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35 results
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ItemFlexural Testing of Molybdenum-Silicon-Boron Alloys Reacted from Molybdenum, Silicon Nitride, and Boron Nitride(Georgia Institute of Technology, 2007-05-16) Rockett, Chris H.MoSiB alloys show promise as the next-generation turbine blade material due to their high-temperature strength and oxidation resistance afforded by a protective borosilicate surface layer. Powder processing and reactive synthesis of these alloys has proven to be a viable method and offers several advantages over conventional melt processing routes. Microstructures obtained have well-dispersed intermetallics in a continuous matrix of molybdenum solid-solution (Mo-ss). However, bend testing of pure Mo and Mo-ss samples has shown that, while the powder processing route can produce ductile Mo metal, the hardening effect of Si and B in solid-solution renders the matrix brittle. Testing at elevated temperatures (200°C) was performed in order to determine the ductile-to-brittle transition temperature of the metal as an indication of ductility. Methods of ductilizing the Mo-ss matrix such as annealing and alloying additions have been investigated.
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ItemA Nitride-Based Reaction for the Formation of a Three-Phase Molybdenum-Silicon-Boron Intermetallic Alloy(Georgia Institute of Technology, 2005-07-18) Middlemas, Michael RobertThe alloy Mo-3Si-1B (wt%) may have the fracture toughness and oxidation resistance required for use as jet turbine engine blades. Mo-3Si-1B (wt%) forms a three-phase mixture of and #945;-Moss, A15 (Mo3Si) and T2 (Mo5SiB2). It has been observed that at high-temperatures, the A15 and T2 intermetallics form a oxidation resistant borosilicate glass coating. To achieve the proper combination of mechanical and thermal properties, the material must have a molybdenum matrix with a fine dispersion of intermetallics to produce a continuous protective layer. In this project, reactive sintering of molybdenum, Si3N4 and BN powders was used to create a semi-continuous molybdenum matrix with a fine dispersion of the A15 and T2 intermetallics. Sintering of the materials was further enhanced by the use of submicron-sized reactants. X-ray diffraction analysis was used verify the desired phases were formed. It was determined that formation of the A15 intermetallic phases begins as low as 1200?nd formation of T2 begins at 1300? The reactions are complete by 1400? Samples with bulk densities as high as 95% of theoretical were produced. Scanning electron microscopy images reveal a microstructure with dispersed intermetallics in a semi-continuous molybdenum matrix with grain sizes on the order of 1-4 and #956;m. It was found that by varying parameters such as mixing method and heating rates, it is possible to engineer the final microstructure, changing the level of dispersion of the intermetallics and continuity of the matrix.
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ItemThe influence of honeycomb dies on paste extrusion mechanics(Georgia Institute of Technology, 2002-05) Oh, Raymond H.
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ItemCompression behavior of linear cellular steel(Georgia Institute of Technology, 2001-08) Hayes, Alethea M.
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ItemCapillary rheometric evaluation of honeycomb extrusion pastes(Georgia Institute of Technology, 2001-05) Seay, Wesley Daniel
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ItemStainless steel hollow sphere foams : processing and properties(Georgia Institute of Technology, 1999-12) Clark, Justin Lewis
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ItemThe processing of titanium hydride powders into uniform hollow spheres(Georgia Institute of Technology, 1998-08) Hurysz, Kevin Michael
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ItemClosed cell steel foams from oxide reduction(Georgia Institute of Technology, 1997-12) Nagel, Adam Richard
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ItemPrediction of thin films obliquely deposited in rotating recessed cones(Georgia Institute of Technology, 1997-08) Fraser, Samuel Carroll
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ItemApplication of hollow sphere ceramic foams for high intensity radiant burners(Georgia Institute of Technology, 1995-08) McEntyre, John Eric