The aim of this study was to investigate a zirconia-matrix reinforced with metal powder (chromium, iron and stainless steel (AISI 316)) including processing, characterisation, and measurements of their properties (mechanical, thermal and electrical). Zirconia stabilised with 5.4 wt% Y₂0₃ (3 mol%) as the matrix was first studied and followed by an investigation of the effects of metal reinforcement on zirconia-matrix composites. Monolithic zirconia was pressureless sintered in air and argon to observe the effect of sintering atmosphere, while the composites were pressureless sintered in argon to avoid oxidation. Sintering was carried out at various temperatures for 1 hour and 1450°C was chosen to get almost fully dense samples. The density of the fired samples was measured using a mercury balance method and the densification behaviour was analysed using TMA (Thermo-mechanical Analysis). The TMA was also used to measure the coefficient of thermal expansion. In addition, thermal analysis using DTA and TGA was performed to observe reactions and phase transformations. Moreover, optical microscopy and SEM were used to observe the microstructures, XRD was used for phase identification, and mechanical properties including Vickers hardness, fracture toughness and bending strength were measured. The effect of thermal expansion mismatch on thermal stresses was also analysed and discussed. Finally, thermal diffusivity at room temperature and as a function of temperature was measured using a laser flash method, and to complete the study, electrical conductivity at room temperature was also measured. The investigation of monolithic zirconia showed that there was no significant effect of air and argon atmosphere during sintering on density, densification behaviour, microstructures, and properties (mechanical and thermal). Furthermore, the results were in good agreement with that reported by previous researchers. However, the presence of metal in the composites influenced the sintering behaviour and the densification process depends on the metal stability, reactivity, impurity, particle size, and volume fraction. Iron reacted with yttria (zirconia stabiliser), melted and reduced the densification temperature of monolithic zirconia, while chromium and AISI 316 did not significantly affect the densification temperature and did not react with either zirconia or yttria. AISI 316 melted during fabrication. Moreover, all of the metal reinforcements reduced the final shrinkage of monolithic zirconia. In terms of properties, the composites showed an increase in fracture toughness, and a reduction in Vickers hardness and strength with increasing reinforcement content. In addition, the thermal diffusivity of the composites showed an increase with reinforcement content for the zirconia/chromium and zirconia/iron composites, but not for the zirconia/AISI 316 composites due to intrinsic mircocracking. Furthermore, all the composites became electrically conductive with 20 vol% or more of reinforcement. It has been concluded that of those composites the zirconia/chromium system may be considered as having the best combination of properties and although further development is needed for such composites to be used in real applications in structural engineering, the materials may be developed based on these findings. In addition, these findings may be used in development of ceramic/metal joining as composite interlayers are frequently used.

1 Abstract Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of: Pharmaceutical Technology Consultant: Doc. PharmDr. Zdeňka Šklubalová, Ph.D. Student: Barbora Jonášová Title of Thesis: Flow equation. Sorbitol and magnesium stearate. This thesis describes influence of the addition of magnesium stearate on bulk properties to size fractions of sorbitol for direct compression in the range 0,100 - 0,346 mm. I studied influence of particle size and the size of the opening hopper to the gravitational speed of flow. The dependence of the flow rate (g/s) on the size of the opening conical hopper was modeled by the squares equation Jones-Pilpel. No significant effect of addition of magnesium stearate 0,5% and 1,0% for the exponent equation was found. This model allows the re-estimation of the flow rate with an accuracy about 11% for the size fraction regardless of the amount of added magnesium stearate; for polydisperse MS200 is the deviation of the experimentally determined values of the flow rate of approximately 19%.

Charles University in Prague, Faculty of Pharmacy in Hradci Králové Department of: Pharmaceutical technology Consultant: doc.PharmDr.Zdeňka Šklubalová, Ph.D Student: Hana Čermáková Title of Thesis: Flow equation. Sorbitol In this diploma thesis, the granulometric, bulk and consolidation properties of sorbitol for direct compression are studied. The effect of particle size on bulk and tapped density, angle sprinkles and the flow rate through the model conical hopper with a different orifice diameter are examined. The relationship of the flow rate (g/s) of particle size fractions on the orifice diameter is modelled by the Jones-Pilpel equation with the accuracy of the flow rate prediction approximately 10 %.

The family of phases Li3M2XO6 (M = Mg, Co, Ni; X = Nb, Ta, Sb) has a novel rock salt superstructure in which the X cations occupy one set of octahedral sites with the Li and M cations distributed over three octahedral sites in a non-random manner. The non-random site occupancies vary depending on M and X and appear to be an equilibrium feature of the structure. Li3Ni2NbO6 undergoes a continuous order-disorder transition and can be doped with Cr3+ by a number of mechanisms to give either ordered or disordered rock salt structures. The phase diagram of the solid solutions of general formula Li3-xNi2-xCr xNbO6 has been determined and shows solid solutions for both ordered and disordered polymorphs with a transition zone that is 200-300A°C wide. Li3Ni2TaO6 and Cr-doped Li3Ni 2NbO6 compositions are modest semiconductors. The alpha and beta structures of polymorphic Li2CuZrO 4 have been determined. Both structures are ordered rock salt with unique sites for Zr and one set of Li atoms; in the alpha polymorph, Cu and the other set of Li atoms are partially ordered over two sites, but in beta-Li 2CuZrO4 all cations are uniquely ordered. In the phase transition from alpha-Li2CuZrO4 to the low temperature beta polymorph, the CuO6 octahedra, which predominantly corner-share in alpha, become edge-sharing. Magnetic susceptibility data indicate that, in both polymorphs, there are both ferromagnetic and antiferromagnetic interactions. The predominant interactions in the alpha phase are antiferromagnetic whereas in the beta polymorph, they are ferromagnetic. Conductivity measurements show that beta-Li2CuZrO4 is a modest semiconductor.

M.Tech. / The study into the effect of additives used in nickel powder precipitation by sodium hypophosphite has been carried out. Reduction experiments were conducted in a 10 L stainless steel batch reactor fitted with 3 baffles, 4-bladed axial impeller, heating element, thermocouple and thermostat. Nickel seed was used to initiate the reduction process, sodium hypophosphite was used as a reducing agent, and ammonia solution was used to adjust pH, poly(ethylene-comaleic anhydride) (EMA) was used as the first additive and poly(acrylic acid) (PA) as the second additive. Reduction experiments were conducted at a temperature between 60oC to 70oC, pH around 8 and a reaction time of 3 min. Synthetic nickel sulfate solution and sodium hypophosphite solutions at concentration of 0.5 g/L were used as nickel feed solution and reducing agent, respectively. Additives were investigated at high and low concentrations of 5 mg/L and 10 mg/L. The effect of additives on reduction behavior of nickel was investigated by studying the evolution of the volume distribution, moments, specific surface area, and rate of reduction and purity of the powder product. EMA was found to be a growth promoter and PA was found to be a growth inhibitor. The highest reduction rate was observed in the presence of EMA and the lowest in the presence of PA. The SEM micrographs of the powder obtained in the presence of EMA and PA showed that the powder was spherical shaped, open, dentritic and more porous compared with that of the seed particles. Both additives were found to increase the pore size of the powder particles. The presence of particle fragments observed in the scanning electron micrographs confirmed breakage as one of the major particulate process. The addition of additives significantly affected the volume distribution at lower concentrations of 5 mg/L. The extent of aggregation increased with increasing dosages of PA and decreased with increasing dosages of EMA. The highest specific surface area was obtained in the presence of 5 mg/L of EMA.

Chong, Kam Cheong. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references. / Text in English; abstract also in Chinese. / Chong, Kam Cheong. / ACKNOWLEDGMENT --- p.i / ABSTRACT --- p.ii / 摘要 --- p.iv / Table of contents --- p.v / Chapter 1 --- Introduction / Chapter 1.1 --- Metal Matrix Composites / Chapter 1.1.1 --- Background --- p.1-1 / Chapter 1.1.2 --- Some metallic matrix materials --- p.1-2 / Chapter 1.1.2.1 --- Aluminum alloys --- p.1-2 / Chapter 1.1.2.2 --- Titanium alloys --- p.1-3 / Chapter 1.1.3 --- Different kinds of reinforcements --- p.1-3 / Chapter 1.2 --- Conventional fabrication Methods --- p.1-5 / Chapter 1.2.1 --- Primary liquid phase processing --- p.1-5 / Chapter 1.2.1.1 --- Squeeze casting --- p.1-5 / Chapter 1.2.1.2 --- Spray deposition --- p.1-5 / Chapter 1.2.1.3 --- Slurry casting --- p.1-5 / Chapter 1.2.1.4 --- In Situ processing --- p.1-6 / Chapter 1.2.2 --- Primary solid state processing --- p.1-6 / Chapter 1.2.2.1 --- Physical vapour deposition (PVD) --- p.1-6 / Chapter 1.2.2.2 --- Powder blending and sintering --- p.1-7 / Figures for chapter 1 --- p.1-9 / Tables for chapter 1 --- p.1-14 / References --- p.1-15 / Chapter 2 --- Powder metallurgy --- p.2-1 / Chapter 2.1 --- Introduction --- p.2-1 / Chapter 2.2 --- Fabrication of metal matrix-particulate composites --- p.2-2 / Chapter 2.3 --- Our motivation --- p.2-4 / Figures for chapter 2 --- p.2-5 / References --- p.2-7 / Chapter 3 --- Effects of sintering in processing of metal matrix composites --- p.3-1 / Chapter 3.1 --- Introduction of sintering processing --- p.3-1 / Chapter 3.1.1 --- Solid state sintering --- p.3-2 / Chapter 3.1.2 --- Liquid state sintering --- p.3-5 / Chapter 3.1.3 --- Sintering in metal matrix composites(reactive sintering) --- p.3-7 / Figures for chapter 3 --- p.3-11 / Reference --- p.3-14 / Chapter 4 --- Experiments --- p.4-1 / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2 --- Methodology --- p.4-3 / Chapter 4.2.1 --- High temperature furnace experiment --- p.4.3 / Chapter 4.2.2 --- Arc-melting furnace experiment --- p.4-4 / Chapter 4.3 --- Sample preparations --- p.4-4 / Chapter 4.3.1 --- Sample requirements --- p.4-4 / Chapter 4.3.2 --- Sample milling --- p.4-6 / Chapter 4.3.3 --- Cold pressing --- p.4-6 / Chapter 4.3.4 --- Annealing conditions for high-temperature furnace --- p.4-7 / Chapter 4.3.4.1 --- Different sintering temperatures --- p.4-7 / Chapter 4.3.4.2 --- Different sintering duration --- p.4-8 / Chapter 4.3.5 --- Sample conditions in arc-melting furnace --- p.4-8 / Chapter 4.4 --- Instrumentation --- p.4-10 / Chapter 4.4.1 --- Arc-melting furnace --- p.4-10 / Chapter 4.4.2 --- Vickers hardness tester --- p.4-11 / Chapter 4.4.3 --- X-Ray powder diffractometer (XPD) --- p.4-13 / Chapter 4.4.4 --- Scanning electron microscopy & energy dispersive x-ray analysis --- p.4-15 / References --- p.4-18 / Chapter 5 --- Results / Chapter 5.1 --- High-temperature furnace --- p.5-1 / Chapter 5.1.1 --- XPD results --- p.5-1 / Chapter 5.1.2 --- Different sintering temperatures in 10 weight percent of Cr203 - A1 samples with 1 hour sintering time --- p.5-2 / Chapter 5.1.3 --- Different sintering temperatures in 15 weight percent of Cr203 一 A1 samples with 1 hour sintering time --- p.5-6 / Chapter 5.1.4 --- Different sintering temperatures in 20 weight percent of Cr203 ´ؤ A1 samples with 1 hour sintering time --- p.5-10 / Chapter 5.1.5 --- Different sintering temperatures in 30 weight percent of Cr203 ´ؤ A1 samples with 1 hour sintering time --- p.5-13 / Chapter 5.1.6 --- Different sintering time for 10 weight percent of Cr203 ´ؤ A1 samples at 1100°C sintering temperature --- p.5-19 / Chapter 5.1.7 --- Different sintering time for 15 weight percent of Cr203 ´ؤ A1 samples at 1100°C sintering temperature --- p.5-21 / Chapter 5.2 --- Arc-melting furnace --- p.5-24 / Chapter 5.2.1 --- XPD results --- p.5-24 / Chapter 5.2.2 --- Samples that were melted in arc-melting furnace --- p.5-25 / Chapter 5.2.3 --- Powder samples that were melted in arc-melting furnace --- p.5-28 / Figures for chapter 5 --- p.5-30 / References --- p.5-55 / Chapter 6 --- Discussions --- p.6-1 / Chapter 6.1 --- Chemical reactions --- p.6-1 / Chapter 6.2 --- Sintering --- p.6-6 / Chapter 6.2.1 --- Conditions for having larger Al13Cr2 intermetallic compound --- p.5-7 / Chapter 6.3 --- Vickers hardness results --- p.6-10 / Chapter 6.4 --- Comparisons between the two furnace results --- p.6-12 / Chapter 6.4.1 --- Cooling rates --- p.6-12 / Chapter 6.4.2 --- Volume fraction of all the intermetallic compounds --- p.6-14 / Chapter 6.4.3 --- Pore sizes --- p.6-15 / Chapter 6.4.4 --- Vickers hardness --- p.6-16 / References --- p.6-17 / Chapter 7 --- Conclusions and suggestions for further studies --- p.7-1 / BIBLIOGRAPHY

For additive manufacturing, research has shown that the chemistry and microstructural properties of the feedstock powder can significantly affect the properties of the consolidated material. Thermal treatment and recycling parameters for powders used in both solid and liquid state processes can further affect the microstructure and properties of the consolidated parts. Understanding the powder microstructure and effects of powder pre-treatment can aid in optimizing the properties of the final consolidated part. This research proposes a method for the characterization and optimization of powder pre-processing thermal parameters using aluminum alloy powder as examples. Light microscopy, electron microscopy, and hardness were used to evaluate each condition.

En el presente trabajo se estudia el método denominado powder-in-tube(PIT), para la elaboración y fabricación de cintas y cables superconductores; empleando matrices en forma de tubitos de plata (Ag) peruana conteniendo el compuesto superconductor diboruro de magnesio(MgB2) y tratado térmicamente a diferentes temperaturas. En la primera fase, se caracterizó la composición de las matrices de Ag peruana, elaboradas artesanalmente, empleando la técnica de Fluorescencia de Rayos X (FRX), obteniendo una pureza de 63,8% de Ag y un 36,2% compuesto de Fe, Cu y Zn. Asimismo, se caracterizó el compuesto MgB2, adquirido a la compañía americana Alfa Aesar, empleando técnicas de Difracción de Rayos X (DRX) con refinamiento Rietveld y Espectroscopía Raman. Los resultados de DRX muestran como única fase al MgB2 con PDF174−0972, mediante el refinamiento Rietveld se corroboró la pureza de 99% indicado en la ficha técnica de Alpha Aesar, el espectro Raman mostró la presencia del modo E2g a la frecuencia de588 cm−1 y el pico de densidad de estados de fonones (PDOS) a la frecuencia de 740cm−1. Luego se realizó el acondicionamiento de las muestras por el esquema PIT para realizar los tratamientos térmicos a 800,850 y900◦C. Luego se cortó la matriz de manera longitudinal para remover el núcleo superconductor y sea analizado por DRX, Microscopía Electrónica de Barrido(MEB)y Espectroscopía Raman, para analizar si la Ag había contaminado al MgB2 o si alguna de las propiedades del MgB2 habían sido afectadas. De los resultados de DRX en los tres tratamientos térmicos la fase principal resultó ser el MgB2,en el tratamiento de 800◦C se obtuvo como fase secundaria al óxido de magnesio (MgO) con PDF79−612, para el tratamiento a 850◦C se obtuvo como fases secundarias al MgO y al tetraboruro de magnesio (MgB4) con PDF73−1014 y para el tratamiento a 900◦C resultó como fase secundaria el MgO, además se realizó la estimación del tamaño medio de los cristalitos resultando 262.81, 254.68 y 406.79 nm respectivamente. De los análisis por MEB se mostró la conectividad que van adquiriendo los granos conforme se incrementa la temperatura, es decir, se puede observar la formación de aglomerados; además para el tratamiento a 800◦C se estimó el tamaño medio de partícula 125,2±4 µm. De los análisis de espectroscopía Raman se identificó para las tres temperaturas el modoE2 g (modo activo Raman del MgB2) a las frecuencias de 600cm−1, 610cm−1 y 608cm−1 respectivamente. La matriz de Ag fue analizada mediante Microscopía Electrónica de Barrido de Emisión de Campo (FE-SEM siglas en ingles), mostrando para las tres temperaturas que no ha sucesido ningún proceso de difusión del MgB2 en la Ag y que únicamente la matriz cumplió el papel de contenedor. / Tesis

Frequency domain photon migration consists of launching an intensitymodulated near-infrared light into the powder medium and measuring the amplitude, mean-intensity, and phase shift of detected intensity modulated light for extracting both the isotropic scattering and absorption coefficients of the powder bed. The dependence of absorption coefficient upon the active pharmaceutical ingredient (API) concentration of powder blend enables FDPM to monitor blending homogeneity. The volume sampled by FDPM in powder blend was investigated through a designed heterogeneity experiments. A model which describes the visitation probability of a local region by migrating photons was developed to theoretically determine the sampled volume of FDPM in terms of signal-to-noise ratio. The applicability of FDPM in monitoring blending homogeneity was directly verified by measuring the API contents in a series of industrial samples, which were retrieved from various locations at various times in an actual pharmaceutical blending process. The FDPM measurement results were consistent with the traditional analysis using high performance liquid chromatography. The homogeneity evolution revealed through FDPM agreed with the well-established first order model of blending. A simulation method was developed which consisted of (i) dynamic simulation for generating the powder structure; (ii) the completely-randommixture model for predicting the spatial distribution of API particles within the powder bed; and (iii) Monte Carlo simulation for tracking photon trajectories within the powder bed. The simulation of photon migration in powder blend revealed that while both the isotropic scattering and absorption coefficients increased with the solid-volume fraction, the ratio of absorption coefficient to the isotropic scattering coefficient is (i) independent of the solid-volume fraction; (ii) linearly dependent upon the API concentration; and (iii) appropriate for monitoring the powder blending homogeneity under simultaneous variations of solid-volume fraction and API content. Finally, a rigorous two-speed diffusion equation for describing photon migration in powders was derived from the two-group radiative transfer equations and the analytical expression of the isotropic scattering coefficient was provided. The theoretical results agreed well with the experimental measurements in resin powder media and resin suspensions.

Thesis (M.S.)--Drexel University, 2003. / Includes abstract. Includes bibliographical references (leaves 57-59).