In-situ pore structure analysis during aging and drying of gels

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6550279

Smith, D M; Davis, P J ^[1]; Brinker, C J ^[2]

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1. New Mexico Univ., Albuquerque, NM (USA). Center for Micro-Engineered Ceramics
2. Sandia National Labs., Albuquerque, NM (USA)

The use of NMR relaxation measurements for the in-situ study of pore structure evolution during gel aging and drying is illustrated. The change in the pore size distribution and surface area of other wet and dried gels is examined as a function of aging conditions including temporal aging, thermal aging, changing pH, and changing pore fluid. The effect of pore fluid pH on dissolution/reprecipitation in ordered packings of monodisperse silica spheres is also examined as a model system for particulate gels. As expected, the pore size distribution narrows with increasing time of treatment in high pH pore fluids. Interpretation of high pH results for the wet state is complicated by a microporous layer which forms on colloidal silica resulting in significantly large wet surface area as compared to the final dried material. Narrowing of the pore size distribution, which is of interest for maximizing drying rates, is maximized in the least time by using either high pH or repeated ethanol washes for the base-catalyzed gel (B2) used. 21 refs., 10 figs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• Sponsoring Organization: DOE/DP
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6550279
• Report Number(s): SAND-90-2203C; CONF-900466--86; ON: DE91000044
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
AGING
CHALCOGENIDES
COLLOIDS
DISPERSIONS
DRYING
GELS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PH VALUE
POROSITY
RELAXATION
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SOL-GEL PROCESS
SPHERES
SPIN-LATTICE RELAXATION
SURFACE AREA
SURFACE PROPERTIES