP - 8 PB - Deutsche Glastechnische Gesellschaft CY - Offenbach AN - OPUS4-16212 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Thiel, A. A1 - Eberstein, Markus A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Deubener, J. A1 - Schiller, Wolfgang Arno T1 - Viskosität von sinternden Glas/Kristallphasen-Kompositen T2 - 80. Glastechnische Tagung CY - Dresden, Deutschland DA - 2006-06-12 PY - 2006 SN - 3-921089-46-8 SP - 1(?) EP - 3(?) PB - Verl. d. Dt. Glastechn. Ges. CY - Offenbach AN - OPUS4-14045 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Eberstein, Markus A1 - Thiel, A. A1 - Reinsch, Stefan A1 - Müller, Ralf A1 - Deubener, J. A1 - Schiller, Wolfgang Arno T1 - Sinterkinetik von Glasmatrix-Kompositen mit reaktiver Dispersphase T2 - 80. Glastechnische Tagung CY - Dresden, Deutschland DA - 2006-06-12 PY - 2006 SN - 3-921089-46-8 SP - 4 Seiten PB - Verl. d. Dt. Glastechn. Ges. CY - Offenbach AN - OPUS4-14046 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf T1 - Viscosity and degassing of hydrous silicate glasses T2 - 80. Glastechnische Tagung und 8th Int. Conference "Advances in Fusion and Processing of Glass" CY - Dresden, Germany DA - 2006-06-12 PY - 2006 AN - OPUS4-14259 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Reinsch, Stefan T1 - DMTA measurements on PTR glasses T2 - TC7, International Commission on Glass CY - Jena, Germany DA - 2006-07-23 PY - 2006 AN - OPUS4-14243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Müller, Ralf A1 - Eberstein, Markus A1 - Thiel, A. A1 - Reinsch, Stefan A1 - Deubener, J. A1 - Schiller, Wolfgang Arno T1 - Sintering of glass matrix composites for LTCC applications T2 - 8th International Symposium Crystallization, American Ceramic Society CY - Jackson, WY, USA DA - 2006-09-24 PY - 2006 AN - OPUS4-14245 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Reinsch, Stefan A1 - Meng, S. A1 - Eberstein, Markus A1 - Thiel, A. A1 - Müller, Ralf A1 - Deubener, J. T1 - Partial Solution of Dispersed alpha-Al2O3-Particles in Alumoborosilicate Glass T2 - 81. Glastechnische Tagung CY - Aachen, Deutschland DA - 2007-06-04 KW - Glasmatrixkomposite KW - Lösung KW - Sintern PY - 2007 SN - 978-3-921089-52-1 IS - CD-ROM SP - 1 EP - 5 PB - Deutsche Glastechnische Gesellschaft CY - Offenbach AN - OPUS4-16108 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 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 - TY - JOUR A1 - Schiller, Wolfgang Arno A1 - Müller, Ralf A1 - Rabe, Torsten ED - R. Clasen, ED - M. Herrmann, ED - Roosen, A. T1 - Über das Sintern von LTCC KW - LTCC KW - Komposite KW - Multilayer-Technik KW - Sintern KW - Simulation PY - 2007 SN - 0177-6983 VL - 21 IS - 1 SP - 41 EP - 46 PB - Göller CY - Baden-Baden AN - OPUS4-16428 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reinsch, Stefan A1 - Gaber, Martin A1 - Müller, Ralf A1 - Schiller, Wolfgang Arno T1 - Rate controlled debindering of glass ceramic composites N2 - Green compacts of ceramics, glass ceramic composites and sinter glass ceramics contain different amounts of organic materials added as pressing aids or binders. Before sintering, these organics have to burn out completely. In oxidising atmospheres, the debindering process is mostly exothermic and therefore difficult to control. This uncontrolled heat production due to locally enhanced debindering and respective gas release may cause damages in the green compact microstructure. Therefore, debindering is usually operated with very low heating rates (< 3 K/min) which requires long processing times of many hours. In this paper, we will show that it is possible to reduce the processing time for debindering dramatically by using the decomposition rate of the organic binder, detected by the weight loss of the sample, as a control factor of the furnace. T2 - 9th ESG (European Society of Glass) Conference with the Annual Meeting of the ICG Glass - "The challenge for the 21st century" CY - Trencin, Slovakia DA - 2008-06-22 KW - Debindering KW - Thermo gravimetry KW - Glass ceramic composites PY - 2005 SN - 1022-6680 SN - 1662-8985 VL - 39-40 SP - 583 EP - 586 PB - Trans Tech Publ. CY - Zurich AN - OPUS4-17840 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Deubener, J. A1 - Behrens, H. A1 - Müller, Ralf A1 - Zietka, S. A1 - Reinsch, Stefan T1 - Kinetic fragility of hydrous soda-lime-silica glasses N2 - The effect of hydration on the kinetic fragility of soda-lime-silica glasses was investigated by viscometry in the glass transition range. Water-bearing glasses were prepared from industrial float glass (FG) and a ternary model glass (NCS = 16Na2O 10CaO 74SiO2 in mol%) by bubbling steam through the melt at 1480 °C and up to 7 bar. Additionally, a sodium borosilicate glass (NBS = 16Na2O 10B2O3 74SiO2 in mol%) was hydrated under equal conditions. As detected by infrared spectroscopy water dissolves in the glasses exclusively as OH-groups. The hydration resulted in a total water content CW up to ~ 0.2 wt% for FG, NCS and NBS glasses. Kinetic fragility, expressed by the steepness index m, was determined from the temperature dependence of η at the glass transition. Viscosity data from previous studies on hydrous float glasses (CW > 1 wt%) were surveyed together with literature data on the (H2O)–Na2O–CaO–SiO2, (H2O)–Na2O–SiO2 and (H2O)–SiO2 systems to expand the range of water concentration and bulk composition. We could demonstrate that m decreases for all glasses although water is dissolved as OH and should depolymerize the network. An empirical equation of the general type m = a - b logCW where a, b are fitting parameters, enables m to be predicted, for each glass series as function of the water content CW. The enlarged data base shows that the parameter B of the Arrhenius viscosity-temperature relation decreases much stronger than the isokom temperature at the glass transition. KW - Soda-lime-silica KW - Fragility KW - Viscosity KW - Water in glass PY - 2008 DO - https://doi.org/10.1016/j.jnoncrysol.2008.04.021 SN - 0022-3093 VL - 354 IS - 42-44 SP - 4713 EP - 4718 PB - North-Holland Publ. Co. CY - Amsterdam AN - OPUS4-18187 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -