Novelis Global Technology Centre (NGTC) in Kingston, Ontario have been developing a relatively new technology known as Novelis Fusion™ Technology, which is a new variant of the traditional direct chill (DC) casting process that allows co-casting of multi-layered composite aluminum alloy ingots. One of the first steps in this development program is to create a mathematical model of conventional DC casting and validate it through experimentation before proceeding to the next step of modeling, designing, testing, and experimenting with the co casting process. The focus of this document is on the design of the experiments, measurement technique, and analysis of the experimental results to be used to validate the models for conventional DC casting. A series of experiments was conducted using a lab scale caster using a 95 mm × 227 mm rectangular mould available at the Novelis Global Technology Centre in Kingston, Ontario. AA3003, AA6111, and AA4045 aluminum alloys were chosen for this study since these aluminum alloys are commonly used in clad products. Two series of experiments were performed to investigate the effect of casting parameters on the solidification and cooling of the ingots such as casting speed, water flow rate, and the superheat of the molten aluminum. A set of seven thermocouples were embedded in the ingot during the cast to capture the thermal history of the ingot. Melt poisoning with a zinc rich alloy was also performed as an independent method of determining the sump depth and shape. Experienced gained from the first series of experiments allowed improvements to be made to the experiment design for the second series of experiments. Thermocouples must be supported so they are not pushed out of position by the jet of molten aluminum entering the mould. Grounded thermocouples of at least 1.5 mm in diameter were recommended to survive the high temperatures of the molten aluminum. Knowledge gained from the experiments of the conventional DC caster allowed design and development of an experimental co-caster mould that will be useful for future research at NGTC. Melt poisoning and thermocouples were complementary measurement methods that should be used together. In all three alloys, the liquidus sump profile generated by the thermocouple implants correlated well with the etched sumps of the melt poisoned ingots. Primary and secondary water flow rates beyond 1.79 L/s and increasing the superheat by 30°C did not have significant effect of the cooling rate with solidified ingots, but all casting experiments showed that the thermal histories and sump profiles were very sensitive to the casting speed. The sump depth increased with increasing casting speed in all casting experiments. The sump depth increased directly proportionally to the Péclet number and the sump depth could be predicted using a linear regression model by calculating the Péclet number. The formation of remelting bands were seen in the surface of the AA3003 and AA4045 ingots, but were not apparent in the AA6111 ingots. A fast Fourier transform performed on the data obtained from the thermocouples that were inserted in the mould wall showed that remelting occurred at regular intervals and that the frequency increased with casting speed. The thermocouples in the mould also indicated that AA6111 had a higher rate of heat transfer than AA3003 or AA4045. The AA6111 ingots had a higher rate of heat transfer in the mould than for the other alloys. This was evidence that there was a smaller air gap formation between the ingot and the mould in AA6111. This research on the effects of casting parameters on DC cast ingots made using the three alloys, AA3003, AA6111, and AA4045, is beneficial in the development of a design of an experimental lab-scale co-caster for validation of a computational fluid dynamics (CFD) model of the Fusion™ Technology process.

The present study aims to explore flow behavior in the mold during centrifugal casting process by numerical simulations. The theoretical model comprises two groups of steady conservation equations of mass and momentum and the governing equations are solved numerically with k-£` turbulence model and iterative SIMPLE(Semi-Implicit for Pressure-Linked Equations) algorithm to determine the flow property. The numerical results indicate that the melt liquids of titanium compound metal flow near the walls in the high rotation rate. With the high rotation rate, the outflow velocity is rapid. The products depend on the flow of the melt liquids. The flow is rapid, the filled process is quick, and the temperature is uniform. But if the flow is slow, the temperature is not uniform in the filled process. Therefore, the products may result in faults. When the rotation rate is up to 50 rpm, the melt liquids flow near the walls with the affect of centrifugal force. The velocity is larger than the velocity with zero rotation rate . Thus the flow with rotation rate can help to fill quickly, and reduce the temperature loss.

A direct historical approach is used in this thesis to document the lost wax casting technique as currently practiced by indigenous metallurgists in northeastern Thailand. The smiths observed at Ban Pba Ao, Ubon Ratchathani Province are the last practicing members of a bronze working tradition that has been in continuous operation at the village for two centuries. An account of the processes used to create bronze bells is provided. Of particular significance is the fact that the yard in which casting activities are performed did not receive clean up operations following the bells production. As a result, hearths, bowl furnaces, crucibles and fragments of clay moulds are left scattered about the yard. These materials accumulating in one location would eventually create a mound of cultural debris. The discarded materials from the lost wax casting process as practiced at Ban Pba Ao provide considerable insight into what might be found in the stratigraphy of Peninsular Southeast Asian prehistoric sites that were involved in the production of bronze objects. The study concludes that attention needs to be paid to the stratigraphic sequences from which bronze artifacts are extracted, rather than relying on the artifacts to determine the type of process used in their manufacture.

Τα τελευταία χρόνια παρατηρείται μια ραγδαία αύξηση της χρήσης των προηγμένων κεραμικών σε τεχνολογικές εφαρμογές και στην παρασκευή διαφόρων τεχνολογικών- προϊόντων, λόγω των σημαντικών ιδιοτήτων που παρουσιάζουν. Επιπλέον, μεγάλο ενδιαφέρον παρουσιάζει και ο συνδυασμός κεραμικών με μέταλλα τόσο σε τεχνικές συνένωσης όσο και στην παρασκευή σύνθετων υλικών κεραμικού μετάλλου (κεραμομεταλλικών) με πυροσυσσωμάτωση (sintering) παρουσία ή μη ρευστής μεταλλικής φάσης, με βελτιωμένες ιδιότητες. Σημαντικό ρόλο στη μικροδομή και τις ιδιότητες των υλικών αυτών παίζουν τα φαινόμενα διαβροχής και η ισχύς του δεσμού που αναπτύσσεται στη διεπιφάνεια κεραμικού μετάλλου, καθώς και οι επιφανειακές και διεπιφανειακές ενέργειες των υλικών η των συστημάτων των υλικών που βρίσκονται σε επαφή. Σκοπός της παρούσας εργασίας είναι η μελέτη της συνάφειας και των διεπιφανειακών ιδιοτήτων σε συστήματα κεραμικών οξειδίων σε επαφή με ρευστές μεταλλικές οάσεις και ιδιαίτερα σε συστήματα του κεραμικού οξειδίου του δημητρίου σε επαφή με ρευστά μέταλλα. Στο πρώτο μέρος της εργασίας, στα πλαίσια του προγράμματος ΠΕΝΕΔ 2001 με τίτλο «ΧΥΤΕΥΣΗ ΑΚΡΙΒΕΙΑΣ: Πυροσυσσωμάτωση (sintering) κεραμικών καλουπιών και διεπιφανειακές τους αλληλεπιδράσεις σε επαφή με ρευστά κράματα μετάλλων», πραγματοποιήθηκε μία μελέτη της παραγωγικής διαδικασίας παρασκευής μεταλλικών αντικειμένων με τη μέθοδο της χύτευσης ακριβείας, η οποία οδήγησε στη βελτιστοποίηση των συνθηκών στα στάδια όπου είναι δυνατόν να δημιουργηθούν και να αναπτυχθούν ρωγμές στο κεραμικό κέλυφος (αποκέρωση. έψηση, χύτευση), ενώ επιπλέον διερευνήθηκαν οι διεπιφανειακές αλληλεπιδράσεις κεραμικού κελύφους ρευστών μεταλλικών φάσεων κατά τη χύτευση. οι οποίες επηρεάζουν το σχήμα και τις διαστάσεις του τελικού προϊόντος. Στο δεύτερο μέρος της εργασίας, προσδιορίσθηκε η θερμοκρασιακή εξάρτηση της επιφανειακής ενέργειας και της ενέργειας ορίων κόκκων του πολυκρυοσταλλιικού οξειδίου του δημητρίου (CeO2) σε υψηλές θερμοκρασίες, καθώς και η διεπιφανειακή ενέργεια και το έργο συνάφειας σε συστήματα του κεραμικού CeO2 σε επαφή με ρευστό Cu, με εφαρμογή της τεχνικής εξισορρόπησης πολλαπλών φάσεων. Παράλληλα, από τη μελέτη της ανάπτυξης εσοχών στα όρια κόκκων του πολυκρυσταλλικού CeO2 προέκυψε ότι ο κυρίαρχος μηχανισμός μεταφοράς μάζας κατά τη θερμική διάβρωση του κεραμικού είναι η επιφανειακή διάχυση και προσδιορίσθηκε ο αντίστοιχος συντελεστής επιφανειακής διάχυσης στο θερμοκρασιακό διάστημα 1473-1773Κ. Χρησιμοποιώντας τη μέθοδο αποτυπώματος σκληρόμετρου υπολογίσθηκε ο συντελεστής δυσθραυστότητας του κεραμικού CeO2 και προσδιορίσθηκε η επιφανειακή ενέργεια του οξειδίου του δημητρίου σε θερμοκρασία δωματίου. Η συνεισφορά των ασθενών δiαμοριακών δυνάμεων Van der Waals (πολικών και διασποράς) στην επιφανειακή ενέργεια του πολυκρυσταλλικού CeO2 σε θερμοκρασία δωματίου προσδιορίσθηκε από πειράματα διαβροχής του κεραμικού σε επαφή με διάφορα πολικά υγρά. Με χρήση ενός συνδυασμού βιβλιογραφικών και πειραματικών δεδομένων σχετικά με τις επιφανειακές ενέργειες και τις γωνίες επαφής σε συστήματα κεραμικών οξειδίων σε επαφή με διάφορα ρευστά μέταλλα εξήχθη μια εμπειρική σχέση η οποία, σε δεδομένη θερμοκρασία, συνδέει άμεσα την επιφανειακή ενέργεια των στερεών οξειδίων με την επιφανειακή ενέργεια των ρευστών μετάλλων και τη γωνία επαφής. Μέσω αυτής της σχέσης είναι δυνατή η εκτίμηση της επιφανειακής ενέργειας ενός στερεού οξειδίου ή της γωνίας επαφής σε μη διαβρέχοντα και μη αντιδρώντα συστήματα κεραμικών οξειδίων ρευστών μετάλλων, όπου η μερική διαλυτοποίηση οξυγόνου του κεραμικού μέσα στο ρευστό μέταλλο δεν επηρεάζει τις διεπιφανειακές ιδιότητες του συστήματος. Η σχέση αυτή επαληθεύθηκε για διάφορα συστήματα κεραμικών οξειδίων ρευστών μετάλλων και επιπλέον εφαρμόσθηκε για τον προσδιορισμό της επιφανειακής ενέργειας του πολυκρυσταλλικού οξειδίου του δημητρίου από τα αποτελέσματα πειραμάτων διαβροχής στο σύστημα CeO2 σε επαφή με ρευστό Sn. / Engineering ceramics are being considered for technological applications due to their strong and sometimes unique properties. The pronounced evolution in the quality of advanced engineering ceramics has stimulated interest in the combination of ceramics with metallic phases for ceramic joining purposes or for the manufacturing of composite materials with enhanced properties. In all this cases the surface and interfacial energies of the materials or the materials systems used, as well as the wetting and bonding phenomena at the interface, play a key role in obtaining materials with the desired properties and microstructure. The aim of the present work is the study of adhesion and interfacial properties in ceramic oxide / liquid metal systems and particularly in systems of polycrystalline ceria (CeO2) in contact with liquid metals. At the first part of this work, in framework of the PENED 2001 programs, the investment casting process was studied at the stages where fracture of the ceramic shell can occur (dewaxing, sintering, casting of liquid metal) in order to optimize the conditions of the production procedure. Moreover, the interactions at the ceramic shell / liquid metal interface which can affect the shape and dimensions of the final cast product were investigated. At the second part of the present work the multiphase equilibration technique has been used for the determination of the equilibrium angles that develop at the interphase boundaries of a solid-liquid-vapor system and the surface and interfacial energies in polycrystalline CeO2 and CeO2/Cu systems were determined in argon atmosphere at the temperature range 1473-1773 K. Linear temperature functions were obtained by extrapolation, for the surface energy and the grain-boundary energy of the ceramic, as well as for the interfacial energy and the work of adhesion of the CeO2/Cu system. Grain-boundary grooving studied on polished surfaces of CeO2 annealed in argon atmosphere at the same temperature range has shown that surface diffusion was the dominant mechanism for the mass transport and the surface diffusion coefficient has been estimated. Engineering ceramics are being considered for technological applications due to their strong and sometimes unique properties. The pronounced evolution in the quality of advanced engineering ceramics has stimulated interest in the combination of ceramics with metallic phases for ceramic joining purposes or for the manufacturing of composite materials with enhanced properties. In all this cases the surface and interfacial energies of the materials or the materials systems used, as well as the wetting and bonding phenomena at the interface, play a key role in obtaining materials with the desired properties and microstructure. The aim of the present work is the study of adhesion and interfacial properties in ceramic oxide / liquid metal systems and particularly in systems of polycrystalline ceria (CeO2) in contact with liquid metals. At the first part of this work, in framework of the PENED 2001 programs, the investment casting process was studied at the stages where fracture of the ceramic shell can occur (dewaxing, sintering, casting of liquid metal) in order to optimize the conditions of the production procedure. Moreover, the interactions at the ceramic shell / liquid metal interface which can affect the shape and dimensions of the final cast product were investigated. At the second part of the present work the multiphase equilibration technique has been used for the determination of the equilibrium angles that develop at the interphase boundaries of a solid-liquid-vapor system and the surface and interfacial energies in polycrystalline CeO2 and CeO2/Cu systems were determined in argon atmosphere at the temperature range 1473-1773 K. Linear temperature functions were obtained by extrapolation, for the surface energy and the grain-boundary energy of the ceramic, as well as for the interfacial energy and the work of adhesion of the CeO2/Cu system. Grain-boundary grooving studied on polished surfaces of CeO2 annealed in argon atmosphere at the same temperature range has shown that surface diffusion was the dominant mechanism for the mass transport and the surface diffusion coefficient has been estimated.

Novelis Global Technology Centre (NGTC) in Kingston, Ontario have been developing a relatively new technology known as Novelis Fusion™ Technology, which is a new variant of the traditional direct chill (DC) casting process that allows co-casting of multi-layered composite aluminum alloy ingots. One of the first steps in this development program is to create a mathematical model of conventional DC casting and validate it through experimentation before proceeding to the next step of modeling, designing, testing, and experimenting with the co casting process. The focus of this document is on the design of the experiments, measurement technique, and analysis of the experimental results to be used to validate the models for conventional DC casting. A series of experiments was conducted using a lab scale caster using a 95 mm × 227 mm rectangular mould available at the Novelis Global Technology Centre in Kingston, Ontario. AA3003, AA6111, and AA4045 aluminum alloys were chosen for this study since these aluminum alloys are commonly used in clad products. Two series of experiments were performed to investigate the effect of casting parameters on the solidification and cooling of the ingots such as casting speed, water flow rate, and the superheat of the molten aluminum. A set of seven thermocouples were embedded in the ingot during the cast to capture the thermal history of the ingot. Melt poisoning with a zinc rich alloy was also performed as an independent method of determining the sump depth and shape. Experienced gained from the first series of experiments allowed improvements to be made to the experiment design for the second series of experiments. Thermocouples must be supported so they are not pushed out of position by the jet of molten aluminum entering the mould. Grounded thermocouples of at least 1.5 mm in diameter were recommended to survive the high temperatures of the molten aluminum. Knowledge gained from the experiments of the conventional DC caster allowed design and development of an experimental co-caster mould that will be useful for future research at NGTC. Melt poisoning and thermocouples were complementary measurement methods that should be used together. In all three alloys, the liquidus sump profile generated by the thermocouple implants correlated well with the etched sumps of the melt poisoned ingots. Primary and secondary water flow rates beyond 1.79 L/s and increasing the superheat by 30°C did not have significant effect of the cooling rate with solidified ingots, but all casting experiments showed that the thermal histories and sump profiles were very sensitive to the casting speed. The sump depth increased with increasing casting speed in all casting experiments. The sump depth increased directly proportionally to the Péclet number and the sump depth could be predicted using a linear regression model by calculating the Péclet number. The formation of remelting bands were seen in the surface of the AA3003 and AA4045 ingots, but were not apparent in the AA6111 ingots. A fast Fourier transform performed on the data obtained from the thermocouples that were inserted in the mould wall showed that remelting occurred at regular intervals and that the frequency increased with casting speed. The thermocouples in the mould also indicated that AA6111 had a higher rate of heat transfer than AA3003 or AA4045. The AA6111 ingots had a higher rate of heat transfer in the mould than for the other alloys. This was evidence that there was a smaller air gap formation between the ingot and the mould in AA6111. This research on the effects of casting parameters on DC cast ingots made using the three alloys, AA3003, AA6111, and AA4045, is beneficial in the development of a design of an experimental lab-scale co-caster for validation of a computational fluid dynamics (CFD) model of the Fusion™ Technology process.

Master of Science in Dentistry / This work was digitised and made available on open access by the University of Sydney, Faculty of Dentistry and Sydney eScholarship . It may only be used for the purposes of research and study. Where possible, the Faculty will try to notify the author of this work. If you have any inquiries or issues regarding this work being made available please contact the Sydney eScholarship Repository Coordinator - ses@library.usyd.edu.au

Thesis (M.S.)--Ohio University, March, 1988. / Title from PDF t.p.

Thesis(M.S.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (M.App.Sc.) - Carleton University, 2002. / Includes bibliographical references (p. 102-104). Also available in electronic format on the Internet.

Thesis (M.S.)--Ohio University, June, 1991. / Title from PDF t.p.