Tortuosity measurements of porous ceramics using superfluid acoustics

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7072178

Bernard-Chavarria, M

The surface and bulk tortuosites of porous aluminum oxide ceramics have been measured using third sound and fourth sound propagation in superfluid Helium-4. The index of refraction of third sound measures the surface tortuosity. The main feature observed is a rapid increase in the index of refraction of both sound modes as the pore-space percolation threshold is approached, to much higher values than previously observed. There is also an increase in the attenuation of both sounds, and a nonlinear dependence of the resonant frequencies on drive amplitude. The bulk tortuosity exceeds the surface tortuosity for porosities below 30%, a reversal of the behavior observed at high porosities. The overall results of this study suggest divergent behavior of both tortuosities near the percolation threshold, leading to a strong departure from the behavior predicted by Archie's law.

• Research Organization: California Univ., Los Angeles, CA (United States)
• OSTI ID: 7072178
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ACOUSTIC TESTING
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
EVEN-EVEN NUCLEI
HELIUM 4
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MATERIALS
MATERIALS TESTING
MICROSTRUCTURE
NONDESTRUCTIVE TESTING
NUCLEI
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PORE STRUCTURE
POROUS MATERIALS
REFRACTIVE INDEX
STABLE ISOTOPES
TESTING