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1
de, Carvalho Joana Nunes. "The Corrosion of Float Glass." Thesis, University of Surrey, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.518719.
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Saewong, Pakamard. "Erosion of glass and glass-ceramic matrix composites." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300838.
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Lenting, Christoph [Verfasser]. "Glass corrosion : Towards a Unifying Mechanistic Model / Christoph Lenting." Bonn : Universitäts- und Landesbibliothek Bonn, 2019. http://d-nb.info/1201727863/34.
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Lynch, Matthew Earl. "The Effect of Microwaves on Aqueous Corrosion of Glass." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/34187.
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Glass corrodes in aqueous environments. The corrosion process is well-understood for many circumstances involving long periods of time at room temperature as well as processes that involve conventional heating, but the effect of microwave energy on glass corrosion has never been fully investigated. It was suspected that microwaves may alter or accelerate the aqueous corrosion processes that occur in glass which contribute to migration into foods or other materials. Lithium disilicate (Li2O-2SiO2) and commercial soda-lime glass were corroded using both conventional and microwave heating in this study. The results did not clearly show substantial differences in corrosion under the test conditions, but leave open the possibility of an altered mechanism in some circumstances. These findings suggest the need for testing at a lower microwave frequency, specifically 2.45 GHz.Master of Science
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Lynch, Matthew. "The Effect of Microwaves on Aqueous Corrosion of Glass." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34187.
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Glass corrodes in aqueous environments. The corrosion process is well-understood for many circumstances involving long periods of time at room temperature as well as processes that involve conventional heating, but the effect of microwave energy on glass corrosion has never been fully investigated. It was suspected that microwaves may alter or accelerate the aqueous corrosion processes that occur in glass which contribute to migration into foods or other materials. Lithium disilicate (Li2O-2SiO2) and commercial soda-lime glass were corroded using both conventional and microwave heating in this study. The results did not clearly show substantial differences in corrosion under the test conditions, but leave open the possibility of an altered mechanism in some circumstances. These findings suggest the need for testing at a lower microwave frequency, specifically 2.45 GHz.Master of Science
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Sundaram, S. K. "Corrosion and electrochemical protection of molybdenum and molybdenum disilicide in molten silicate glass environments." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/18906.
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Li, Chunling. "Al-Co-Ce glass forming alloys and their corrosion behaviour." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14473/.
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There is growing interest in Al-TM (transition metal)-RE (rare earth) amorphous alloys because of the combination of their good mechanical properties and corrosion resistance. However, the high critical cooling rate required to form the amorphous structure leads to difficulties in generating bulk amorphous material. Therefore, there has been greater interest in producing amorphous Al-TM-RE alloys as surface layers. In this study, wedge mould casting, laser surface melting (LSM) and large area electron beam (LAEB) surface melting were used to fabricate Al Co-Ce alloys in both crystalline and amorphous form. An eutectic Al 33Cu (wt.%) alloy was also used to quantify the solidification conditions based on the well-known relationship. The microstructures formed by different processes were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, image analysis and X ray and glancing angle X-ray diffraction. In particular, LAEB surface melting was found to be able to provide a sufficiently high solidification velocity for the generation of an amorphous layer on the remelted surface of bulk crystalline Al Co-Ce alloys. Experimental results show that the LAEB treatment can remelt, homogenise the multiphase crystalline starting material and generate a predominantly amorphous layer, although it also caused cracking of the treated layer. However, the cracking was largely reduced in the laser refined starting microstructure. Laser microstructural refinement also improved the homogenisation and amorphisation generated by the subsequent LAEB treatment. The temperature field of multi-pulse LAEB irradiated Al-Co-Ce and Al-Cu alloys was numerically simulated through a finite difference method. The simulation results were generally consistent with the experimental results. The corrosion behaviour of Al-Co-Ce alloys with different microstructures was studied through potentiodynamic polarisation tests. Al-Co-Ce amorphous layer exhibited an enhanced corrosion resistance compared to the crystalline counterpart, although cracking in the amorphous layer greatly influenced the effectiveness of the amorphous layer protecting the substrate.
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Zhang, Li [Verfasser]. "Exploring float glass powder as corrosion resistant glass coating applied to concrete by flame spraying / Li Zhang." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2014. http://d-nb.info/1054632707/34.
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Farn, Sharon. "Thermochemical corrosion of alumina-zirconia-silica refractories for glass furnace regenerators." Thesis, Keele University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522676.
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McMillan, Alan Robert. "Environmental degradation of glass reinforced polyesters in the wastewater treatment industry." Thesis, University of Nottingham, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362912.
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Attou, Abdelkader. "Cracking and stress corrosion cracking in glass fibre materials using acoustic emission." Thesis, Robert Gordon University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277702.
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Miller, Jason. "Devitrification Effects on the Structure and Corrosion of an Fe-based Bulk Metallic Glass." Cleveland, Ohio : Case Western Reserve University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1252371978.
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Thesis(M.A.)--Case Western Reserve University, 2010Title from PDF (viewed on 2010-01-28) Department of Materials Science and Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
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Davies, C. M. A. "Failure mechanisms in glass-ceramic matrix composite laminates." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387305.
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Green, Stuart. "Creep behaviour of short glass fibre reinforced nylon 66." Thesis, University of Liverpool, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.279696.
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Carrière, Charly. "Influence de la corrosion du fer sur les processus d’altération du verre : approche analytique multi-échelle." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066299/document.
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La gestion des déchets produits par l’industrie nucléaire est un enjeu majeur de nos sociétés. En France, l’Agence nationale pour la gestion des déchets radioactifs (Andra), est chargée de la mise en œuvre du projet Cigéo, centre industriel de stockage géologique, un concept de stockage profond en milieu argileux des déchets radioactifs HA et MAVL. Dans ce concept, le verre a été choisi comme matrice de confinement pour les déchets radioactifs de haute activité et la prédiction du comportement du colis de déchet sur le long terme est l’un des éléments essentiels de sureté. Afin d’identifier les mécanismes d’altération du verre en présence de fer issu du conteneur de stockage, différents systèmes verre/fer/argilite ont été altérés dans des conditions proches du probable site de stockage géologique. Un couplage de techniques de caractérisation post-mortem de l’échelle micro à nanométrique a permis de caractériser les systèmes et d’identifier les silicates de fer qui se forment dans la couche d’altération du verre SON68 et dans les produits de corrosion du fer. A 50°C, les smectites dioctaédriques de FeIII (assimilées à de la nontronite) se forment préférentiellement, tandis que des serpentines trioctaédriques riches en FeII (greenalite, berthierine) ne sont détectées que pour une température de 90°C. Ces phyllosilicates nanométriques ont un impact macroscopique sur l’altération du verre nucléaire. En effet les interactions silicium/fer entretiennent l’altération du verre et retardent l’atteinte du régime d’altération en vitesse résiduelleManagement of waste generated by the nuclear industry is a major challenge for our societies. In France, the French national radioactive waste management agency (Andra) is responsible for the implementation of the Cigéo project, an industrial geological storage center planning to use deep storage in clay medium for high level and intermediate-level long lived waste. Glass has been chosen in this project as a containment matrix for high-level radioactive waste. Understanding the long-term expected evolution of the waste package's behavior is critical for safety purposes.In order to identify the alteration mechanisms of the glass in the presence of iron from the storage container, different glass/iron/argillite systems have been altered under conditions close to those in the probable geological storage site. A coupling of post-mortem characterization techniques from the micrometric to nanometric scale allowed to characterize the systems and to identify the iron silicates formed in the glass alteration layer of the SON68 glass and in the iron corrosion products. At 50°C dioctahedral smectites of FeIII (assimilated to nontronite) are preferentially formed, while FeII-rich trioctaedric serpentines (greenalite, berthierine) are detected only at a temperature of 90°C.These nanometric phyllosilicates have a macroscopic impact on the alteration of nuclear glass. Indeed silicon/iron interactions maintain the alteration of the glass and delay the achievement of the residual rate in its alteration regime
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Mallet, Céline. "Etude de la fissuration des verres de stockage : comportement en condition de stockage géologique." Thesis, Paris, Ecole normale supérieure, 2014. http://www.theses.fr/2014ENSU0001/document.
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L'objet de cette thèse est l’étude du comportement des fissures dans le verre. En particulier, l’évaluationde l’effet à long terme des contraintes en compression, est étudié par des essais de fluage. Le dispositifexpérimental utilisé est une presse triaxiale qui permet de confiner des échantillons cylindriques et de leurappliquer des contraintes axiales, une pression de pore ainsi qu’une variation de température. Un réseaude capteurs fixés sur chaque échantillon permet de mesurer la déformation, les vitesses de propagation desondes élastiques et les émissions acoustiques. Les échantillons de verre fournis pour cette étude sont fabriquéspar le CEA de Marcoule. Nous avons observé que le verre sain présente un comportement élastiquefragileet une grande résistance mécanique. Un réseau de fissures est ensuite introduit par choc thermique.L’étude de la microstructure du réseau initial a révélé que le choc thermique induit des contraintes detension aux bords de l’échantillon qui nucléent les fissures. Le réseau introduit est homogène et présenteune symétrie transverse isotrope. La densité de fissure du réseau peut être mesurée à partir d’images demicroscopie et aussi à partir des mesures de vitesses. L’étude de fluage a mis en évidence la propagationsouscritique des fissures. Un modèle théorique, reliant une loi de propagation des fissures à une descriptionen “wing-crack”, décrit bien le comportement expérimental. Une dernière étude est abordée qui met enévidence le rôle des fluides dans la propagation des fissures. À l’échelle du temps du laboratoire on montrealors que l’eau peut accentuer la propagation des fissures et qu’une corrosion chimique est aussi mesurableThe purpose of this thesis is the study of crack behavior in glass. In particular, the long term effects ofcompressive stresses are observed through creep tests. The used experimental apparatus is a triaxial celldesigned to investigate the mechanical and physical properties of rocks under conditions of effective pressure,deviatoric stress, pore pressure and temperature. A set of sensors allows to measure radial and axialstrain, elastic wave velocities and acoustic emissions. The original boro-silicate glass samples are producedby the French Atomic Energy Commission (CEA). We observe that original glass has an elastic-brittlebehavior and a high mechanical strength. Then, the studied crack network is introduced with a thermalshock. The microstructural study of the initial crack network reveals that the thermal shock induces tensilestresses at sample edges which nucleate cracks. The network is homogeneous and has a transverseisotropic symmetry. The crack density can be measured from Scanning Electron Microscopy images andcan also be inferred from elastic wave velocities. Creep experiments evidenced the sub-critical crack propagation.A theoretical model, that links a crack propagation law to a “wing-crack” geometry, describesthe experimental behavior. A last point is reported that investigates the fluid role in crack behavior. Weobserve that the crack propagation is enhanced by the presence of a pore fluid. Chemical corrosion canalso be measured at our laboratory scale
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Mashal, Yosry A. "A fracture mechanics approach to the wear of ceramics and glass." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295606.
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Maldia, Leopoldo C. "Sodium sulfate corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composites." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA277224.
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Newton, Peter J. "Sodium sulfate corrosion of silicon carbide fiber-reinforced calcium aluminosilicate glass-ceramic matrix composites." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA283703.
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Caddock, Brian David. "The influence of diffusion processes on the stress-corrosion of E-glass/polyester composites." Thesis, University of Liverpool, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237537.
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Suh, Kwangsuk. "Underwater FRP repair of corrosion damaged prestressed piles." [Tampa, Fla] : University of South Florida, 2006. http://purl.fcla.edu/usf/dc/et/SFE0001601.
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Ayyagari, Venkata Aditya. "Effect of Alloy Composition, Free Volume and Glass Formability on the Corrosion Behavior of Bulk Metallic Glasses." Thesis, University of North Texas, 2015. https://digital.library.unt.edu/ark:/67531/metadc822824/.
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Bulk metallic glasses (BMGs) have received significant research interest due to their completely amorphous structure which results in unique structural and functional properties. Absence of grain boundaries and secondary phases in BMGs results in high corrosion resistance in many different environments. Understanding and tailoring the corrosion behavior can be significant for various structural applications in bulk form as well as coatings. In this study, the corrosion behavior of several Zr-based and Fe-Co based BMGs was evaluated to understand the effect of chemistry as well as quenched in free volume on corrosion behavior and mechanisms. Presence of Nb in Zr-based alloys was found to significantly improve corrosion resistance due to the formation of a stable passive oxide. Relaxed glasses showed lower rates compared to the as-cast alloys. This was attributed to lowering of chemical potential from the reduced fraction of free volume. Potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) techniques helped in quantifying the corrosion rate and polarization resistance. The effect of alloy composition was quantified by extensive surface analysis using Raman spectroscopy, energy dispersive x-ray spectroscopy and auger spectroscopy. Pitting intensity was higher in the as-cast glasses than the relaxed glasses. The electrochemical behavior of a Zr-Ti-Cu-Ni-Be bulk metallic glass subjected to high strain processing was studied. High strain processing caused shear band formation and an increase in the free volume. Potentiodynamic polarization and EIS showed a strong correlation between the enthalpy of structural relaxation and corrosion rate and polarization resistance. Pitting was observed to preferentially occur on shear bands in the processed samples, while it was stochastic in unprocessed glass. The corrosion analysis of Co-Fe glasses showed an increase in corrosion current density when Fe content was increased from 0 to 7 at%. The corrosion resistance improved when Fe content was further increased to 15 at%. Similar trend was seen in EIS studies. The improved corrosion resistance at 15 at% Fe can be attributed to the large supercooled region that facilitates the formation of completely amorphous alloy, in contrast to lower Fe containing alloys, where short range ordering may deteriorate the corrosion resistance. Porous metallic glass structure was developed by electrochemical dealloying via cyclic voltammetry. Mechanical properties and changes in electrical conductivity were measured as a function of depth from surface by nano-indentation and nano electrical contact resistance technique. The nanoporous layer was found have hardness of 0.41 GPa and elastic modulus of nearly 22 GPa. The resistivity of the nanoporous layer continuously decreased when moving towards the substrate as the indentation depth increased which is attributed to the gradient in pore size.
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Dicic, Zorana. "High Temperature Corrosion of Single Crystal Sapphire and Zirconia in Coal Gasification and Commercial Glass Environments." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/10004.
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To meet the requirements of precise temperature monitoring at high temperatures in extremely corrosive environments, such as in coal gasifiers, a new sensor technology has been developed. This optical, ultra high temperature measurement system utilizes single crystal sapphire as a sensing element. A series of experiments was performed to determine the corrosion resistance of single crystal sapphire and single crystal fully stabilized cubic zirconia at high temperatures in coal slag and soda lime glass. The amount of corrosion of sapphire and zirconia in corrosive slags was measured at 1200°C, 1300°C, and 1400°C for different exposure times. The microstructural features at the interface of sapphire and zirconia were investigated using SEM and EDX analysis. The experimental measurements as well as SEM micrographs show very little or no degradation of sapphire and zirconia samples in corrosive slags. An interesting phenomenon was observed in the EDX scans of sapphire in the coal slag: the iron from the slag appears to have completely separated from the silicon and deposited at the sapphire surface. This interesting observation can be further explored to study whether this iron layer can be used to control the corrosion of sapphire.Master of Science
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Mills, Paula Jayne. "A study of the atmospheric corrosion of mediaeval stained glass windows in the United Kingdom." Thesis, University of York, 1995. http://etheses.whiterose.ac.uk/10858/.
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Sohi, A. M. "Metal oxide films on glass and steel substrates." Thesis, Teesside University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391529.
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Jihan, Sha. "Studies of structure cracking and fracture strength of E-glass fibres using acoustic emission." Thesis, Robert Gordon University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294825.
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Chapekar, Vasant Krishna. "Corrosion resistance of iron-base & cobalt-base metallic glass alloys in condensing acidic flue gas environment." Thesis, Imperial College London, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252297.
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Wheeler, Megan Caroline. "Parameters Influencing the Corrosion Protection Service Life of Epoxy Coated Reinforcing Steel in Virginia Bridge Decks." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/9687.
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This study is an evaluation of epoxy coated reinforcing steel (ECR) and its ability to effectively provide corrosion protection in reinforced concrete highway bridge decks. An analysis was conducted on 10 bridge decks built in the state of Virginia between the years 1981 and 1995.
A total of 141 cores containing either ECR or bare steel were evaluated. A chloride solution was applied to the surface on a weekly cycle (for a total duration of 3.06 years) and a nondestructive electrochemical testing was performed on each core on a monthly cycle. Cores were also inspected for surface cracks, the thermal properties of the epoxy coating, and the concrete conditions at bar depth. The concrete was tested for saturation percentages, diffusion coefficients, and chloride contents, while the epoxy was tested for its glass transition temperature, moisture content, and amount of surface cracking.
The results indicate that the best predictor for estimating the times to corrosion initiation and cracking is the amount of chlorides present in the concrete encasing the ECR. The presence of chloride ions will have a determining effect on corrosion regardless of the epoxy coating condition. As a result, it is likely that ECR is not the solution to corrosion prevention and it is recommended that closer attention be given to improving concrete conditions that reduce the diffusion of chloride ions. The conclusion that ECR is an unreliable corrosion prevention method is in agreement with the results of previous studies.Master of Science
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Shiomi, Shohei. "Silicate Glass Coating on Copper Nanoparticles and Its Further Application to a Transparent Corrosion Resistant Film for Magnesium Alloys." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188590.
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Ha, Hung M. "Micro- and Nano-Scale Corrosion in Iron-Based Bulk Metallic Glass Sam 1651 and Silver-cored MP35N Lt Composite." Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1260391940.
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Cawrse, Jason Kyle. "Laboratory Tests of a Bridge Deck Prototype With Glass Fiber Reinforced Polymer Bars as the Top Mat of Reinforcement." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35262.
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The primary objective of this project was to test a full-scale prototype of an actual bridge deck containing GFRP bars as the top mat of reinforcement. The purpose of the tests was to verify that the design would resist the loads for which it was designed and provide assurance that the deck would not unexpectedly fail due to the use of this new material. Behavior of the bridge and deck, such as failure load, failure mode, cracking load, crack widths, deflections, and internal stresses, were examined. Four tests were performed on the deck, all of which tested the deck in negative moment regions. From the tests, it was concluded that the design of the deck was very conservative and that unexpected failure should be of no concern.
The secondary objective of this project was to comment on the construction of a bridge deck reinforced with GFRP bars and to note its advantages and disadvantages along with a critique of the current state-of-the-art of designing bridge decks with FRP reinforcement. It was found that the advantages of construction with GFRP bars far outweighed the disadvantages, and that the placing of the top mat of GFRP bars was much easier than the placing of the bottom mat of steel bars. It was also concluded that the current state-of-the-art of designing bridge decks reinforced with GFRP is, for the most part, inaccurate in its prediction of behavior and that more research is needed to create more accurate design equations and procedures. Although current methods do not result in accurate predictions of behavior, they do, as mentioned above, result in conservative designs.Master of Science
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Harlan, Matthew. "Field Test of a Bridge Deck with Glass Fiber Reinforced Polymer Bars as the Top Mat of Reinforcement." Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/9987.
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The primary objective of this research project was to perform live load tests on a bridge deck with GFRP reinforcement in the field under service conditions. The strains and deflections in the span reinforced with GFRP in the top mat were recorded under a series of truck crossings, and these were compared to the span reinforced with all steel bars under identical loading conditions, as well as design values and other test results. Transverse strains in the GFRP bars, girder distribution factors, girder bottom flange strains, dynamic load allowances, and weigh-in-motion gauge results were examined. From the live load tests, it was concluded that the bridge was designed conservatively for service loads, with measured strains, stresses, distribution factors, and impact factors below allowables and design values.
The second objective was to monitor the construction of the bridge deck. To carry out this objective, researchers from Virginia Tech were on site during the bridge deck phase of the construction. The construction crews were observed while installing both the all-steel end span and the steel bottom/GFRP top end span. The installation of the GFRP bars went smoothly when compared to that of the steel bars. The workers were unfamiliar with the material at first, but by the end of the day were handling, installing, and tying the GFRP bars with skill. It was concluded that GFRP bars are an acceptable material in bridge deck applications with respect to constructibility issues.
The third objective was to set up the long term monitoring and data collection of the bridge deck. Electrical resistance strain gauges, vibrating wire strain gauges, and thermocouples were installed in the deck prior to concrete casting to provide strain and temperature readings throughout the service life of the bridge. It was concluded that the span reinforced with GFRP was instrumented sufficiently for long-term health monitoring.Master of Science
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Abdullah, Tuti Katrina. "Study of the redox and acid-base properties of soda-lime silicate glass : application to the high temperature corrosion of Ni-based alloys and ceramic materials." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0290/document.
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Le comportement en corrosion d'alliages chromine (Cr2O3) et alumine (Al2O3) formeurs dans des verres sodo-calciques à haute température a été étudié en utilisant des techniques électrochimiques. Les mécanismes réactionnels de la corrosion par ce type de milieu ont ainsi pu être abordés, de même que les aspects cinétiques. Les résultats ont montré que l'alumine n'est pas capable de protéger les alliages, étant donnée sa très forte solubilité dans le verre. Cependant, les alliages chromine formeurs ont montré une meilleure résistance à la corrosion, et ce s'ils ont subi un traitement de pré-oxydation. Une compétition entre la croissance de la couche de chromine et sa dissolution régit la durée de vie de la couche protectrice. Ainsi la physico-chimie de la chromine en milieu verre fondu a été étudiée. Sa solubilité a été mesurée afin de comprendre l'influence des paramètres température (T), fugacité en oxygène (fO2) et composition du verre. Une étude cinétique a mis en évidence l'influence de ces paramètres sur les mécanismes et le temps de mise à l'équilibre. D'un point de vue thermodynamique, l'influence des paramètres T et fO2 sur la solubilité du chrome dans des verres ternaires Na2O-CaO-xSiO2 est cohérente avec celle déjà observée sur des verres binaires Na2O-xSiO2, la solubilité de la chromine étant bien plus faible dans les verres ternaires. L'influence de la basicité a été étudiée en prenant en compte la basicité optique théorique (^th) et l'activité en oxyde de sodium (aNa2O). Les rapports redox (CrII/CrIII et (CrVI/CrIII) ont été déterminés suite à un affinement mathématique. Les grandes différences observées par rapport aux résultats théoriques (vérifiés dans les verres binaires) dans le cas où la spéciation du chrome intervient laissent penser que l'oxyde de calcium CaO influe sur les réactions impliquant le couple O2/O2-The corrosion behaviour of chromia (Cr2O3) and alumina (Al2O3) forming alloys in soda-lime silicate melts was studied by using electrochemical measurements. The general aspects of the corrosion by molten glass as well as the redox reactions and the kinetics ruling the corrosion process were determined. The results revealed that Al2O3 is not able to provide protection against corrosion since it has a high dissolution in the melt. However Cr2O3 forming alloy could resist against corrosion if the alloy was subjected to a preoxidation treatment. A competition between the oxide growth and its dissolution in the melt rules the durability of the protective Cr2O3 layer. Thus, the physicochemistry of Cr2O3 in molten glass was then studied in order to understand the influence of temperatures (T), oxygen fugacities (fO2) and glass composition on the limit of solubility of Cr2O3. A preliminary kinetics study revealed that the time to reach equilibrium varies with these parameters. A thermodynamic study showed that the influence of T and fO2 on the Cr2O3 solubility in ternary soda-lime silicate melts (Na2O-CaO-xSiO2) is in coherence with results previously obtained in binary melts (Na2O-xSiO2). Nevertheless, the Cr2O3 solubility in ternary melts is lower than in binary melts. The influence of basicity was studied in both melts by taking into account the theoretical optical basicity (^th) and the activity of Na2O (aNa2O). The redox ratios (CrII/CrIII and CrVI/CrIII) were determined through a mathematical refinement. The comparison with the results obtained in binary melts and the deviation from the theoretical values expected when speciation of Cr is involved, induced assumptions on the role played by CaO in influencing the reactions involving species from O2-/O2 couple
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Hunt, Richard K. "A transmission electron microscope characterization of sodium sulfate hot corrosion of silicon carbide fiber-reinforced lithium aluminosilicate glass-ceramic matrix composite." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1994. http://handle.dtic.mil/100.2/ADA286164.
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Beltrán, González Martí. "Analysis and degradation mechanisms of enamels, grisailles and silver stains on Modernist stained glass." Doctoral thesis, Universitat Politècnica de Catalunya, 2021. http://hdl.handle.net/10803/671478.
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Materials and methods used in the production of modernist (late 19th and early 20th century) stained glass from the city of Barcelona with special regards to the degradation mechanisms of enamels, grisailles and silver stains have been studied. Coloured enamels from the raw materials used in the Rigalt, Granell & cia modernist workshops from Barcelona were produced and compared to those found in the buildings and belonging to the private collection of J.M. Bonet workshop to explore the reason for the reduced stability of the blue and green enamels. The chemical composition has been determined (and pigments identified) by means of Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS), X-Ray Diffraction (XRD) and UV-Vis-NIR spectroscopy, and the thermal properties of the enamels measured by Differential Scanning Calorimetry (DSC) and Hot Stage Microscopy (HSM). The enamels are made of a lead-zinc borosilicate glass characterised by its low sintering temperatures and high stability against chemical corrosion, in particular to water corrosion. However, the relatively narrow range of firing temperatures necessary for correct adherence of the enamels to the contemporary glass base may have required the addition of a high lead borosilicate flux, which would have increased the lead content of the enamel, decreasing the firing temperature but also its stability. The historical enamels show a lead, boron and zinc depleted silica rich amorphous glass, with precipitated lead and calcium sulphates or carbonates, characteristic of extensive atmospheric corrosion. The blue and green enamels show a heterogeneous layered microstructure more prone to degradation which is augmented by a greater heating and thermal stress affectation produced by the enhanced Infrared absorbance of blue tetrahedral cobalt colour centres and copper ions dissolved in the glass and, in particular, of the cobalt spinel particlesS'han estudiat els materials i mètodes utilitzats en la producció dels vitralls modernistes (finals del segle XIX i començaments del segle XX) de la ciutat de Barcelona, especialment en relació als mecanismes de degradació d’esmalts, grisalles i grocs de plata. S'han produït i estudiat els esmalts de color a partir de les matèries primeres utilitzades pel taller Rigalt, Granell & cia de Barcelona, per comparar amb mostres originals pertanyents a la col·lecció privada del taller J.M. Bonet vitralls per així estudiar la raó de la reduïda estabilitat dels esmalts blaus i verds. La composició química i els pigments han estat identificats per LA-ICP-MS, espectroscòpia d'UV-Vis-NIR i XRD, i les propietats tèrmiques dels esmalts han estat mesurades amb DSC i HSM. Els esmalts són vidres borosilicats de plom i zinc caracteritzats per baixes temperatures de sinterització i una gran estabilitat contra la corrosió química, especialment respecte a la corrosió de l'aigua. No obstant, el relativament estret marge de temperatures necessari per una correcta adherència dels esmalts al vidre base de l’època podria haver requerit l’addició d’un fundent amb un alt tant per cent de plom i bor, que podria haver augmentat la proporció de plom a l’esmalt disminuint la temperatura de treball juntament amb la seva estabilitat. Els esmalts històrics presenten una composició alterada a on plom, bor i zinc han disminuït en front a un augment de la proporció de silici a la fase vítria, amb l’aparició de precipitats de sulfats o carbonats de plom i calci, característics de l’efecte de la corrosió atmosfèrica. Els esmalts blaus i verds presenten una microestructura en capes heterogènies que són més susceptibles a la degradació, la qual augmenta degut a la calor i l’estrès tèrmic respecte al vidre base que provoca una major absorbància a la regió de l’infraroig proper deguda a la presència d’estructures tetraèdriques dels ions de cobalt i coure dissoltes a la fase vítria, i en particular de les partícules d'espinel·les de cobalt
Se han estudiado los materiales y métodos utilizados en la producción de los vitrales modernistas (finales del siglo XIX y principios del siglo XX) de la ciudad de Barcelona, especialmente en relación a los mecanismos de degradación de esmaltes, grisallas y amarillos de plata. Se han producido y estudiado los esmaltes de color a partir de las materias primas utilizadas por el taller Rigalt, Granell & cia de Barcelona, para luego comparar con muestras originales de la colección privada del taller J.M. Bonet vitralls y así estudiar la razón de la reducida estabilidad de los esmaltes azules y verdes. La composición química y los pigmentos han sido identificados por LA-ICP-MS, espectroscopía UV-Vis-NIR, y las propiedades térmicas de los esmaltes han sido medidas con DSC y HSM. Los esmaltes son vidrios borosilicatos de plomo y zinc caracterizados por bajas temperaturas de sinterizado y una gran estabilidad contra la corrosión química, especialmente contra la corrosión del agua. No obstante, el relativamente estrecho margen de temperaturas necesario para una correcta adherencia de los esmaltes al vidrio base de la época podría haber requerido la adición de un fundente con un alto tanto por ciento de plomo y boro, que podría haber aumentado la proporción de plomo en el esmalte disminuyendo la temperatura de trabajo junto con su estabilidad. Los esmaltes históricos presentan una composición alterada donde plomo, boro y zinc han disminuido a favor de un aumento de la proporción de silicio en la fase vítrea, con la aparición de precipitados de sulfatos o carbonatos de plomo y calcio, característicos del efecto de la corrosión atmosférica. Los esmaltes azules y verdes presentan una microestructura en capas heterogéneas que es mas susceptible a la degradación, que aumenta debido a la temperatura y al estrés térmico respecto al vidrio base que provoca una mayor absorbancia en la región del infrarrojo cercano debido a la presencia de estructuras tetraédricas de los iones de cobalto y cobre disueltos en la fase vítrea, así como a la presencia de partículas de espinelas de cobalto
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Datsiou, Kyriaki Corinna. "Design and performance of cold bent glass." Thesis, University of Cambridge, 2017. https://www.repository.cam.ac.uk/handle/1810/269408.
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The demand for flat glass is high and increasing significantly in the building industry as a direct result of architectural requirements for lightness, transparency and natural light. Current architectural trends require glass in curvilinear forms for smooth free-form façades. Two principal challenges arise from this: to cost-effectively produce the desired curvature and; to ensure its safe performance after exposure to ageing. The recent availability of high strength glass provides an opportunity to address the first challenge by developing cold bent glass. Cold bending involves the straining of relatively thin glass components, at ambient temperatures, and is a low energy and cost effective manner of creating curvilinear forms. However, cold bending is not yet widely established as a reliable method. The aim of this thesis is to develop the understanding of cold bent glass during the bending process and to evaluate its post-ageing performance. This thesis, firstly, investigates the mechanical response of monolithic glass plates during the cold bending process. The stability of cold bent glass is investigated experimentally by bending it in double curved anticlastic shapes. A parametric numerical analysis involves different boundary conditions, geometrical plate characteristics and bending parameters. The principal outcome is that a local instability, now termed cold bending distortion, occurs when certain displacement limits are exceeded and could degrade the optical quality of the glass. An evaluation procedure is also formulated to set limits and aid designers/manufacturers to predict the mechanical response and the optical quality of the glass. Cold bent glass is subjected to permanent bending stresses throughout its service life and therefore, its strength degradation after ageing needs to be quantified. Analytical, experimental and numerical investigations are undertaken in this thesis to identify the most effective method for estimating glass strength (evaluation of destructive tests, required number of specimens, statistical analysis methods and sub-critical crack growth). The limited availability of naturally aged toughened glass and the absence of a reliable ageing standard impede the evaluation of its aged performance. Therefore, a parametric experimental investigation of artificial ageing methods on glass is undertaken in this thesis. A procedure for the evaluation of the strength of aged glass is finally, formulated to allow the selection of artificial ageing parameters that correspond to a target level of erosion. The knowledge on artificial ageing and strength prediction acquired above is finally implemented on different types of glass to determine their strength after ageing and assess their safe use in cold bending / load bearing applications. The investigation showed that fully toughened glass has a superior performance to chemically toughened or annealed glass. Overall, the research presented in this thesis demonstrates that high quality cold bent toughened glass can be created when certain applied displacement limits are respected. These can be used as a safe, cost-effective and energy efficient replacement to the more conventional hot bent glass. However, cold bending / load bearing applications in which the stressed glass surface is exposed to ageing, require glass with a relatively high case depth such as fully toughened or bi-tempered glass.
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Dohmen, Lars [Verfasser]. "In situ observations of reaction and transport phenomena during silicate glass corrosion by fluid-cell Raman spectroscopy : Method development and applications / Lars Dohmen." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1218474939/34.
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Scheffler, Christina. "Zur Beurteilung von AR-Glasfasern in alkalischer Umgebung." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-27035.
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AR-Glas wird in Form von Multifilamentgarn zur Verstärkung in textilbewehrtem Beton eingesetzt. Während des Herstellungsprozesses wird auf die AR-Glasfilamente die Schlichte aufgebracht, deren chemische Zusammensetzung maßgeblich die Qualität der Filament-Matrix-Grenzschicht bestimmt, sowie die chemische Beständigkeit im alkalischen Milieu gewährleistet. Zur Beurteilung der chemischen Beständigkeit in alkalischer Umgebung werden beschleunigte Alterungsversuche in wässrigen, alkalischen Lösungen durchgeführt. Die Reaktion von Hydroxid-Ionen mit dem Si-O-Si-Gruppen des Glasnetzwerkes führt zur Ausbildung hydratisierter Oberflächen und gelösten Silikaten. Das Ausmaß der Glaskorrosion ist von der chemischen Zusammensetzung der Glasfaser, der Schlichte bzw. Beschichtung und der alkalischen Lösung sowie von Zeit und Temperatur abhängig. Die beschleunigte Alterung von verschiedenen AR-Glasfasern in NaOH-Lösung sowie Zementlösung zeigt, dass sich der Korrosionsmechanismus aufgrund der vorhandenen Calcium-Ionen unterscheidet. Die Filamentbruchspannung wird anhand der Weibull-Verteilungsfunktion analysiert. Das mechanische Verhalten hängt deutlich von der chemischen Zusammensetzung der Alterungslösung ab, was zu unterschiedlichen Parametern der Weibull-Verteilungsfunktion sowie vermengten Verteilungen führen kann. Die Alterung in NaOH-Lösung führt zur Ausbildung einer korrodierten Schicht an der Filamentoberfläche. In Ca-haltigen Zementlösungen kommt es dagegen zu einer lokal begrenzten Korrosion. Für die Beurteilung verschiedener Polymerbeschichtungen werden Betonverbunde bei unterschiedlichen Temperaturen und Umgebungsfeuchten gelagert, wodurch geeignete Alterungsbedingungen evaluiert werden und den Vergleich der chemischen Beständigkeit unterschiedlicher Beschichtungen ermöglichenRovings made of AR-glass are used in textile reinforced concrete. During the manufacturing process the sizing is applied on the AR-glass filaments. The chemical constitution of the sizing determines the quality of the filament-matrix-interface but also the chemical durability of the glass filaments in alkaline environment. The durability is evaluated by accelerated ageing tests in aqueous, alkaline solutions. In alkaline solutions, the reaction of hydroxyl ions with Si-O-Si-groups of the glass network leads to the formation of hydrated surfaces and dissolved silicate. The rate of this corrosion depends on the chemical constitution of the fibre and the alkaline solution as well as on time and temperature. The investigation of the ageing of glass fibres with different chemical constitutions in NaOH and cement solutions shows that the corrosion mechanism changes due to the inhibiting effect of calcium ions. The strength distributions have been evaluated using a Weibull distribution function. The mechanical behaviour strongly depends on the chemistry of the solution and determines the parameters of the Weibull distribution function in terms of either single or mixed distributions. The corrosion in NaOH solution leads to a strong dissolution of the outer layer of the glass fibres, whereas during aging in cement solution at the same pH-value a limited, local attack was revealed. The evaluation of polymer coatings is realised by the ageing of concrete composites at different temperatures and humidities to deduce adequate ageing conditions for the comparison of different coatings
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MARIGGIO', GREGORIO. "A novel functional coating and a reliable design approach to fully exploit the strength of annealed glass." Doctoral thesis, Politecnico di Torino, 2022. http://hdl.handle.net/11583/2971516.
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Ayyagari, Venkata A. "Surface Degradation Behavior of Bulk Metallic Glasses and High Entropy Alloys." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062863/.
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In this study, the surface degradation behavior was studied for typical examples from bulk metallic glasses (BMGs), metallic glass composites (MGCs) and high entropy alloys (HEAs) alloy systems that are of scientific and commercial interest. The corrosion and wear behavior of two Zr-based bulk metallic glasses, Zr41.2Cu12.5Ni10Ti13.8Be22.5 and Zr57Cu15.4Ni12.6Al10Nb5, were evaluated in as-cast and thermally relaxed states. Significant improvement in corrosion rate, wear behavior, and friction coefficient was seen for both the alloys after thermal relaxation. Fully amorphous structure was retained with thermal relaxation below the glass transition temperature. This improvement in surface properties was explained by annihilation of free volume, the atomic scale defects in amorphous metals resulting from kinetic freezing. Recently developed MGCs, with in situ crystalline ductile phase, demonstrate a combination of mechanical properties and fracture behavior unseen in known structural metals. The composites showed higher wear rates but lower coefficient of friction compared to monolithic amorphous glasses. No tribolayer formation was seen for the composites in sharp contrast to that of the monolithic metallic glasses. Corrosion was evaluated by open circuit potential (OCP) analysis and potentiodynamic polarization. Site-specific corrosion behavior was studied by scanning vibration electrode technique (SVET) to identify formation of galvanic couples. Scanning kelvin probe microscope was used to map elecropositivity difference between the phases and linked to wear/corrosion behavior. Phases with higher elecropositivity were more susceptible to surface degradation. Wear and corrosion synergy in marine environment was evaluated for two high entropy alloys (HEAs), CoCrFeMnNi and Al0.1CoCrFeNi. Between the two alloys, Al0.1CoCrFeNi showed better wear resistance compared to CoCrFeMnNi in dry and marine conditions due to quicker passivation, a higher magnitude of polarization resistance and significantly larger pitting resistance.
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Scheffler, Christina. "Zur Beurteilung von AR-Glasfasern in alkalischer Umgebung: Evaluation of AR-glas fibres in alkaline environment." Doctoral thesis, Leibniz-Institut für Polymerforschung Dresden e.V, 2009. https://tud.qucosa.de/id/qucosa%3A25230.
Full textAbstract:
AR-Glas wird in Form von Multifilamentgarn zur Verstärkung in textilbewehrtem Beton eingesetzt. Während des Herstellungsprozesses wird auf die AR-Glasfilamente die Schlichte aufgebracht, deren chemische Zusammensetzung maßgeblich die Qualität der Filament-Matrix-Grenzschicht bestimmt, sowie die chemische Beständigkeit im alkalischen Milieu gewährleistet. Zur Beurteilung der chemischen Beständigkeit in alkalischer Umgebung werden beschleunigte Alterungsversuche in wässrigen, alkalischen Lösungen durchgeführt. Die Reaktion von Hydroxid-Ionen mit dem Si-O-Si-Gruppen des Glasnetzwerkes führt zur Ausbildung hydratisierter Oberflächen und gelösten Silikaten. Das Ausmaß der Glaskorrosion ist von der chemischen Zusammensetzung der Glasfaser, der Schlichte bzw. Beschichtung und der alkalischen Lösung sowie von Zeit und Temperatur abhängig. Die beschleunigte Alterung von verschiedenen AR-Glasfasern in NaOH-Lösung sowie Zementlösung zeigt, dass sich der Korrosionsmechanismus aufgrund der vorhandenen Calcium-Ionen unterscheidet. Die Filamentbruchspannung wird anhand der Weibull-Verteilungsfunktion analysiert. Das mechanische Verhalten hängt deutlich von der chemischen Zusammensetzung der Alterungslösung ab, was zu unterschiedlichen Parametern der Weibull-Verteilungsfunktion sowie vermengten Verteilungen führen kann. Die Alterung in NaOH-Lösung führt zur Ausbildung einer korrodierten Schicht an der Filamentoberfläche. In Ca-haltigen Zementlösungen kommt es dagegen zu einer lokal begrenzten Korrosion.
Für die Beurteilung verschiedener Polymerbeschichtungen werden Betonverbunde bei unterschiedlichen Temperaturen und Umgebungsfeuchten gelagert, wodurch geeignete Alterungsbedingungen evaluiert werden und den Vergleich der chemischen Beständigkeit unterschiedlicher Beschichtungen ermöglichen.Rovings made of AR-glass are used in textile reinforced concrete. During the manufacturing process the sizing is applied on the AR-glass filaments. The chemical constitution of the sizing determines the quality of the filament-matrix-interface but also the chemical durability of the glass filaments in alkaline environment. The durability is evaluated by accelerated ageing tests in aqueous, alkaline solutions. In alkaline solutions, the reaction of hydroxyl ions with Si-O-Si-groups of the glass network leads to the formation of hydrated surfaces and dissolved silicate. The rate of this corrosion depends on the chemical constitution of the fibre and the alkaline solution as well as on time and temperature. The investigation of the ageing of glass fibres with different chemical constitutions in NaOH and cement solutions shows that the corrosion mechanism changes due to the inhibiting effect of calcium ions. The strength distributions have been evaluated using a Weibull distribution function. The mechanical behaviour strongly depends on the chemistry of the solution and determines the parameters of the Weibull distribution function in terms of either single or mixed distributions. The corrosion in NaOH solution leads to a strong dissolution of the outer layer of the glass fibres, whereas during aging in cement solution at the same pH-value a limited, local attack was revealed. The evaluation of polymer coatings is realised by the ageing of concrete composites at different temperatures and humidities to deduce adequate ageing conditions for the comparison of different coatings.
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Galai, Leila. "Les mécanismes réactionnels régissant les interactions verre-fer en solution aqueuse." Thesis, La Rochelle, 2021. http://www.theses.fr/2021LAROS029.
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Le projet de stockage géologique profond des déchets hautement radioactifs et à vie longue développé par l’ANDRA prévoit que les colis de déchets vitrifiés soient placés dans des surconteneurs en acier faiblement alliés avant leur introduction dans des alvéoles de stockage situées à 500 m de profondeur. Cette proximité entre le verre et l’acier implique, en présence d’eau, une interaction entre les deux matériaux. Les études précédemment menées sur le système verre-fer en condition de stockage géologique ont permis de mettre en évidence la phénoménologie liée à cette interaction. Le fer est décrit comme augmentant l’altération du verre, notamment en raison de la formation de silicates de fer. Néanmoins, dans les dispositifs expérimentaux choisis, l’altération simultanée du verre et du fer rend difficile l’identification des mécanismes prévalant à l’interface de chaque matériau. Dans cette thèse, nous avons donc choisi de décomposer le système réel et complexe Verre/Acier/Argile/Solution en deux systèmes d’études modèles afin d’essayer de mieux caractériser les différents mécanismes siégeant à chaque interface. Les expériences du premier système, dit simplifié, sont des expériences de corrosion d’une poudre de fer en présence de Si. Ces expériences ont montré qu'une augmentation de [Si] favorisait la formation de silicates de Fe au détriment des oxydes de Fe, mais sans conduire à une augmentation de la quantité de fer corrodé. L’étude de la cinétique de ces expériences a révélé qu’un mécanisme de germination-croissance complexe est à l’origine de la formation des silicates de fer. Un modèle cinétique simplifié a par ailleurs été proposé. Les expériences du deuxième système, dit recombiné, met en contact la poudre de fer d’abord avec le verre CJ1 puis avec le verre ISG. Ces expériences ont mis en évidence que la présence de fer conduit certes à une augmentation de l’altération du verre mais cette augmentation est fortement limitée par trois paramètres principaux : la composition du verre, le flux de fer associé à la cinétique de corrosion du métal et le pH. La démarche de simplification choisie a donc permis de dissocier l’effet de chaque paramètre et de localiser l’effet du Si sur la corrosion du fer, de dissocier l’effet du fer de l’effet du pH sur l’altération du verre et surtout de mettre en évidence l’importance des paramètres tels que le flux de fer et la composition initiale du verre sur l’effet qu’aura le fer sur l’altération du verreThe geological disposal of high-level waste (HLW) developed by ANDRA, in France, is based on a multi-layer concept. The vitrified radioactive waste is placed in a stainless-steel container itself placed in a carbon steel overpack and disposed in Callovo-Oxfordian (Cox) claystone. The proximity between iron, glass and groundwater should involve a chemical interaction between them which can impact the long-term behaviour of nuclear vitrified waste. Previous study on the glass-iron system in geological storage conditions have highlights the phenomenology linked to this interaction. Iron has been almost unanimously described as increasing the alteration of glass. However, in the experimental setups chosen, the simultaneous alteration of glass and iron makes it difficult to identify the mechanisms prevailing at the interface of each material. In this thesis, we have therefore chosen to decompose the real and complex Glass / Steel / Clay / Solution system into two model study systems in order to better characterize the different mechanisms at each interface. The first experiments were about the corrosion of iron powder in the presence of Si. These experiments have shown that an increase in [Si] promotes the formation of Fe silicates at the expense of Fe oxides, but without leading to an increase in the amount of corroded iron. Kinetic investigations revealed that a complex germination-growth mechanism is behind the formation of Fe silicates. A simplified kinetic model has also been proposed. Then, the experimental system has been complexified with iron corrosion experiments in the presence of CJ1 simple glass and ISG glass. These experiments have shown that the presence of iron certainly leads to the deterioration of the glass, but this increase is strongly limited by three main parameters : the glass composition, the iron flux associated with the corrosion kinetics of the metal and pH. The chosen simplification approach therefore made it possible to dissociate the effect of each parameter and to locate the effect of Si on the corrosion of iron, to dissociate the effect of iron from the effect of pH on alteration of the glass and above all to highlight the importance of parameters such as the iron flow and the initial composition of the glass on the effect that the iron will have on the deterioration of the glass
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Klemm, Julia [Verfasser], Martin [Gutachter] Stratmann, and Wolfgang [Gutachter] Schuhmann. "Element resolved corrosion analysis of stainless steel-type glass forming steels and the correlation to their microstructure / Julia Klemm ; Gutachter: Martin Stratmann, Wolfgang Schuhmann ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2013. http://d-nb.info/122862402X/34.
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Repina, Maria. "Modélisation du transport réactif dans les milieux fracturés de verre nucléaire d’intérêt industriel." Thesis, Paris Sciences et Lettres (ComUE), 2019. http://www.theses.fr/2019PSLEM007/document.
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Comprendre l'altération du verre nucléaire dans un réseau de fracture au sein d'un bloc de verre vitrifié est important pour la sûreté du conditionnement des déchets nucléaires (quantification des risques associés au relâchement des radionucléides). L’évaluation de la performance du stockage géologique des déchets nucléaires passe obligatoirement par la modélisation de l’altération aqueuse d’un bloc de verre nucléaire fracturé, l’échelle de temps envisagée (plusieurs milliers d’années) dépassant toute possibilité d’expérience directe. Cette thèse vise donc à combler le fossé entre les simulations d'écoulement et de transport à l'échelle du réservoir et la modélisation à l'échelle micrométrique des processus interfaciaux verre-eau, en apportant l'évaluation quantitative de la dégradation aqueuse du verre à l'échelle d’un bloc.Pour aborder ce problème, les objectifs principaux de cette thèse ont été fixés comme suit : (i) la reproduction des résultats expérimentaux obtenus précédemment (pour quelques fractures modélisées de manière discrète en mode diffusif), (ii) l’analyse de l'impact des géométries de fractures sur la quantité de verre altéré pour quelques fissures modélisées de manière discrète, (iii) l’étude de la possibilité d'adaptation du modèle géochimique à la modélisation dans le cadre de l’approche milieu équivalent, (iv) la mise au point d'une méthodologie de caractérisation, (v) la modélisation géostatistique et géométrique de réseau de fractures à l’échelle d’un conteneur de verre, (vi) le calcul des paramètres équivalents diffusifs, hydrauliques et les paramètres qui contrôlent la cinétique de dissolution de verre, et au final, (vii) la modélisation de transport réactif à l’échelle d’un conteneur.À titre illustratif, la méthodologie de la caractérisation de réseau fracturé proposée, basée sur le traitement des images, a été appliquée aux images bidimensionnelles (2D) de haute résolution de deux blocs de verre. Cette application a permis de mettre en œuvre à la fois les données directes obtenues par mesures des paramètres d’un réseau fracturé de verre vitrifié et les données indirectes explicatives issues des simulations thermomécaniques. L’application a abouti à la création de multiples réalisations de tessellation de réseaux fracturés équivalents qui ont ensuite été utilisées comme représentations physiques pour les calculs de la perméabilité équivalente, de la diffusion équivalente et des paramètres contrôlant la cinétique de dissolution de verre borosilicaté. L'évolution de la quantité de verre altéré obtenue en effectuant la modélisation de transport réactif appliquée à plusieurs réalisations de la tessellation de réseau fracturé équivalent a été comparée aux données expérimentales d’un essai d'altération aqueuse d'un conteneur non radioactif de verre nucléaire. Les résultats montrent que la méthodologie conçue offre une opportunité pour mieux comprendre l'impact de la fracturation sur l'altération aqueuse du verre vitrifié et constitue un outil fiable permettant de prendre en compte différents scénarios d'évolution du stockageUnderstanding the alteration of nuclear glass in a fracture network of a vitrified glass block is important for the safe conditioning of nuclear waste (quantification of the risks associated with radionuclide release). Performance assessment of geological nuclear waste repositories entails modelling of the long-term evolution of the fractured nuclear glass block aqueous alteration, because the considered time scale, of several thousands of years, is beyond the range of any direct experimental perspectives. This dissertation aims then to bridge the gap between the reservoir-scale flow and transport simulations and the micron-scale modeling of the glass-water interfacial processes, by bringing the quantitative evaluation of the glass aqueous degradation at the block scale.To tackle this issue, the main objectives of this thesis were fixed as follows: (i) reproduction of the experimental results previously obtained (for some fractures modeled in a discrete way in the diffusive mode),(ii) analysis of the impact of fractures geometries on the quantity of altered glass at the scale of some fractures modeled in a discrete way, (iii) investigation of the possibilities of the geochemical model adaptation for the equivalent homogenous modeling, (iv) establishment of a methodology for glass block fracture network characterization, (v) geostatistical and geometric modeling, (vi) calculation of the equivalent diffusive, hydraulic and glass dissolution kinetics controlling properties and (vii) upcoming reactive transport modeling at the scale of one canister.As an illustrative example, the proposed image processing-based fracture network characterization methodology was applied to two-dimensional (2D) high-resolution images of two blocks of vitrified glass. This application brought into service both hard data obtained by direct measurement of the fracture network and soft physics-based explanatory data and resulted in the creation of multiple realizations of fracture network equivalent tessellation that were further used as physical representation for the calculation of the equivalent hydraulic, diffusive, and alteration kinetics - controlling properties. The evolution of the quantity of altered glass obtained by conducting reactive transport modeling applied to several realizations of the equivalent fracture network tessellation was compared with the experimental data of the aqueous alteration test of a non-radioactive full-scale nuclear glass canister. The results show that implementation of the devised procedure presents an opportunity for better understanding the impact of fracturing on aqueous alteration of borosilicate glass and provides a reliable tool enabling different scenarios of repository evolution to be accounted for
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REIS, SIGNO T. dos. "Durabilidade quimica de vidros sinterizados a base de fosfato de ferro e chumbo." reponame:Repositório Institucional do IPEN, 1999. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10728.
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Made available in DSpace on 2014-10-09T12:43:23Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:09:43Z (GMT). No. of bitstreams: 1 06528.pdf: 7080627 bytes, checksum: 21b5c941bd62d915113928c48d6e1209 (MD5)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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ATASSI, HANAE. "Evaluation de la resistance a la corrosion en solution aqueuse de quelques verres silicates." Université Louis Pasteur (Strasbourg) (1971-2008), 1989. http://www.theses.fr/1989STR13057.
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Des experiences ont ete realisees afin d'evaluer la resistance chimique de verres volcaniques et industriels, mis en contact avec de l'eau distillee et des solutions tampons a ph 6, 7, 8 et 9. On a etudie au microscope electronique les couches d'alteration en surface et les resultats ont ete compares a un modele cinetique de la dissolution du verre ainsi qu'a un modele thermodynamique (modele de paul)
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Khoe, Chandra K. "Oxygen Diffusion Characterization of FRP Composites Used in Concrete Repair and Rehabilitation." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3181.
Full textAbstract:
Many independent studies have conclusively demonstrated that fiber reinforced polymers (FRP) slow down chloride-induced corrosion of steel in concrete. The mechanism for this slow down is not well understood but it has been hypothesized that FRP serves as a barrier to the ingress of chloride, moisture, and oxygen that sustain electrochemical corrosion of steel.
This dissertation presents results from an experimental study that determined the oxygen permeation rates of materials used in infrastructure repair. In the study, the oxygen permeation constants for epoxy, carbon and glass fiber laminates, concrete, epoxy-concrete and FRP-concrete systems were determined and a method developed to use these results for designing the corrosion repair of FRP-concrete systems.
A new diffusion cell was developed that could be used to test both thin polymer specimens and much thicker FRP-concrete specimens. Concentration gradients were introduced by exposing one face of the specimen to air and the other face continuously to 100% oxygen for the duration of the test to achieve steady state conditions. Partial pressures on the two surfaces were measured using electronic sensors and oxygen permeation constants extracted from the data using a quasi-steady state theoretical model based on Fick's law. Results obtained using this system were in agreement with published data for specimens such as Teflon and Polyethylene Terephthalate (PET) Mylar whose oxygen permeation constant is available in the published literature.
Following the successful calibration of the system, oxygen permeation constants for epoxy, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) laminates were determined. It was found that the oxygen permeation constant for epoxies was an order of magnitude lower than that for FRP. Furthermore, two layer FRP laminates were found to be more permeable than single layer laminates. This finding had been reported previously in the literature but had been considered anomalous. Scanning electron micrographs showed that this was due to the wet layup process that inevitably trapped air between the multiple FRP layers.
The oxygen permeability of FRP-concrete systems was evaluated for three different water-cementitious ratios of 0.4, 0.45 and 0.50 for both CFRP and GFRP materials. Results showed that the performance of CFRP and GFRP were comparable and the best results were obtained when FRP was used with concrete with the highest water-cementitious ratio. A simple design method is proposed to apply the findings from the research. This uses the concept of an equivalent FRP thickness derived following Fick's law.
The findings from the research can be used to optimize FRP applications in corrosion repair. The experimental set up can easily be adapted to measure diffusion of carbon dioxide through FRP and other materials. This has potential applications in other disciplines, e.g. climate change.
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Scheffler, Christina, Theresa Förster, and Edith Mäder. "Beschleunigte Alterung von Glasfasern in alkalischen Lösungen: Einflüsse auf die mechanischen Eigenschaften." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244042771688-80994.
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In alkalischen Lösungen führt die Reaktion von Hydroxylionen mit den Si-O-Si-Bindungen des Glasnetzwerks zur Bildung hydratisierter Oberflächen und gelöstem Silikat. Der Grad der Korrosion bzw. der Alterung der Glasfaser ist abhängig von der chemischen Zusammensetzung des Glases und Korrosionslösung sowie von Zeit und Temperatur. Die Untersuchung von Glasfasern verschiedener chemischer Zusammensetzung in NaOH- sowie Zementlösungen zeigte, dass die inhibierende Wirkung von Ca-Ionen zu einem veränderten Korrosionsmechanismus führt. Dies konnte anhand der mechanischen Eigenschaften der Glasfasern sowie rasterelektronenmikroskopischen Untersuchungen gezeigt werden. Während die Korrosion in NaOH-Lösung zu einer ausgeprägten Umwandlung der gesamten äußeren Glasfaserschicht in Reaktionsprodukte führte, zeigten Glasfasern in Zementlösung bei gleichem pH-Wert einen stark lokal begrenzten, punktförmigen Angriff. Daraus resultieren unterschiedliche mechanische Eigenschaften der Glasfasern in Abhängigkeit von der gewählten Korrosionslösung.
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Bouakkaz, Rachid. "Altération aqueuse et hydratation en phase vapeur du verre SON68 à basse température (35-90°C)." Thesis, Nantes, Ecole des Mines, 2014. http://www.theses.fr/2014EMNA0168/document.
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Le verre SON68 est dans un premier temps altéré en mode dynamique dans l’eau de COx riche en silicium (42mg/L) à pH 8, à fort S/V (14000 m⁻¹) et à 35, 50 et 90°C. Les résultats montrent que l’altération du verre semble être gouvernée par un mélange de processus de diffusion et de réaction de surface. La vitesse résiduelle à 90°C est de l’ordre de 10⁻⁴ g.m⁻².j⁻¹, l’énergie d’activation est de l’ordre de 70 kJ.mol⁻¹. Un mécanisme de dissolution/précipitation et d’hydrolyse/condensation sont responsables du développement de la couche d’altération. Les silicates de Mg et la calcite précipitent à 35 et 50°C, mais en plus la powellite et l’apatite ont été identifiées à90°C. Les résultats de la modélisation géochimique reproduisent les données expérimentales. Le verre est ensuite hydraté à des températures allant de 35 à 125°C et des valeurs d’humidité relative (HR) entre 92 et 99,9%. L’hydratation du verre augmente avec la température et l’HR. L’énergie d’hydratation est de l’ordre de 34,2 kJ.mol⁻¹. Les épaisseurs des couches d’altération varient entre 0,3μm à 35°C et 5μm à 125°C. La couche d’altération est appauvrie en (B, Li, Na) et enrichie en (Si, Al, Fe, Ca, Zn et Ni). Les principales phases secondaires formées sont la calcite, la powellite, l’apatite, la tobermorite et un gel hydraté.L’influence des matériaux en champ proche sur l’altération du verre SON68 dopé en ²⁹Si a été étudiée. La présence d’acier augmente le pH et diminue la concentration en Si et en Mo sans modifier la vitesse globale de corrosion du verre. Le Si est retenu sur les produits de corrosion d’acier, sa concentration en solution semble être contrôlée par la dissolution de l’argilite. La corrosion du verre en présence d’acier et d’argile à 90°C conduit à la formation de magnétite, sidérite, ferrosilicates, silice pure, sulfures de fer (pyrite, troïlite, pyrrhotite etmackinawite), calcite, apatite, powellite et silicates de Mg. Les résultats de modélisation sont en bon accord avec les données expérimentalesThe SON68 glass is initially altered in dynamic mode under silica rich COx water (42 mg/L) at pH8, high S/V ratio (14000 m⁻¹) and at 35, 50 and 90°C. The results showed that the glass alteration seems to be governed by both diffusion and surface reaction process. The residual rate at 90°C is around 10-4 g.m⁻².d⁻¹. The activation energy is about 70 kJ.mol⁻¹. The dissolution /precipitation and hydrolysis/condensation mechanisms are responsible for the development of the alteration layer. Mg silicates and calcites precipitate at 35 and 50°C, the same phases in addition to powellite and apatite precipitate at 90°C. The results predicted by the model reproduce well experimental data. The glass is then hydrated at temperatures ranging from 35 to 125°C and relative humidity values (RH) between 92 an 99.9%. The glass hydration increases with the temperature and RH, the hydration energy is about 34.2 kJ.mol⁻¹. The alteration layers thicknesses vary between 0.3μm at 35°C and 5μm at 125°C. The alteration layer is depleted in (B, Li, Na) and enriched in (Si, Al, Fe, Zn and Ni). The secondary phases are calcite, powellite, apatite and tobermorite in adition to a hydration gel. The effect of near field materials on the ²⁹Si doped SON68 glass alteration was studied. The presence of steel increases the pH and decreases the Si and Mo concentrations without changing the overall rate of glass corrosion. The Si is retained on the steel corrosion products, its concentration in solution seems to be controlled by the clay dissolution. The glass corrosion in the presence of steel and clay at 90°C leads to the formation of magnetite, siderite, ironsilicates, pure silica, iron sulphur (pyrite, troilite,pyrrhotite and mackinawite), calcite, apatite, powellite and Mg silicates. The modelling results agree well with the experimental data
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Cormier, Daniel. "Repair of Conductive Layer on Carbon Fibre Reinforced Polymer Composite with Cold Gas Dynamic Spray." Thesis, Université d'Ottawa / University of Ottawa, 2015. http://hdl.handle.net/10393/33160.
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Carbon fibre reinforced composites are known for their high specific strength-to-weight ratio and are of great interest to the aerospace industry. Incorporating these materials into the fuselage, like in Boeing's 787 "Dreamliner", offers considerable weight reduction which increases flying efficiency, and reduces the cost of flying.
In flight, aircraft are often subject to lightning strikes which, in the case of composites, can result in localized melting given the high resistive nature of the material. Aerospace carbon fibre composites often incorporate a metallic mesh or foil within the composite layers to dissipate the electrical charge through the large aircraft. The damage to the aircraft is minimized but not always eliminated. This research aims to elaborate a practical technique to deposit thin layers of conductive material on the surface of aerospace grade composites. Using Cold Gas Dynamic Spray (CGDS), such coatings could be used to repair damaged components.
An experimental research approach was used to develop metallic coated composites. Using the CGDS equipment of Centerline (SST-P), specific parameters (such as gas temperature and stagnation pressure) were determined for each type of metallic coating (tin-based & copper-based). The use of bond coats was explored in order to attain the desired coatings. Once optimized, these coatings were evaluated with respect to their corrosive, adhesive, and electrical properties following industry standards.