Academic literature on the topic 'Phase Equlibria Diagrams'

The thermodynamic description of the Ti-U binary system is obtained by the CALPHAD method using Thermo-Calc software and based on the estimated thermodynamic properties using ion-bonding model and Miedema model as well as the experimental phase diagram information. The liquid, αU, βU, δTi, and γ phases are assumed to be substitutional solutions with Redlich-Kister formula for the expressions of their excess Gibbs energy. The intermetallic compound TiU2 is treated as a stoichiometric compound. The calculated phase equlibria are in good agreement with the estimated and available experimental phase diagram data.

Abstract The ternary Al –Ca –Mg phase equlibria were investigated using X-ray diffraction methods, metallography, scanning electron microscopy with energy- and wave-length-dispersive X-ray microanalysis, and differential thermal analysis. The phase diagram was determined in the complete composition range. Large ternary solubilities were found for the binary phases CaMg2, Al2Ca and Al3Ca8. Microstructures of samples with compositions near the ternary monovariant eutectic L → CaMg2 + Al2Ca show remarkable rod-like crystals that are identified as intergrowth between CaMg2 and Al2Ca. A consistent thermodynamic model was developed using the Calphad method incorporating all experimental data. It was used to calculate all pertinent phase equilibria of the Al –Ca –Mg system.

In this work,Ti-V-based hydrogen storage alloys have been studied because of their high hydrogen absorption/desorption capacities and good activated properties. Experimental data of phase equlibria and thermodynamic assessments of the sub-binary/ternary systems in the Ti-V-based multi-component systems are reviewed in reported literature. Based on the measured phase diagram data and thermochemica information, thermodynamic parameters formulating the Gibbs energies of various phases in some sub-binary/ternary systems of Ti-V-based multi-component alloys are assessed using the CALPHAD method. A set-consistent thermodynamic database of the Ti-V-based multi-component system is developed, which is helpful to study the relations between alloy compositions, microstructure and hydrogen storage properties in order to design novel Ti-V-based hydrogen storage alloys.

ABSTRACTThis work represents a continuation of earlier studies of blends of polymer liquid crystals (PLC) with ordinary engineering polymers (EP). We now focus on connections between mechanical and other properties and phase structures and phase diagrams. Pure PLC are already two-phase systems; in each case addition of an EP complicates the situation further. In particular, we are concerned with phases which we call quasi-liquids, at temperatures between the glass transition and the melting point. Quasi-liquids do not have the mobility usually associated with liquids - because of the presence of other constituents and also because of orientational effects produced by the mesogenic groups. In phase diagrams of PLC-containing systems one should also take into account non-equlibrium phases. We are trying to show how such diagrams make possible Intelligent processing and a better control of properties of the PLC + EP materials.

Calcium alumniate-spinel phases have been developed for synthetic aggregate from ESP dolomite dust and calcined alumina. A huge amount of dolomite dust is collected at electrostatic precipitator (ESP) during dead burning of raw dolomite in Rotary Kiln. This dust is waste material and does not have any practical use in refractory plants. The Present thesis focuses the utilization of these waste dolomite dust for the development of value added calcium aluminate spinel aggregates. Dolomite is a double carbonate of calcium and magnesium. An attempt has been made to different calcium aluminates and spinel aggregates by solid state reaction between the ESP precipitated dolomite dust and calcined alumina. The phase formation behaviour has been reported from the study of the XRD diffraction pattern as function of calcination temperature. The different physical properties of the aggregated have also been reported.

Bioactive glasses of chemical composition 48.4SiO2 -23.8Na2O- 23.8CaO- 4.0P2O5 wt% was prepared through Sol-Gel route. It was then crystallized through thermal treatment. Porous samples of the mentioned composition using Naphthalene (0, 30, and 50 weight percentage) as pore former were made and tested for Bulk Density, Apparent porosity, Linear Shrinkage, Cold Crushing Strength, and Bi-axial flexural strength. Maximum porosity of 50% was obtained by this process. The maximum value of CCS obtained was 7.8MPa without any pore former and a minimum of 2.3 MPa for 50% Naphthalene. The Bi-axial flexural strength varied between the extremes of 16.3 MPa and 5.6 MPa. Their pore size distribution was also studied to ensure the presence of pores with size greater than 100 µm, which happens to be the critical lower limit for Angiogenesis. Samples were also prepared with a radial porosity gradient similar to the structure of the cancellous part of the Bone structure. The samples contained a central core of higher porosity and a outer concentric ring of lower porosity. These samples were also tested for the above mentioned mechanical properties. The Bioactivity of the samples was also studied by immersing them in a SBF solution for a period of 1, 3, and 7 days. These samples were then studied using XRD, SEM, EDX, and FTIR and showed significant formation of HCA ensuring their Bioactivity.

Lithium-based ceramic, Li4SiO4, is being considered as promising solid breeder materials in the tritium breeding blanket of thermonuclear fusion reactors, because of its high Li- density, high thermal conductivity and prominent tritium release rate at low temperatures between 300 and 500oC, its low activation characteristics, low thermal expansion coefficient and high thermal conductivity. For tritium recovery purpose samples having 85-90% of true density with open porosity (around 5%) is required. Uniform small grain size distribution (having diameter between 2-4μm) is preferable as activation energy for tritium diffusion through grain is higher compared to grain boundary. Solid state method requires higher calcination temperature, producing coarser particle and impurity, which adversely affects in achieving high sintered density (above 85% of theoretical density) and forms large grain size with entrapped closed pore inside the grain. In the current work Li4SiO4 powder was synthesized by solution combustion technique using cheaper precursor of silica i.e. from rice husk ash (an agricultural waste). We found that by controlling the metal to citrate ratio of the solution and calcination temperature of the as-burnt powder phase purity can be achieved. The particle size of Li4SiO4 powder (prepared at M/C=1.4) was found to be 100-200 nm with low surface area (2m2/gm). It was found that Li4SiO4 powder can be sintered at a temperature as low as 900oC with a density ~ 85% of the theoretical density. Phase stability in the sintered sample was studied. Attempts were made to minimize the lithium loss from the sintered specimens. Moisture reactivity studies were conducted together with FTIR spectroscopy on calcined powder to find out the moisture affinity of the samples. Kinetics of the initial stage of sintering from the shrinkage data has been analyzed to find out the sintering mechanism. Thermal diffusivity measured by laser flash method. Thermal conductivity value depends on the density of the sample. AC impedance method has been used to characterize electrical property of the sintered sample as tritium diffusion is related to the Li+ ion conductivity in Li4SiO4.