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The International Workshop on "Measuring Techniques in Liquid Metal Flows" (MTLM Workshop) was organised in frame of the Dresden "Innovationskolleg Magnetofluiddynamik". The subject of the MTLM Workshop was limited to methods to determine physical flow quantities such as velocity, pressure, void fraction, inclusion properties, crystallisation fronts etc. The present proceedings contain abstracts and viewgraphs of the oral presentations. During the last decades numerical simulations have become an important tool in industry and research to study the structure of flows and the properties of heat and mass transfer. However, in case of liquid metal flows there exists a significant problem to validate the codes with experimental data due to the lack of available measuring techniques. Due to the material properties (opaque, hot, chemical aggressive) the measurement of flow quantities is much more delicate in liquid metals compared to ordinary water flows. The generalisation of results obtained by means of water models to real liquid metal flows has often to be considered as difficult due to the problems to meet the actual values of non-dimensional flow parameters (Re, Pr, Gr, Ha, etc.). Moreover, a strong need has to be noted to make measuring techniques available to monitor and to control flow processes in real industrial facilities.

The International Workshop on "Measuring Techniques in Liquid Metal Flows" (MTLM Workshop) was organised in frame of the Dresden "Innovationskolleg Magnetofluiddynamik". The subject of the MTLM Workshop was limited to methods to determine physical flow quantities such as velocity, pressure, void fraction, inclusion properties, crystallisation fronts etc. The present proceedings contain abstracts and viewgraphs of the oral presentations. During the last decades numerical simulations have become an important tool in industry and research to study the structure of flows and the properties of heat and mass transfer. However, in case of liquid metal flows there exists a significant problem to validate the codes with experimental data due to the lack of available measuring techniques. Due to the material properties (opaque, hot, chemical aggressive) the measurement of flow quantities is much more delicate in liquid metals compared to ordinary water flows. The generalisation of results obtained by means of water models to real liquid metal flows has often to be considered as difficult due to the problems to meet the actual values of non-dimensional flow parameters (Re, Pr, Gr, Ha, etc.). Moreover, a strong need has to be noted to make measuring techniques available to monitor and to control flow processes in real industrial facilities.

<p> Phase equilibrium relations were determined in the system NaAlSiO8-NaAlSiO4-H2O on a P-T projection in the P-T range 0.5-10Kb and 150°-900°C, and on three isobaric (2Kb, 5.15Kb and 7. 32Kb) T-X projections. The T-X stability field of analcite determined in this study has a relatively large distorted pentagonal shape. The petrogenetic problem of analcite is fully discussed. On the composition join NaAlSiO4-H2O, the phase relation is not binary for the transition: nepheline hydrate I = nepheline + H2O; there exists a narrow three-phase zone for the transition. The true P-T curve was determined in terms of a ternary univariant reaction: nepheline hydrate I+ analcite = nepheline + H2O. Another univariant reaction (zeolite species P. = analcite + nepheline hydrate I+ H2O) was found at 2Kb/215°C and 5.15Kb/235°C and determined on a P-T projection. In the system NaAlSi3O8-SiO2-H2O, albite contains a maximum of about 5 Wt.% silica in solid solution at 5.15Kb/670°C.</p> <p> The equilibrium compositions of various univariant phases were determined essentially by phase boundary-location on several isobaric T-X projections. Three singular points were determined: two of them are approximately located at 0.8Kb/390°C and 9.4Kb/475°C on a univariant curve (N-h I+ Anl =Ne+ H2O). The other one is approximately located at 6Kb/655°C on the (Ab) univariant curve.</p> </p> A simple method for determining H2O-solubility in melts was developed and applied to the study of the system NaAlSi3O8-NaAlSiO4-H2O. Using this method, solubility data are simply obtained as by-products of the experimental runs made for the investigation of the phase equilibria. The amount of water required to make an H2O-saturated melt (from the total amount of water in the original charge) is taken as the dissolved water in the melt; the solubility value is corrected by determining the amount of moisture originally absorbed in the starting powder. The method is generally applicable to the determination of H2O-content in any hydrous phase. The H2O-solubility in a melt is not too sensitive to a variation in anhydrous composition of the melt (~ 6±1 Wt.% H2O at 2Kb and ~11±1 Wt.% H2O at ~5Kb in the range of compositions Ab100Ne0-An40Ne60). H2O-solubility in the (Anl) and (Ne) univariant melts was determined up to l0Kb (H2O contents: 4.7 Wt.%/1.1Kb and 850°C, 6.2 Wt. %/2Kb and 804°C, 10.8 Wt. %/5.2Kb and 672°C, l2.2 Wt.% /6.6Kb and 655°C, 13.2 Wt. %/7.3Kb and 652°C and 14(?) Wt.% /10Kb and 632°C ). The origin of water bubbles in quenched hydrous glasses is essentially attributed to the exsolution of the dissolved water in melts upon quenching.</p> <p> The sequence of P-T curves around a quaternary invariant point (~5Kb and ~635°C) in the system NaAlSiO4-KAlSiO4-SiO2-H2O was theoretically discussed. The most probable four P-T diagram types are proposed, one of which is expected to be the real one.</p> <p> Phase relations in the system NaAlSi3O3-NaAlSiO4-H2O are theoretically discussed up to ~15Kb. The discussion is largely based on the equilibrium compositions of invariant phases approximately estimated from data presented in Parts 1 and 2. Six invariant points are examined. Two of them, I5 and I6, have been predicted to occur; I5 is inferred to be located at ~13Kb/~500°C where five phases Jd, N-h I, Anl, Ne and V coexist, and I6 to be located at ~0.5Kb/-375°C where Ab, Ne, Anl, N-h I and V coexist. The phase relations around the other four are partly modified. The maximum P-T stability field of analcite is deduced. The stability field of solidus analcite is extremely large whereas that of liquidus analcite is very much limited. The maximum stability field of liquidus analcite is a small triangular area defined by three invariant points I1 (5.15Kb/657°C), I2 (11Kb/650°C) and I4 (12.5Kb/575°C).</p> / Thesis / Doctor of Philosophy (PhD)

No / The finite element simulation of a selection of two- and three-dimensional flow problems is presented, based upon the use of four different constitutive models for polymer melts (Oldroyd-B, Rolie-Poly, Pom-Pom and XPP). The mathematical and computational models are first introduced, before their application to a range of visco-elastic flows is described. Results demonstrate that the finite element models used here are able to re-produce predictions made by other published numerical simulations and, significantly, by carefully conducted physical experiments using a commercial-grade polystyrene melt in a three-dimensional contraction geometry. The paper also presents a systematic comparison and evaluation of the differences between two- and three-dimensional simulations of two different flow regimes: flow of an Oldroyd-B fluid around a cylinder and flow of a Rolie-Poly fluid into the contraction geometry. This comparison allows new observations to be made concerning the relatively poor quality of two-dimensional simulations for flows in even quite deep channels.

Two magmatic systems were investigated using different petrological tools: 1) Origin of Ponza trachyte was studied combining data from MI with trends predicted by thermodynamic modeling. MI data were compared with known phase relations in the ternary feldspar and anorthite-diopside-albite systems to constrain the parameters used in the modeling. MI data are consistent with melt evolution from a basaltic parent via a fractional crystallization mainly of pyroxene and feldspars. These data and the results from the modeling, suggest a genetic link between the Ponza trachyte and coeval alkali olivine basalts on the nearby Ventotene Island. 2) We evaluated the range of magmatic temperatures within the crystallization interval for a basanite with different olivine-spinel geothermometers. While olivine spinel pair records the evolution of the basanite during crystallization, low temperatures calculated with the geothermometers are unrealistic. This is likely due to the presence of significant amounts of Ti in our magmatic spinels. Indeed Ti is not taken into account in the geothermometers. We tested the possibility of accounting for the presence and effects of Ti using a linear correction for the Fe+2 content in our spinels. While this generated more realistic temperatures at the low end of the range, it also increased the dispersion in the data, suggesting that spinel behavior is more complex and that the presence of Ti affects content and site occupancy of other elements as well. / Ph. D.

The paper describes the Rossendorf Beamline (ROBL) built by the Forschungszentrum Rossendorf at the ESRF. ROBL comprises two different and independently operating experimental stations: a radiochemistry laboratory for X-ray absorption spectroscopy of non-sealed radioactive samples and a general purpose materials research station for X-ray diffraction and reflectometry mainly of thin films and interfaces modified by ion beam techniques. The radiochemistry set-up is worldwide an unique installation at a modern synchrotron radiation source.

In dieser Studie wurde der alleinige und gemeinsame Einfluss von 1.6 bis 14.5 mol% Wasser, 1.1 bis 18.3 mol% Fluor (F) und 0.5 bis 1.4 mol% Chlor (Cl) auf die Struktur und Viskosität von peralkalinen und peraluminösen Na2O CaO Al2O3 SiO2 Gläsern und Schmelzen mit ~ 66 mol% SiO2 (auf volatilfreier Basis) untersucht. Die Zusammensetzung der peralkalinen Proben entspricht einem Modellsystem für Phonolithschmelzen. Die wasserfreien Proben wurden in 1 atm Öfen aus Oxid und Karbonatverbindungen sowie Halogeniden hergestellt. Die wasserhaltigen peralkalinen Proben wurden in einer innenbeheizten Gasdruckanlage und die wasserhaltigen peraluminösen Proben in einer Stempelzylinderpresse hergestellt. Die Viskosität der Proben wurde mit der Mikropenetrationstechnik (108.5 1013 Pa s) und der „parallel plate“ Methode (105.5 Pa s 109 Pa s) gemessen. Die Struktur der Gläser wurde mittels „magic angle spinning“ (MAS) Kernspinresonanzspektroskopie (NMR) anhand der Nuklide 19F, 23Na, 27Al, 29Si and 35Cl analysiert. Fluor und Wasser allein oder in Kombination verringern die Viskosität der Schmelzen, wobei der Effekt von Wasser stärker ist als der von F. Beide Volatile verringern die Viskosität von peraluminösen Schmelzen stärker als in den peralkalinen Schmelzen. Für die peralkalinen Schmelzen wurde eine Verringerung der Viskosität durch F bis zu einer Konzentration von 1.9 mol% F festgestellt, jedoch für eine Konzentration von 6.2 mol% F wurde keine weitere Verringerung der Viskosität festgestellt. In den peraluminösen Schmelzen hingegen wurde bis zu einer Konzentration von 18.3 mol% F ein stetiger Abfall der Viskosität mit zunehmendem Fluorgehalt beobachtet. Der gemeinsame Einfluss von F und Wasser ist auf Grund ihrer jeweiligen Einzeleffekte geringer als angenommen, was zeigt, dass die Effekte von F und Wasser auf die Viskosität nicht unabhängig voneinander sind. Der zusammensetzungs und konzentrationsabhängige Effekt von F auf die Viskosität der Schmelzen stimmt mit Unterschieden im Einbaumechanismus von F überein. 19F MAS NMR Spektren zeigen, dass in den peralkalinen Gläsern F sowohl in „salzartigen“ F Ca(n) und F Na(n) als auch in nicht brückenbildenden Si F Na(n), Al F Ca(n), Al F Na(n) und brückenbildenden Al F Al Umgebungen vorkommt („n“ bedeutet, dass die Anzahl der Atome unklar oder variabel ist). F Ca(n) ist die am häufigsten vorkommende Umgebung, obwohl Ca das am wenigsten häufige Kation in den Proben ist. In den peraluminösen Gläsern existiert F nur in Si F und Al F Umgebungen, wobei Al F Na(n) die am häufigsten vorkommende Umgebung ist. Die Bildung von salzartigen F Ca(n) und F Na(n) Umgebungen sollte zu einem Anstieg der Viskosität durch eine Verringerung der netzwerkmodifizierenden Kationen führen. Die Bildung von Si F und Al F Umgebungen sollte die Viskosität entweder auf Grund einer Reduzierung von brückenbildenden Sauerstoffen durch nicht brückenbildende F oder durch einen Austausch von brückenbildenden Sauerstoffen durch brückenbildende F, welche eine niedrigere Bindungsstärke haben, verringern. Daraus lässt sich schließen, dass F die Viskosität in peralkalinen Schmelzen weniger stark verringert als in peraluminösen Schmelzen, weil F in den peralkalinen Schmelzen in Umgebungen existiert, welche die Viskosität erhöhen oder erniedrigen können, während F in den peraluminösen Schmelzen nur in Umgebungen existiert, welche die Viskosität verringern. Der konzentrationsabhängige Einfluss von F auf die Viskosität in den peralkalinen Schmelzen scheint in Zusammenhang mit einer Änderung in der Fluorspeziation zu stehen: Der relative Anteil von F Ca(n) Umgebungen, von denen anzunehmen ist, dass sie die Viskosität erhöhen, steigt von 42 auf 53% bei einem Anstieg im F Gehalt von 1.2 auf 6.2 mol% F. Veränderungen in der Fluorspeziation scheinen ebenfalls verantwortlich dafür zu sein, dass der Effekt von F und Wasser in Kombination geringer ist als erwartet. 19F MAS NMR Spektren von fluor und wasserhaltigen Proben zeigen, dass der relative Anteil von Al F Umgebungen, von denen anzunehmen ist, dass sie die Viskosität verringern, mit zunehmendem Wassergehalt abnimmt und dass im Gegenzug der relative Anteil von F Ca(n) Umgebungen zunimmt. Mit IR Spektroskopie wurde in den peralkalinen Proben kein Unterschied im OH/H2O Verhältnis bei gleichem Gesamtwassergehalt durch die Präsenz von F beobachtet. Im Gegensatz dazu gibt es starke Hinweise darauf, dass F in den peraluminösen Proben das OH/H2O Verhältnis bei gleichem Gesamtwassergehalt verringert, was erklären würde, weshalb F und Wasser in Kombination die Viskosität weniger verringern als von ihren Einzeleffekten zu erwarten wäre. Der Einfluss von Cl auf die Viskosität und Struktur der Schmelzen und Gläser ist sehr unterschiedlich verglichen mit F. Cl erhöht die Viskosität in den peralkalinen Schmelzen und verringert die Viskosität in den peraluminösen Schmelzen. Viskositätsmessungen von wasserhaltigen, chlorfreien und chlorhaltigen peralkalinen Schmelzen zeigen, dass der Effekt von Cl auf die Viskosität nicht durch die Präsenz von Wasser beeinflusst wird. Das beobachtete 35Cl NMR Signal zeigt, dass sowohl in den peralkalinen als auch in den peraluminösen Gläsern Cl in Na Ca Cl Umgebungen mit einem hohen Na Anteil existiert, was auf Grund des Ca/Na Verhältnisses von 1/5 zu erwarten war. Die Cl Umgebung in den peralkalinen und peraluminösen Gläsern ist ähnlich, jedoch beinhaltet die Cl Umgebung in den peraluminösen Gläsern mehr Ca. In den 35Cl MAS NMR Spektren wurde im Vergleich zu einem Natriumsilikatglas nur ein Teil des 35Cl NMR Signals der peralkalinen und der peraluminösen Proben beobachtet. Das fehlende Signal deutet darauf hin, dass ein Teil der Cl Atome in verzerrten oder ungeordneten Umgebungen existiert, welche eine Signalbreite haben, die zu groß ist, um mit den verwendeten NMR Spektroskopie Methoden gemessen werden zu können. Der Anstieg der Viskosität durch Cl in den peralkalinen Schmelzen kann dadurch erklärt werden, dass Cl die Anzahl der netzwerkmodifizierenden Kationen reduziert, während mehrere Möglichkeiten zur Diskussion stehen, weshalb Cl die Viskosität in peraluminösen Schmelzen verringert. Die Effekte von F und Cl auf die Viskosität sind unabhängig voneinander und summieren sich auf. Es wurde mit NMR Spektroskopie kein Hinweis dafür gefunden, dass F einen Einfluss auf den Einbaumechanismus von Cl hat.

The kinetics of incongruent reduction between sapphire and oxygen-controlled Mg-Al melts was studied by measuring spinel-layer thickness, sample-weight change and sample-thickness change as a function of time at various temperatures. To eliminate the crucible contamination caused by impurities in commercial MgO crucibles, self-made high-purity MgO crucibles were achieved by gelcasting method, which is an attractive ceramic-forming technique for making high-purity ceramic parts. The oxygen-controlled alloys were obtained by the three-phase-equilibrium experiments at various temperatures. To avoid MgO formation, the oxygen-controlled alloys prepared at relatively lower temperatures were used for incongruent reaction at relatively higher temperatures. That is to say, the oxygen-controlled alloys prepared at 900°C, 1000°C, and 1100°C were used for spinel formation at 1000°C, 1100°C, and 1200°C, respectively. The experiments were conducted in a vertical furnace, and sapphire wafers were hung vertically in high-purity MgO crucibles so that the natural convection induced by the density change in the melt could be investigated. Experimental results obtained at 1000°C, 1100°C, and 1200°C showed that the spinel layer thickness on two kinds of sapphire wafers, namely {0001} and , followed orientation-independent parabolic kinetics, indicating the diffusion in spinel was one of the rate-limiting steps. In addition, the spinel layer thickness was not a function of position. The results of sample-thickness- change measurements also indicated that the effect of natural convection could be neglected. XPS, XRD, and TEM were also employed to characterize some samples in this study. Based on a simple model where the diffusion in spinel was the only rate-limiting step, the governing partial differential equations for diffusion and fluid dynamics were solved by the finite element method. The calculated theoretical parabolic constants at various temperatures were compared with these experimental results, and a good agreement was obtained. Some preliminary studies were also made on the morphologies of spinel particles at the nucleation stage. It was found that the triangular {111} faces of spinel particles were parallel to the surface of {0001} sapphire substrate. The product shape was consistent with the tetrahedron composed of {111} faces. The morphology of spinel particles on a sapphire substrate was more complicated in that the triangular {111} faces of spinel had to be inclined at a certain angle to the substrate in order to maintain the orientation relationship.

Orientadores: Carlos Roberto de Souza Filho, Cristiano de Carvalho Lana / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-15T00:06:50Z (GMT). No. of bitstreams: 1 Machado_RogerioAmaro_M.pdf: 6890579 bytes, checksum: 4c4acd981fd71f6ac0d9f9db67e88ee3 (MD5) Previous issue date: 2009 / Resumo: Fundidos de impacto ricos em clastos e brechas de impacto pseudotaquilíticas são encontrados nos embasamentos cristalinos de muitas estruturas de impacto ao redor do mundo. São formados sob condições extremas de temperatura e pressão, geradas na colisão de um meteorito e também registram importantes pistas sobre os processos associados aos impactos em hipervelocidade e evolução planetária. Este trabalho forneceu importantes pistas sobre a produção, extração e cristalização das rochas fundidas na estrutura de impacto de Araguainha, no Brasil central. Os fundidos de impacto localizados no soerguimento central da estrutura são caracterizados por uma matriz de composição granítica rica em álcalis, envolvendo minerais e fragmentos de rochas derivados estritamente do granito impactado. Apesar da natureza mista das rochas impactadas neste evento (rochas sedimentares e graníticas) os dados de rocha total para os elementos maiores e menores (incluindo elementos do grupo da platina) indicam que o fundido foi gerado localmente, sem contato com a sequência sedimentar ou o bólido impactante. Similar a brechas pseudotaquilíticas, as rochas fundidas em Araguainha formaram-se isoladas, provavelmente abaixo da zona de fusão por impacto. A análise multispectral dos mapas químicos obtidos por raios-X e de química mineral do embasamento granítico e dos fundidos de impacto e seus clastos indicaram que o fundido originou-se por fusão seletiva do plagioclásio, feldspato potássico e biotita. O plagioclásio e o feldspato potássico fundiram-se discretamente e de forma isolada, produzindo domínios no fundido que combinam estequiometricamente com estes minerais. O fundido derivado da biotita mostrou maior mobilidade e misturou-se mais facilmente com os outros fundidos. Nenhuma evidência de fusão por fricção foi encontrada. Os fundidos em sua fase inicial migraram por uma densa rede de micro fraturas antes de serem incorporados pelos principais bolsões de rocha fundida. Evidências encontradas nesse trabalho indicam que fundidos produzidos localmente, como as brechas pseudotaquilíticas, são produzidos por fusão seletiva de minerais dentro da rocha impactada. Associou-se, desta forma, a fusão dos minerais com as temperaturas de pós-choques, que podem ter aumentado para além do ponto de fusão de feldspatos e biotita. / Abstract: Clast-bearing impact melts and pseudotachylitic breccias are found in crystalline target rocks of many impact structures around the world. They are formed under the extreme pressure-temperature conditions that accompany the meteorite collision, and record important clues to the process associated with hypervelocity impacts and planetary evolution. Here we provide important insights into the generation, extraction and crystallization of clast-laden melt rocks from the Araguainha impact structure in central Brazil. The melt bodies in the central uplift are characterized by an alkalai-rich granitic matrix embedding mineral and rock fragments derived strictly from granite target rocks. Despite the mixed nature of the target rocks - sedimentary and granitic rocks -bulk-rock major and trace element (including platinum group elements) data indicate that the granitic melts were generated locally, without direct contact with the sedimentary sequence or the projectile. Similarly to pseudotachylitic breccias, the Araguainha melt rocks formed in isolation, probably below the zone of impact melting. Multispectral analysis of X-ray maps and mineral chemistry from clasts and granitic targets indicate that the melt originated by selective melting of plagioclase, K-feldspar and biotite. Plagioclase and K-feldspar melted discretely and in isolation, producing domains in the melt which closely match the stoichiometry of these minerals. The biotite derived melt component appears to have been more mobile and mixed more readily with the other melts. No textural evidence for friction melting has been found. The initial melt phases have migrated through a dense network of microfractures before being assembled into main melt bodies. Evidence provided here indicates that locally produced melt bodies such as pseudotachylitic breccias, are produced by selective melting of minerals within the target rocks. We relate the melting of the minerals to the post-shock temperatures that may have risen beyond the melting point of biotite and feldspars. / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências