STABILIZATION OF SILICA BUBBLES IN ULTRA HIGH TEMPERATURE CERAMIC NANOCOMPOSITES
Abstract
The proposed research is to study high-temperature oxidation behavior of nanoporous ultrahigh temperature ceramics (UHTCs) infiltrated with SiO2. This dual-phase nanocomposite will possess high-temperature structural integrity and oxidation resistance unattainable in its monolithic counterparts- molten SiO2 will act as a high temperature barrier to prevent UHTC oxidation, whereas the nanoporous UHTC scaffolding will prevent aero-shearing of molten SiO2 and increase the superheat required to nucleate the deleterious SiO vapor that plagues Si-based compounds. Although this project will entail the fabrication of a novel UHTC nanocomposite, our aim is to use this material as a platform to advance the fundamental understanding between material architecture (i.e., the local curvature, microstructural length scale, and composition) and the nucleation kinetics of vapor bubbles at the nanoscale. It is postulated that, as the porosity length scale is decreased into the nanometer regime, the threshold for heterogeneous nucleation will increase (due to a decrease in active surface sites) and vapor will eventually only nucleate homogeneously at superheats well above its typical boiling point. In addition, the nucleation rate can be further tuned by altering the interfacial energy and ratio of positive-to-negative curvature. If successful, this program will form the foundation of a new class of nanoarchitectured UHTC materials with unprecedented high-temperature behavior.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502210221
Entities
People
- Ian Mccue
Organizations
- Air Force Office of Scientific Research
- Northwestern University
- United States Air Force