Thin Films of Reduced Hafnium Oxide with Excess Carbon for High- Temperature Oxidation Protection

摘要

The overall objective of this 3-year project was to achieve controlled synthesis of carbon-rich hafnia, Hf02-xCy, and investigate the fundamental and high-temperature properties of this material. Hf02-xCy is naturally formed as a compact and pore-free oxide interlayer during oxidation of hafnium carbide (HfC), where it is though to act as a primary oxygen diffusion barrier. The specific project goals were to: 1) use pulsed laser deposition (PLD) to establish routes for direct synthesis of films in the Hf02- xCy system; 2) investigate high-temperature oxygen diffusion in Hf02-xCy films; and 3) evaluate the potential of Hf02-xCy films for high-temperature oxidation protection coatings. As an additional activity in the third project year, we investigated the correlation between the luminescent properties and microstructure of Hf02 in the bulk and thin film forms.