Digital Commons Network^™

The Study Of Gas-Phase Oxidation In Incoloy 800 By Surface Analytical Techniques, Michael W. Edwards

Digitized Theses

A comprehensive assessment of the oxide grown on Incoloy alloy 800 has enhanced the understanding of the oxide film’s composition and growth, specifically for application as a protective pre-treatment. Surface morphology, chemical composition, oxide film thicknesses and kinetics have all been studied using, principally, X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). Gas-phase oxidations were performed at temperatures of 300°C in atmospheres of 1% O2 at 1 atm for up to 24h. All samples displayed similar oxidation behaviour over the exposure period. A multi-layered oxide film was detected and was composed primarily

of an exterior …

Investigations Of Crystallization Of Molecular Sieves And Their Behaviour Under High Pressures, Yueqiao Fu

Digitized Theses

The behaviour of completely siliceous zeolite ZSM-5 under high pressure up to 16 GPa were investigated by in situ Raman spectroscopy, Infrared spectroscopy and X-ray diffraction with synchrotron radiation using diamond anvil cell. Pressure-induced amorphization was observed in both as-made and calcined siliceous ZSM-5 which transform to a low-density amorphous silica first and then to a high-density amorphous silica. However, transition pressures and reversibility were different for the as-made and calcined siliceous ZSM-5. It was found that the occluded template molecules are the major factor for these differences.

The crystallization mechanism of AIPO4-I6 molecular sieve was preliminarily investigated under dry …

High-Pressure Study Of Nanostructured Sno2 By Raman Spectroscopy And X-Ray Diffraction With Synchrotron Radiation, Zhaohui Dong

Digitized Theses

Tin dioxide (SnO2) nanowires and nanobelts were compressed in a diamond anvil cell to around 40 gigapascal (GPa) at room temperature followed by decompression. Raman spectroscopy was employed to monitor the pressure effect on the SnO2 nanobelts. Synchrotron X-ray powder diffraction measurements were also carried out on both nanomaterials during both compression and decompression. The diffraction patterns were analyzed quantitatively by the Rietveld refinement. Pressure-induced phase transformations were observed in both nanomaterials and compared with those observed previously in the bulk materials. However, transition pressures, phase abundances, reversibilities, as well as compressiblities were found to be different from those of …