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Full-Text Articles in Engineering
Processing, Microstructural And Mechanical Characterization Of Mechanically Alloyed Al-Al2o3 Nanocomposites, Pushkar Katiyar
Processing, Microstructural And Mechanical Characterization Of Mechanically Alloyed Al-Al2o3 Nanocomposites, Pushkar Katiyar
Electronic Theses and Dissertations
Aluminum-alumina nanocomposites were synthesized using mechanical alloying of blended component powders of pure constituents. This study was performed on various powder mixtures with aluminum as the matrix and alumina as the reinforcement with volume fractions of 20, 30, and 50 % and Al2O3 particle sizes of 50 nm, 150 nm, and 5 µm. X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used for the crystal structure and microstructural characterization of the powders at different stages of milling. Al2O3 powders with 50 nm and 150 nm particle size were predominantly of γ-type, while Al2O3 of 5 µm size was …
Phenomenology And Experimental Observations In High Temperature Ternary Interdiffusion, Abby Lee Elliott
Phenomenology And Experimental Observations In High Temperature Ternary Interdiffusion, Abby Lee Elliott
Electronic Theses and Dissertations
A new method to extract composition dependent ternary interdiffusion coefficients from a single diffusion couple experiment is presented. The calculations involve direct determination of interdiffusion fluxes from experimental concentration profiles and local integration and differentiation of Onsager's formalism. This new technique was applied to concentration profiles obtained from selected semi-infinite, single-phase diffusion couple experiments in the Cu-Ni-Zn, Fe-Ni-Al, and Ni-Cr-Al systems. These couples exhibit features such as uphill diffusion and zero flux planes. The interdiffusion coefficients from the new technique along with coefficients reported from other methods are graphed as functions of composition. The coefficients calculated from the new technique …
Development Of Titanium Nitride/Molybdenum Disulphide Composite Tribological Coatings For Cryocoolers, Anil Pai
Electronic Theses and Dissertations
Hydrogen is a clean and sustainable form of carrier of energy that can be used in mobile and stationary applications. At present hydrogen is produced mostly from fossil sources. Solar photoelectrochemical processes are being developed for hydrogen production. Storing hydrogen can be done in three main ways: in compressed form, liquid form and by chemical bonding. Near term spaceport operations are one of the prominent applications for usage of large quantities of liquid hydrogen as a cryogenic propellant. Efficient storage and transfer of liquid hydrogen is essential for reducing the launch costs. A Two Stage Reverse Turbo Brayton Cycle (RTBC) …
Commissioning Of An Arc-Melting/Vacuum Quench Furnace Facility For Fabrication Of Ni-Ti-Fe Shape Memory Alloys, And The Characterization, Jagat Singh
Electronic Theses and Dissertations
Shape memory alloys when deformed can produce strains as high as 8%. Heating results in a phase transformation and associated recovery of all the accumulated strain, a phenomenon known as shape memory. This strain recovery can occur against large forces, resulting in their use as actuators. The goal of this project is to lower the operating temperature range of shape memory alloys in order for them to be used in cryogenic switches, seals, valves, fluid-line repair and self-healing gaskets for space related technologies. The Ni-Ti-Fe alloy system, previously used in Grumman F-14 aircrafts and activated at 120 K, is further …