Date of Award

2008

Degree Type

Dissertation

Department

Chemistry

First Advisor

Ng, Lily M.

Subject Headings

Space vehicles -- Materials, Heat resistant materials, Ceramic materials, Titanium alloys, Silicon alloys, Aerospace, Ceramic, Combustion environment, Hydroxyl species

Abstract

Titanium (Ti) and silicon (Si) containing materials are of high interest to the aerospace industry due to its high temperature catability, strength, and ligh weight. A continuous exterior oxide layer is desirable to reduce the oxidation rate of these two materials. At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study first evaluated several hot-pressed Ti and Si-containing compositions at high temperatures as a function of oxidation environments to determine the volatile hydoxy! species using the transpiration method. The water content ranged from 0-76 mole and the oxygen content range was 0-100 mole during the 20-250 hour exposure times. Results indicate that oxygen is not a key contributor at these temperatures and a volatile Ti-O-H species has been identified

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