Electronic Theses and Dissertations

Sagar Ghimire

Date

2022

Document Type

Thesis

Degree Name

Master of Science

Department

Physics

Committee Chair

Firouzeh Sabri

Committee Member

Muhammad S Dr. Jahan

Committee Member

Xiao Dr. Shen

Abstract

Aerogels are highly porous and lightweight materials with a unique combination of physical and chemical properties that can be customized to fit the parameter space desired, for the application at hand. The number of applications that have enlisted the use of aerogels have grown substantially in recent years ranging from biomedicine to aerospace. This work investigates the interaction of aerogels and aerogel composites with its environment namely interaction with two types of incident waves: pressure waves and UV radiation. In the first case, the effect of aerogel porosity and stiffness on ultrasound wave propagation in an aqueous and a non-aqueous environment was explored. The detection, tracking, attenuation, and damping caused by aerogels was investigated both computationally and experimentally. Image analysis techniques for acoustic parameter extraction such as acoustic attenuation coefficient was developed. The motivation behind this work was to achieve a real time visualization of wave interactions with aerogels in the two different media mentioned earlier, using k wave tool, and by recording the regions of maximum and minimum pressure at the interfaces. Results indicate the relationship between the degree of attenuation, porosity, and material stiffness and can be applied to any combination of parameter space. In the second phase of the study, aerogel composites were exposed to direct UV radiation outside of the Earth’s atmosphere and the effect of the prolonged exposure (6 months) on the behavior of the composites was studied. Specifically, the effect of the radiation on the excitation/ emission behavior of thermographic phosphors coated on aerogels under low Earth orbit conditions. Investigating the effect of the radiation on the mechanical properties of the aerogels was not in the scope of this work and will not be discussed.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

Notes

Open Access

Download

Share

COinS