Date of Award

2021-05-01

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Advisor(s)

Chintalapalle V. Ramana

Abstract

Nanostructured materials have many potential applications in the fields of power generation and transportation technologies, particularly in the areas of gas sensing technology, industrial gas turbines and protective coatings. In the former case β-Ga2O3 represents a promising candidate due to its high degree of stability and functionality for oxygen sensing at higher temperatures (>700oC). In the latter case, the application of Y-Si-Fe compounds acting as environmental barrier coatings for gas turbine and aerospace engine applications to protect from corrosion effects has been demonstrated in recent years. In both cases, however, there is room for improvement whether it is in the form of innate material properties for the reduction of response time and increase sensitivity for sensors to resistance to harmful airborne particulates for protective coatings. In this work, a multi-stage approach was adopted for testing the chemical and physical properties of these classes of materials after a variety of fabrication methods to ensure nanoscale structures was completed. For sensor work making use of gallium oxide, RF-magnetron sputtering, pulsed laser deposition, and electrospinning was employed to manufacture thin films, epitaxial nanocolumnar structures, and nanofibers, respectively. All of these were subjected to high temperature fabrication and post fabrication processes (>500oC) to simulate effects of these conditions on crystal structure, optical, electrical, and mechanical properties. This was done in order to determine suitability for extreme environmental applications and the extent that properties of gallium oxide could be fine tuned via nanostructure as opposed to dopant inclusion. For structural components the Y-Si-Fe coatings where subjected to simulated, destructive, airborne particulates to determine their ability to maintain structural integrity in real world situations. Throughout the work a wide variety of analytical techniques were employed to derive conclusions on the structure, morphology, chemical states, and thermos-mechanical properties of the materials. The results are presented and discussed in this thesis on determining the feasibility of utilizing nanoscale structures for extreme environmental conditions as well as implications and potential future work regarding integrated sensing and structural components to maximize combustion efficiency and durability.

Language

en

Provenance

Received from ProQuest

File Size

129 p.

File Format

application/pdf

Rights Holder

Nanthakishore Makeswaran

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